a study on efficacy of helical computed tomography in determination of cause

A STUDY ON EFFICACY OF HELICAL COMPUTED

TOMOGRAPHY IN DETERMINATION OF CAUSE,

SITE OF HIGH GRADE SMALL BOWEL

OBSTRUCTION, BOWEL VIABILITY AND

CORRELATION WITH INTRAOPERATIVE

FINDINGS.

BY DR. SATHISH RAVIRALA

Regn. No: 140-41159-112-101908

A thesis submitted as part of fulfillment of the requirements for the

DIPLOMATE OF NATIONAL BOARD OF EXAMINATIONS

RADIODIAGNOSIS.

MEENAKSHI MISSION HOSPITAL& RESEARCH CENTRE

MADURAI -625107

TAMILNADU, INDIA.

JUNE-2014

CERTIFICATE

This is to certify that A study on efficacy of helical computed

tomography in determination of cause, site of high grade small bowel

obstruction, bowel viability and correlation with intra operative

findings. Is a bonafide work of Dr.Sathish Ravirala, DNB Resident,

carried out in the Department of Imaging sciences, Meenakshi Mission

Hospital and Research Centre, Madurai.

I have great pleasure in forwarding this dissertation to the National

Board of Examinations, New Delhi in part of fulfillment of the regulations

for the award of DNB post graduate Degree in Radio Diagnosis prior to the

examination to be held in June 2014.

Madurai Dr.RameshArdhanari MS.,MCh.(SGE)FRCS Medical Director, Sr.Consultant and Head of Department, Department of Surgical Gastro-enterology , Meenakshi Mission Hospital and Research Centre, Madurai, Tamilnadu.

CERTIFICATE



obstruction ,bowel viability and correlation with intra operative

findings is a bonafide work has been carried out by the candidate himself

under my direct supervision and the findings presented have been checked

thoroughly by me. I am fully satisfied with the work of Dr.Sathish Ravirala,

which is being presented by him as a dissertation for Diplomate of National

Board in the subject of Radio Diagnosis during his training period at

Meenakshi Mission Hospital and Research Centre, Madurai, Tamilnadu.

Madurai Dr. S. Manohar MD., DMRD.

Head of the Department. Department of Imaging sciences, Meenakshi Mission Hospital and Research Centre, Madurai, Tamilnadu.

CERTIFICATE



obstruction ,bowel viability and correlation with intra operative

findings is a bonafide work has been carried out by the candidate himself

under my direct supervision and the findings presented have been checked

thoroughly by me as a guide , i am fully satisfied with the work of

Dr.Sathish Ravirala, which is being presented by him as a dissertation for

Diplomate of National Board in the subject of Radio Diagnosis during his

training period at Meenakshi Mission Hospital and Research Centre,

Madurai, Tamilnadu.

Madurai Dr. N.S. Mani MD., DMRD., Consultant, Department of Imaging sciences, Meenakshi Mission Hospital and Research Centre, Madurai, Tamilnadu.

DECLARATION

I declare that this dissertation titled A study on efficacy of helical

computed tomography in determination of cause, site of high grade

small bowel obstruction ,bowel viability and correlation with

intraoperative findings has been conducted by me under the guidance and

supervision of Dr.N.S.MANI., MD., DMRD., Consultant, Department of

Imaging sciences, Meenakshi Mission Hospital and Research Center,

Madurai. It is submitted as part of fulfillment of the requirement for the

award of the D.N.B. RadioDiagnosis, June 2014 examination held under

National Board of Examinations, New Delhi.

Dr. Sathish Ravirala

]

ACKNOWLEDGEMENT

I am extremely thankful to the Chairman, ViceChairman and

Medical Director of Meenakshi Mission Hospital and Research Center,

Madurai, who have been kind enough to permit me to use the hospital

resources. I thank all the patients who have been a part of this study making

my thesis possible.

I express my sincere and heartful gratitude to my guide

Dr.N,S.Mani.,MD.,DMRD for his guidance and support. My sincere thanks

also goes to Dr. S.Manohar MD., DMRD. (Head of the department)

My sincere thanks to Dr.T.Mukuntharajan.,DMRD., (Sr.Consultant),

Dr.N.Karunakaran., DMRD.,DNB.,(Consultant), Dr.R.Ganesh.,DMRD.,

DNB.,(Consultant), Dr.Nancy manodoss., MD., (Registar) for their ideas,

wisdom, supervision and guidance without whom I could not have done my

dissertation. I thank my other consultants Dr.M.S.Senthilnathan.,MD., for

their valuable ideas.

My special acknowledgement to Department of Surgical -

Gastroenterology for their co-operation throughout my thesis work.

I wish to thank my department seniors Dr.Kokilan, Dr.SunilBorade,

who always helping me throughout my course period, My special thanks to

my colleagues Dr.Kiranmai, Dr.Mohan, Dr.Chetan, my juniors Dr.Kiran

Kumar, Dr.Jayanthan & Dr.Divya., my friends Dr.Srikanth, Dr.Naresh .

I thankful to Medical records Department , Mr.Mani Bio-statistician ,

nursing staff, ward secretaries Lakshmi, Elizabeth for helping me in

conducting the study.

Last but not least my parents, and my wife Dr.Sindhuri, my sister

Dr.Manjula, my brother Dr.Sandeep for their support as always.

CONTENTS

S.NO. TITLE PAGE NO

1. Introduction 1

2. Aims & Objectives 6

3. Review of Literature 26

4. Materials and Methods 38

5. Results and Analysis 43

6. Discussion 53

7. Conclusion 59

Annexure

Bibliography

Proforma

Master chart

INTRODUCTION

Small Bowel Obstruction (SBO) is a common clinical condition, one

of the important causes of pain abdomen and forms 20% of surgical

emergencies. Small Bowel Obstruction usually suspected on the basis of

clinical signs and patient history .It can be self-limiting or life threatening

and therefore prompt diagnosis to determine the site and cause of obstruction

is mandatory to reduce the morbidity and mortality.

Till last decade, conventional Radiographs played a major role in the

diagnosis of small bowel obstruction but it has a low sensitivity of 69% and

specificity of 57% .With the advent of multi-slice imaging techniques, rapid

comprehensive assessment of the entire abdomen can be done in a matter of

few seconds thus allowing the entire small bowel to be studied for the cause

and site of obstruction and also more importantly the viability of the bowel.

Several studies have shown the value of CT in demonstrating diagnosis and

determining the cause of high grade obstruction with the sensitivity of about

94-100% and specificity of 90%-95%1.

History:

X-Rays were discovered by Wilhelm-Conrad Roentgen in November

1895, Whilst he was experimenting with the passage of electricity through

gases at very low pressure. When an electric discharge at high voltage was

passed through the almost evacuated tube, Roentgen noticed a glow on a

piece of cloth covered with Zinc Sulphide, which was lying at a short

distance from the tube. The glow persisted even when the tube was covered

with black paper and Roentgen was quickly able to recognize this as a

hitherto undiscovered radiation and named it as X-Rays.

At the Annual congress of the British Institute of Radiology, in April

of 1972, G.N.Hounsfield, a senior research scientist at EMI limited in

Middlesex, England, announced the invention of a revolutionary new

imaging technique, which he called Computerized axial transverse

scanning. The basic concept was very simple, a thin cross section of the

head, a tomographic slice, was examined from multiple angles with a pencil

like x-ray beam. The transmitted radiation was counted by a scintillation

detector, fed into the computer for analysis by a mathematical algorithm and

reconstructed.

The image had a remarkable characteristic, one never before seen in a

x-ray imaged; it demonstrated a radiographic difference in the various soft

tissues; blood clots, gray matter, white matter, cerebrospinal fluid, tumors

and cerebral edema all appeared as separate entities. The soft tissues could

no longer be assigned the physical characteristics of water. The computer

had changed that concept.

