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OverviewAetiologyPathophysiologyClinical features and red flagsInvestigationsDifferential diagnosisManagementComplicationsMonitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Genital herpes and syphilis in gynaecological care

Obstetrics and gynaecology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Ulcers can signal neurological or systemic disease

Urinary retention, meningism, encephalopathy, ocular or otological symptoms, disseminated herpes, cardiovascular instability or severe systemic syphilis requires urgent specialist assessment.

Action: Assess observations and neurological function, examine eyes or hearing symptoms urgently, obtain diagnostic samples without delaying indicated antivirals or specialist penicillin therapy, and admit when complications cannot be managed safely as an outpatient.

Overview

Assess genital ulcers without relying on stereotyped appearances, start timely herpes care, stage and treat syphilis correctly, and escalate neurological or pregnancy-related risk.

Genital ulceration requires parallel consideration of infection, inflammatory dermatosis, trauma, aphthous ulceration and neoplasia. Herpes simplex virus is the commonest infectious cause in UK sexual-health practice, while syphilis is less common but has profound neurological, cardiovascular, fetal and public-health consequences. Ask about onset, prodrome, pain, new lesions, previous episodes, systemic rash, neurological and eye or ear symptoms, pregnancy, medicines, immune status and sexual exposures. Offer examination and sampling with explicit consent and attend to assault or safeguarding cues.

Primary genital herpes often begins with tingling, burning or systemic symptoms followed by grouped vesicles that erode into painful shallow ulcers, tender lymphadenopathy and dysuria. Yet recurrent disease may be a single fissure, excoriation or subtle erosion. Clinical appearance is insufficient because trauma, Candida fissuring, dermatitis and aphthae overlap. Take a firm swab from the lesion base for HSV NAAT and type the virus, which informs recurrence counselling. A negative swab from an old healing lesion does not fully exclude herpes.

Practice

Two practice questions

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Obstetrics and gynaecologyOriginal SBA

Testing an active herpetic lesion

A patient presents within 48 hours of developing painful grouped genital vesicles and shallow ulcers. Which investigation best confirms the cause of the active lesions?

Choose one answer, then submit
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Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • BASHH anogenital herpes guideline 2024
  • BASHH and RCOG herpes in pregnancy guideline 2024
  • BASHH syphilis guideline 2024
  • UKHSA syphilis public-health guidance
  • NHS genital herpes guidance

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom

Start oral antiviral treatment for a first episode within five days or later if new lesions, systemic symptoms or complications persist. Aciclovir 400 mg three times daily or valaciclovir 500 mg twice daily for five days are recommended options. Provide regular analgesia, saline bathing and topical lidocaine 5% ointment for selected painful lesions. Encourage hydration and strategies to pass urine; urinary retention, meningism or severe disease warrants admission. Antivirals shorten symptoms and viral shedding but do not eradicate latency.

Syphilis staging depends on history, examination and prior serology, not a rash label alone. Primary infection may cause a chancre and regional nodes; secondary infection may cause a diffuse rash, condylomata lata, mucous patches, hepatitis or neurological manifestations. Early latent syphilis is asymptomatic infection acquired within the preceding two years under UK definitions. Disease of longer or uncertain duration is managed as late latent unless evidence establishes an earlier stage. Ask directly about visual, auditory and neurological symptoms at every stage.

Use a treponemal screening assay with confirmatory testing and a quantitative RPR or VDRL to assess activity and follow response. Very early lesions can precede seroconversion, so direct lesion NAAT or dark-ground examination and repeat serology are important after a convincing exposure. Neurological, ocular or otological symptoms change investigation and require urgent specialist pathways; uncomplicated early benzathine penicillin is inadequate for neurosyphilis. Screen for HIV and other STIs and test partners through a staged lookback.

Benzathine penicillin G is the treatment anchor for uncomplicated syphilis: one 2.4-million-unit intramuscular dose for early infection and three weekly doses for late latent or unknown-duration infection. Explain the Jarisch-Herxheimer reaction, a transient febrile inflammatory response after treatment that is not penicillin allergy. Pregnancy demands urgent specialist penicillin treatment and obstetric assessment because delay risks congenital syphilis. For genital herpes in pregnancy, timing of first episode and proximity to birth guide suppressive antivirals and delivery planning under the joint BASHH and RCOG guideline.

