Maternity Care Calendar and Guidelines: Screening for Chlamydia

Current MCC Guideline (1998):

screen for chlamydia by culture
in bold font
listed under "Investigations" for early pregnancy
if high risk: repeat screening for chlamydia in third trimester
in plain font
listed under "Investigations" between 20 and 40 weeks

Literature Search:
Not done

Summary of Evidence:

Canadian Task Force on Preventive Health Care (CTFPHC)

The CTFPHE has not published an update on screening for chlamydia since the 1998 version of the Maternity Care Calendar was printed. The most recent recommendations, published in 1996¹, are as follows:

fair evidence (level II-2) to support screening of pregnant women during their first prenatal visit and subsequent treatment (B Recommendation). The authors note that the improved pregnancy outcomes attributed to screening in the first trimester may be due to the subsequent treatment with erythromycin.

Notes:

The CTFPHC lists the following options for screening
- Culture
- Polymerase chain reaction (PCR) - all sites
- Direct fluorescent antibody (DFA) - genitourinary, conjunctival, rectal, nasopharyngeal
- enzyme-linked immunoassay (ELISA) - genitourinary, conjunctival
- DNA probes - genitourinary
For pregnant women, treatment should be with erythromycin or amoxicillin

U.S. Preventive Services Task Force (USPSTF)
The USPSTF published updated recommendations for screening for chlamydial infection in 2001.² They found:

at least fair evidence (level II-2, II-3) that screening and treatment of women at risk for chlamydial infection improves pregnancy outcomes and concludes that the benefits of screening outweigh potential harms. They recommend that clinicians routinely screen asymptomatic pregnant women age 25 and younger or others at increased risk. Risk factors include being unmarried, African American, having a prior history of STD, new or multiple sexual partners, cervical ectopy and inconsistent use of barrier contraception. (B recommendation)
fair evidence that the benefits of screening low-risk pregnant women are small and may not justify the possible harms. They make no recommendation for or against routine screening of asymptomatic, low risk pregnant women aged 26 and older for chlamydial infections. (C recommendation)

Notes:

"The optimal timing of screening in pregnancy is uncertain. Screening early in pregnancy provides greater opportunities to improve pregnancy outcomes (low birth weight, premature delivery). However, screening in the third trimester may be more effective at preventing transmission of chlamydial infection to the infant during birth."
"Partners of infected individuals should be tested and treated if infected or treated presumptively."
"Chlamydia can be easily diagnosed by a number of new tests with relatively high sensitivity and specificity that outperform the traditional gold standard of culture." DNA and RNA amplification tests that use urine specimens provide a quick, noninvasive method of screening.

Recommendations of Others:

Recommendations from the Centers for Disease Control and Prevention

The CDC released STD treatment guidelines in 2002, stating that

a test for Chlamydia trachomatis should be performed at the first prenatal visit.³ Women under age 25 or at increased risk of infection (women with new or multiple sexual partners) should also be tested in the third trimester to prevent postnatal complications and transmission to the infant. The authors note that the evidence for preventing adverse effects during pregnancy is lacking.

Notes:

Doxycycline and ofloxacin are contraindicated in pregnancy. Erythromycin estolate is contraindicated during pregnancy because of drug-related hepatotoxicity. Clinical experience and preliminary data suggest that azithromycin is safe and effective. Recommended regimens include erythromycin base 500mg orally, 4 times per day for 1 week or amoxicillin 500mg orally, 3 times per day for 1 week.
Repeat testing (preferably by culture) 3 weeks after treatment is recommended
The CDC guidelines were developed based on a systematic review of the literature and after "CDC staff reviewed the published recommendations from other knowledgeable groups"

American College of Obstetricians and Gynecologists (ACOG):

ACOG states that "universal testing for all pregnant women for C. trachomatis is not recommended."⁴

Society of Obstetricians and Gynaecologists of Canada (SOGC)
SOGC guidelines recommend screening women at increased risk of infection (those in areas of high prevalence, women < 20, those with multiple sexual partners or a history of STD.⁵ They also state, there is fair evidence to support routine screening of pregnant women for chlamydia. (CTFPHE 1996 report referenced)

Conclusions:
The new guideline on the MCC will be as follows:

Screen women age <= 25 years or at high risk for chlamydia. (consider screening all women)
The recommendation to screen women under age 25 or at high risk will be bolded.
The recommendation to consider routinely screening all pregnant women will no longer be bolded as the most recent systematic review (that of the USPSTF, 2001) considered it a C recommendation. It will however be included in plain font as it is still currently recommended by the CTFPHE, 1996 and the CDC, 2002.
It will be listed under "Investigations' suggested for the first prenatal visit consistent with the CTFPHE and CDC recommendations (although screening may also be appropriate at the preconception visit)
If high risk: repeat chlamydia screen in third trimester
The recommendation will be in plain font as the optimal frequency and timing of chlamydia screening has not yet been defined.
It will be listed under "Investigations" to be considered in later pregnancy (20-40 weeks)

Note: "screen by culture" will be dropped from the guideline as there is no clear evidence that culture is the preferred method of screening

Reviewer: Colleen Kirkham, MD, CCFP January 2003

1/28/03 10:18 PM

¹ Davies HD, Wang EEL. Periodic health exam, 1996 update 2. Screening for chlamydial infections. CMAJ. 1996;154:1631-1644. (http://www.ctfphc.org)
² Nelson HD, Helfand M. Screening for Chlamydial infection: recommendations and rationale, U.S. Preventive Services Task Force. Am J Prev Med. 2001;20 (suppl 3):90-93. (www.ahcpr.gov)
³ Centers for Disease Control and Prevention. Sexually transmitted disease treatment guidelines 2002. MMWR 2002;51 (No. RR-6):1-84 (http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5106a1.htm)
⁴ Guidelines for Perinatal Care, Fourth Edition. American Academy of Pediatrics, The American College of Obstetricians and Gynecologists. 1997
⁵ SOGC Clinical Practice Guidelines. No 71. Healthy Beginnings: guidelines for care during pregnancy and childbirth. 1998 (http://www.sogc.org/sogcnet/sogc%5Fdocs/common/guide/doorway/68.html)