The basic principle behind CT is that the internal structure of an

object can be reconstructed from multiple projections of the object. CT

scanners have gone through a number of design changes since the

technology was first introduced in 1971.They can be conveniently classified

under five categories.

They are-

1. First generation (translate-rotate, one detector.)

2. Second generation (translate-rotate, multiple detectors.)

3. Third generation (rotate-rotate)

4. Fourth generation (rotate-fixed.)

5. Other geometries.

Time reduction is the predominant reason for introducing new

configurations. Scan time has been reduced in newer configurations by the

reduction or simplification of mechanical motion. For example, the stop-start

motion in the first two generations has been replaced by continuous rotation.

Devices that have no moving parts and an extremely short scan time have

come. Initial research papers reported by Alec Megibow and his colleagues 2

in the evaluation of bowel obstruction with computed tomography (CT)

came in the year 1991 and since then CT has emerged as a versatile &

invaluable modality for the diagnosis and evaluation of Small Bowel

Obstruction.

Four important basic questions should be answered in any case of

suspected Small Bowel Obstruction.

a. Is the bowel obstructed?

b. What is the level, cause and degree of obstruction?

c. Is strangulation present?

d. Is conservative therapy sufficient or surgery needed?

Helical CT answers all these questions comfortably most of the times

and more superior to conventional radiographs and contrast studies. Recent

innovations like multi-detector CT has really revolutionized the imaging of

abdominal pathologies and CT is useful in evaluate the site and type of

hernia and its content3,4,5, especially the diagnosis of internal hernia, always

require radiological findings6,7.

Multiplanar reformatted imaging at a work station is a new technology

in a Multi Detector Computed Tomography (MDCT)8, its gaining more

importance and promising in the diagnosis of small bowel obstruction.

Volume data of the abdomen are acquired with helical technique during a

single breath- hold, usually with a collimation of 5-7 mm. Thinner

collimation for better spatial resolution is possible with a multi detector CT

scanner. Axial, sagittal, coronal and curved multiplanar reformatted images

are created at a work station from the acquired volume data. These

multiplanar views may help to identify the site and cause of obstruction

when axial findings are indeterminate.

AIM OF THE STUDY

* A study on efficacy of helical computed tomography in determination of

cause, site of high grade small bowel obstruction, bowel viability and

correlation with intraoperative findings.

Objectives

1. Confirm the high grade Small Bowel Obstruction

2. To assess Cause, Site of Small Bowel Obstruction

3. To assess the Viability of Bowel loops

4. Correlation of CT findings with Intraoperative findings.

5. To assess the Sensitivity, Specificity, Accuracy of Spiral CT with

Intraoperative findings.

NORMAL ANATOMY

The small intestine is a convoluted tube, extending form the pylorus to

the ileocaecal valve, where it ends in the large intestine. It is about 7meters

long, and gradually diminishes in size from its commencement to its

termination. It is contained in the central and lower part of the abdominal

cavity. It is in relation, in front, with the greater omentum and abdominal

parieties, and is connected to the posterior abdominal wall by a fold of

peritoneum, the mesentery. The small intestine is divisible into three portions

: the duodenum, the jejunum, and the ileum.

Duodenum:

The duodenum has received its name from being about equal in length to

the breadth of twelve fingers (25cm). It is the shortest, the widest, and the

most fixed part of the small intestine, and has no mesentery, being only

partially covered by peritoneum. It is divided into 4 parts. i.e, superior,

descending, horizontal and ascending. As it unites with the jejunum it turns

abruptly forward, forming the duodeno-jejunal flexure.

The common bile duct and pancreatic duct together perforate the medial

side of 2nd part of duodenum, obliquely 7 to 10cm below the pylorus, the

accessory pancreatic duct sometimes pierces it about 2cm above and slightly

in front of these.

Vessels and nerves :

The arteries supplying the duodenum are the right gastric and superior

pancreatico- duodenal branches of the hepatic, and the inferior pancreatico-

duodenal branch of the superior mesenteric arteries. The veins end in

superior mesenteric vein & others. The nerves are derived from the celiac

plexus.

Jejunum and ileum :

The remainder of the small intestine from the end of the duodenum is

named jejunum and ileum, the former term being given to the upper two-

fifths and the latter to the lower three-fifths. There is no morphological line

of distinction between the two, and the division is arbitrary, but at the same

time the character of the intestine gradually undergoes a change from the

commencement of the jejunum to the end of the ileum, so that a portion of

bowel taken form these two situations would present characteristic and

marked differences. These are briefly as follows.

The jejunum is wider, thicker, more vascular, and of a deeper color than

the ileum, so that a given length weighs more. The circular folds (valvulae

conniventes) of its mucous membrane are large and thickly set and its villi

are larger than in the ileum, The aggregated lymph nodules are almost absent

in the upper part of the jejunum, and in the lower part are less frequently

found than in the ileum, and are smaller and tend to assume a circular form.

By grasping the jejunum between the finger and thumb the circular folds

can be felt through the walls of the gut, these being absent in the lower part

of the ileum, it is possible in this way to distinguish the upper from the lower

part of the small intestine.

The ileum is narrow, thinner and less vascular than those of the jejunum.

It possesses but few circular folds, and they are small and disappear entirely

towards its lower end, but aggregated lymph nodules (peyer's patches) and

larger and more numerous. The jejunum for the most part occupies the,

umbilical and left iliac regions, while the ileum occupies chiefly the

umbilical, hypogastric, right iliac and pelvic regions. The terminal part of

the ileum usually lies in the pelvis, from which it ascends over the right

psoas and right iliac vessels; it ends in the right iliac fossa by opening into

the medial side of the commencement of the large intestine. The jejunum

and ileum are attached to the posterior abdominal wall by an extensive fold

of peritoneum, the mesentery, which allows the free motion, so that each coil

can accommodate itself to changes in form and position.

The root of the small bowel mesentery (SBM) is located in the central

portion of the abdomen, connecting the intraperitoneal structures and is

contiguous to other peritoneal ligaments. The small bowel mesentery is a

voluminous, fat laden peritoneal reflection that fixes the jejunum and ileum

to the posterior abdominal wall. The attached parietal border which is

approximately 15cm long runs obliquely down from the deudenojejunal

flexure to the ileocaecal region. The root of the small bowel mesentery

contains two major vessels, the superior mesenteric artery (SMA) and

superior mesenteric vein (SMV)

Meckels diverticulum

This consists of a pouch which projects from the lower end of ileum in

about 2 percent of subjects. Its average position is about 1 meter from

ileocaecal valve, and its average length about 5cm.Its caliber is generally

similar to that of ileum, and its blind extremity may be free or may be

connected with the abdominal wall or with some other portion of the

intestine by a fibrous band. It represents the remains of the proximal end of

the vitelline duct, the duct of communication between the yolk-sac and the

primitive digestive tube in early fetal life.

Vessels and nerves:

The jejunum and ileum are supplied by the superior mesenteric artery,

the intestinal branches of which, having reaches the attached border of the

bowel, run between the serous and muscular coats, with frequent

inosculations to the free border, where they also anastomose with other

branches running around the opposite surface of the gut. Form these vessels

numerous branches are given off, which submucous tissue. From this plexus

minute vessels pass to the glands and villi of the mucous membrane.

The veins have a similar course and arrangement to the arteries. The

lymphatics of the small intestine (lacteals) are arranged in two sets, those of

the mucous membrane and those of the muscular coat. The lymphatics of the

villi commence in these structures in the manner described above. They

form an intricate plexus in the mucous and submucous tissue, being joined

by the lymphatics from the lymph spaces at the bases of the solitary nodules,

and from this pass to larger vessels at the mesenteric border of the gut. The

lymphatics of muscular coat are situated to a great extent between the two

layers of muscular fibers, where they form a close plexus, throughout their

course they communicate freely with the lymphatics from the mucous

membrane, and empty themselves in the same manner as these into the

origins of the lacteal vessels at the attached border of the gut.