Key points

  • Describe ulcers by number, pain, depth, edge, base, vesicles, lymph nodes and extragenital findings, but never use appearance alone to exclude herpes, syphilis or another serious cause.
  • Swab a fresh lesion for HSV-1 and HSV-2 NAAT; routine HSV antibody testing is not a substitute for lesion diagnosis and is rarely useful in a typical presentation.
  • Treat a first genital-herpes episode within five days of onset or while new lesions and systemic symptoms continue, using oral aciclovir or valaciclovir and extending after review if healing is incomplete.
  • Syphilis chancres are classically painless and indurated but may be multiple, painful or atypical; secondary syphilis can cause rash involving palms and soles, mucous patches and systemic symptoms.
  • Investigate suspected syphilis with treponemal and quantitative non-treponemal serology plus direct lesion testing where available, accounting for an early seronegative window.
  • Treat early syphilis with benzathine penicillin G 2.4 million units intramuscularly once; late latent infection requires the same dose weekly for three doses after correct staging.
  • Pregnant patients with syphilis require penicillin through specialist care; doxycycline is not an acceptable pregnancy substitute and fetal assessment must not delay maternal treatment.

Aetiology

01

Herpes simplex viruses

HSV-1 and HSV-2 enter through mucosa or damaged skin, establish sensory-ganglion latency and later reactivate with or without lesions.

02

Treponema pallidum

The syphilis spirochaete crosses mucosa or skin during sexual contact, disseminates early and can persist through prolonged latent infection.

03

Host and pregnancy context

Immunosuppression can amplify herpes severity, while transplacental syphilis and peripartum HSV exposure create distinct fetal and neonatal risks.

Pathophysiology

  1. 1
    HSV epithelial lysis

    Viral replication destroys epithelial cells, creating vesicles and painful erosions before sensory axonal transport establishes lifelong neural latency.

  2. 2
    HSV reactivation and shedding

    Virus periodically returns along sensory nerves, causing recurrent lesions or clinically silent mucosal shedding that permits transmission.

  3. 3
    Early treponemal dissemination

    Spirochaetes spread through lymphatics and blood from the inoculation site, explaining generalised secondary rash and multi-organ manifestations.

  4. 4
    Chronic syphilitic injury

    Untreated infection can persist and later produce inflammatory neurological, cardiovascular or gummatous damage despite intervening asymptomatic latency.

Clinical features and red flags

First genital-herpes episode

Painful grouped vesicles or shallow ulcers with dysuria, tender nodes and systemic symptoms support herpes, although atypical fissures require lesion NAAT.

Recurrent genital herpes

A local prodrome followed by fewer, shorter-lived lesions in a similar distribution reflects reactivation, often without constitutional illness.

Primary syphilis

An indurated chancre with regional lymphadenopathy is classic, but lesions may be painful, multiple or hidden in the vagina or cervix.

Secondary syphilis

A generalised eruption including palms and soles, mucous patches, condylomata lata, lymphadenopathy or systemic organ involvement follows dissemination.

Neuro-ocular-otic disease

Headache, meningism, cranial neuropathy, cognitive change, visual symptoms, hearing loss or vertigo can occur at any stage and changes treatment urgency.

Red flags requiring action

  • Genital herpes with urinary retention, severe sacral pain, leg weakness, meningism, confusion or disseminated lesions needs urgent hospital assessment.
  • Visual loss, eye pain, hearing change, vertigo, cranial neuropathy or other neurological symptoms with possible syphilis requires same-day specialist care.
  • Pregnancy with a first genital-herpes episode, lesions near labour or newly diagnosed syphilis requires urgent obstetric and sexual-health coordination.

