Vulval pain and burning

Vulval pain is pain, burning, stinging or rawness of the vulva. Vulvodynia is vulval pain lasting at least 3 months without a clear identifiable cause that explains it, and it is a diagnosis of exclusion made with positive findings (focal tenderness on cotton swab testing). Before diagnosing vulvodynia, exclude infection, dermatosis, neoplasia, neurological disease and trauma.

Anatomy. The vestibule lies between the hymenal ring and Hart line and contains the openings of the Bartholin and minor vestibular glands. Innervation is by the pudendal nerve (S2 to S4), ilioinguinal and genitofemoral nerves, and the posterior femoral cutaneous nerve.

Mechanisms. Peripheral nociceptor proliferation in vestibular mucosa, central sensitisation, pelvic floor hypertonicity, chronic inflammation and neuropathic mechanisms. Combined hormonal contraceptives, repeated candidiasis and genetic factors have been proposed as contributors; evidence is limited.

Classification. By site: localised (vestibulodynia, clitorodynia), generalised, or mixed. By provocation: provoked (sexual, non sexual or both), spontaneous, or mixed. By onset: primary (from first tampon use or intercourse) or secondary after a pain free period. By time course: constant, intermittent, persistent, immediate or delayed.

Key distinctions. Burning on touch of the vestibule suggests provoked vestibulodynia. Pain worse when sitting and relieved by standing or on a toilet seat suggests pudendal neuralgia. Pain after a vesicular rash suggests post herpetic neuralgia.

History

• Pain: location, quality (burning, stinging, rawness, knife like, aching), onset, time course, provocation (intercourse, tampon, tight clothing, cycling, sitting, wiping, exercise), relation to menses.
• Dyspareunia: insertional or deep, primary or secondary.
• Previous infections, repeated antifungals, topical agents tried, and the effect of each.
• Urinary symptoms (dysuria, frequency, bladder pain), bowel symptoms, other pain syndromes (fibromyalgia, migraine, temporomandibular disorder).
• Neurological symptoms: numbness, saddle anaesthesia, back pain, bladder or bowel dysfunction, previous vesicular rash.
• Contraception, menopause, childbirth, episiotomy, surgery, radiotherapy, chemotherapy, female genital cutting.
• Topical medicines: 5 fluorouracil, imiquimod, podophyllotoxin.
• Mood, anxiety, sleep, relationship and sexual function. Ask about past abuse sensitively, with permission.

Examination

• Chaperone and consent. Inspect the vulva: erythema around the gland openings, erosions, fissures at the posterior fourchette, atrophy, scarring, ulcers, vesicles.
• Cotton swab test: touch at the 2, 4, 6, 8 and 10 o'clock positions of the vestibule, and on the labia, perineum and thighs. Ask the patient to score pain from 0 to 10. A positive result reproduces the symptom at a specific site (pain over 4 at the vestibule supports provoked vestibulodynia). Map any allodynia or hyperalgesia.
• Bartholin glands, urethra and Skene glands.
• Pelvic floor: palpate levator ani and obturator internus for tenderness and hypertonicity. Palpate the pudendal nerve at the ischial spine for tenderness or Tinel sign.
• Neurological: perineal sensation, anal and bulbocavernosus reflexes, lower limb power and reflexes.
• Hips, sacroiliac joints and lumbar spine.
• Speculum and bimanual examination if tolerated.

Red flags

• Saddle anaesthesia, bladder or bowel dysfunction, or progressive lower limb weakness (cauda equina compression).
• Vesicles or dermatomal rash (herpes zoster) within 72 hours.
• Non healing ulcer, mass, bleeding, or pigmented lesion.
• Fever with vulval swelling or abscess.
• Weight loss or night pain suggesting malignancy.

Identifiable vulval causes

• Infection: vulvovaginal candidiasis, genital herpes, herpes zoster, bacterial vaginosis, trichomoniasis.
• Dermatoses: lichen sclerosus, erosive lichen planus, plasma cell vulvitis (Zoon), contact dermatitis, pemphigus vulgaris, mucous membrane pemphigoid.
• Aphthous ulceration and Behçet disease.
• Crohn disease with vulval involvement.
• Genitourinary syndrome of menopause and lactational atrophy.
• Bartholin gland cyst or abscess, and Skene gland abscess.
• Trauma: obstetric tear, episiotomy scar, female genital cutting, radiotherapy, chemotherapy.
• Topical irritation from 5 fluorouracil, imiquimod or podophyllotoxin.
• Serious: vulval intraepithelial neoplasia, vulval squamous cell carcinoma, extramammary Paget disease.

Neurological and musculoskeletal

• Pudendal neuralgia (entrapment), post herpetic neuralgia, sacral radiculopathy, small fibre neuropathy (diabetes), postsurgical neuroma.
• Serious: spinal cord or cauda equina compression, Tarlov cyst, tethered cord.
• Pelvic floor hypertonicity, coccydynia, and referred hip or sacroiliac pain.

Vulvodynia

• Provoked vestibulodynia: the commonest cause of insertional dyspareunia in premenopausal women.
• Generalised unprovoked vulvodynia.
• Clitorodynia.