Image 1-Small intestine with arterial blood supply.

(Image taken from Netters Atlas of Human anatomy-4 th edition)

The nerves of the small intestines are derived from the plexuses of

sympathetic nerves around the superior mesenteric artery. From this source

they run to the myenteric plexus (Auerbach's plexus) of nerves and ganglia

situated between the circular and longitudinal muscular fibers from which

the nervous branches are distributed to the muscular coats of the intestine.

From this a secondary plexus, the plexus of the submucosa (Meissner's

plexus) is derived, and is formed by branches which have perforated the

circular muscular fibers. This plexus lies in the submucous coat of the

intestine, it also contains ganglia from which nerve fibers pass to the

muscularis mucosa and to the mucous membrane. The nerve bundles of the

submucous plexus are finer than those of the myenteric plexus.

SMALL BOWEL OBSTRUCTION - AN OVERVIEW

Small bowel obstruction (SBO) can be partial or complete, simple (i.e.,

non- strangulated) or strangulated. Strangulated obstructions are surgically

emergencies. If not diagnosed and properly treated, vascular compromise

leads to bowel ischemia and further increase morbidity and mortality rates.

History

Abdominal pain

Pain, often described as crampy and intermittent, is more

prevalent in simple obstruction.

Often, the presentation may provide clues to the approximate

location and nature of the obstruction. Usually, pain that occurs

for a shorter duration of time and is colicky and accompanied by

bilious vomiting may be more proximal. Pain lasting as many as

several days, which is progressive in nature and with abdominal

distention, may be typical of a more distal obstruction.

Changes in the character of the pain may indicate the

development of a more serious complication (i.e., continuous

pain of strangulated or ischemic bowel)

Nausea

Vomiting, which is associated more with proximal obstructions.

Diarrhoea (an early finding)

Consitpation (a late finding) as evidenced by the absence of flatus or

bowel movements.

Fever and tachycardia - occur late and may be associate with

strangulation.

Previous abdominal or pelvic surgery, previous radiation therapy, or both

(may be part of patient's medical history).

History of malignancy (particularly ovarian and colonic)

Clinical examination

Radiologist before imaging, being primarily a clinician should look for

the following features.

Abdominal distension.

Hyperactive bowel sounds occur early as GI contents attempt to

overcome the obstruction.

Hypoactive bowel sounds occur late.

Exclude incarcerated hernias of the groin, femoral triangle and obturator

foramina.

Proper genitourinary and pelvic examinations are essential.

Look for the following during rectal examination

Gross or occult blood, which suggest late strangulation or

malignancy.

Masses, which suggest obturator hernia.

Check for symptoms commonly believed to be more diagnostic of

intestinal ischemia, including the following

Fever (temperature >100F )

Tachycardia (>100beats /min).

Peritoneal signs.

No reliable way exists to differentiate simple from early strangulated

obstruction on physical examination. Serial abdominal examinations are

important and may detect changes early.

A small bowel obstruction (SBO) is caused by a variety of pathologic

processes. They can be broadly classified into congenital and acquired

(Gore's classification)

Congenital causes of SBO

Duodenal atresia

Jejunal atresia

Ileal atresia/stenosis

Midgut volvulus

Meckels diverticulum

Inspissated meconium

Acquired causes of SBO

Extrinsic lesions Intrinsic lesions

Adhesions

Hernias

External

Inguinal

Femoral

Obturator

Umbilical

Sciatic

Perineal

Supravesical

Spigelian

Lumbar

Incisional

Internal

Paraduodenal

Epiploic foramen

Diaphragmatic (traumatic)

Transomental

Tumors infiltrating wall of small

intestine

Adenocarcinoma

Carcinoid tumor

Lymphoma

Leiomysarcoma

Inflammatory conditions

Crohn's disease

Tuberculosis.

Potassium chloride stricture

Eosinophilic gastroenteritis

Radiation enteropathy

Hematoma

Post- traumatic hematoma

Thrombocytopenia

Anticoagulants

Henoch-schonlein purpura.

Transmesenteric

Masses

Extrinsic tumors in mesentery

Lymphoma

Peritoneal metastasis

Carcinoid

Desmoid

Inflammations / Abscess

Diverticulitis

Appendicitis

Pelvic inflammatory disease

Crohn's disease

Hematoma

Aneurysm

Endometriosis

Insussusception

Polyps, lipoma

Tumor

Duplication

Intraluminal causes

Gall stone

Bezoar

Foreign body

Ascariasis

PATHOPHYSIOLOGY

Early in the course of an obstruction, intestinal motility and contractile

activity increase in an effort to propel luminal contents past the obstructing

point. The increase in peristalsis that occur early in the course of bowel

obstruction is present both above and below the point of obstruction, thus

accounting for the diarrhea that may accompany partial or even complete

small bowel obstruction in the early period.

Obstruction of the small bowel leads to proximal dilatation of the

intestine due to accumulation of gastrointestinal secretions and swallowed

air. This bowel dilatation, stimulates increased cell secretory activity

resulting in more fluid accumulations, leading to increased peristalsis both

above and below the obstruction with fragment loose stools and flatus early

in its course.

Increased small bowel distension leads to increased intraluminal

pressures. This can cause compression of mucosal lymphatics leading to

bowel wall lymphedema. Later in the course of obstruction, the intestine

becomes fatigued and dilated, with contractions becoming less frequent and

less intense.

As the bowel dilates, water and electrolytes accumulate both

intraluminally and in the bowel wall itself. This massive third -space fluid

loss accounts for the dehydration and hypovolemia. The metabolic effects of

fluid loss depend on the site and duration of the obstruction. With a proximal

obstruction, dehydration may be accompanied by hypochloremia,

hypokalemia, and metabolic alkalosis associated with increased vomiting.

Distal obstruction of the small bowel may result in large quantities of

intestinal fluid into the bowel; however, abnormalities in serum electrolytes

are usually less dramatic. Oliguria, azotemia, and hemoconcentration can

accompany the dehydration. Hypotension and shock can ensue. Other

consequences of bowel obstruction include increased intra abdominal

pressure, decreased venous return and elevation of the diaphragm,

compromising ventilation. These factors can serve to further potentiate the

effects of hypovolemia.

As the intraluminal pressure increases in the bowel, a decrease in

mucosal blood flow can occur. These alterations are particularly noted in

patients with a closed - loop obstruction in which greater intraluminal

pressures are attained. A closed - loop obstruction, produced commonly by

twist of the bowel, can progress to arterial occlusion and ischemia if left

untreated and may potentially lead to bowel perforation and peritonitis.

In the absence of intestinal obstruction, the jejunum and proximal ileum

of the human are virtually sterile. With obstruction, however, the flora of the

small intestine changes dramatically, in both the type of organism (most

commonly Escherichia coli, streptococcus faecalis, and klebsiella) and the

quantity with organisms reaching concentrations of 109 to 10 10per ml

studies have shown an increase in the number of indigenous bacteria

translocating to mesenteric lymph nodes and even systemic organs.

Imaging studies

Plain radiography

* Obtain plain radiographs first for patients in whom SBO is suspected

* At least 2 views, supine or flat and upright, are required.

* Plain radiographs are diagnostically more accurate in cases of simple

obstruction; however, diagnostic failure rates of as much 30% have

been reported. In one small study, the sensitivity of plain radiographs was

reported as 75% and specificity was reported to be 53%.Similar findings

were reported in a second study.

* In one study, plain films were more accurate in the detection of an

acute SBO and the accuracy was higher if interpreted by more experienced

radiologists.

* Plain radiography is of little assistance in differentiating strangulation

from simple obstruction. Some have used abdominal radiography to

distinguish between complete obstruction and partial or no SBO. A study by

Lappas et al9 proposed that two findings were more predictive of a higher

grade of complete SBO: present of air-fluid differentiation height in the

same small- bowel loop and presence of a mean level width greater than

25mm. The study found that when the two findings are present, the

obstruction is most likely high grade or complete. When both are absent, the

authors proposed that a low grade (partial) SBO is likely or nonexistent.

