Intestinal ObstructionAhmed Badrek-Amoudi FRCS

The common Scenario

A 50 year old gentleman presents with abdominal pain, distension and absolute constipation. With repeated episodes of vomiting.His vital sign were stable, abdomen distended with diffuse tenderness but minimal peritonism. Bowel Sounds are hyperactive.

The plain abdominal xray was taken on admission.

What are your objectives?

You should be able to address the following questions1. Is this bowel obstruction or ileus?2. Is this a small or large bowel obstruction?3. Is this proximal or distal obstruction?4. What is the cause of this obstruction?5. Is this a complex or simple obstruction?6. How should I start investigating my patient?7. What is the role of other supportive investigations?8. What is my immediate/ intermediate treatment plan?9. What are the indications for surgery?10. What are the medico-legal and ethical issues that I

should address?

Introduction and Definitions

Accounts for 5% of all acute surgical admissions Patients are often extremely ill requiring prompt assessment, resuscitation and intensive monitoring

Obstruction A mechanical blockage arising from a structural abnormality that presents

a physical barrier to the progression of gut contents. Ileus is a paralytic or functional variety of

obstruction

Obstruction is: Partial or completeSimple or strangulated

Patho-physiology I 8L of isotonic fluid received by the small intestines

(saliva, stomach, duodenum, pancreas and hepatobiliary ) 7L absorbed 2L enter the large intestine and 200 ml excreted in the

faeces Air in the bowel results from swallowed air ( O2 & N2) and

bacterial fermentation in the colon ( H2, Methane & CO2), 600 ml of flatus is released Enteric bacteria consist of coliforms, anaerobes and

strep.faecalis. Normal intestinal mucosa has a significant immune role

Distension results from gas and/ or fluid and can exert hydrostatic pressure.

In case of BO Bacterial overgrowth can be rapid If mucosal barrier is breached it may result in translocation of

bacteria and toxins resulting in bactaeremia, septaecemia and toxaemia.

Patho-physiology IIObstruction results in:

1. Initial overcoming of the obstruction by increased paristalsis

2. Increased intraluminal pressure by fluid and gas3. Vomiting 4. sequestration of fluid into the lumen from the surrounding

circulation5. Lymphatic and venous congestion resulting in oedematous

tissues6. Factors 3,4,5 result in hypovolaemia and electrolyte

imbalance7. Further: localised anoxia, mucosal depletion necrosis and

perforation and peritonitis.8. Bacterial over growth with translocation of bacteria and it’s

toxins causing bacteraemia and septicaemia.

Decompress with NGT Replace lost fluid Correct electrolyte abnormalities Recognise strangulation and perforation Systemic antibiotics.

Causes- Small BowelExtraluminal

Mural Luminal

Postoperative adhesions

Congenital adhesions

Hernia

Volvulus

Neoplasims lipoma polyps leiyomayoma hematoma lymphoma carcimoid carinoma secondary

TumorsCrohnsTBStrictureIntussusceptionCongenital

F. BodyBezoarsGall stoneFood

ParticlesA. lumbricoides

Small Bowel Adhesions• Accounts for 60-70% of All SBO• Results from peritoneal injury, platelet activation and fibrin

formation.• Associated with starch covered gloves, intraperitoneal sepsis,

haemorrhage and wash with irritant solutions iodine and other foreign bodies.

• As early as 4 weeks post laparotomy. The majority of patients present between 1-5 years

• Colorectal Surgery 25%• Gynaecological 20%• Appendectomy 14%

• 70% of patients had a single band• Patients with complex bands are more likely to be readmitted• Readmission in surgically treated patients is 35%

ADHESIVE INTESTINAL OBSTRUCTION

ADHESIVE INTESTINAL OBSTRUCTION

ADHESIVE INTESTINAL OBSTRUCTION

ADHESIVE INTESTINAL OBSTRUCTION

ADHESIVE INTESTINAL OBSTRUCTION

Hernia• Accounts for 20% of SBO• Commonest 1. Femoral hernia

2. ID inguinal

3. Umbilical

4. Others: incisional and internal H.

• The site of obstruction is the neck of hernia• The compromised viscus is with in the sac.• Ischaemia occurs initially by venous occlusion,

followed by oedema and arterialc ompromise.• Attempt to distinguish the difference between:

