The necessity and efficiency of wound surveillance after discharge.

A surgical wound surveillance program followed up 16,453 consecutive patients from 1983 through 1988. Patients were followed up for 30 days after operation, and 516 (35%) of the surgical wound infections first became manifest after discharge. In-hospital surveillance alone would have estimated the surgical wound infection rate to be 5.8% when the true rate was 8.9%. Infections that occurred after discharge were more likely in clean operations, in shorter operations, in obese patients, and in nonalcoholic patients. The probability that infections would begin after discharge was inversely associated with the duration of postoperative stay in the hospital. Postdischarge follow-up of patients who previously have undergone surgery is necessary to avoid underestimated of the infection rates and biases related to known risk factors. The most efficient time to survey patients appears to be at 21 days after the operation, at which time 90% of surgical wound infections have occurred.