Hormonal factors and the laboratory detection of Chlamydia trachomatis in women: implications for screening?

Abstract

One thousand and fifty-six new and re-registered consecutive women attending a genitourinary medicine clinic requiring speculum examination were screened for Chlamydia trachomatis by enzyme immunoassay (IDEIA, Dako Diagnostics Ltd). Of 1022 women who had results available for both cervix and urethra C. trachomatis was detected in 8.8% (89/1022) in any site, 2.3% (23/1022) in both sites, 4.9% (51/1022) at the cervix alone and 1.5% (15/1022) at the urethra alone. Thus sampling at the urethra increased detection by 17% (15/89). Analysis of 808 women with a regular menstrual cycle showed a significant association of combined oral contraceptive use, age and ectropion with the detection of C. trachomatis. The detection of C. trachomatis showed a significant variation with the menstrual cycle (P = 0.023) (relative risk (rr) 1.7 (95% confidence intervals (CI) 1.0-2.8)). It was detected significantly more often in the latter part. Stepwise logistic regression analysis revealed that ectropion and age were the stronger determinants of C. trachomatis detection and not oral contraceptive use or menstrual cycle. The variation in detection of C. trachomatis with the menstrual cycle was independently associated with combined oral contraceptive use and the lack of a cervical ectropion. The increased detection at the cervix was present after the second week in combined oral contraceptive users (P = 0.008) (rr = 2.3 (1.2-4.5)) but only after the 3rd week in women without an ectropion (P = 0.004) (rr = 2.7 (1.3-5.5)). Combined oral contraceptives, ectropion and youth, are markers for the carriage of C. trachomatis in the lower genital tract of women. It is also detected significantly more often in the latter part of the menstrual cycle in women who are oral contraceptive users.

PIP: In England, clinical researchers enrolled 1056 women aged 13-56 years attending the genitourinary medicine clinic in Bristol during February-October 1994 in a study on the relationship between the menstrual cycle and the detection rate of Chlamydia trachomatis from the cervix. They conducted a routine speculum examination and an amplified enzyme immunoassay (EIA) to take a swab from the cervix and a swab from the urethra. The chlamydia incidence rate was 8.8% (93 women) at any site, 2.3% at both sites, 4.9% at the cervix alone, and 1.5% in the urethra alone. Sampling at the urethra increased the detection of C. trachomatis by 17%. 808 women had a regular menstrual cycle. C. trachomatis was more likely to be detected in women aged under 25 years than in those of older age groups (14% for age 15-19 and 12.2% for 2-24 vs. 3.6-8%; p 0.0001). Detection of C. trachomatis at the cervix had a significant association when weeks 1-2 were compared to weeks 3 and later (5.4% vs. 9.4%; p = 0.029) and when weeks 1-3 were compared to week 4 and later (6.2% vs. 10.8%; p = 0.023). It had a relative risk (RR) of 1.7. Detection of C. trachomatis at any site was also significant when weeks 1-3 were compared to weeks 4-5 (11.8% vs. 7.5%; p = 0.048) (RR = 1.6). Combined oral contraceptive (OC) use and the lack of a cervical ectropion (i.e., cervix turning outward) both had an independent association with the variation in detection of C. trachomatis with the menstrual cycle. Specifically, the elevated detection at the cervix occurred after the second week in OC users (14.2% vs. 6%; RR = 2.3; p = 0.008) and only after the third week in women without a cervical ectropion (9.3% vs. 3.5%; RR = 2.7; p = 0.004). Based on these findings, the authors recommend sampling the urethra in addition to the cervix to increase chlamydia detection and chlamydia screening for young women with no cervical ectropion who use OCs. They also recommend that screening for chlamydia be performed in the latter part of the menstrual cycle in OC users who do not have a cervical ectropion.