• Incaceration• Sliding• Obstruction

• Strangulation is noted by: » Persistent pain» Discolouration» Tenderness» Constitutional symptoms

Other causes

IBDGall stone IleusIntussusception

Inversion of the bowel upon itself secondary to a leading pointJuvenile Intussusception most often idiopathic

Also secondary to Meckel"s diverticulumPresents 6 months to 2 years of ageAs early as 1 monthAcute painful episodes followed by periods of lethargyWhen incarcerated progress to continuous lethargyMay or may not have “currant-jelly” stoolBut often stool is heme positiveRule out with a left lateral Decubitus film

INTUSSUSCEPTION

Bad Intussusception

Intussusception

Large Bowel Obstruction

Aetiology:1. Carcinoma: The commonest cause, 18% of colonic ca. present

with obstruction2. Benign stricture: Due to Diverticular disease, Ischemia,

Inflammatory bowel disease.3. Volvulus: 1. Sigmoid Volvulus: Results from long redundant,

faecaly loaded colon with a narrow pedicle 2. Caecal Volvulus4. Hernia.5. Congenital : Hirschusbrung, anal stenosis and agenesis

•Distinguishing ileus from mechanical obstruction is challenging

•According to Leplac’s law: maximum pressure is at the it’s maximum diameter. Cecum is at the greatest risk of perforation

•Perforation results in the release of formed feaces with heavy bacterial contamination

Sigmoid Volvulus Colonic Obstruction

Radiological EvaluationNormal Scout

Always request: Supine, Erect and CXR

Gas pattern:• Gastric, • Colonic and 1-2 small bowel

Fluid Levels:• Gastric• 1-2 small bowel

Check gasses in 4 areas:1. Caecal

2. Hepatobiliary

3. Free gas under diaphragm

4. Rectum

Look for calcification

Look for soft tissue masses, psoas shadow

Look for fecal pattern

The Difference between small and large bowel obstruction

Small Bowel Large bowel

•Central ( diameter 5 cm max)•Vulvulae coniventae•Ileum: may appear tubeless

•Peripheral ( diameter 8 cm max)•Presence of haustration

SymptomsThe four cardinal features of intestinal obstruction:

-abdominal pain- vomiting- distension

- constipation

Vary according to-:location of obstructionage of obstructionunderlying pathologyintestinal ischemia

SymptomsAbdominal pain

colicky in nature, around the umbilicus in SBO while in the lower abdomen in LBO

if it becomes continuous, think about perforation or strangulationVomiting

- starts early in SBO and late in LBO- vomitus starts with clear color then becomes thick,

brown and foul ( faeculent)-more with lower or complete obstruction

- diarrhea may be present with partial obstructionDistension

-more with lower obstruction

SymptomsConstipation

-more with lower or complete obstruction

- diarrhea may be present with partial obstruction

-either absolute (no feces or flatus)<-cardinal in absolute IO

or relative (flatus passed)

Distension

-more with lower obstruction

Symptoms

In strangulation:• severe constant abdominal pain

• distended abdomen• fever

• tachycardia• tender abdomen

Role of CT• Used with iv contrast, oral and

rectal contrast (triple contrast).• Able to demonstrate

abnormality in the bowel wall, mesentery, mesenteric vessels and peritoneum.

• It can define – the level of obstruction– The degree of obstruction– The cause: volvulus,

hernia, luminal and mural causes

– The degree of ischaemia– Free fluid and gas

• Ensure: patient vitally stable with no renal failure and no previous alergy to iodine

Role of barium gastrografin studies

• As: follow through, enema• Limited use in the acute

setting• Gastrografin is used in

acute abdomen but is diluted

• Useful in recurrent and chronic obstruction

• May able to define the level and mural causes.

