Imperforate hymen and haematocolpos

Definition

• Imperforate hymen is present when the hymen, a thin membrane of stratified squamous epithelium at the vaginal introitus, fails to rupture spontaneously during neonatal development.
• Accumulation of menstrual blood in the vagina or uterus is termed haematocolpos or haematometra respectively.

Occurrence & epidemiology

Epidemiology

• The incidence is estimated at about 1 in 1,000 to 2,000 female births (0.05–0.1%); the anomaly usually occurs in isolation, and familial clusters have rarely been reported.
• Imperforate hymen is usually diagnosed during adolescence between 12 and 18 years of age; it is a rare cause of primary amenorrhoea.

Aetiopathogenesis

Aetiology and pathogenesis

• Embryologically, the hymen marks the junction of the urogenital sinus and the sinovaginal bulbs and derives from invaginations of the posterior wall of the urogenital sinus.
• The atresia is thought to arise when the hymen fails to canalise together with the rest of the vagina as the sinovaginal bulbs canalise.

Clinical features

• In newborns, a mucocele may form due to maternal oestrogen stimulation and usually resolves spontaneously.
• Many remain asymptomatic until menarche and then present with cyclical abdominal pain and amenorrhoea.
• The pelvic mass can mechanically obstruct the urinary tract, leading to urinary retention, hydronephrosis and acute kidney injury, and may also compress the bowel.
• Retrograde flow of blood increases the risk of endometriosis.

Diagnosis

• Inspection reveals a blue, bulging perineal mass at the introitus.
• Ultrasound and MRI are the preferred imaging modalities; MRI is particularly suited to assessing Müllerian duct anomalies.

Keep learning in the app

Further reading (selection)

1. StatPearls: Imperforate Hymen (NCBI Bookshelf)
2. Familial occurrence of imperforate hymen in premature monozygotic twins and their mother: a case report and literature review (Front Pediatr 2024, PubMed Central)
3. Severe Abdominal Pain Mimicking Appendicitis Caused by Imperforate Hymen: Case Report and Narrative Review (Pediatr Rep 2026, PubMed Central)

Cross-references