Abdominal ultrasonography for the diagnosis of strangulation in small bowel obstruction.

The efficacy of abdominal ultrasonography for the recognition of strangulation was evaluated prospectively in 231 patients with adhesive small bowel obstruction. The diagnosis based on ultrasonographic criteria was accurate in 35 of 39 patients with strangulation and in 176 of 192 with simple obstruction. Abdominal ultrasonography revealed the presence of strangulation in 13 of 15 patients with strangulation who were clinically diagnosed as having simple obstruction, and ruled it out in 28 of 36 with simple obstruction who were clinically suspected to have strangulation. An akinetic dilated loop observed on real-time ultrasonography proved to have high sensitivity (90 per cent) and specificity (93 per cent) for the recognition of strangulation; however, its positive predictive value for strangulation was only 73 per cent. The presence of peritoneal fluid was sensitive for strangulation. Compared with clinical judgment based on conventional parameters, abdominal ultrasonography proved to be useful for the early recognition of strangulation.