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Sexually Transmitted Infections in Women

Sexually transmitted infections (STIs) intersect daily urogynecologic and pelvic-reconstructive practice. Cervicitis presents as discharge or postcoital bleeding workups, untreated chlamydia and gonorrhea drive pelvic inflammatory disease and tubal-factor infertility, and active infection alters the risk profile of pelvic-floor and continence surgery. STIs in women encompass a broad range of pathogens — chlamydia, gonorrhea, syphilis, trichomoniasis, genital herpes, HPV, and Mycoplasma genitalium — with distinct screening, diagnostic, treatment, and prevention considerations. Approximately 1 in 5 U.S. adults had an STI in 2018, and rates of gonorrhea, chlamydia, and syphilis have continued to rise.[1]

Screening Recommendations​

The USPSTF and CDC recommend annual screening for chlamydia and gonorrhea in all sexually active women ≤24 years and in older women with risk factors (new or multiple partners, partner with STI, inconsistent condom use).[2][3] Key additional screening points:

  • Syphilis. The CDC (2023) expanded screening to all sexually active persons aged 15–44 in counties exceeding 4.6 primary/secondary syphilis cases per 100,000 females per year — a threshold met by 72% of the U.S. population. In pregnancy, screening is recommended at the first prenatal visit, during the third trimester (~28 weeks), and at delivery.[4][5][6]
  • HIV. Universal screening at least once for all adults; annual screening for those at increased risk.[7]
  • Hepatitis B and C. At least once for all adults; hepatitis C screening in all pregnant patients.[7]
  • Trichomoniasis. Consider testing asymptomatic women at high risk or in high-prevalence settings; annual screening recommended for women with HIV.[8][9]
  • Extragenital screening. Pharyngeal and rectal NAAT testing should be considered in women based on sexual practices and shared decision-making, as urogenital-only testing misses a substantial proportion of infections.[3]

Diagnosis​

Nucleic acid amplification tests (NAATs) are the preferred diagnostic method for chlamydia, gonorrhea, trichomoniasis, and M. genitalium, with sensitivities of 86–100% and specificities of 97–100%.[1] Vaginal specimens (clinician- or self-collected) are preferred for women.[10]

  • Syphilis relies on serologic testing using a sequential algorithm (treponemal followed by nontreponemal, or vice versa). Both tests may be nonreactive in ~30% of primary syphilis cases.[4][1]
  • Genital herpes. Type-specific PCR of lesions is preferred over culture; two-step serologic testing is recommended when serology is used.[11][12]
  • M. genitalium. FDA-cleared NAATs are available; testing is recommended only in symptomatic women with persistent cervicitis, not for routine screening.[1][13]

Treatment​

The 2021 CDC STI Treatment Guidelines introduced several key updates. The following table summarizes recommended regimens.

InfectionFirst-line RegimenNotes
ChlamydiaDoxycycline 100 mg PO BID × 7 dPreferred over azithromycin; superior efficacy at rectal sites
GonorrheaCeftriaxone 500 mg IM × 1 (1 g if ≥150 kg)Azithromycin co-treatment no longer recommended
Early syphilisBenzathine penicillin G 2.4 million U IM × 1Penicillin only therapy in pregnancy; desensitize if allergic
Late latent syphilisBenzathine penicillin G 2.4 million U IM weekly × 3
Trichomoniasis (women)Metronidazole 500 mg PO BID × 7 d7-day regimen superior to single 2 g dose in women (unlike in men)
Genital herpesAcyclovir, valacyclovir, or famciclovirDaily suppression reduces recurrences and transmission risk by ~50%
M. genitalium (macrolide-sensitive)Doxycycline × 7 d → azithromycinResistance-guided sequential therapy
M. genitalium (macrolide-resistant / unknown)Doxycycline × 7 d → moxifloxacin 400 mg daily × 7 dMacrolide resistance >50% in many regions
PIDCeftriaxone 500 mg IM + doxycycline 100 mg BID × 14 d + metronidazole 500 mg BID × 14 dMetronidazole now routinely included

Key treatment highlights:

