RESUMEN
The Chlamydia antibody titre (CAT) is a test used to identify subfertile couples at increased risk for tubal pathology. The usefulness of the routine performance of CAT was evaluated in a multicentre prospective cohort study, in women without regular ovulation. Consecutive couples presenting with subfertility due to an irregular menstrual cycle or amenorrhoea were included. A total of 711 women were studied, all of whom underwent CAT. Tubal status was verified in 190 of these women. Two-sided tubal pathology was found in 5% of these women, and one-sided occlusion in 10%. Of all the women in the study group, 33 (4.6%) had an abnormal CAT, of which 21 underwent further tubal testing. Tubal pathology was found in two (10%) of these 21 patients. The sensitivity and specificity of CAT were respectively 20% and 89%. Correction for verification bias increased the specificity to 96% with a drop of the sensitivity to 9%. In subfertile couples with anovulation, the performance of CAT is not useful. It is proposed that testing for tubal disease in these women is delayed until treatment with clomiphene citrate has failed.