imaging modalities of intestinal obstruction mithilesh kumar medical college kolkata

IMAGING MODALITIES IN INTESTINAL OBSTRUCTIONBy – MITHLESH KUMAR

Third Professional MBBS Part – IIMedical College Kolkata

OVERVIEW

• Radiography• Computed Tomography• Magnetic Resonance Imaging• Ultrasonography• Nuclear Imaging• Angiography

Radiography

• Plain upright abdominal X – Ray• Conventional barium follow – through

examination and enteroclysis• Barium enema study

Radiological features of plain X - Ray

• Small bowel – straight segments generally central and lie transversely

• Jejunum – valvulae conniventes, spaced regularly, concertina or ladder effect

• Ileum – featureless• Caecum – rounded gas shadow in right iliac fossa• Large bowel except caecum – haustral folds, spaced

irregularly

Some special points• In intestinal obstruction fluid level appear later than gas shadow as it takes

time for gas and fluid to separate• In adults, two inconstant fluid levels – one at the duodenal cap and the

other in the terminal ileum may be regarded as normal • In infants fluid levels in small bowel may be physiological, in this age group

it is difficult to distinguish large from small bowel in the presence of obstruction because the characteristic features seen in adults are not present or are unreliable

• In small bowel the number of fluid levels is directly proportional to the degree of obstruction and to its site, the number increasing the more distal the lesion

• Limited water soluble enema differentiates large bowel obstruction from pseudo-obstruction

Supine view of the abdomen in a patient with intestinal obstruction. Dilated loops of small bowel are visible(arrows)

Upright view of abdomen in a patient with intestinal obstruction,Showing multiple air fluid levels

Lateral decubitus view of abdomen, showing air fluid levels consistent with intestinal obstruction (arrows)

Plain abdominal radiograph shows dilated loops of small bowel associated with thickened edematous valvulae conniventes

Barium follow - throughFollowing features may assist in diagnosis

• Delay in the transit time• Snakehead appearance• Beak sign• Fixation and kinking

The contrast enhanced study shows dilated loops of small bowel with stretching of the mucosal folds and a narrowed segment ending in a beak

(arrow)

EnteroclysisDivide small bowel obstruction into 3 groups

• Low – grade or incomplete obstruction• High – grade obstruction • Complete small – bowel obtruction

Barium enema study

• Useful in large bowel obstruction• In children with intussusception it is

diagnostic as well as therapeutic

Postevacuation image from part of a barium enema study, shows a coiled spring appearance at the hepatic flexure of the colon typical of an intussusception

Computed Tomography

• Recommended when initial clinical findings and plain radiographs are inconclusive

• When strangulation is suspected• Clearly demonstrate abnormalities of bowel

wall, mesentery, mesenteric vessels, peritoneum

• Should be performed with intravenous contrast enhancement

Axial computed tomography scan showing dilated, contrast filled loops of the bowel on the patient’s left( yellow arrows), with decompressed distal small bowel on the patient’s right(red arrows)

Magnetic Resonance Imaging

• Assessment of small – bowel obstruction with strangulation

Ultrasonography

• It is of particular value in looking at the dynamics of the small bowel

• Used to assess peristalsis

A sonogram of right iliac fossa shows a bowel mass

Nuclear Imaging

• White blood scanning for detection and localization of intra abdominal inflammatory disease

99mTc HMPAO labeled white blood cell scan shows active uptake of the radionuclide in the terminal ileum and caecum/ascending colon indicative of an active inflammatory process

Angiography

• Superior mesenteric angiography used in diagnosis of internal herniation, intussusception, volvulus, malrotation, and adhesions.

Imaging in Intussusception

• Plain abdominal X – Ray shows features of small and large bowel obstruction

• Barium follow through of ileocolic intussusception shows claw sign

• Abdominal ultrasonography demonstrate doughnut appearance

‘Claw ‘sign of iliac intussusception , the barium in the intussusception is seen as a claw around a negative shadow of the intussusception

Postevacuation image from part of a barium enema study shows a coiled spring appearance in the region of caecum suggestive intussusception

Imaging in Volvulus

Caecal volvulus – bird beak deformity in barium enema

Sigmoid volvulus – dilated loop

Grossly dilated loop of bowel in the central abdomen with the ends of the loop pointing towards the right half of the pelvis

Shows a medially pointed end column of the barium (beak sign) in the mid ascending colon