  • Chlamydia. Doxycycline 100 mg twice daily for 7 days is now preferred over azithromycin, based on superior efficacy particularly at rectal sites.[9][7]
  • Gonorrhea. Ceftriaxone 500 mg IM single dose (1,000 mg if ≥150 kg); azithromycin cotreatment is no longer recommended.[9][8]
  • Syphilis. Benzathine penicillin G 2.4 million units IM — single dose for early syphilis, weekly × 3 for late latent. Penicillin is the only recommended therapy in pregnancy; desensitization is required for penicillin-allergic pregnant patients.[4][1]
  • Trichomoniasis in women. Metronidazole 500 mg twice daily for 7 days (the 7-day regimen is superior to a single 2 g dose in women, unlike in men).[9][8]
  • Genital herpes. Acyclovir, valacyclovir, or famciclovir for episodic and suppressive therapy. Daily suppressive therapy reduces recurrences and transmission risk by ~50%.[11]
  • M. genitalium. Resistance-guided sequential therapy — doxycycline 100 mg twice daily for 7 days, followed by azithromycin (if macrolide-sensitive) or moxifloxacin 400 mg daily for 7 days (if macrolide-resistant or unknown). Macrolide resistance exceeds 50% in many regions.[1][6]
  • PID. Ceftriaxone 500 mg IM + doxycycline 100 mg twice daily for 14 days + metronidazole 500 mg twice daily for 14 days — metronidazole is now routinely included.[9][14]

All patients diagnosed with chlamydia, gonorrhea, or trichomoniasis should be retested in 3 months due to high reinfection rates.[7]

Complications in Women​

Untreated STIs carry significant reproductive consequences:

  • Pelvic inflammatory disease (PID). Develops in approximately 2–10% of women with untreated chlamydia within weeks to a year. C. trachomatis is the most common identified pathogen (~23% of PID cases).[15][14]
  • Infertility. Reported in 8% after one PID episode, 18% after two, and 38% after three. Most women with tubal factor infertility have no known history of PID but are seropositive for C. trachomatis.[15][16]
  • Ectopic pregnancy. Nearly 10% of first pregnancies after PID are ectopic.[15]
  • Chronic pelvic pain. Reported 3× more frequently in women with a history of PID (18% vs. 5%).[15]
  • Adverse pregnancy outcomes. Syphilis in pregnancy can cause stillbirth in up to 40% of exposed fetuses; congenital syphilis cases increased 106% from 2019 to 2023. Chlamydia and gonorrhea are associated with preterm delivery, PPROM, and neonatal ophthalmia.[4][17]
  • Repeat chlamydial infections are associated with increased risk of PID and reproductive sequelae.[18][19]

STIs During Pregnancy: Screening, Treatment, and Complications​

InfectionScreening ScheduleTreatment in PregnancyMaternal / Fetal Complications
SyphilisFirst prenatal visit, ~28 wk, deliveryBenzathine penicillin G (desensitize if allergic)Stillbirth up to 40%; congenital syphilis ↑106% (2019–2023)
HIVFirst prenatal visit (universal)Antiretroviral therapyVertical transmission
Hepatitis BFirst prenatal visit (universal)per HBV protocols; neonatal HBIG + vaccineVertical transmission
Hepatitis CAll pregnant patientsPostpartum DAA therapyVertical transmission
ChlamydiaRisk-based at first prenatal visitAzithromycin (doxycycline contraindicated)Preterm delivery, PPROM, neonatal ophthalmia
GonorrheaRisk-based at first prenatal visitCeftriaxonePreterm delivery, neonatal ophthalmia
TrichomoniasisIf symptomatic or high-risk / HIV+MetronidazolePPROM, preterm delivery

Prevention​

HPV Vaccination​

The 9-valent HPV vaccine (Gardasil 9) targets HPV types responsible for ~90% of cervical cancers and is the only HPV vaccine available in the U.S.[20][21]

  • Routine vaccination. Ages 9–12 (2-dose series); catch-up through age 26 (3-dose series if initiated ≥15 years).[20][22]
  • Ages 27–45. Shared clinical decision-making for previously unvaccinated individuals.[23][24]
  • Population-level impact. Cervical cancer incidence has declined ~69% in vaccinated females aged 20–24; CIN3 declined 34% in ages 15–19.[22]
  • Screening recommendations apply regardless of vaccination status.[25]

