About This Page
This is a clinician-written, evidence-based guide aligned to the MCC Examination Objectives. It is structured by clinical presentation — the way the MCCQE tests and the way patients actually present. Management reflects current Canadian guidelines (CMA, CFPC, CPS). Always cross-reference with institutional protocols and clinical judgment.
The Bottom Line
- Use a syndromic approach: ulcer, discharge, dysuria, pelvic pain, proctitis, epididymitis or vaginitis
- NAAT testing for chlamydia and gonorrhoea is central; collect site-specific specimens based on exposure
- Genital ulcers in Canada are most commonly HSV or syphilis — syphilis must not be missed
- Always offer HIV, syphilis, hepatitis B/C and pregnancy testing where appropriate
- Management includes treatment, abstinence counselling, partner notification, public-health reporting and confidential trauma-informed care
Approach to the Presentation
The MCCQE1 tests STI presentations as communication, public health and clinical reasoning problems. Start with a respectful, confidential, non-judgemental sexual history: partners, practices, protection, past STIs, pregnancy risk, prevention needs and safety/consent. Then identify the syndrome: genital ulcer, urethritis, cervicitis, vaginitis, proctitis, epididymitis, PID or systemic illness. PHAC STBBI guidance supports syndrome-based assessment, site-specific testing, treatment of infections of public health importance, partner management and prevention.
Differential Diagnosis
| diagnosis | likelihood | key features | distinguishing test |
|---|---|---|---|
| Syphilis | must-not-miss | Painless chancre, regional nodes; secondary disease causes rash including palms/soles, mucous patches, condylomata lata and systemic symptoms | Syphilis serology using local algorithm; lesion PCR/dark-field where available |
| Gonorrhoea | must-not-miss | Purulent urethral/cervical discharge, dysuria, pelvic pain, epididymitis, proctitis or pharyngitis; disseminated disease causes rash/tenosynovitis/arthritis | NAAT from exposed sites; culture for susceptibility when treatment failure, assault or public-health indication |
| Pelvic inflammatory disease | must-not-miss | Lower abdominal/pelvic pain, cervical motion tenderness, uterine/adnexal tenderness, fever, discharge or abnormal bleeding | Clinical diagnosis; pregnancy test, NAATs and pelvic ultrasound if abscess/ectopic concern |
| HIV acute seroconversion | must-not-miss | Fever, rash, pharyngitis, lymphadenopathy, oral/genital ulcers or diarrhoea after exposure | HIV Ag/Ab plus HIV RNA if acute infection suspected |
| Genital HSV | common | Painful grouped vesicles/ulcers, dysuria, tender nodes and recurrent episodes; primary infection may cause fever and severe pain | HSV PCR/NAAT from lesion |
| Chlamydia | common | Often asymptomatic; dysuria, mucoid discharge, cervicitis, postcoital bleeding, epididymitis or PID | NAAT from urine/vaginal/cervical/rectal/pharyngeal sites based on exposure |
| Trichomoniasis | common | Vaginal discharge, odour, vulvar irritation and dysuria; strawberry cervix is uncommon but classic | NAAT or wet mount depending on local availability |
| Bacterial vaginosis / candidiasis | common | BV: thin grey discharge/fishy odour; candida: pruritus, thick discharge and vulvar erythema | Vaginal pH, microscopy/NAAT and clinical features |
| UTI unrelated to STI | common | Dysuria, frequency and urgency without discharge, pelvic pain or exposure risk | Urinalysis/culture when indicated; consider STI testing in sexually active patients |
| Mycoplasma genitalium | less common | Persistent or recurrent urethritis/cervicitis and PID association; macrolide resistance relevant | NAAT where available, often after persistent symptoms |
Red Flags & Key History
Symptoms
Pelvic pain, fever, cervical motion tenderness, pregnancy or positive pregnancy test
Painful swollen testis, systemic symptoms or torsion-like presentation
Disseminated gonococcal infection: fever, migratory polyarthralgia, tenosynovitis, dermatitis or septic arthritis
Neurologic, ocular or otic symptoms with syphilis risk
Sexual assault, coercion, intimate partner violence, age-related safeguarding concern or inability to consent