Investigations

  1. 01
    HSV lesion NAAT with typingFirst step
    Why
    Confirm herpes sensitively from a fresh vesicle or ulcer and distinguish HSV-1 from HSV-2.
    Interpretation and limitations
    A positive result confirms infection; a negative result from an old or dry lesion has lower exclusion value and does not justify routine indiscriminate serology.
  2. 02
    Treponemal serology and quantitative RPR or VDRL
    Why
    Diagnose syphilis, help stage activity and establish a titre for treatment-response monitoring.
    Interpretation and limitations
    Treponemal tests often remain positive lifelong; a quantitative non-treponemal titre changes with activity, while very early infection can still be seronegative.
  3. 03
    Direct syphilis testing from a lesion
    Why
    Detect T. pallidum by NAAT or dark-ground microscopy before serology becomes reactive where the service offers it.
    Interpretation and limitations
    A positive result confirms early infectious syphilis; a negative sample does not exclude disease and must be paired with serology and repeat testing.
  4. 04
    HIV and complete exposure-site STI screen
    Why
    Detect co-infection and identify other causes or consequences of the same sexual exposure.
    Interpretation and limitations
    Account for window periods and offer repeat testing; HIV status can affect disease severity and follow-up but does not replace clinical staging.

Differential diagnosis

01

Trauma or aphthae

Mechanical fissures and reactive non-sexually acquired ulcers can be painful and require history, examination and exclusion of infectious causes.

02

Inflammatory dermatosis

Erosive lichen planus, lichen sclerosus, dermatitis and Behçet disease cause recurrent erosions or ulcers with broader mucocutaneous clues.

03

Candidal fissuring

Intense itch, erythema and superficial splits with yeast evidence can resemble subtle recurrent herpes without true vesicles.

04

Neoplasia

A persistent indurated, irregular, bleeding or non-healing vulval ulcer requires biopsy rather than repeated empirical antiviral treatment.

05

Other genital infections

Lymphogranuloma venereum, mpox and uncommon imported ulcer diseases are considered through exposure, travel, nodes and public-health context.

Management

01Genital ulcerSample broadly and assess urgencyFirst stepA patient presents with a new genital vesicle, erosion, fissure or ulcer.+
  1. 1Take a private exposure, pregnancy, systemic, neurological and safeguarding history and inspect genital and extragenital sites with consent.
  2. 2Swab a fresh lesion for HSV NAAT, obtain syphilis and HIV serology and add direct syphilis testing or bacterial samples when phenotype supports them.
  3. 3EscalationEscalate urinary retention, meningism, ocular or auditory symptoms, systemic toxicity, pregnancy risk or possible assault immediately.
02HerpesTreat the episode and explain latencyA first clinical episode is present within five days or continues to produce lesions or systemic symptoms.+
  1. 1Start five days of aciclovir or

Complications

01

Herpetic neurological disease

Sacral radiculitis can cause urinary retention, while meningitis, encephalitis and disseminated infection require urgent systemic therapy.

02

Neonatal herpes

New maternal infection near birth carries high transmission risk and changes obstetric antiviral and delivery planning.

03

Neurosyphilis and sensory disease

Syphilis can affect meninges, brain, spinal cord, eyes or ears at any stage, causing permanent functional loss.

04

Congenital syphilis

Untreated maternal infection can cause miscarriage, stillbirth, prematurity or multisystem fetal and neonatal disease that timely penicillin prevents.

Monitoring and follow-up

  • Review first-episode herpes after five days when lesions are still forming, systemic symptoms persist, pain is uncontrolled or urine passage is difficult.
  • For recurrent herpes, monitor episode frequency, severity, triggers, pregnancy plans and psychosocial burden to decide between episodic and suppressive strategies.
  • Record baseline quantitative RPR or VDRL and repeat at stage-appropriate intervals, interpreting change alongside treatment history and reinfection risk.
  • Act on new visual, auditory, neurological or cardiovascular symptoms at any syphilis follow-up rather than waiting for a scheduled titre.
  • Verify partner-notification outcomes, HIV testing and pregnancy coordination while preserving confidentiality and avoiding unsupported assumptions about acquisition timing.

Special situations

Ulcer pain is not definitive

Herpes is often painful and a chancre often painless, but both infections produce atypical lesions that defeat a pain-based diagnostic rule.

HSV typing helps counselling

Genital HSV-1 generally recurs and sheds less often than HSV-2, so type-specific lesion results refine expectations.

