gi: overview: organ systems gastrointestinal (gi) tract [alimentary canal] a continuous muscular...
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GI: Overview: Organ systems
Gastrointestinal (GI) tract [Alimentary canal] a continuous muscular digestive tube Digests:
breaks food into smaller fragments Absorbs:
digested material is moved through mucosa into the blood
Eliminates: unabsorbed & secreted wastes.
Organ systems
Includes: Mouth, pharynx &
esophagus Stomach Small intestine Large intestine
Accessory digestive organs: teeth, tongue, gall bladder, salivary glands, liver & pancreas
ANATOMY OF ESOPHAGUS Flattened muscular tube,
size 18 to 26cm beginning at lower border
of cricoid cartilage (opposite 6th cervical vertebra)
ending at cardiac orifice of stomach(opposite 11th cervical vertebra)
Divided into 3 anatomical segments i.e., cervical, thoracic & abdominal
Normal barium swallow showing normal esophageal caliber with no evidence of filling defects, ulcerations, strictures or diverticulae
Esophageal disorders
1. Filling defects: Intraluminal or extraluminal
2. Stricture: Corrosive, Achalasia, malignant
3. Diverticulum• Zenker ’s diverticulum• Traction diverticulum• Epi - phrenic diverticulum
Esophageal abnormalities
[1] Filling defect
[A] Intraluminal lesion
A lesion inside the bowel lumen
totally surrounded by Barium
[B]Extraluminal lesion
Arises from outside+ compresses
the bowel
Causes narrowing from one side only
Forms a shallow angle with the
bowel wall
[2] Stricture
A segment of luminal
narrowing
[3] Diverticulum
A saccular out pouching connected
to the bowel lumen usually fills
with barium
[A] Corrosive Stricture
Affect Long segment starts at the level of
the aortic arch
Accidentally in children or Suicide
attempts in adults
Radiographic appearance of the stricture:
long, with smooth outline
Upper end of which is funnel shaped and
tapers into normal oesophagus
Lost mucosal pattern
Corrosive stricture: Barium swallow showing a long segment of esophageal narrowing with mild proximal esophageal dilatation
[B] Achalasia of the cardia Achalasia is an esophageal motility
disorder that occurs due to the inability
of the lower esophageal sphincter (LES)
to relax.
As a result, the esophagus fills with
ingested food and fluids.
Barium swallow showing smooth
tapering "Bird's beak" of the distal
esophageal segment with marked
proximal esophageal destination
"megaesophagus
"Bird's beak" appearance and "megaesophagus," typical in achalasia.
[c] Malignant Stricture
Occur anywhere in the
oesophagus Commonly seen in
the middle third of esophagus
Post cricoid carcinoma affects
the upper third
Lower third lesions may simulate
achlasia
Radiographic appearance:
Barium swallow showing
esophageal stricture with
overhanging edges resulting in
the typical apple core
configuration
[2] Filling defect
Esophageal filling defects
may be due to benign lesion
as benign liomyoma or
malignant lesion like
esophageal carcinoma or
lymphoma.
In all cases endoscopic
evaluation is needed for
biopsy taking Esophageal carcinoma: Barium swallow showing a large midesophageal filling defect distending the esophageal lumen
[3] Esophageal diverticulae
Zenker ’s diverticulum: arise from the posterior wall of
the upper esophagus in the area of the pharynx.
Traction diverticulum: forms in the mid esophagus area ;
may form due to scarring from pulmonary tuberculosis or
an inflammatory process within the mediastinum.
Epi - phrenic diverticulum arises in the distal esophagus
just superior to the lower esophageal sphincter (LES).
They may form as a complication to achalasia.
STOMACH
Muscular bag that forms the widest & most distensible part of digestive tube
Extened from Oesophagus to duodenum
Location – epigastric, umbilical & left hypochondriac• 25cm long• Capacity – 1.5 to 2L
Gastric disorders
1. Hiatus hernia2. Filling defect Gastric bezoar Benign lesions Malignant lesions 3. Peptic Ulcer Disease (PUD)
Hiatus hernia Herniation of the stomach through the esophageal hiatus above the diaphragmTypes:1. sliding hiatal hernia (commonest). 2. A rolling (paraesophageal
hiatal hernia) (rare)
Bezoars : This is a hard mass of entangled material
found within the stomach or intestines that cannot be digested.
They are often made of hair and food fibers.
The artifact (arrows) depicted on this radiograph consists of a hard ball of entangled materials called a bezoar.