Site-specific exposure history: oral, vaginal, anal, shared sex toys, condom use and partner symptoms
Signs
Purulent urethral or cervical discharge
Painless indurated chancre suggests syphilis; painful vesicles/ulcers suggest HSV
Cervical motion, uterine or adnexal tenderness
Rash on palms/soles, mucous patches, condylomata lata or generalized lymphadenopathy
Septic joint or tenosynovitis in a sexually active patient
Approach to Investigation
First-line
NAAT for chlamydia and gonorrhoea from exposed sitesFirst-void urine, vaginal/cervical, rectal and pharyngeal specimens according to sexual practices
Syphilis serologyUse local screening algorithm; repeat if early exposure and initial test negative but suspicion remains
HIV Ag/Ab, hepatitis B/C testing, pregnancy testOffer broader STBBI screening and prevention counselling
HSV PCR/NAAT from lesionBest diagnostic test when an active vesicle/ulcer is present
Urinalysis/cultureWhen urinary symptoms could reflect UTI, pregnancy, pyelonephritis or complicated features
Second-line
Gonorrhoea culture and susceptibilityFor treatment failure, resistance concern, sexual assault/medico-legal context or public health recommendation
Wet mount/pH/NAAT for vaginitisFor discharge, odour or pruritus syndromes
Pelvic ultrasoundIf tubo-ovarian abscess, ectopic pregnancy, severe PID, adnexal mass or uncertain diagnosis
Mycoplasma genitalium NAATFor persistent/recurrent urethritis or cervicitis depending on local availability
Specialist
Public health involvementReportable STBBIs, partner notification and outbreak/resistance management
Specialist referralOcular/neurosyphilis, disseminated gonorrhoea, pregnancy with syphilis, complex PrEP/PEP or recurrent treatment failure
Management Principles
PHAC Sexually Transmitted and Blood-Borne Infection (STBBI) Guides1
Clinical and communication approach
- Provide confidential, trauma-informed, non-judgemental care
- Take a sexual history: partners, practices, protection, past STIs, pregnancy/prevention
- Assess for coercion, assault, safeguarding and intimate partner violence
2
Testing
- Use site-specific NAATs for chlamydia/gonorrhoea based on exposure
- Test for syphilis and HIV; add hepatitis B/C, pregnancy and vaginitis testing as appropriate
- Do not rely on urine NAAT alone if rectal or pharyngeal exposure occurred
3
Empiric treatment
- Treat syndromically when follow-up is uncertain, symptoms are significant, PID/epididymitis is suspected or public-health risk is high
- Use current PHAC/provincial regimens because gonorrhoea resistance and recommended therapy change
- Advise abstinence from sexual contact until treatment complete, symptoms resolved and partners treated
4
Partner management and prevention
- Discuss partner notification and public health support
- Offer hepatitis B and HPV vaccination review
- Discuss condoms, HIV PrEP/PEP eligibility and follow-up testing windows
Complications & Pitfalls
- Urine-only testing: Rectal and pharyngeal infections are missed if exposed sites are not tested.
- Missing syphilis: Secondary syphilis can mimic viral illness, rash or autoimmune disease.
- Failure to test pregnancy: Pregnancy changes imaging, antibiotic choices and urgency.
- Not treating partners: Reinfection is common without partner notification.
- Confidentiality error: STI care tests CanMEDS communicator/professional roles.
MCCQE1 Exam Tips
- 1STI presentations are syndromic: identify ulcer, urethritis/cervicitis, PID, epididymitis, proctitis or vaginitis
- 2Dysuria in a sexually active patient is not automatically cystitis; discharge or exposure risk should trigger NAATs
- 3Painless genital ulcer suggests syphilis; painful grouped vesicles suggest HSV, but test for syphilis too
- 4PID is a clinical diagnosis; do not wait for NAATs before treating when pelvic pain and CMT/adnexal tenderness are present
- 5Site-specific testing is frequently examined: urine NAAT misses rectal/pharyngeal infection
- 6Always include counselling, partner notification, public health reporting and prevention
practicetest your knowledge on sexually transmitted infection presentation (genital ulcer, discharge, dysuria)Apply what you've learnt with MCCQE1-style questions from the iatroX Q-Bank — infectious disease and beyond.
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