Stepwise reasoning

1. Exclude infection and dermatoses with swabs and careful inspection.
2. Exclude neoplasia by biopsy of any suspicious lesion.
3. Map pain with the cotton swab test and examine the pelvic floor and nerves.
4. Image the spine and pelvis if neurological signs are present.

Tests

• Vaginal swabs: pH, microscopy, Candida culture with species identification, and amplification tests for sexually transmitted infection. Candida carriage does not prove it is the cause.
• Herpes simplex virus and varicella zoster virus PCR from any vesicle, erosion or fissure.
• Vulval punch biopsy (4 mm) from any ulcer, erosion, pigmented, hyperkeratotic or non healing lesion.
• HbA1c for candidiasis and neuropathy, and thyroid function tests when other features suggest.
• MRI of the lumbosacral spine and pelvis for neurological signs, suspected cauda equina compression or pudendal nerve entrapment.
• Diagnostic pudendal nerve block with local anaesthetic at the ischial spine; relief supports pudendal neuralgia.
• Patch testing when allergic contact dermatitis is suspected.

Limitations. Acetic acid application is non specific and not used for diagnosis. Nerve conduction studies of the pudendal nerve are of limited value. Normal examination with a positive cotton swab test supports vestibulodynia.

Immediate steps. Treat the identifiable cause. Start antivirals for herpes zoster if the rash is under 72 hours old. Refer urgently for cauda equina features or suspected cancer.

Herpes zoster. Valaciclovir 1 g orally three times daily for 7 days (maximum 3 g daily). Reduce to 1 g twice daily for creatinine clearance 30 to 49 mL/min, 1 g once daily for 10 to 29, and 500 mg daily if under 10. Alternatives are aciclovir 800 mg orally five times daily for 7 days, or famciclovir 500 mg three times daily for 7 days. Add analgesia with the oral neuropathic agents.

General measures. Stop irritants, use cotton underwear and bland emollients, avoid shaving and over washing, use a water based or silicone lubricant for intercourse, and cool gel packs. Explain that vulvodynia is a recognised pain disorder and not an infection.

Topical and cause specific treatment

• Lidocaine 5% ointment to the vestibule 15 to 20 minutes before intercourse using a cotton ball, or nightly overnight; keep within the product's labelled daily maximum; warn about partner numbness. Wipe off before intercourse if the partner is affected.
• Lichen sclerosus: clobetasol propionate 0.05% ointment, 0.5 g to affected skin nightly for 4 weeks, then on alternate nights for 4 weeks, then twice weekly for 4 weeks; review at 3 months; monitor for skin thinning and candidiasis.
• Atrophy: oestradiol 10 microgram vaginal tablet nightly for 2 weeks, then twice weekly; maximum one tablet daily; review at 3 months; report any bleeding.
• Candidiasis: fluconazole 150 mg orally as a single dose or clotrimazole 500 mg pessary once.
• Recurrent herpes simplex: aciclovir 400 mg orally three times daily for 5 days for an episode; suppression with aciclovir 400 mg twice daily for 6 to 12 months if frequent.
• Bartholin abscess: incision and drainage with a catheter. Add antibiotics only for cellulitis.

Oral neuropathic agents (for provoked vestibulodynia and generalised vulvodynia)

• Amitriptyline 10 mg orally at night, increased by 10 mg every 1 to 2 weeks to a usual 50 to 75 mg at night; maximum 100 mg; ECG when over 50 years or with heart disease; avoid with MAO inhibitors.
• Amitriptyline cautions: caution with SSRIs and tramadol (serotonin syndrome), epilepsy, glaucoma and urinary retention. Use lower doses in older adults and hepatic impairment. Monitor sedation and anticholinergic effects.
• Gabapentin 300 mg orally at night, increased by 300 mg every 3 to 7 days to a usual 900 to 1800 mg daily in 3 doses; maximum 3.6 g daily.
• Gabapentin in renal impairment: reduce for creatinine clearance 30 to 59 mL/min (400 to 1400 mg daily in 2 doses), 15 to 29 (200 to 700 mg daily) and under 15 (100 to 300 mg daily).
• Gabapentin cautions: monitor for sedation, dizziness and misuse; do not stop abruptly; avoid in pregnancy.
• Pregabalin 75 mg orally twice daily, increased after 3 to 7 days to 150 mg twice daily; maximum 300 mg twice daily; reduce the dose for renal impairment; monitor for sedation, dizziness and misuse; do not stop abruptly.

Non drug and procedural treatment

• Pelvic floor physiotherapy, including biofeedback and dilators, and cognitive behavioural therapy or sex therapy.
• Pudendal nerve block with bupivacaine 0.25% (with or without a corticosteroid) for pudendal neuralgia.
• Botulinum toxin injection into the pelvic floor has limited evidence.
• Vestibulectomy for severe provoked vestibulodynia that fails all other measures.

Monitoring. Review at 4 to 6 weeks and at 3 months. Monitor drug side effects and pain scores.

Referral and escalation. Refer to a vulval or pain clinic for failure of two treatments. Refer to neurosurgery or spinal surgery for cauda equina signs the same day. Refer urgently within 2 weeks for suspected cancer.

Admission criteria. Cauda equina syndrome, abscess with sepsis, or severe zoster with retention.

Discharge and follow up. Provide written advice, a named contact, and review.

Safety netting. Return for new neurological symptoms, ulcers, a mass, fever or retention.