A 71-Year-Old Woman With Nausea and Vomiting

Caroline R. Taylor, MD


February 01, 2006

Which of the following are possible causes of small bowel obstruction?

  1. Adhesions only

  2. Luminal mass only

  3. Internal hernia only

  4. Abdominal hernia only

  5. All of the above

View the correct answer.

A CT scan was performed (Figures 2a and 2b). CT is useful in evaluating a patient with suspected small bowel obstruction because the level of obstruction, and often the etiology, may be rapidly determined. It is helpful if the patient has had a nasogastric tube placed prior to the CT scan, with decompression of gastric contents, so that oral contrast may be introduced to delineate intraluminal structures from extraluminal fluid, but the succus entericus can be delineated without oral contrast in dilated small bowel. Intravenous contrast is often more useful in demonstrating abnormal mucosal enhancement, which might suggest ischemia.

Figure 2a.

Axial CT through the pelvis, showing a fluid-containing structure in the right groin medial to the femoral vein and artery (blue arrow). There is a prominent enhancing blood vessel anterior to the hernia sac, suggesting the presence of inflammation or hyperemia. The sac contains a small amount of extraluminal fluid and a loop of thickened, enhancing small bowel. Femoral artery and vein (medial to artery) is shown by yellow arrow. Defect in transversalis fascia is adjacent to pubis (red arrow).

Figure 2b.

A parasagittal reconstruction through the right side of the abdomen (obtained by reformatting the original CT data) shows a small amount of ascites (A) adjacent to the liver. There is right lower lobe consolidation and a right-sided pleural effusion (P). Air-fluid levels are present in the small bowel (green arrow). In the pelvis, there is a loop of nondilated small bowel contiguous with a dilated segment in the right hernia sac (blue arrow), which is protruding through a defect in the transversalis fascia adjacent to the pubis (yellow arrow). Additional findings show consolidation and volume loss in the right lower lobe and a large pleural effusion.

The CT findings in this case clearly delineate the level of obstruction and its cause. If adhesions are present, they are not generally seen, but a cut-off point, angulation of small bowel, with the appropriate history of intra-abdominal surgery, are strongly suggestive. CT is extremely helpful in delineating both internal and abdominal wall hernias through characteristic location. A surgical consultation was requested. The abdominal examination disclosed a moderately distended abdomen, with positive tympany diffusely, and tenderness to palpation in lower quadrants bilaterally, with no rebound or guarding. A well-healed appendectomy scar was noted in the right lower quadrant, and there was a palpable hernia mass that was firm, nonreducible, and tender to touch.