A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
A 32-year-old female presents to the gynecologist with a primary concern of infertility. She has been unable to become pregnant over the last 16 months despite consistently trying with her husband. She has not used any form of contraception during this time and her husband has had a normal semen analysis. She has never been diagnosed with any chronic conditions that could explain her infertility; however, she remembers testing positive for a sexually transmitted infection about four years ago. Which of the following is the most likely cause for her infertility?
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A
Chlamydia serovars A, B, or CIncorrect. Chlamydia serovars A–C cause trachoma (eye disease, leading infectious cause of blindness) — not genital infection or tubal infertility.
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B
Chlamydia serovars D-KCorrect. Chlamydia serovars D–K cause cervicitis and PID with tubal scarring, the leading infectious cause of tubal-factor infertility in young women.
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C
SyphilisIncorrect. Syphilis presents with a painless chancre, then systemic disease (rash, condylomata lata, neurosyphilis), but doesn't classically cause tubal infertility.
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D
Herpes simplex virusIncorrect. HSV causes painful recurrent genital ulcers but is not a major cause of tubal scarring or infertility.
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E
Chlamydia serovars L1, L2, or L3Incorrect. L serovars cause lymphogranuloma venereum (painful inguinal lymphadenopathy, anorectal disease) and are rare in the U.S.; serovars D–K are the cause of cervicitis and tubal-factor infertility.
↑ Tap an answer to reveal the reasoning
Answer: B. Sixteen months of infertility in a young woman with a normal-semen-analysis partner and a history of an STI four years ago strongly suggests tubal-factor infertility from prior pelvic inflammatory disease (PID). The most common cause of PID in young women is Chlamydia trachomatis serovars D–K (along with Neisseria gonorrhoeae), which ascend from the cervix and cause salpingitis, often subclinically. Resulting tubal scarring causes infertility and increases ectopic pregnancy risk.
Chlamydia serovars are clinically important to distinguish: A, B, Ba, and C cause trachoma (chronic keratoconjunctivitis and the leading infectious cause of blindness worldwide); D–K cause urogenital infection (cervicitis, urethritis, PID, epididymitis), neonatal conjunctivitis and pneumonia, and reactive arthritis; L1–L3 cause lymphogranuloma venereum (LGV) with painless genital ulcer and tender inguinal buboes.
Syphilis and HSV do not classically cause tubal infertility — syphilis produces a painless chancre and systemic disease, and HSV causes painful recurrent ulcers but not salpingitis.
**Why each option:**
**A.** Chlamydia serovars A–C cause trachoma (eye disease, leading infectious cause of blindness) — not genital infection or tubal infertility.
**B.** Correct — Chlamydia serovars D–K cause cervicitis and PID with tubal scarring, the leading infectious cause of tubal-factor infertility in young women.
**C.** Syphilis presents with a painless chancre, then systemic disease (rash, condylomata lata, neurosyphilis), but doesn't classically cause tubal infertility.
**D.** HSV causes painful recurrent genital ulcers but is not a major cause of tubal scarring or infertility.