Stem

A 23-year-old nulliparous woman presents to the gynaecology outpatient department with a 5-day history of bilateral lower abdominal pain, deep dyspareunia, increased yellowish vaginal discharge and fever (38.6 degrees C). She also reports postcoital bleeding. She has had a new male sexual partner for the past month and uses condoms inconsistently. Her last menstrual period was 3 weeks ago. She has no significant past medical history.^[1]

On examination: temperature 38.6 degrees C, pulse 98/min, BP 112/72 mmHg. The abdomen is soft with bilateral lower quadrant tenderness but no guarding or rebound. Speculum examination reveals mucopurulent discharge at the cervical os with easy bleeding on swabbing. Bimanual examination demonstrates marked cervical motion tenderness and bilateral adnexal tenderness without a palpable mass. A urine pregnancy test is negative.^[1]

Questions

a) What is the most likely clinical diagnosis, and state the minimum CDC clinical criteria that justify immediate empirical treatment. (2 marks)^[1]

Pelvic inflammatory disease (PID) — ascending infection of the upper female genital tract, most commonly due to gonorrhoea, chlamydia and anaerobes (often polymicrobial).^[1][3]

CDC 2021 minimum criteria for empirical PID treatment (treat if no other cause identified and ANY ONE present): cervical motion tenderness, OR uterine tenderness, OR adnexal tenderness. This patient meets all three and has additional specificity criteria (fever above 38.3 degrees C, mucopurulent cervical discharge). A pregnancy test is negative, excluding ectopic pregnancy.^[1]

b) Outline the investigations you would send, and explain why you would NOT wait for the results before treating. (2 marks)^[1]

Investigations: NAAT (nucleic acid amplification test) on a vaginal/cervical swab (self- or clinician-collected) and a first-catch urine for N. gonorrhoeae and C. trachomatis; a full STI screen (HIV, syphilis RPR/TPHA, hepatitis B and C); full blood count and CRP/ESR (raised in PID); transvaginal ultrasound to exclude a tubo-ovarian abscess; vaginal pH and saline/KOH microscopy (to distinguish vaginitis); and a pregnancy test (done — negative).^[1]

I would NOT wait for the NAAT because PID is the leading PREVENTABLE cause of tubal-factor infertility and ectopic pregnancy — every day of delay increases tubal mucosal destruction and scarring. Cumulative infertility is about 12 percent after one PID episode and over 50 percent after three. Empirical antibiotics are indicated immediately on clinical grounds.^[1]

c) Give the definitive outpatient antibiotic regimen with agent, dose, route and duration, and state the indication for inpatient (IV) treatment. (3 marks)^[1]

Outpatient (CDC 2021):

• Ceftriaxone 500 mg intramuscularly as a single dose (cover gonorrhoea; 1 g IM if body weight over 150 kg),^[1]
• PLUS doxycycline 100 mg orally twice daily for 14 days (cover chlamydia and other pathogens),^[1][3]
• PLUS metronidazole 500 mg orally twice daily for 14 days (cover anaerobes).^[1]
• Review at 48 to 72 hours; admit if no improvement. Treat partners; re-test at 3 months.^[1]

Indications for inpatient IV therapy (ceftriaxone 1 g IV daily + IV doxycycline + IV metronidazole): severe illness, pregnancy, suspected or confirmed tubo-ovarian abscess, failed outpatient therapy, a surgical abdomen not excluded, inability to tolerate oral intake, non-adherence, or an intrauterine device in situ with severe disease. Drainage is required for a tubo-ovarian abscess over 8 cm or one that is ruptured or persistent.^[1]

d) During the same clinic visit her partner is contacted. Outline partner management and the four public-health measures that must accompany treatment. (2 marks)^[1]

Partner management: trace and treat all partners of the last 60 days; offer expedited partner therapy (EPT) where legal (provide a prescription or medication for the partner without clinical evaluation); advise sexual abstinence for 7 days after single-dose therapy (or until a 7-day course is completed) and until all partners are treated; re-test the patient at 3 months for re-infection (10 to 20 percent re-infection rate).^[1]

Four accompanying public-health measures: (1) screen and treat for co-infections — HIV, syphilis, hepatitis B and C; (2) counsel on condom use and safer sex; (3) notify public health (gonorrhoea and chlamydia are notifiable diseases); (4) consider HIV pre-exposure prophylaxis (PrEP) for high-risk patients and offer vaccination (hepatitis B, HPV).^[1][3]

e) The patient asks whether PID will affect her future fertility. Quantify the risk and explain the mechanism of tubal damage. (1 mark)^[1]

Even with correct treatment, fertility is reduced — cumulative tubal-factor infertility is about 12 percent after one PID episode, 25 percent after two, and over 50 percent after three; the risk of ectopic pregnancy rises 6 to 10 fold, and chronic pelvic pain occurs in up to 30 percent. The mechanism is ascending infection of the fallopian tubes (salpingitis) causing mucosal destruction, oedema and a T-cell/IFN-gamma-mediated fibrotic response (amplified by chlamydial heat-shock protein 60) that produces tubal scarring, fimbrial damage and tubal occlusion — the structural basis of tubal-factor infertility and ectopic implantation.^[1][3]

References3ShowHide

1. [1]Workowski KA, Bachmann LH, Chan PA, et al. Sexually Transmitted Infections Treatment Guidelines, 2021 MMWR Recomm Rep, 2021.PMID 34292926
2. [2]Luckey A, Balasegaram M, Barbee LA, et al. Zoliflodacin versus ceftriaxone plus azithromycin for treatment of uncomplicated urogenital gonorrhoea: an international, randomised, controlled, open-label, phase 3, non-inferiority clinical trial Lancet, 2026.PMID 41391465
3. [3]Peuchant O, Lhomme E, Martinet P, et al. Doxycycline versus azithromycin for the treatment of anorectal Chlamydia trachomatis infection in women concurrent with vaginal infection (CHLAZIDOXY study): a multicentre, open-label, randomised, controlled, superiority trial Lancet Infect Dis, 2022.PMID 35550262