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Screening all sexually active adolescent females for Chlamydia every 6 months: a new guideline


  • Is yearly screening of all sexually active adolescent females for infection with Chlamydia trachomatis adequate and if not, can we identify a subset of adolescent females at greater risk for infection to screen more aggressively?

Clinical Bottom Lines

  1. All sexually active female adolescent females should be screened for infection with Chlamydia trachomatis at 6 month intervals in order to better prevent PID and its sequelae (tubal infertility, chronic abdominal pain, ectopic pregnancy).
  2. If one were to only screen "high risk" female adolescents one would miss a large portion of those with infection (>50% in this study). This calls for universal screening of all sexually active females regardless of their reported risk factors.

Summary of Key Evidence

  1. The prevalence of Chlamydia infection was 29.1% among population of 12-19 yo females attending 2 STD, 2 Family Planning and 5 school based clinics; the incidence was 28.0 cases per 1000 person months.
  2. Median time to + Chlamydia infection after initial negative test result was 7.2 months; 25% were diagnosed within 5.0 months.
  3. Median time to repeat infection (visits separated by at least 30 days) was 6.3 months; 25% were diagnosed within 4.1 months.
  4. Only 32.2% of + infections would have been diagnosed if only those patients who reported that they had symptoms or had had contact with someone with an STD had been screened.
  5. Nucleic acid amplification tests (PCR) were used on both cervical and urine specimens.
  6. Sensitivity of PCR assumed to be 87.6% and specificity 99% (based on prior studies).

Additional Comments

  • Authors recognize that patient population was homogenous and high risk and thus recognize the possible limitations of the generalizability of the study.
  • Authors also recognize that data collection asked limited questions regarding risk factors and relied on patient's ability to self-report risky behaviors and symptoms.
  • The ability to screen more frequently than every year relies on the availability of nucleic acid amplification tests that can be used on urine specimens.
  • Estimates range from 10-40% of all inadequately treated patients with Chlamydia infections will progress to PID.


  1. Burstein GR. Incident Chlamydia trachomatis infections among inner-city adolescent females. JAMA 1998; 260: 521-6.
  2. Howell, MR, Quinn TC, Braithwhite W, Gaydos CA. Screening women for Chlamydia trachomatis in family planning clinics. Sexually Transmitted Diseases. 1998;25: 108-17.
  3. Hillis S, Wasserheit, J. Screening for Chlamydia-A Key to the Prevention of Pelvic Inflammatory Disease. New England Journal of Medicine. 1996;334: 1399-1400.

CAT Author: Tracy Richmond, MD

CAT Appraisers: John G. Frohna, MD

Date appraised: September 25, 2000

Last updated October 15, 2002
Department of Pediatrics and Communicable Diseases
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