Subclinical pelvic inflammatory disease and infertility.

OBJECTIVE: The reported incidence of acute pelvic inflammatory disease (PID) has decreased but rates of tubal infertility have not, suggesting that a large proportion of PID leading to infertility may be undetected. Subclinical PID is common in women with uncomplicated chlamydial or gonococcal cervicitis or with bacterial vaginosis. We assessed whether women with subclinical PID are at an increased risk for infertility.
METHODS: A prospective observational cohort of 418 women with or at risk for gonorrhea or chlamydia or with bacterial vaginosis was recruited. Women with acute PID were excluded. An endometrial biopsy was performed to identify endometritis (subclinical PID). After provision of therapy for gonorrhea, chlamydia and bacterial vaginosis participants were followed-up for fertility outcomes.
RESULTS: There were 146 incident pregnancies during follow-up, 50 pregnancies in 120 (42%) women with subclinical PID and 96 in 187 (51%) women without subclinical PID. Women with subclinical PID diagnosed at enrollment had a 40% reduced incidence of pregnancy compared with women without subclinical PID (hazard ratio 0.6, 95% confidence interval 0.4-0.8). Women with Neisseria gonorrhoeae or Chlamydia trachomatis, in the absence of subclinical PID, were not at increased risk for infertility.
CONCLUSION: Subclinical PID decreases subsequent fertility despite provision of treatment for sexually transmitted diseases. These findings suggest that a proportion of female infertility is attributable to subclinical PID and indicate that current therapies for sexually transmitted diseases are inadequate for prevention of infertility.