Genital ulcers and sexually transmitted infection mimics — Rapid

Synopsis

Assess genital ulceration with consent and confidentiality, test common infectious causes without relying on appearance, recognise inflammatory, drug and malignant mimics, and coordinate treatment, partner care and safeguarding proportionately.

Genital-ulcer morphology is not sufficiently reliable to rule an STI in or out; HSV and syphilis can be painful, painless, multiple, atypical or coexist.
Take a private anatomy- and practice-based history, explain confidentiality and its limits, obtain consent for each examination and test and offer a chaperone.
Swab the base of a fresh vesicle or ulcer for HSV PCR; a dry late crust gives a poorer sample and a negative result does not exclude earlier herpes.

Key red flags

Pregnancy near delivery, neonatal or immune vulnerability, retention, inability to drink, severe pain out of proportion, necrosis, fever or neurological signs, ocular symptoms, widespread mucosal blistering, a persistent indurated or bleeding ulcer, groin nodes, or recurrent oral and genital ulcers with eye or neurological disease requires urgent escalation.

Malignant ulcer

A persistent indurated, rolled, keratotic, bleeding or enlarging ulcer and firm node requires urgent biopsy even when an initial infection test is positive.

Investigation priorities

HSV nucleic-acid amplification testFirst step

Confirm HSV-1 or HSV-2 from an active genital lesion.

Management branches

First-line ulcer screenTest common infections together

A new genital vesicle, erosion or ulcer has no immediate surgical or skin-failure emergency.

With consent, sample a fresh lesion base for HSV PCR and obtain syphilis serology, recording onset and whether an early repeat sample will be required.
Offer HIV plus gonorrhoea and chlamydia testing from each exposed anatomical site and assess hepatitis, pregnancy and vaccination needs.

Key medicines

Aciclovir for first-episode genital herpesGive 400 mg orally three times daily for 5 days in an adult with an uncomplicated first episode; extend if new lesions continue, healing remains incomplete or complications persist. Use specialist age-, weight-, pregnancy- and renal-adjusted dosing when these factors apply.

Topical lidocaine for short-term pain reliefApply a small amount of an appropriate licensed topical local-anaesthetic preparation to external painful skin as directed, or use shortly before urination; combine with simple oral analgesia and cool saline or water care.

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