* Fixed, dilated U or C shaped bowel loops may suggest closed loop

obstruction.

* Small amounts of air trapped between the plicae circularis in an

upright films produce a " string of beads or pearls" appearance (most

specific sign). Multiple Air- Fluid levels, Step ladder configuration, Gasless

abdomen are the other specific signs.

Ultrasonography

Ultrasonography is less costly and less invasive than CT scanning.

It may reliably exclude SBO in as may as 89% of patients.

Specificity is reportedly 100%.

Enteroclysis

Enteroclysis is valuable in detecting the present of obstruction and in

differentiating partial from complete blockage.

This study is useful when plain radiographic findings are normal in

the presence of clinical signs of SBO or if plain radiographic findings

are nonspecific.

It distinguishes adhesions form metastases, tumor recurrence, and

radiation damage.

Enteroclysis offers a high negative predictive valve and can be

performed with 2 types of contrast..

Barium is the classic contrast agent used in this study. It is safe and

useful when diagnosing obstructions provided no evidence of bowel

ischemia or perforation exists. Barium has been associated with

peritonitis and should be avoided if perforation is suspected.

Enteroclysis with multiplanar CT is being used to overcome the

limitations of use of either modality (enteroclysis or CT individually)

and may ultimately simplify the understanding of the obstructive

process and assist with management.

CT enteroclysis can be performed by using positive enteral material

without I.V. contrast material (or) neutral enteral contrast material with

I.V.contrast10.

Computed tomography (CT).

Routine CT is good in diagnosing high grade small bowel

obstruction,with accuracy of more than 90%2,11 , however it is less

accurate in cases of low grade small bowel obstruction with

sensitivity of 50% &specificity of 94%1,12.

CT is useful in making an early diagnosis of strangulated obstruction

and in delineating the myriad other causes of acute abdominal pain,

particularly when clinical and radiographic findings are inconclusive.

It also has proved useful in distinguishing the etiologies of SBO,

that is extrinsic causes such as adhesions and hernia from intrinsic

causes.

It is capable of revealing abscess, inflammatory process, extra

luminal pathology resulting in obstruction, and mesenteric ischemia.

CT enables the clinicians to distinguish between ileus and

mechanical small bowel obstruction in post-operative patients.

CT does not require oral contrast for the diagnosis of SBO because

the retained intraluminal fluid severe as a natural contrast agent.

Obstruction is present if the small bowel loop is greater than 2.5cm

in diameter dilated proximal to a distinct transition zone of collapsed

bowel.

Following patterns of entero-enteric intussusception namely target

sign, reniform mass and a sausage shaped mass with alternating

layers of low and high attenuation can be visualized13.

U or C - shaped dilated loops, radial distribution of mesenteric

vessels, beak sign and whirl sign suggest closed loop obstruction.

A smooth beak indicates simple obstruction without vascular

compromise; a serrated beak may indicate strangulation.

Pneumatosis, portal venous gas indicates early strangulation.

REVIEW OF LITERATURE

There are several studies have been published in evaluating the role of CT in

detecting the site and cause of high grade small bowel obstruction.Computed

Tomography has emerged as a premier modality and has a tremendous

impact in the evaluation and management of high grade small bowel

obstruction.A brief review of literature will be discussed below.

Omair Shakil et al 14 retrospectively studied the spiral CT in cases of

small bowel obstruction over a period of 5 years in adult Pakistani

population, who underwent exploratory laparotomy. He studied the

accuracy of spiral CT in identification & cause of bowel obstruction, and

calculated the sensitivity, specificity, positive and negative predictive values.

A total of 271 patients were studied, 104 cases had intestinal obstruction

intra operatively but CT has diagnosed 97 cases with sensitivity of 93%,

specificity of 93% and positive predictive value of 89% . Spiral CT

identified cause in 72 cases(74%) .This study concluding that spiral CT

scans shows high sensitivity and specificity in diagnosing intestinal

obstruction, but less efficacy in determining the cause of the obstruction.

David Frager et al 15 evaluated the value of spiral CT in establishing

the diagnosis and determining the degree, cause of small bowel obstruction

as compared with traditional clinical-radiographic assessment. A total of 90

examinations were evaluated over a period of 11 months. On the basis of the

combined clinical-radiographic findings, the diagnosis was complete

obstruction in 21 of 46 cases with sensitivity, 46%. When CT was used, the

diagnosis was established in all 46 cases with sensitivity 100%. In the 25

cases in which the traditional assessment failed, the early CT able to identify

complete obstruction, so that reduces delay in surgery. On the basis of the

combined clinical-radiographic findings, partial obstruction of the small

bowel was diagnosed in 6 of 20 cases with sensitivity of 30% , whereas all

cases were detected with CT. Thus this study concluded that CT is highly

sensitive and superior to combined clinic-radiographic findings.

Marc Zalcman et al 16 prospectively evaluated the reliability and

usefulness of helical CT in diagnosing ischemic signs in cases of small

bowel obstruction. He studied a total of 144 examinations over a period of 3

years with correlation with intraoperative findings. The following signs of

strangulation and ischemia taken into consideration: reduced enhancement

of the small-bowel wall, mural thickening, mesenteric fluid, congestion of

small mesenteric veins, and ascites. If enhancement of the bowel wall was

reduced or if at least two of the other signs were noticed, are the criteria for

ischemia on spiral CT. Intraoperatively ischemic bowel loops were noted in

24 cases. CT correctly identified ischemia in 23 cases ,with sensitivity of

96%, 9 false positives with specificity of 93% &The negative predictive

value of CT was 99%.Coming to individual parameters, reduced

enhancement of the bowel wall had a sensitivity of 48% and specificity of

100%, mural thickening had a sensitivity of 38% and specificity of 78%,

mesenteric fluid had a sensitivity of 88% and specificity of 90%, congestion

of mesenteric veins had a sensitivity of 58% and specificity of 79%, and

ascites had a sensitivity of 75% and specificity of 76%.This study highlights

the role of spiral CT in diagnosing ischemia in cases of small bowel

obstruction.

Alec J. Megibow and his colleagues2 retrospectively evaluated the

role of spiral CT in intestinal obstruction (included large bowel also in his

study) over a period of 2 years. A total of 167 cases were studied, in this 84

cases referred as intestinal obstruction, remaining 83 cases are control group.

CT evaluation done by two radiologists, who un aware of patient history,

confirmation of bowel obstruction by intraoperative findings ,clinical course

and barium studies and the results were analyzed .Among 84 cases, which

referred as intestinal obstruction, 64 cases only having intestinal obstruction

and 20 cases does not have obstruction. In this 64 cases of confirmed

intestinal obstruction, CT able to identify 60 cases correctly and 4 cases

were missed with false negative of 4 cases. Among 20 cases of not having

obstruction, CT showed 4 cases having obstruction and 16 cases not having

obstruction with a false positive of 4 cases. In 83 control group, none of

them was diagnosed as obstruction by CT. analysis showed the spiral CT has

a sensitivity of 94%, specificity of 96% and accuracy of 95% in this study.

In 64 cases of intestinal obstruction 55 cases were small bowel obstruction

and 9 cases were large bowel obstruction. The etiology was correctly

identified in 47 of 64 cases (73%).The cause of the obstruction was correctly

predicted in 47 of 64 cases (73%). Adhesions were correctly diagnosed as

the cause of the obstruction in 27 of 37 cases (73%). In this study adhesions

are the most common cause of intestinal obstruction. This study concludes

that spiral CT has role in identification and etiology of bowel obstruction.

