The frequency of salpingitis and ectopic pregnancy as epidemiologic markers of Chlamydia trachomatis.

BACKGROUND: To study the incidence of non-gonococcal salpingitis, gonococcal salpingitis and ectopic pregnancy in a defined population over a 28-year period on the assumption that the frequency of salpingitis and ectopic pregnancy may indirectly illustrate the epidemiological pattern of Chlamydia trachomatis.
DESIGN: A retrospective epidemiological study.
SETTING: University hospital with an urban catchment area. PATIENTS: Five thousand two hundred and thirty-three patients admitted to the hospital between 1969 and 1996 with a diagnosis of ectopic pregnancy, non-gonococcal salpingitis, or gonococcal salpingitis.
RESULTS: The frequencies of both non-gonococcal and gonococcal salpingitis increased steeply early in the period under study, rising to a peak in the early 1970s, then decreasing throughout the period except for the last 3 years when a slight increase was seen again. The frequency of ectopic pregnancy showed a steady increase, peaking in the late 1980s and early 1990s and then declining at the end of the study period. While the introduction of more sensitive pregnancy tests and programs for assisted fertility would increase the rate of ectopic frequency the decline during the 'nineties cannot be accounted for in this way. The peak of salpingitis cases in the early 'seventies seems to be mirrored exactly by the peak of ectopic pregnancies fifteen years later in the late 'eighties.
CONCLUSION: The frequencies of salpingitis and of ectopic pregnancy can probably be used to estimate the incidence of preceding Chlamydia trachomatis. Thus the incidence of C. trachomatis has probably declined since the early 'seventies like that of N. gonorrheae.