Reading the abdominal x-ray in bowel obstruction

The patient the film belongs to

A 45-year-old lady presents with a 2 days history of abdominal distension and pain, more in the umbilical area, with anorexia, nausea and vomiting. She also describes not passing stool for the last 5 days, and flatus for the past 2 days as well. The rest of the review of systems is unremarkable. She has no significant medical history, and her surgical history is positive for an open appendectomy done 15 years back.

That is small bowel obstruction, and the scar is the whole of the etiology: the abdomen is not virgin, so the cause is adhesions. The questions asked of the case run in the same order every time - what is the most likely diagnosis, how will you confirm bowel obstruction, what is the most likely etiology, what are the other causes of SBO, does this patient require a CT, and how will you manage the patient.

How it is diagnosed

Bowel obstruction is confirmed on an abdomen x-ray, and it is 2 views, erect and supine.

The first question when seeing an abdominal x-ray is what is dilated, and the limits are SB more than 3 cm, LB more than 6 cm and cecum more than 9 cm.

To tell small from large bowel on the supine film: SB is in the center while large bowel is in the periphery, and large bowel has haustrations while small bowel has valvulae, written on the page as pilace circularis. The erect film is set out the other way: air fluid levels in the center are LB and in the periphery SB. The supine line and the erect line do not agree on which bowel lies in the center; both are reported and neither is chosen here.