Funda Obuz et al 17prospectively studied the ability of helical CT

(computed tomography) in determining the cause & viability in 41 patients

who presented with small bowel obstruction, he found that there is high

correlation, helical CT has sensitivity of 84% and specificity of 90% in

demonstrating the cause of obstruction, all 6 cases with no bowel

enhancement in CT were confirmed with intra operative findings. Thus he

concluded helical CT has a role in determining the etiology and vascular

complications in cases of small bowel obstruction.

Emil J. Balthazar et al 18 prospectively studied100 consecutive spiral

CT examinations, who suspected small bowel obstruction clinically over a

period of 2 years. He studied accuracy of spiral CT in confirming the small

bowel obstruction and diagnosing the viability of bowel loops. Among 100

cases, 60 were men, 40 women and age group ranging from 19 to 90 years

with mean of 52 years. The CT features compared with operative findings in

77 patients and clinical follow-up in 23 patients. The interval between CT

and surgical exploration in patients with ischemic bowel was mean duration

of 13 hours. Criteria for bowel ischemia taken consideration in this study

were -slight circumferential thickening of the bowel wall, increased

attenuation, target or halo sign, pneumatosis intestinalis, lack of

enhancement of the wall on I.V. contrast and haziness of the mesenteric

vessels, or mesenteric hemorrhage obscuring mesenteric vessels. Spiral CT

diagnosed small bowel obstruction in 90 cases, and ileus in 10 cases with

two false negatives & no false positives. Correlation of CT findings of

strangulation with surgical findings showed 72 cases true-negative, 19 true-

positive, five false-positive, and four false-negative CT results with

sensitivity of 83%, specificity of 93%, accuracy was 91%, positive

predictive value was 79%, and negative predictive value was 95%.This

study showed spiral CT help in accurate diagnosis of bowel ischemia in

cases of small bowel obstruction. Exploratory laparotomy should be done,

when disparity between equivocal CT findings and a deteriorating clinical

condition.

Scaglione M et al 19 retrospectively reviewed 120 cases of small

intestine closed loop obstruction over a period of 3 years. All these cases are

operated, with in a period of 6 hours after doing spiral CT. These 120 cases

of closed loop obstruction were evaluated for bowel ischemia and results

were analyzed. CT signs taken into consideration for diagnosing ischemia

were: submucosal edema, increased, reduced, or no enhancement of the loop

walls, edema of the mesenteric vessels, fluid within the loops or in the

intraperitoneal spaces. 120 cases were thoroughly evaluated, Spiral CT

diagnosed ischemia in 26 cases, but in reality there are 51 cases showed non-

viable bowel loops intraoperatively. In this study of 120 cases they missed

bowel ischemia in 25 cases preoperatively. In 26 cases which were

diagnosed ischemia by CT ,all were came as non-viable intraoperatively,

thus in this study they showed Spiral CT had 100% positive predictive value

in bowel viability. In this study CT showed 94 cases have viable bowel

loops, but 25 cases had non-viable bowel loops intraoperatively with

negative predictive value of 73%. Thus he concluded that even though Spiral

CT had good positive predictive value for diagnosing bowel ischemia ,

depending up on CT we cant say confidently, which dont show bowel

ischemia on CT ,cant be viable in reality, there is a chance of missing

ischemia on CT. So if any change in trophic status of bowel loops or its

mesentery may imply ischemic changes, and need for emergency

laparotomy.

Catel L et al 20 retrospectively reviewed 43 cases of Adhesive small

bowel obstruction for evaluation of bowel ischemia. All cases were

evaluated by three experienced radiologists. Signs for complicated small

bowel obstruction in this study were reduced enhancement of the small

bowel wall, mural thickening, congestion of small mesenteric veins, and

ascites. In this study 15 patients had ischemic signs on CT, 28 patients does

not have. Coming to individual parameters in diagnosing bowel ischemia a

sensitivity of 57% and a specificity of 100% noted with reduced bowel wall

enhancement and sensitivity of 35% and a specificity of 100% noted with

bowel wall thickness greater than 3 mm, and sensitivity of 35% and a

specificity of 93%noted if bowel wall thickness less than 1 mm taken as

criteria. In this study ascites and congestion of small mesenteric veins were

not much useful in diagnosing bowel ischemia. If u consider bowel-wall

thickening and reduced bowel wall enhancement ,the sensitivity of 71%,

specificity 100%, and accuracy 90%. So this study concluding that in

evaluation of bowel ischemia, enhancement of small bowel wall, mural wall

thickening & thinning of bowel wall were have significant role.

E J Balthazar et al 21 retrospectively collected data of 19 cases of

small bowel closed loop intestinal obstruction. Spiral CT films were

examined by two radiologists. In this study they are examining for signs of

bowel ischemia in spiral CT in cases of small bowel closed loop obstruction

and comparing with intraoperative findings. Signs of strangulation taken

consideration in this study were wall thickening, high attenuation and target

sign and abnormalities in attached mesentery. Among 19 cases, spiral CT

showed 10 cases had signs of ischemia but intraoperatively16 cases showed

ischemic bowel loops. In this study Spiral CT had missed 6 cases of

strangulation. Among 10 cases CT showed ischemic signs were came as

non-viable intraoperatively with 100% positive predictive value. This study

highlights that absence of ischemic signs in CT, bowel ischemia & necrosis

in closed loop obstruction cant be ruled out.

Michael H. Fuchsjager et al 22studied the Small bowel feces sign in

cases of small bowel obstruction. It is the appearance of feces like matter in

small bowel loops. This sign because of increased water absorption in the

small bowel loops, in cases of small bowel obstruction because of more

transit time, making the intestinal content to be hard and mixing with gas

bubbles, look like feces. The chance of forming this appearance ,more with

prolonged periods of obstruction, so more incidence in sub-acute or low

grade small bowel obstruction. Similar mimicking appearance noted in

conditions like cystic fibrosis, infectious or metabolic Bowel disease,

bezoars and sometimes it can be normal finding because of reflux of fecal

content from cecum to distal ileum. This study suggesting that in a clinical

setting of suspected small bowel obstruction, finding this sign, adding extra

weight age to obstruction. Usually this sign noted in distal portion of dilated

bowel loops. This study summarized that in cases of not much dilated bowel

loops ,especially in low grade obstruction and borderline cases, finding this

sign, may help in diagnosis & these cases frequently requires surgical

treatment .

Another study on small bowel feces sign by J SINGH et al 23, shown

that because of this sign is visualized in distal part of dilated bowel loops,

help in identification of site of obstruction, and more chance of diagnosing

cause of obstruction. Thus he concluded that role of Small bowel feces sign,

in identification of site and cause of obstruction.

Dawn E. Lazarus et al 24 prospectively studied cases of small bowel

obstruction over a period of 5 months. A total of 34 cases with age ranging

from 21-82 years (mean age of 52 years) were included in the study. Among

34 cases 20men and 14 women. His main aim to identify the occurrence of

small bowel feces sign and its capability in demonstrating transition zone.

He divided cases into mild, moderate and high grade small bowel

obstruction on the basis of caliber of proximal and distal bowel loops. A

single experienced radiologist studied the all 34 cases. In this study they

calculated the incidence of this sign in cases of mild, moderate, severe small

bowel obstruction. Among 34 cases, small bowel obstruction was high grade

in 17 cases, moderate in 11 cases, mild in 6 cases. In 34 cases, this sign

noted in 19 cases (55.9%).This sign was demonstrated in 10 cases of high

grade (58.8%), 8 cases of moderate (72.7%), one case(16.6%) of mild small

bowel obstruction. In patients with feces sign, this appearance can be

identified up to transition point. And the extent of this appearance lengthier

in moderate and high grade than mild obstruction. Thus this study highlights

the role of feces sign in identifying transition zone in patients with SBO and

this sign more frequently associated with moderate, severe SBO than mild

SBO.