• Can be used to distinguish adynamic and mechanical obstruction

Barium should not be used in a patient with peritonitis

How to initially investigate your patient• Lab:

• CBC (leukocytosis, anaemia, hematocrit, platelets)• Clotting profile• Arterial blood gasses• U& Crt, Na, K, Amylase, LFT and glucose, LDH• Group and save (x-match if needed) • Optional (ESR, CRP, Hepatitis profile

• Radilogical:• Plain xrays• USS ( free fluid, masses, mucosal folds, pattern of paristalsis,

Doppler of mesenteric vasulature, solid organs)• Other advanced studies (CT, MRI, Contrast studies……senior

decision)

• ECG and other investigations for co-morbid factors

Understanding the clinical findings

Clinical Findings1. History

• Persistent pain may be a sign of strangulation• Relative and absolute constipation

The Universal FeaturesColicky abdominal pain, vomiting, constipation (absolute), abdominal

distension.Complete HX ( PMH, PSH, ROS, Medication, FH, SH)

Colonic•? Preexisting change in bowel habit•Colicky in the lower abdomin•Vomiting is late•Distension prominent•Cecum ? distended

Distal small bowel•Pain: central and colicky•Vomitus is feculunt•Distension is severe•Visible peristalsis•May continue to pass flatus and feacus before absolute constipation

High•Pain is rapid

•Vomiting copious and contains bile jejunal content

•Abdominal distension is limited or localized

•Rapid dehydration

Clinical Findings2. Examination

Others

Systemic examination If deemed necessary.•CNS•Vascular•Gynaecological•muscuoloskeltal

Abdominal

•Abdominal distension and it’s pattern•Hernial orifices•Visible peristalsis•Cecal distension•Tenderness, guarding and rebound•Organomegaly•Bowel sounds

–High pitched–Absent

•Rectal examination

General

•Vital signs: P, BP, RR, T, Sat•dehydration•Anaemia, jaundice, LN•Assessment of vomitus if possible•Full lung and heart examination

Initial Management in the ER• Resuscitate:

• Air way (O2 60-100%)

• Insert 2 lines if necessary• IVF : Crytloids at least 120 ml/h. (determined by estimated fluid

loss and cardiac function). Add K+ at 1mmmol/kg• Draw blood for lab investigations• Inform a senior member in the team.• NPO.• Decompress with Naso-gastric tube and secure in position• Insert a urinary catheter (hourly urinary measurements) and

start a fluid input / output chart• Intravenous antibiotics (no clear evidence)• If concerns exist about fluid overloading a central line should be

inserted• Follow-up lab results and correction of electrolyte imbalance• The patient should be nursed in intermediate care• Rectal tubes should only be used in Sigmoid volvulus.

Indications for Surgery

Immediate intervention:• Evidence of strangulation (hernia….etc)• Signs of peritonitis resulting from perforation or ischemia

In the next 24-48 hours• Clear indication of no resolution of obstruction ( Clinical,

radiological).• Diagnosis is unclear in a virgin abdomen

Intermediate stage

The cause has been diagnosed and the patient is stabalised

Legal issues and consent

Ileus• Associated with the following conditions:

• Postoperative and bowel resection• Intraperitoneal infection or inflammation• Ischemia• Extra-abdominal: Chest infection, Myocardia infarction• Endocrine: hypothyroidism, diabetes• Spinal and pelvic fractures• Retro-peritoneal haematoma• Metabolic abnormalities:

» Hypokalaemia» Hyponatremia» Uraemia» Hypomagnesemia

• Bed ridden• Drug induced: morphine, tricyclic antidepressants

Is this an ileus or obstruction

Clinical features• Is there an under lying cause?• Is the abdomen distended but tenderness is not marked.• Is the bowel sounds diffusely hypoactive.

Radiological features:• Is the bowel diffusely distended• Is there gas in the rectum• Are further investigasions (CT or Gastrografin studies) helpful

in showing an obstruction.

Does the patient improve on conservative measures

Example of ileus