Doxycycline Post-Exposure Prophylaxis (Doxy-PEP)​

Doxy-PEP (200 mg within 72 hours of condomless sex) has demonstrated ~80% reductions in chlamydia and syphilis and ~50% reduction in gonorrhea among MSM and transgender women.[26][27] However, the CDC currently recommends doxy-PEP only for MSM and transgender women with a bacterial STI in the past 12 months — not for cisgender women — based on a trial in Kenyan women that showed no significant benefit, likely due to low adherence (only 29% had detectable doxycycline in hair samples).[27][28]

Other Prevention Strategies​

  • Consistent condom use provides moderate protection (HR 0.70 for HSV-2 transmission).[12]
  • Expedited partner therapy is permitted in most states to limit STI spread.[7]
  • Behavioral counseling is recommended for all adolescents and adults at increased STI risk.[14]

Special Populations​

  • Pregnancy. Universal screening for HIV, syphilis, and hepatitis B; risk-based screening for chlamydia, gonorrhea, and hepatitis C. Syphilis screening should occur at least 3 times during pregnancy.[7][5]
  • Women with HIV. Screen for gonorrhea, chlamydia, syphilis, and trichomoniasis at entry to care and at least annually; every 3–6 months for those with multiple partners.[8]
  • Adolescents. At highest risk for chlamydia and gonorrhea; all states allow minors to consent for STI care.[7]
  • Women who have sex with women. Lower STI risk than women who have sex with men, but screening should be guided by current anatomy and sexual behaviors.[7]

Antimicrobial Resistance Concerns​

Antimicrobial resistance is an escalating threat, particularly for gonorrhea (most strains remain ceftriaxone-sensitive, but resistance monitoring is critical) and M. genitalium (macrolide resistance >50% in many regions, with increasing fluoroquinolone resistance).[8][29][30] All gonorrhea treatment failures should have culture with antimicrobial susceptibility testing.[8]

Cross-references​

References​

1. Tuddenham S, Hamill MM, Ghanem KG. "Diagnosis and Treatment of Sexually Transmitted Infections: A Review." JAMA. 2022;327(2):161-172. doi:10.1001/jama.2021.23487

2. US Preventive Services Task Force, Davidson KW, Barry MJ, et al. "Screening for Chlamydia and Gonorrhea: US Preventive Services Task Force Recommendation Statement." JAMA. 2021;326(10):949-956. doi:10.1001/jama.2021.14081

3. Yonke N, Aragón M, Phillips JK. "Chlamydial and Gonococcal Infections: Screening, Diagnosis, and Treatment." Am Fam Physician. 2022;105(4):388-396.

4. Chevalier FJ, Bacon O, Johnson KA, Cohen SE. "Syphilis." JAMA. 2025. doi:10.1001/jama.2025.17362

5. US Preventive Services Task Force, Silverstein M, Wong JB, et al. "Screening for Syphilis Infection During Pregnancy: US Preventive Services Task Force Reaffirmation Recommendation Statement." JAMA. 2025;333(22):2006-2012. doi:10.1001/jama.2025.5009

6. Workowski KA, Bachmann LH, Chan PA, et al. "Sexually Transmitted Infections Treatment Guidelines, 2021." MMWR Recomm Rep. 2021;70(4):1-187. doi:10.15585/mmwr.rr7004a1

7. Klein DA, Valerio CR, Cofield ZN. "Sexually Transmitted Infections: Updated Guideline From the CDC." Am Fam Physician. 2022;105(5):553-557.

8. Horberg M, Thompson M, Agwu A, et al. "Primary Care Guidance for Providers of Care for Persons With Human Immunodeficiency Virus: 2024 Update by the HIV Medicine Association of the Infectious Diseases Society of America." Clin Infect Dis. 2024. doi:10.1093/cid/ciae479

9. Dalby J, Stoner BP. "Sexually Transmitted Infections: Updates From the 2021 CDC Guidelines." Am Fam Physician. 2022;105(5):514-520.

10. Miller JM, Binnicker MJ, Campbell S, et al. "Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2024 Update by the IDSA and ASM." Clin Infect Dis. 2024. doi:10.1093/cid/ciae104

11. Gnann JW, Whitley RJ. "Genital Herpes." N Engl J Med. 2016;375(7):666-674. doi:10.1056/NEJMcp1603178

12. Plunkett M, Neville CT, Chang JG. "Genital Herpes: Rapid Evidence Review." Am Fam Physician. 2024;110(5):487-492.

13. Wood GE, Bradshaw CS, Manhart LE. "Update in Epidemiology and Management of Mycoplasma genitalium Infections." Infect Dis Clin North Am. 2023;37(2):311-333. doi:10.1016/j.idc.2023.02.009

14. Curry A, Williams T, Penny ML. "Pelvic Inflammatory Disease: Diagnosis, Management, and Prevention." Am Fam Physician. 2019;100(6):357-364.