Usually adhesions as a cause of small-bowel obstruction (SBO) is

diagnosis of exclusion. Bojan Petrovic et al 25 retrospectively studied CT

scans of 142 patients with surgically proven SBO due to adhesions .This

study mainly to evaluate the findings suggestive of an extra luminal band

can be used in diagnosis of adhesive SBO. An extraluminal band was

suggested if any change in the conformation at the transition zone. In 142

patients, the study identified 73 cases having bands, in that 73 cases,

adhesions as cause of obstruction in 52 cases with a positive predictive value

of 71% and a p value of 0.008. This study demonstrated extraluminal band

was sensitivity of 61% and specificity of 63% in diagnosing SBO due to

adhesions. So this study summarized the role of bands in helping the

diagnosis of adhesions in cases of small bowel obstruction.

Diego A. Aguirre et al4 summarizes the role of multidetector CT in

diagnosis of abdominal hernias in problematic situations like scarred tissues,

severe abdominal pain, and obesity. In obese cases, it demonstrates the

location, shape, size and content of abdominal hernias. With 3D imaging and

multiplanar reformations, CT much more helpful in these cases. MDCT

help in identification of signs of strangulation .This study highlights the

importance of MDCT in unrepaired and surgically repaired hernias and thus

help in planning further management.

Akira Furukawa et al 26 confirms that with recent technological

developments, now CT is highly sensitive and specific in determining the

presence of bowel obstruction and clearly demonstrates the site, cause of

obstruction and also recommends CT for evaluation of patients with

suspected bowel obstruction, particularly in the cases, where clinical &

conventional radiographic findings were indeterminate and suspicion of

viability of bowel loops.

MATERIALS AND METHODS

The present prospective study was conducted at Meenakshi Mission

Hospital & Research Centre, Madurai during the period from October 2011

to October 2013.83 patients in the age group between 2 months to 79 years

with strong suspicion of Small Bowel Obstruction on the basis of clinical

grounds, plain radiographs and ultrasonography findings were subjected to

Helical CT evaluation of the abdomen. More importantly all of the above

patients were hemodynamically stable at the time of CT scan.

Several reports have shown the accuracy of CT in the diagnosis of

Small Bowel Obstruction. However, these studies were mostly retrospective

,the effective role & impact of CT in the diagnosis and management of

Small Bowel Obstruction remains to be explored. The aim of our

prospective study was to evaluate the role of CT in determining the cause

and level of high grade obstruction, bowel viability and correlation with

intraoperative findings.

Inclusion criteria:

All the patients with strong clinical suspicion (vomiting, abdominal

pain,distension, malena, constipation, obstipation) and plain radiographic,

sonographic evidence of Small Bowel Obstruction were included in the

study.

Exclusion criteria:

Patient in early post operative period, generalized septicemia,

electrolyte disturbances i.e., hypokalemia and history of trauma were

excluded from study.

CT protocols:

All patients were scanned with GE optima 660- 64 slice multidetector

CT scanner. Initially, plain helical acquisition from the dome of diaphragm

to the inferior edge of the ischium was taken.

Depending up on the plain CT findings ,oral contrast was given to the

patients. All the patients were not administered oral contrast because most of

the patients had severe vomiting and more importantly positive contrast in

the bowel can obscure the etiology of the obstruction & enhancement of the

mucosa of the bowel lumen. The inherent fluid in the dilated bowel acts as a

contrast in most cases of high grade Small bowel Obstruction. Oral contrast

if given, it was given in the form of 30 ml of Gastroscan+ M

(Diatrizoatemeglumine and Diatrizoate sodium solution-370 mg /ml iodine)

mixed in 1200 to 1500 ml of mineral water or flavoured drinks and

administered orally over a period of 45-60 minutes. Around 150-200 ml of

oral contrast is administered just before the I.V.( Intravenous)contrast study

as a table dose. We advocated oral contrast only in few patients who had

previous history of abdominal surgeries suspecting adhesive intestinal

obstruction and in other patients fluid in the dilated bowel acts as inherent

contrast. Venous access was obtained in the preparation room using the 16

or 18G venflon in the antecubital vein or any other large vein in the forearm.

The subjects were trained to hold their breath for at least 20 seconds if

possible, with special intention to avoid diaphragmatic motion.

With the help of pressure injector about 70-90 ml of Non-ionic

contrast, injected intravenously at flow rate of 2-3 ml /sec. Volume scans of

the abdomen and pelvis usually obtained with 5 mm collimation ,512x512

matrix, a pitch of 1.5 and 40-50 sec scan delay. Region of interest was from

the domes of diaphragm to the inferior edge of the ischium. Closer

reconstructions were done and viewed on the work station under wide

window setting namely soft tissue, bone and lung windows.

Thorax was also included in the study when needed (pulmonary

tuberculosis),in which case the region of interest was extended above up to

the sternal notch. Filming was done in soft tissue window. Thin

reconstructed axial sections were used to create sagittal, coronal and curved

multiplanar reformatted images from the acquired volume data, they have

more diagnostic value.27 The CT findings were correlated with intraoperative

findings on case to case basis. The following criteria were studied.

The CT criteria

Bowel Dilatation-Small bowel with a caliber greater than 2.5 cm

is considered dilated.

High grade obstruction is greater than 50% difference in caliber

of proximal dilated small bowel and collapsed distal small bowel.

Bowel wall thickening because of difficulties related to the

precision of this measurement, we have elected to use the 3mm

threshold suggested by Bartnicke.28

Delayed wall enhancement29 of the involved loop compared to

the homogenous enhancement of adjacent normal bowel.

Congestion of small mesenteric veins30,31 characterized by

enlargement of small serpentine vessels in the mesenteric fat.

Peritoneal fluid32,33

Bowel wall pneumatosis34 (intramural air) characterized by gas

bubbles within the bowel wall.

Statistical tools

The information collected regarding all the selected cases were

recorded in a master chart. Data analysis was done with the help of computer

using epidemiological information package (EPI 2002). Using this software,

frequencies, percentage, range, mean and strandard deviation were

calculated.

Sensitivity, specificity,. Accuracy, positive predictive valve and

negative predictive values were calculated using the following formulae and

taking surgical findings as the golden standard.

Sensitivity = True positive x 100

True positive + False negative

Specificity = True positive x 100

False positive + True negative

Accuracy = True positive x True negative

N

Positive predictive value = True positive x 100

True positive + False positive

Negative predictive value = True negative x 100

True negative + False negative

RESULTS AND ANALYSIS

Table 1 Age distribution

Frequency and percentage wise distribution of cases according to their

age:

Age group No. %

Table 2

Sex distribution


sex

Sex No. %

Male 37 44.6

Female 46 55.4

Total 83 100

Out of total 83 patients, 37 were males who constitute of about 44.6%

and 46 were females, that is around 55.4%.

Table 3


CT level of obstruction

CT-level No %

Proximal Jejunum 6 7.2

Distal jejunum 8 9.6

Proximal ileum 18 21.7

Distal ileum 50 60.2

Not clearly made out 1 1.2

Total 83 100

In among 83 cases, according to CT findings, distal ileum constitutes

(60.2%) the most common site of Small bowel Obstruction, 2nd commonest

site is proximal ileum (21.7%). Interestingly in one case, we could not made

out the site of obstruction , but intra operatively distal jejunum is the site of

obstruction.

Table 4


surgical level of obstruction

Surgical -level No %

Proximal Jejunum 5 6.0

Distal jejunum 11 13.3

Proximal ileum 18 21.7

Distal ileum 49 59.0

Total 83 100

According to Surgical findings, in 83 cases distal ileum constitutes

(59.0%) is the most common site of Small bowel Obstruction, 2nd

commonest site is proximal ileum (21.7%).

