Although surgical site infections (SSIs) occurring after hospital disc
harge cause substantial morbidity, their epidemiology is not well unde
rstood, and methods for routine postdischarge surveillance have not be
en validated. Inpatient and outpatient surveillance followed 5572 nono
bstetric procedures among members of a health maintenance organization
with extensive automated records. Records were screened for coded dia
gnoses, tests, and prescriptions and, if positive, were reviewed by re
ading full text. Questionnaires regarding the occurrence of an SSI wer
e sent to the same patients and their surgeons, One hundred thirty-two
SSIs were documented, of which 84% occurred after hospital discharge
and 63% were managed outside the surgical facility. Postdischarge SSIs
led to an average of 4.6 additional ambulatory encounters. Patient an
d surgeon questionnaires had a sensitivity of 28% and 15%, respectivel
y. These data suggest that most SSIs occur after discharge and are not
detectable by conventional surveillance. Nonetheless, they cause subs
tantial resource utilization.