Variables associated with positive findings at relaparotomy in patients with secondary peritonitis

The decision whether and when to perform a relaparotomy in secondary peritonitis is largely subjective and based on professional experience. No existing scoring system aids in this decisional process. Our aim was to search for variables that could predict positive findings at relaparotomy.

Retrospective, clinical study.

Tertiary university hospital.

Two hundred and nineteen patients of a consecutive series who underwent an emergency laparotomy for secondary peritonitis.

None. Sequential prediction models were constructed by accumulation of clinical information in chronological order using logistic regression to determine the strength of association between predictive variables and positive findings at relaparotomy outcome. Positive findings were defined as persistent peritonitis or a new infectious focus at relaparotomy.

Relaparotomy (planned or on demand) for secondary peritonitis was performed in 117 of 219 patients (53%), yielding either positive (n=62) or negative (n=55) findings. Discriminatory power for positive findings at relaparotomy improved in the successive (multivariate) models: general patient characteristics (area under the curve, 0.60; 95% confidence interval, 0.52-0.68), adding peritonitis-related variables (area under the curve, 0.73; 95% confidence interval, 0.66-0.80), adding operation-related variables (area under the curve, 0.74; 95% confidence interval, 0.67-0.81), and adding postoperative variables (area under the curve, 0.87; 95% confidence interval, 0.82-0.92). Bootstrap resampling reduced the areas under the curve of the subsequent models only slightly. Sensitivity and specificity of the final model were 82% and 76%, respectively, at a total error rate of 16%. One preoperative predictor and five postoperative predictors significantly increased the need for relaparotomy: younger age, decreased hemoglobin levels, temperature>39 degrees C, lower Pao2/Fio2 ratio, increased heart rate, and increased sodium levels.

These data suggest that the causes of secondary peritonitis and findings at emergency laparotomy for peritonitis are poor indicators for whether patients will need a relaparotomy. Factors indicative of progressive or persistent organ failure during early postoperative follow-up are the best indicators for ongoing infection and associated positive findings at relaparotomy.