The Israeli Study of Surgical Infection of drains and the risk of wound infection in operations for hernia.

In a prospective follow-up study of 5,571 general surgical patients at 11 hospitals (23 departments) in Israel, 1,487 patients underwent operations for hernia (all types) and were screened daily for the development of postsurgical wound infection. Infection developed in 68 (4.6 per cent) at the site of the incision. Fourteen factors were analyzed for the presumed effect on the risk of infection; only four were significant in a multivariate model. Of these factors (old age, incarcerated or recurrent hernia, coexistent infection and drains), the introduction of drains had the strongest effect (relative risk equaled 4.1; p less than 0.001). Drains increased the risk in all the participating hospitals and in any category of patient. They prolonged the period a wound was susceptible to bacterial infection from nine to 16 days. The risk increased linearly with the duration of the drainage. The over-all proportion of patients who had a drain inserted was 19 per cent, with hospitals varying from 9 to 40 per cent of patients operated upon (p less than 0.001). Our findings suggest that the risk of an infection associated with drains may outweight their worth. Furthermore, there is no concensus among surgeons on the need for drains. Some surgeons use drains indiscriminately and others, rarely.