Table 5

Association between surgical and CT level of obstruction

Surgical_level

CT-Level

Proximal

jejunum

Distal

jejunum

Proximal

ileum

distal

ileum

Total p-value

Proximal

jejunum

5 1 0 0 6

p

Table 6


causes (surgical findings)

Causes No %

Adhesions 32 38.5

Stricture 14 16.8

Closed loop obstruction 24 28.9

Intussusception 1 1.2

Congenital iliac stenosis 1 1.2

Tumors 8 9.6

Radiation enteropathy 1 1.2

Meckels diverticulum 1 1.2

Foreign body 1 1.2

Total 83 100

In 83 cases, Adhesions (38.5%) are the most common cause of SBO. The

other causes are (in the descending order of frequency ) Closed loop

obstruction (28.9%), Stricture(16.8%), Neoplasms(9.6%).

Table 7


CT- ISCHAMIC Parameter of bowel wall enhancement

Bowel wall enhancement No %

Present 76 91.6

Absent 7 8.4

Total 83 100

In 83 patients, CT shows normal bowel enhancement in 76 cases, No

enhancement noted in 7 cases. One case showed poor enhancement, for

statistical purpose it was included in No enhancement category.

Table-8


bowel viability

Viability No %

Present 75 90.4

Absent 8 9.6

Total 83 100

Among 83 patients, intra operatively bowel was viable in 75 cases,

gangrenous bowel loops noted in 8 cases.

Table 9-

Bowel viability comparison of CT findings with surgical findings.

CT-

Finding

Surgical finding

p-value Viable Gangrene

f % f %

p

Table 10


confirmation of CT finding by surgical finding:

CT- Finding Confirmation with CT finding with Surgical

finding

Same as CT Not correlated with CT

f % f %

Level 78 93.9 5 6.1

Cause 77 92.8 6 7.2

Viability 80 96.4 3 3.6

There is a good correlation of CT findings with surgical findings in

respective of level, etiology and viability in cases of small bowel

obstruction.

DISCUSSION

Experience accumulated mainly in the past decade showing that CT

is a valuable diagnostic tool in cases of small bowel obstruction ,in its

diagnosis and evaluation of etiology.35,36,37 In our current study we want to

evaluate cases of small bowel obstruction , answering the following

clinical questions: Where is the Site of obstruction ,What is cause of the

obstruction, Is this bowel viable ?

In our prospective study of 83 cases of small bowel obstruction, most

common age group presented with small bowel obstruction is 50-60 years

with mean of 46.24 15.61 years, similar retrospective study of Omair

Shakil et al14 found mean age of 46 19 years which is more or less

co- inciding with our study.

In our study of 83 cases, 46 cases of female population which comprise 55.4

% of study population and 37 cases of male population, which comprise of

44.6%. Study by of Omair Shakil et al14 found to be males are affected

more, who comprise the 64% of study population.

In our study population of 83 patients the most frequent site of

obstruction is the distal ileum which comprise the 59% of study group (49

cases), next common (in descending order) are proximal ileum (21.7%),

distal jejunum (13.3%).The site of obstruction is correctly diagnosed in 78

cases with accuracy of 93.9%.

In 83 cases, most common cause of small bowel obstruction is adhesions,

comprise of 38.5% (32 cases)of study population, next common causes (in

descending order ) are closed loop obstruction 28.9% (24 cases),stricture due

to infection and inflammatory causes 16.8%(14 cases), Neoplasms 9.6%(8

cases).

The cause of small bowel obstruction is correctly identified in 77 cases with

accuracy of 92.8% , which is more accuracy than study by Omair Shakil et

al14 showed accuracy of 74% .Similar prospective study by Funda Obuz et

al17 showed helical CT has a sensitivity of 84% and specificity of 90% in

demonstrating the cause of obstruction.

In 32casese (38.5%)of adhesive small bowel obstruction , 29 patients

have history of abdominal surgery for various reasons and 2 patients have

recurrent appendicitis with inflammatory omental adhesions. Interestingly 1

patient have a thick encasing membrane with most of the small bowel loops

as its contents for which cause was not known and we included this case

under adhesions .Adhesions are commonly seen in people who undergone

laparotomy.38 The rates of adhesions varies with different studies .39,40 > 80%

adhesions occur after surgery,15% are due to inflammatory and remaining

few are due to congenital (or) unexplained causes.41 Adhesions are

responsible for more than half (50-75%) cases of small bowel

obstruction.42,43

We have 8 cases of neoplasms ( adenocarcinoma-6 cases,carcinoid-2

cases)present as small bowel obstruction. Among 6 cases of adenocarcinoma

three cases of adenocarcinoma present as growth with wall thickening,

another three cases of adenocarcinoma present as wall thickening with

narrowing ,these 3 cases pre-operative diagnosis is stricture, but

histopathology came as adenocarcinoma. We have one interesting case of

radiation enteropathy causing small bowel obstruction ,which is pre-

operatively diagnosed ,due to its characteristic appearance. We missed one

case of meckel s diverticulitis with band formation.

Closed loop obstruction is a form of mechanical bowel obstruction in

which two points along the course of the bowel are obstructed at a single

site.44 Closed loop obstruction is most often caused by an internal or external

hernia. In our study we found that closed loop obstruction is one of the

common cause for high grade small bowel obstruction, comprise of 28.9%

(24 cases)of study population.

Small bowel intussusception may because of various extrinsic,

intrinsic or intraluminal processes.45 Some times intussusception may cause

small bowel obstruction. We have one case of intussusception causing small

bowel obstruction and CT showed Jejuno-jejunal intussusception with

lymph nodes as lead point, histopathology came as chronic reactive lymph

nodes .

Foreign body usually seen in oesophagus, another sites are stomach, colon,

rarely can lodged in small intestine.46 Some times we can see small bowel

obstruction by foreign body, especially in children or mentally disturbed

patients.47 we have seen a case of foreign body (Jelly ball) Obstruction in 6

month old child after accidental swallowing jelly ball becomes swollen and

impacted in distal ileal loops.

A strangulating obstruction is defined as a mechanical obstruction

associated with bowel ischemia. This condition is seen in approximately

10% of patients with small bowel obstruction.Various CT findings are

described in cases of strangulation.48

In evaluation of bowel viability, our study correctly demonstrated

viability in 96.4%(80 cases) of study population with sensitivity of 98.7%,

specificity of 75%,positive predictive value of 97.4% and negative

predictive value of 85.7%. A similar prospective study by

Marc Zalcman et al16 showed CT correctly identified bowel ischemia in 23

cases with sensitivity of 96%, specificity of 93% in determining the bowel

viability. Another prospective study by Funda Obuz et al 17 6 cases with no

bowel enhancement in CT were confirmed with intraoperative findings .

In our case series three cases related to bowel viability was not

consistent with surgical findings. Two cases of bowel ischemia has been

missed ,one patient had a history of laparotomy for blunt injury abdomen 4

years back and we reported as closed loop obstruction with absence of

ischemic changes but preoperatively it turned to be a trans mesenteric hernia

with gangrenous changes. Since this patient was not responding to

conservative treatment and also showed clinical signs of strangulation he

was taken up for surgery i.e. Nearly 48 hours after the CT so, we presume

that he might have developed ischemic changes in his last few hours before

the surgery as closed loop obstruction is very notorious to go for acute

ischemic changes. Another case where we missed ischemia, is a case of

recurrent appendicitis with adhesions, initially conservatively management

tried in this case, likely delay in surgery or inflammatory changes may cause

ischemia in the meantime. In the third case we reported as small bowel

obstruction with ischemic changes because in our perception some of the

bowel loops shows inadequate enhancement but on contrary these bowel

loops were viable during surgery.

A study by Scaglione M et al 19 on bowel viability in cases of closed

loop small intestinal obstruction ,bowel ischemia was identified in 26 cases

with positive predictive value of 100%, negative predictive value of 73%.

Another study by Catel L et al20 on bowel viability in adhesive small bowel

obstruction, In 43 cases, CT identified strangulated bowel loops in 15

patients with accuracy of 90%, sensitivity of 71% and specificity of 100%.

