Strangulating obstruction of the bowel: a reevaluation of radiographic criteria.

Fifty consecutive cases of strangulating obstruction were compared with 100 consecutive cases of surgically proven simple obstruction due to adhesions or hernia. All cases were studied by the usual supine and either erect or decubitus abdominal films, and by two successive supine films made at 5 min intervals. Radiographic criteria previously described as signs of possible strangulation were evaluated in the two series. Reduced activity of the small bowel loops on the successive supine films was the only frequent sign (58% of the cases with strangulating obstruction) which showed a statistically significant difference in incidence between the two groups. Other signs seen with some frequency (22%-28% of the group with strangulation) were long air-fluid levels, loss of valvulae conniventes, retention of bubbly fecal matter in the right colon, and predominance of fluid-filled loops; however, they occurred with the same frequency in simple obstruction. The more specific signs of bowel congestion and necrosis (i.e., a narrow rigid loop or intramural gas) were seen in 10% and 2% of the cases, respectively. Only the incidence of a narrow rigid loop in strangulation reached statistical significance. This study confirms the difficulty of diagnosing strangulating obstruction using plain films of the abdomen. Successive abdominal films were shown to be valuable in providing information about small bowel activity, which can help in the differential diagnosis.