Abdominal Pain - Free CME Quick Quiz

Educational Objective:

Describe the clinical presentation and radiographic findings in small bowel obstruction.

Key Point:

Small obstruction is a common cause of intestinal obstruction, and should be suspected in patients with a prior surgical history. Hallmark findings on an upright abdominal plain film are dilated loops of small bowel, air-fluid levels, and a paucity of air in the distal intestine. 

Explanation:

Although it can occur in patients without a surgical history, especially among people with a prior history of intra-abdominal inflammation or infection, small bowel obstruction is most common among patients with a previous history of abdominal surgery. Obstruction leads to vomiting, “third spacing” of fluid that can cause dehydration and electrolyte abnormalities, and, when a diagnosis is delayed, strangulation and necrosis of bowel. 

Vital signs are often normal in small bowel obstruction, unless dehydration or bowel strangulation has occurred. Abdominal distension and diffuse tenderness are typical; local peritoneal signs indicate strangulation and should prompt urgent surgical consultation. 

While abdominal radiographs are less helpful in other causes of abdominal pain, they can be diagnostic in cases of bowel obstruction without signs concerning for strangulation. Small bowel obstruction on plain film is characterized by dilated loops of small bowel, air-fluid levels, and a paucity of gas in the distal intestine (especially the colon). A CT scan can be helpful in cases that are unclear, or if strangulation is suspected. 

Adynamic ileus usually presents on radiograph with dilated loops of bowel throughout the entire small and large intestine. Cecal and sigmoid volvulus are characterized by profound dilatation of the colon.