Background Chlamydia trachomatis (CT) is one cause of pelvic inflammatory disease (PID) and ectopic pregnancy (EP). Rates of CT testing and diagnosis have increased since the 1990s, especially following full implementation of the National Chlamydia Screening Programme in 2008. We investigated PID and EP trends in the context of increased chlamydia screening.

Methods Rates of clinical PID among 15 to 44 year old women were calculated using the Clinical Practice Research Datalink (CPRD, diagnoses from a sample of primary care sites) for 2000–2011. Diagnoses were classified as ‘definite’, ‘probable’ or ‘possible’ PID according to the assigned medical codes. Incidence of EP per conception among 15–44 year old females was calculated using the CPRD and the Inpatient Hospital Episode Statistics (HES) (1998–2011).

Results The rate of ‘definite/probable’ PID was highest among 20–24 year olds (410/100,000py; 95% CI: 399–308). Between 2000 and 2011, the rate of ‘probable/definite’ cases among women declined in all age groups; on inclusion of ‘possible’ cases, rates of PID increased over the analysis period. Rates of EP (which were similar in HES and CPRD) were fairly stable overall between 1998 and 2010 (10.5/1,000 conceptions). EP rates increased with age and trends differed by age group, with decreases among women aged 30 years or older and small increases among < 30 year olds.

Conclusions We observed homogeneity in declining rates of ‘definite/probable’ PID in all ages, but heterogeneity in EP trends by age. Interpreting trends in CT sequelae is complicated by diagnostic coding (PID), delays in sequelae onset (EP), variation in incidence by age and multiple aetiologies. EP trends in young women should become more informative in coming years for the evaluation of the impact of chlamydia screening. The likelihood of causes other than CT screening leading to changes in EP and PID need to be carefully assessed.