Treponemal tests remain reactive

Persistent treponemal positivity after successful syphilis treatment is expected; quantitative RPR or VDRL and history assess response and reinfection.

Jarisch-Herxheimer is not allergy

Fever, chills and symptom flare soon after syphilis therapy reflect inflammatory response to organism clearance, not IgE-mediated penicillin allergy.

Neurological disease overrides stage

Ocular, auditory or neurological involvement can occur early or late and requires a regimen with adequate nervous-system penetration.

Common pitfalls

  1. 01

    Excluding syphilis because an ulcer is painful or excluding herpes because only one fissure is visible.

  2. 02

    Using serum HSV antibodies to diagnose the cause of a current lesion instead of obtaining lesion NAAT.

  3. 03

    Withholding first-episode antiviral therapy while waiting for the herpes swab result despite ongoing new lesions.

  4. 04

    Treating syphilis without establishing stage, baseline non-treponemal titre and neurological, ocular and auditory symptoms.

  5. 05

    Using one benzathine-penicillin dose for late latent disease or for neurosyphilis, which require different duration or formulation.

  6. 06

    Delaying maternal syphilis treatment for fetal imaging or substituting doxycycline during pregnancy.

Provide partner notification, full STI testing, pregnancy counselling and clear transmission advice without implying that recurrence of herpes identifies when or from whom infection was acquired.
  • Fever, hypotension, rapidly progressive ulceration, necrosis or marked immunosuppression suggests complicated or alternative invasive disease.
  • A genital ulcer in a child or any disclosure of coercion, exploitation or assault requires immediate safeguarding and trauma-informed referral.
    • 05
    Neurological, ophthalmic and CSF assessment
    Why
    Evaluate suspected neurosyphilis, ocular syphilis or complicated herpes under specialist direction.
    Interpretation and limitations
    Symptoms drive urgent specialist assessment; lumbar puncture is not a routine staging test for every serological syphilis diagnosis.
    valaciclovir
    , provide analgesia and practical urine-passing advice, and review severe or non-healing disease for extension.
  • 2Explain asymptomatic shedding, recurrence, condom limitations and that lesion timing cannot reliably date acquisition or identify a transmitting partner.
  • 3Coordinate pregnancy management promptly and discuss episodic versus suppressive therapy later according to recurrence burden and patient preference.
    • 03SyphilisStage before selecting durationSerology or direct testing supports syphilis, or suspicion remains high during an early window.+
    1. 1Review symptoms, prior serology, treatment history and exposure dates to distinguish early infection from late or unknown duration.
    2. 2Give benzathine penicillin promptly for uncomplicated disease, using one dose for early and three weekly doses for late latent infection; route neuro-ocular disease separately.
    3. 3Document baseline quantitative titre, arrange stage-based serological follow-up and partner notification, and coordinate pregnancy care without delay.
    Key medicines and prescribing safety4 treatments · regimens, roles and cautions+
    Shortens lesion duration, symptoms and viral shedding when started during active first-episode disease.

    Aciclovir

    Take 400 mg orally three times daily for five days for a first genital-herpes episode.

    Adjust for significant renal impairment, maintain hydration, and review after five days if new lesions, systemic symptoms or complications continue.

    Provides an effective lower-frequency oral alternative to aciclovir for first-episode genital herpes.

    Valaciclovir

    Take 500 mg orally twice daily for five days for a first genital-herpes episode.

    Review renal function and hydration in susceptible patients; treatment reduces but does not abolish transmission or future recurrence.

    Eradicates T. pallidum in primary, secondary and early latent infection without neurological involvement.

    Benzathine penicillin G for early syphilis

    Give 2.4 million units by intramuscular injection as one dose for uncomplicated early syphilis.

    Verify formulation and allergy assessment, explain Jarisch-Herxheimer reaction, and use specialist desensitisation pathways when penicillin-allergic pregnancy requires treatment.

    Treats late latent syphilis or infection of unknown duration when neurosyphilis has not been identified.

    Benzathine penicillin G for late latent syphilis

    Give 2.4 million units intramuscularly once weekly for three consecutive weekly doses.

    Missed dose intervals may require regimen review; this depot formulation does not achieve adequate CSF levels for neurosyphilis treatment.