Gastric carcinoma It is generally asymptomatic in the early stages and has generally metastasized to other areas of the body by the time it has been diagnosed.As a result, it has a poor prognosis.UGI studies present thick, irregular, and rigid (linitis plastica) folds.
Linitis plastic: Barium meal showing marked reduction of the gastric lumen with irregular outlines compared to the normal stomach seen in the right image
The arrows on this UGI radiograph are pointing to a gastric carcinoma. Note the classic “apple-core” appearance that is a characteristic of an adenocarcinoma.
Peptic Ulcer Disease (PUD)
Gastric Ulcers These are very rare and may be a
complication of gastric carcinoma.Peptic Ulcers These are located in the duodenum and
are much more common than gastric ulcers.
They are mostly located in the duodenal bulb and are usually not associated with cancer.
Peptic Ulcer Disease: normal vs acute
Normal duodenal cap: Spot view of barium meal showing the normal triangular shape of the duodenal cap which should be radiographed when it is filled with barium
Acute duodenal ulcer: Double Contrast barium meal study demonstrating an ulcer in the duodenal bulb with radiating mucosal folds.
Chronic duodenal ulcer
•Duodenal ulcer with scarring and marked
deformity of the base of the duodenal bulb after
healing of a duodenal ulcer.
•By Barium meal showing the classic trefoil
deformity of the duodenal cap due to fibrosis
resulting from healed ulcer
Bowel Obstruction:
The two types of bowel obstructions are as follows:
small bowel and large bowel obstruction.
Signs and symptoms of a bowel obstruction would
include the following:
Abdominal Pain
Abdominal Distention
Vomiting
Constipation
Causes of Bowel Obstruction:
Causes of mechanical bowel obstruction :
1. Hernia2. Adhesions3. Volvulus4. Intussusception5. Neoplasm (Adenoma/Polyp,
adenocarcinoma)6. Crohn’s Disease7. Constipation
Plain film1. colonic distension: gaseous
secondary to gas-producing organisms in faeces
2. collapsed distal colon3. small bowel dilatation, depends
on duration of obstruction incompetence of the ileocaecal
valve CT is the best diagnostic
modality used as: 1. confirm the diagnosis 2. localize the location of
obstruction 3. identify the cause.
Large bowel obstruction
Radiographs reveal dilated small bowel loops with multiple air fluid levels
Small bowel obstruction
Radiographic features Plain film1. In most cases, the abdominal
radiograph will have the following features:
2. Dilated loops (over 3cm) of small bowel predominantly central proximal to the obstruction
3. fluid levels if the study is erect (non-standard technique)
CT is more sensitive than plain radiographs and will demonstrate the cause in ~80% of cases .
Hernia:
It is a weakening of the
abdominal wall that allows a
portion of the intestine to
protrude through it.
A reducible hernia can be pushed
back into the abdominal cavity
while an incarcerated hernia
cannot leading to obstruction.
A common hernia in men is
called an inguinal hernia. inguinal hernia
Sub mucosal lymphoid tissue hyperplasia → thickening and rigidity of the affected segment → luminal narrowing = Stricture
Radiographic appearance: The characteristic of Crohn disease is the presence of
skip lesions. Barium small bowel follow-through mucosal ulcers
when severe leads to cobblestone appearance may lead to sinus tracts and fistulae
thickened folds due to oedema pseudodiverticula formation: due to contraction at the
site of ulcer with ballooning of the opposite site string sign: tubular narrowing due to spasm or
stricture depending on chronicity
Corhn’s disease
Corhn’s disease
This image demonstrates the classic radiograph appearance of the “string sign” that is a characteristic of Crohn’s disease.
cobblestone appearance
Edematous inflammatory infiltration of the mucosa which ulcerates
The colon is diffusely affected with involvement of the rectum
Radiographic features Plain film Non specific but may show evidence of mural thickening
(more common), with thumbprinting also seen in more severe cases.
Fluoroscopy - Barium enema Mucosal ulcers are undermined (button-shaped ulcers). When most of the mucosa has been lost, islands of mucosa
remain giving it a pseudo-polyp appearance. In chronic cases the bowel becomes featureless with loss of
normal haustral markings, luminal narrowing and bowel shortening (lead pipe sign).
Ulcerative Colitis
Ulcerative colitis: Double contrast barium enema shows a featureless descending and sigmoid colon, lacking normal haustral marking.