Early Diagnosis of the Strangulated Obstruction

Shigeru Yamagishi, Shigeki Yamaguchi, Hideaki Kimura, Shouichi Fujii^*, Yoshihiro Moriwaki, Hirohiko Mochizuki, Yasushi Ichikawa, Hideyuki Ike^*, Shigeo Ohki^* and Hiroshi Shimada

Second Department of Surgery, Yokohama City University
Yokohama City University Medical Center Gastroenterological Center^*

Purpose: We determined whether the discriminant formula of multivariate analysis is useful for early diagnosis of strangulation ileus. Methods: Subjects were 39 patients undergoing laparotomy under a diagnosis of bowel obstruction from 1994 to 1999. Based on operative findings, they were divided into a strangulation group (St group, n=11) and a simple obstruction group (Sim group, n=28) and were compared for physical findings, laboratory data, and radiological imaging. Factors leading to a diagnosis of strangulated obstruction were clarified and the discriminant formula by multivariate analysis calculated. We studied the formula prospectively, and its usefulness in diagnosis. Result: Cases with peritoneal irritation sign numbered 6 (54.5%) in the St group (p≤0.001), whose average Pco2 was significantly higher than that in the Sim group. (34.58 vs. 41.20 mmHg; p≤0.001). The St group had a significantly higher frequency of ascites and lack of the to and fro sign than the Sim group (p≤0.001, p≤0.05). All patients in the St group had ascites, wall thickening, and decreased enhancement, while the frequency of findings in the Sim group was 20.0% (p≤0.001) for ascites and 30.0% for wall thickening but no decreased enhancement. Multiple regression analysis showed independent factors in the diagnosis of strangulated obstruction to be peritoneal irritation sign, collection of ascites (US or CT), and Pco2. The discriminant formula was as follows: Y=0.48×Peritoneal irritation sign (1/0) +0.31×Collection of ascites (1/0) -0.052×Pco2 (mmHg) +2.12 (1: positive, 0: negative). In the prospective study of this formula, all instances except for a false-negative example in the St group, all instances can be classified and sensitivity calculated to be 85.7%, specificity 100%, and accuracy 91.7%, indicataing the formula's usefulness. Conclusion: Strangulated obstruction was identified by the peritoneal irritation sign, Pco2<35, and the existence of ascites. The discriminant formula was thus useful in early diagnosis of strangulated obstruction.

Key words
strangulated obstruction, small bowel obstruction, multiple regression analysis, discriminant formula

Reprint requests
Shigeru Yamagishi Second Department of Surgery, Yokohama City University 3-9 Fukuura, Kanazawa-ku, Yokohama-shi, 236-0004 JAPAN

Accepted
September 25, 2002

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