15. Wiesenfeld HC. "Screening for Chlamydia trachomatis Infections in Women." N Engl J Med. 2017;376(8):765-773. doi:10.1056/NEJMcp1412935

16. Tsevat DG, Wiesenfeld HC, Parks C, Peipert JF. "Sexually Transmitted Diseases and Infertility." Am J Obstet Gynecol. 2017;216(1):1-9. doi:10.1016/j.ajog.2016.08.008

17. Reese PC. "STIs During Pregnancy." Am Fam Physician. 2024;109(1):10-12.

18. den Heijer CDJ, Hoebe CJPA, Driessen JHM, et al. "Chlamydia trachomatis and the Risk of Pelvic Inflammatory Disease, Ectopic Pregnancy, and Female Infertility: A Retrospective Cohort Study Among Primary Care Patients." Clin Infect Dis. 2019;69(9):1517-1525. doi:10.1093/cid/ciz429

19. Haggerty CL, Gottlieb SL, Taylor BD, et al. "Risk of Sequelae After Chlamydia trachomatis Genital Infection in Women." J Infect Dis. 2010;201 Suppl 2:S134-155. doi:10.1086/652395

20. Markowitz LE, Unger ER. "Human Papillomavirus Vaccination." N Engl J Med. 2023;388(19):1790-1798. doi:10.1056/NEJMcp2108502

21. DeSieghardt A, Ding L, Ermel A, et al. "Population-Level Effectiveness and Herd Protection 17 Years After HPV Vaccine Introduction." JAMA Pediatr. 2025;179(12):1326-1334. doi:10.1001/jamapediatrics.2025.3568

22. American Cancer Society. Cancer Prevention and Early Detection Facts & Figures. American Cancer Society; 2025.

23. ACOG Committee Opinion No. 809. "Human Papillomavirus Vaccination." Obstet Gynecol. 2020;136(2):e15-e21. doi:10.1097/AOG.0000000000004000

24. Meites E, Szilagyi PG, Chesson HW, et al. "Human Papillomavirus Vaccination for Adults: Updated Recommendations of the Advisory Committee on Immunization Practices." MMWR Morb Mortal Wkly Rep. 2019;68(32):698-702. doi:10.15585/mmwr.mm6832a3

25. Perkins RB, Wentzensen N, Guido RS, Schiffman M. "Cervical Cancer Screening: A Review." JAMA. 2023;330(6):547-558. doi:10.1001/jama.2023.13174

26. Peters RPH, Grinsztejn B, Celum C, et al. "Innovations in the Biomedical Prevention, Diagnosis, and Service Delivery of HIV and Other Sexually Transmitted Infections." Lancet. 2025;406(10515):2133-2151. doi:10.1016/S0140-6736(25)00983-3

27. Bachmann LH, Barbee LA, Chan P, et al. "CDC Clinical Guidelines on the Use of Doxycycline Postexposure Prophylaxis for Bacterial Sexually Transmitted Infection Prevention, United States, 2024." MMWR Recomm Rep. 2024;73(2):1-8. doi:10.15585/mmwr.rr7302a1

28. Stewart J, Oware K, Donnell D, et al. "Doxycycline Prophylaxis to Prevent Sexually Transmitted Infections in Women." N Engl J Med. 2023;389(25):2331-2340. doi:10.1056/NEJMoa2304007

29. Williamson DA, Chen MY. "Emerging and Reemerging Sexually Transmitted Infections." N Engl J Med. 2020;382(21):2023-2032. doi:10.1056/NEJMra1907194

30. Machalek DA, Tao Y, Shilling H, et al. "Prevalence of Mutations Associated With Resistance to Macrolides and Fluoroquinolones in Mycoplasma genitalium: A Systematic Review and Meta-Analysis." Lancet Infect Dis. 2020;20(11):1302-1314. doi:10.1016/S1473-3099(20)30154-7