A systematic review of many studies, CT for ischemia in SBO were

sensitivity of 83% (range, 63-100%), specificity of 92% (range, 61-100%),

PPV of 79% (range, 69-100%), and NPV of 93% (range, 33.3-100%).49

Some times, bowel ischemia can missed in spiral CT, patients with

obvious discrepancy between CT and clinical findings and ischemia of

bowel loops were suspected must undergo immediate surgery.50

In the present study, we conclude that the accuracy of helical CT in

the evaluation of level and cause of small bowel obstruction is 93.9% and

92.8% respectively. For evaluation of bowel viability with sensitivity of

98.7%, specificity of 75%,accuracy of 96.4%,positive predictive value of

97.4% and negative predictive value of 85.7%.

CONCLUSION

Helical CT is useful imaging modality to characterize the cause, site

and possible complications of small bowel obstruction .Reformatting

helical CT scans in multiple planes provides a new perspective for the

evaluation of small bowel obstruction and may be useful in defining and

characterizing obstruction. However, in most patients, the multiplanar

reconstructions simply confirm and complement the information revealed on

axial source images. Helical CT is a highly sensitive method to diagnose or

rule out intestinal ischemia in the context of acute small- bowel obstruction.

CT can also demonstrate findings that indicate the presence of closed loop

obstruction or strangulation, both of which necessitate emergency

exploratory laparotomy.

In our study population we found out that Helical CT has good

accuracy in determining the level, cause of obstruction, viability of bowel

loops ,and also absence of bowel wall enhancement is the most important

specific parameter to diagnose ischemic changes. Historically acute Small

bowel obstruction was surgically operated relatively early, because of

difficulty of identification severity, strangulation on clinical and

conventional imaging grounds. Today with improved diagnostic modalities

and resolution, some obstructions can resolve with conservative

management.51,52 We also strongly believe that Helical CT should be the first

imaging modality of choice in any case of acute small bowel obstruction

with clinical deterioration, because significant percentage of laparotomies

can be avoided if a reliable diagnosis of ischemia was possible

preoperatively.

Chart No .1

0

5

10

15

20

25

Chart No .2- Distribution of cases according to their sex.

0

5

10

15

20

25

30

35

40

45

50

No

.

Distribution of cases according to their sex.

Male Female

37

46

Sex

Distribution of cases according to their sex.

Chart No .3- Distribution of cases according to CT level of obstruction.

0

5

10

15

20

25

30

35

40

45

50

Proximal jejunum

6

No

.

Distribution of cases according to CT level of obstruction.

Proximal jejunum

Distal Jejunum

Proximal ileum

Distal ileum

Not clearly madeout

8

18

50

Distribution of cases according to CT level of obstruction.

Not clearly madeout

1

Chart No .4- Distribution of cases according to surgical level of

obstruction.

5

11

18

49

0

5

10

15

20

25

30

35

40

45

50

freq

uen

cy

Proximal

jejunum

Distal Jejunum Proximal ileum Distal ileum

Chart No.5- Distribution of cases according to their causes(Surgical

findings)

32

14

24

1 1 8

1 1 1

Adhesions

Stricture

Closed loop obstruction

Intussception

Congenital

Tumors

Radiation enteopathy

Meckel's diverticulum

Foreign body

Chart No .6- Distribution of cases according to CT ischemia

parameter of bowel wall enhancement.

0

10

20

30

40

50

60

70

80

Present

No

.

Distribution of cases according to CT ischemia

parameter of bowel wall enhancement.

Present Absent

76

7

Bowel wall Enhancement

Distribution of cases according to CT ischemia

Chart No .7- Distribution of cases according to their bowel viability .

0

10

20

30

40

50

60

70

80

No

.

Distribution of cases according to their bowel viability .

Present Absent

75

8

Distribution of cases according to their bowel viability .

Chart No .8 -Bowel viability

0

20

40

60

80

CT-

fin

din

gs f

req

uen

cy

Bowel viability -comparison of CT and surgical findings .

Viable Gangrene

74

21 6

Surgical findings

Viable

Gangrene

comparison of CT and surgical findings .

Viable

Gangrene

Chart No .9- Comparison of CT findings with surgical findings in terms

of level, cause of small bowel obstruction and bowel viability

0

10

20

30

40

50

60

70

80

Level

78

No

.

Comparison of CT findings with surgical findings in terms


Level Cause Viability

78 77 80

5 6

Parameters

Comparison of CT findings with surgical findings in terms


Viability

3

Same as CT

Not confirmation with CT

IMAGE 2- SCANOGRAM SHOWING THE DILATED SMALL BOWEL LOOPS.

Image 2

IMAGE 3- DILATED SMALL BOWEL LOOPS IN

CROSS SECTIONAL IMAGING

Image 3

IMAGES 4 A& B: 40 Year old gentle man , case of Ca. rectum -

post abdominoperineal resection(APR) , presented with small

bowel obstruction because of adhesions ( Arrow pointing to the

adhesions of bowel loops to pelvic side walls)

Image 4a

Image 4b

IMAGES 5a & 5b - 26 years old woman history of hysterectomy

presenting with small bowel obstruction because of adhesions (

Arrow pointing to adhesions to lower anterior abdominal wall

Image 5a

Image 5b

IMAGES 6a & 6b Adhesions with fat notch sign cross sectional

view (6a), coronal view (6b)

Image 6a

Image 6b

IMAGES 7a & 7b 46 year old gentle man presented with small

bowel obstruction showing Cocoon with encasing membranes &

adhesions ( arrows pointing to cocoon)

Image 7a

Image 7b

IMAGES 8a , 8b & 8c 36 year old gentle man presented with

small bowel obstruction showing Jejuno-jejunal intussusception

(arrows in image 8a pointing to sausage shaped mass , see fat and

vessels are surrounded by two layers of bowel loops ., Image 8b

showing target sign , Image 8c arrow pointing to lymph nodes

which act as lead point

Image 8a

Image 8b

Image 8c

IMAGES 9a , 9b & 9c 28 year old gentle man presented with small bowel obstruction showing Left femoral hernia with dilated bowel loops (Image 9c showing bowel loops in femoral triangle)

Image 9a

Image 9b

Image 9c

IMAGES 10a & 10b - 47 year old woman presented with small bowel obstruction showing Stricture as cause ( arrows pointing to

stricture)

Image 10a

Image 10b

IMAGES 11a & 11b - 69 year old male patients presented with small bowel obstruction showing Stricture as cause ( arrows

pointing to stricture)

Image-11a

Image-11b

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PROFORMA

NAME : AGE/SEX :

DATE : HOSP.NO :

ADDRESS :

COMPLAINTS & H/O PRESENT ILLNESS :

CO-MORBID FACTORS :

PREVIOUS SURGICAL HISTORY :

PLAIN RADIOGRAPHIC FINDINGS :

HELICAL CT FINDINGS :

Parameters for SBO :

Bowel dilatation

Level of SBO

Cause of SBO

Parameters for Associated Ischemia :

Bowel wall thickening

Bowel wall enhancement

Mesenteric congestion

Peritoneal fluid

Bowel wall pneumatosis

SURGICAL FINDINGS :

RECOMMENDATIONS

1. Helical CT should be the first imaging modality of choice in any case

of acute small bowel obstruction .

2. Always use I.V.Contrast studies to rule out bowel ischemia

3. If there is a disparity between CT findings and clinical situation,

deterioration of clinical condition always go for exploratory

laparotomy

4. Try to reduce radiation dosage to patient, by using new techniques&

different softwares.Try to get adequate information at a lower dose of

exposure.

5. Training doctors &CT technicians in management of contrast induced

side effects & emergencies.

a study on efficacy of helical computed tomography in determination of cause

Documents

bowel viability

madurai dr

determination of cause

intraoperative findings

intra operative findings

department of imaging

head of department

bonafide work of dr