Monday, June 1, 2015

Dilated Small Bowel Differential Diagnosis

A common finding in patients with abdominal pain is dilated loops of small bowel. Dilated loops may be noted on plain X-ray, fluoroscopic studies, or CT. The first step to forming a focused differential diagnosis is determining whether the folds are thin, thick (> 3 mm), or thick and nodular.

If the folds are thin, the mnemonic MISS can be used to recall the common diagnoses:

MMechanical obstructionDue to intraluminal impaction (high fiber foods), adhesions post-operatively, or a mass
IIleusPost-operatively, medications
Systemic sclerosis due to deposition of collagen
Sacculations of anti-mesenteric border
Hidebound bowel (unchanging on dynamic studies)
SSprueVillous atrophy and crypt hypertrophy → chronic fluid overload → ‘congestive gut overload’ → featureless mucosal pattern proximally in small bowel = reversal of jejunal / ileal fold pattern

Moulage sign: moulage means casted or molded structure; the jejunum appears a cast of itself due to featureless appearance because of lack of mucosal folds

Small Bowel Obstruction
Source: Radiology Assistant

If there is segmental thickening of the folds, think of the three Is: ischemia, infection, or idiopathic. Diffuse fold thickening is usually due to systemic processes such as venous congestion or cirrhosis.

Nodular fold thickening is usually due to infiltrative processes of the bowel wall. Common etiologies include Crohn disease, infection, lymphoma, metastases, and Whipple disease.

If the dilatation is thick walled, check out the differential diagnosis for small bowel aneurysmal dilatation.

If you want to learn more about GI imaging, specifically fluoroscopy, the Mayo Clinic Gastrointestinal Imaging book is a wonderful reference with over 500 images:

No comments:

Post a Comment