What can serology tell us about the burden of infertility in women caused by chlamydia?

Paddy J Horner*, Gloria Anyalechi, William M Geisler

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review


Chlamydia trachomatis (CT) causes pelvic inflammatory disease, which may result in tubal factor infertility (TFI) in women. Serologic assays may be used to determine the proportion of women with and without TFI who have had previous CT infection and to generate estimates of infertility attributable to chlamydia. Unfortunately, most existing CT serologic assays are challenged by low sensitivity and sometimes specificity for prior CT infection, however they are currently the only available tests available to detect prior CT infection. Modeling methods such as finite mixture modeling may be a useful adjunct to quantitative serologic data to obtain better estimates of CT-related infertility. In this paper, we review CT serological assays, including the use of antigens preferentially expressed during upper genital tract infection, and suggest future research directions. These methodologic improvements coupled with creation of new biomarkers for previous CT infection should improve our understanding of chlamydia’s contribution to female infertility.

Chlamydia trachomatis (CT) is the most common sexually transmitted bacteria in the world[1]. In CT-infected women who go untreated, approximately 17% develop pelvic inflammatory disease (PID), inflammation of upper genital tract structures, and this may result in chronic sequelae, including ectopic pregnancy and tubal factor infertility (TFI)[2]. In the United Kingdom, it has been estimated that CT causes approximately 35% of PID cases in women under 25 years of age and 20% in aged 16-44 years[2, 3]. Other PID-associated pathogens include Neisseria gonorrhoeae, Mycoplasma genitalium, and bacterial vaginosis-associated bacteria [4]. The majority of symptomatic PID cases have no pathogen identified[2, 4, 5]. Further, many PID cases remain undiagnosed due to atypical or absent symptoms [2-4]. There is good evidence from a longitudinal cohort study of 1884 women with PID that the persistence of fallopian tube pathology (adhesions/scarring) can cause infertility in women – tubal factor infertility (TFI)[5]. Only women with PID who have macroscopic fallopian tube inflammation (salpingitis) are at risk of TFI, which is present in some but not all diagnosed PID[2, 5]. A dose response relationship has been observed with more severe macroscopic salpingitis and more PID episodes leading to a greater risk for adverse reproductive outcomes, especially for CT infection[2, 5, 6]. There is also evidence that upper genital tract CT infection may also impair fertility in the absence of tubal pathology, this is reviewed elsewhere in this supplement by Horner et al
Original languageEnglish
JournalJournal of Infectious Diseases
Publication statusAccepted/In press - 21 Jan 2021


  • infertility
  • chlamydia
  • serology
  • antibody
  • diagnosis

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