A middle aged man presented with worsening bloating, cramping abdominal pain, nausea, and vomiting. He had been in the ED the day before for similar symptoms, his x-rays were normal, and he had been diagnosed with gastroenteritis. With vomiting and cramping pain, you wonder about a bowel obstruction. Can physical diagnosis help?
LIMITATIONS OF RADIOGRAPHS
This is a very important topic because plain films have a sensitivity for small bowel obstruction approximately 50% and even noncontrast CT scan has limitations in sensitivity (Ros J Am Coll Radiol 2006).
DISTENSION IS HUGE!
The first thing is to recognize that intestinal obstruction is a heterogenous event, and presents differently according to the level of obstruction, whether proximal or distal. In general the more proximal obstructions present with dominant vomiting, and the distal obstructions present with prominent distension. This is huge (literally). When you see distension, pursue this finding, as it has high discriminatory value.(Eskelinen 1994)
SCARS OUTSIDE PREDICT SCARS INSIDE
The majority of patients (85%) with bowel obstruction have a history of previous abdominal surgery.(Eskelinen Scand J Gastroenterol 1994) In the poor historian, an abdominal scar is a useful proxy.
Diminished bowel sounds indicate ileus and increased bowel sounds indicate bowel obstruction, though there is overlap and these are neither sensitive nor specific.(Gu Dig Surg 2010) Listen for an increase in loudness, faster cycle times, and a higher pitch of sound. SBO can make everything higher: volume, frequency, pitch. If the radiologist says it is SBO vs ileus then the presence of bowel sounds is helpful in arguing against ileus. Gastroenteritis will cause increased bowel sounds.
A history of constipation is present in only 37% but is 90% specific. Relief with vomiting is not common (19% sensitive) but very specific for bowel obstruction (93%) .
Take home points
-Note the history of abdominal surgeries or look for a scar
-Distension is huge! (sensitive and specific)
-Auscultation may have some value in ileus vs gastroenteritis vs SBO