Chlamydia antibody titre as screening test for tubal factor infertility – a case-control study

Background: Infertility is a socially distressing medical condition that remains a public health concern in many developing countries including Nigeria. Tubal disease is the most common cause of female infertility in Africa. Sero-epidermiological studies have indicated that Chlamydial infections account for a large proportion of asymptomatic genital tract infections by demonstrating a strong link between tubal pathology and the presence of chlamydial antibodies. OBJECTIVE: To compare the serum Chlamydia antibodies between infertile women with tubal and non-tubal factor infertility. Methodology: Prospective case control study involving one hundred and forty seven subjects with tubal factor infertility (cases) and similar number of subjects with non-tubal factor infertility (controls) following hysterosalpingography. Exclusion criteria were previous clinical or laboratory evidence of pelvic infection in the previous 6 months, history of endometriosis, tubal surgery and abdominal or pelvic surgeries like ruptured appendix and ruptured ectopic. Structured interviewer-administered questionnaire was applied to obtain information on socio-demographic data and relevant gynaecology history. The weight and height were measured and body mass index calculated. Five milliliters of venous blood samples was collected from each subject to assay antibodies to Chlamydia trachomatis using ELISA Ig G kit. The data obtained was processed and analyzed using the Statistical Package for Social Sciences (SPSS), version 20.0 Chicago Illinois. Result: The prevalence of positive Chlamydia trachomatis antibodies was 48% giving a sensitivity of 70.1% and specificity of 74.1%. The accuracy of Chlamydia antibody test to distinguish subjects with bilateral tubal blockage diagnosed with HSG was 72.1%. One hundred and three cases (70.1%) and 38 (25.9%) controls tested positive to the Chlamydia antibody test (P of <0.001). A higher proportion of subjects with induced abortion (54.7%) compared with 42.8% without induced abortion had positive Chlamydia antibody index (p = 0.043) while 51.2% of subjects with secondary infertility compared with 29.8% subjects with primary infertility had positive Chlamydia index (p = 0.007). The median Chlamydia IgG index of subjects with tubal blockage was significantly higher (1.06 IQR 0.59, 1.65) than those without tubal blockage (0.47 IQR 0.29, 0.82) p <0.001. Median Chlamydia IgG index of subjects with history of induced abortion and secondary infertility was significantly higher than subjects with no history of induced abortion and primary infertility respectively (p <0.05). Conclusion: The predictability of tubal blockage using Chlamydia trachomatis antibody was relatively high with sensitivity and specificity of 70.1% and 74.1% respectively. Subjects with secondary infertility had a two-fold chance of having positive Chlamydia index than primary infertility.