Testing for Chlamydia and Gonorrhea in Pregnancy
Abstract & Commentary
By Rebecca H. Allen, MD, MPH, Assistant Professor, Department of Obstetrics and Gynecology, Warren Alpert Medical School of Brown University, Women and Infants Hospital, Providence, RI, is Associate Editor for OB/GYN Clinical Alert.
Dr. Allen reports no financial relationships relevant to this field of study.
Synopsis: In this national retrospective study, 59% and 57% of women were tested at least once during pregnancy for Chlamydia trachomatis or for Neisseria gonorrhoeae, respectively. Of those women testing positive, 78% and 76% underwent a test of cure for C. trachomatis and N. gonorrhoeae, respectively.
Source: Blatt AJ, et al. Chlamydial and gonococcal testing during pregnancy in the United States. Am J Obstet Gynecol 2012;207:55.e1-8.
The authors performed a retrospective cohort study of 1,293,423 pregnant women aged 16 to 40 in the United States from June 1, 2005 to May 30, 2008, using data from the Quest Diagnostics Informatics Data Warehouse. Women aged 16-40 years who had an obstetrical panel (that included a rubella antibody test) performed at Quest Diagnostics were assumed to be pregnant, and those who had any further laboratory tests at Quest Diagnostics during what was estimated to be the third trimester (to ensure continuity) were enrolled as subjects. Of these women, 525,258 (41%) had race data available through the maternal serum screen test. In addition, the authors identified Medicaid insurance as a marker of socioeconomic status. Chlamydial and gonoccocal testing results were then extracted, and testing was determined to be at the first prenatal visit if it occurred shortly before or during the visit when the obstetric lab panel test was performed.
The study population was similar in race and proportion on Medicaid (18.1%) to the total U.S. pregnant population. Although the study population was older than the total U.S. pregnant population, the authors adjusted for this in the results. The authors found that 761,315 (59%) and 730,796 (57%) of women were tested at least once during pregnancy for Chlamydia trachomatis or for Neisseria gonorrhoeae, respectively (the age-adjusted rates were 60% and 58%, respectively). In addition, 37% of women were tested for C. trachomatis during the first prenatal visit. Testing rates for chlamydia were highest for younger women (71.5% for age 16 to 24 compared to 58.5% for age 35 to 40) and African American women (74% compared to 59.2% for whites). Of those tested at least once, the prevalence of C. trachomatis was 3.5% and the prevalence of N gonorrhoeae was 0.6% (the age-adjusted rates were 4.6% and 0.8%, respectively). Not surprisingly, the prevalence of infection was highest among younger ages with 16% of 16-year-olds testing positive compared to < 1% of women older than age 35 years. A test of cure was performed for 78% of chlamydia-positive women and 76% for gonorrhea-positive women. Test of cures were positive among 6% of women with chlamydia and 3.8% of women with gonorrhea.
Commentary
The American College of Obstetricians and Gynecologists (ACOG) recommends that all pregnant women be screened for chlamydial infection during their first prenatal care visit.1 The rationale for universal screening is the relatively high prevalence of infection (2 -13%), the existence of effective treatment options, and the negative sequelae of chlamydial infection for the pregnancy and neonate. If negative, the test should be repeated for pregnant women at increased risk (women aged 25 years or younger, or women who have a new, or more than one, sexual partner) in the third trimester. If positive, a test of cure should be performed 3 weeks after completing therapy to confirm successful treatment, and the woman should be rescreened in the third trimester. The Centers for Disease Control and Prevention (CDC) issued similar recommendations.2 For gonorrhea, ACOG and the CDC recommend screening only for pregnant women at increased risk for infection.1,2 However, in clinical practice, commercially available assays most frequently test for both infections simultaneously. Therefore, testing rates for both infections are usually identical, as this study demonstrates.
The authors of this study report the prevalence of chlamydia and gonorrhea among pregnant women and compliance with ACOG and CDC recommendations. The study population was similar to the population of pregnant women in the United States; therefore, the results are generalizable to those women with access to health care. As a retrospective study, the most important limitation is lack of access to the clinical records of participants to determine why they were not screened or whether follow-up took place at another laboratory. Nevertheless, the report provides a picture of compliance, with ACOG and CDC recommendations among insured pregnant women. Unfortunately, compliance was not ideal with 40% of pregnant women not tested at all for chlamydia. Test of cures also were not performed according to recommendations. The fact that younger women were more likely to be tested indicates that clinicians were probably using a risk-based screening strategy, which was ACOG's position prior to 2007 and is the recommendation for non-pregnant women. In defense of these clinicians, screening guidelines were changed during the study period.
Not all organizations agree with ACOG and the CDC regarding universal testing for chlamydia among pregnant women. One might ask whether a 36-year-old, pregnant woman in a monogamous sexual relationship really needs to be screened for chlamydia. There is a significant harm from a false-positive diagnosis for the pregnant woman's relationship, and false-positive results increase when the prevalence is low. This study showed a very low prevalence in older women. The United States Preventive Services Task Force (USPSTF) only recommends chlamydial screening among pregnant women aged 24 and younger and among older pregnant women at increased risk.3 The USPSTF recommends against routine screening of women age 25 and older, whether pregnant or not, who have no risk factors. Clinical practice likely varies within and between communities. In our hospital, the low-income prenatal care clinic where I work always has screened universally for chlamydia. In contrast, a few of the private OB/GYN practices are only now beginning to adopt universal testing of pregnant women. Which testing strategy you employ depends on which organization you adhere to, with ACOG and the CDC on one side and the more conservative USPSTF on the other. Clinical judgment is paramount and screening can be individualized according to the USPSTF. Nonetheless, since a pelvic exam is routinely performed at the first prenatal visit, it is not difficult to collect a cervical sample for chlamydia (and gonorrhea).
References
- Guidelines for Perinatal Care, 6th ed. Washington DC: American Academy of Pediatrics, American College of Obstetrician Gynecologists; 2007.
- Workowski KA, et al; Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines, 2010. MMWR Recomm Rep 2010;59:1-110.
- United States Preventive Services Task Force. Screening for chlamydial infection. Available at: www.uspreventiveservicestaskforce.org/uspstf/uspschlm.htm. Accessed Aug. 24, 2012.
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