Imperforate Hymen and Transverse Vaginal Septum
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Direct answer
Imperforate hymen and transverse vaginal septum are congenital obstructions of the lower genital tract that trap menstrual blood behind a closed barrier after menarche. The classic presentation is cryptomenorrhoea, with cyclical lower abdominal pain, a bulge at the introitus or in the vaginal fornix, and haematocolpos on ultrasound. Definitive treatment is prompt surgical drainage with excision of the membrane or septum.
What you must remember
- Imperforate hymen: failure of the hymenal membrane between the vaginal plate and urogenital sinus to perforate leaves it intact at the introitus, usually recognised at puberty as a bluish, tense bulge.
- Transverse vaginal septum: a horizontal barrier, commonly in the upper or middle vagina, with a blind pouch above it and a patent lower vagina.
- Cryptomenorrhoea: menstrual blood is retained within the genital tract, causing cyclical pain, a palpable mass and urinary symptoms when the swollen vagina presses on the bladder.
- Haematocolpos and haematometra: blood fills the vagina and, in long-standing cases, the uterus or tubes, which appear as fluid-filled distension on ultrasound.
- Associated renal anomaly: ipsilateral renal agenesis goes with an obstructed hemivagina (a longitudinal septum with uterine didelphys), called OHVIRA; transverse septum is also screened for urinary tract anomalies.
- Treatment: drain the collection and excise the hymen with a cruciate incision or a septum with its membrane, then keep the new opening patent with dilation or a stent.
A clue-to-cure pathway in an adolescent
A 15-year-old girl has had monthly lower abdominal pain for six months and has never menstruated visibly. Examination shows a tense, bluish bulge at the introitus. The steps below move from history to definitive treatment.
- Take a focused history: Ask about menarche, cyclical pain and urinary symptoms, since primary amenorrhoea with cyclical pain points to outflow obstruction.
- Examine the introitus: An intact bluish membrane that bulges with straining suggests imperforate hymen, whereas a transverse septum is felt as a blind upper pouch with a patent lower vagina.
- Image the pelvis: Ultrasound shows fluid within the vagina and sometimes the uterus, confirming haematocolpos or haematometra.
- Examine the renal tract: Renal ultrasound is advised, because urinary tract anomalies accompany vaginal septa, and ipsilateral renal agenesis marks the OHVIRA pattern of obstructed hemivagina.
- Drain and excise: Incise the hymen or excise the septum under anaesthesia, drain the blood and maintain the opening with a dilator or stent.
- Follow up: Watch for infection, stenosis and recurrence, and review menstrual and sexual function over subsequent years.
Where the exam tries to catch you
Examiners test whether you can recognise outflow obstruction early and choose drainage over hormonal suppression.
- Trap: Suppress the periods with hormones to treat cryptomenorrhoea. Correct: The blood is trapped behind a barrier, so it must be drained surgically, because hormonal suppression does not clear the obstructed outflow.
- Trap: Confuse imperforate hymen with complete vaginal agenesis. Correct: In imperforate hymen the vagina and uterus exist beyond the membrane, so the collection is drained, not a neovagina created.
- Trap: Regard a transverse septum as a simple finding. Correct: It can coexist with uterine and renal anomalies, so imaging of the kidneys and uterus is part of the assessment.
- Trap: Wait for the membrane to open spontaneously. Correct: Retained blood causes pain, infection and reflux of menstrual blood, which may predispose to endometriosis, so surgery should follow diagnosis promptly.
Frequently asked questions
Which sign suggests imperforate hymen in an adolescent girl?
A tense, bluish bulge at the introitus, with primary amenorrhoea and cyclical lower abdominal pain, suggests imperforate hymen. The intact membrane traps menstrual blood, and examination should be gentle and followed by ultrasound to confirm the collection.
What is haematocolpos and how is it diagnosed?
Haematocolpos is retained menstrual blood in the vagina, and it is diagnosed by pelvic ultrasound showing a fluid-filled vagina behind an intact membrane or septum. MRI defines the anatomy further when the uterus, cervix or septum is uncertain.
Why is renal imaging advised when a vaginal septum is found?
Renal imaging is advised because vaginal septa are associated with urinary tract anomalies, and ipsilateral renal agenesis is the hallmark of the OHVIRA pattern, an obstructed hemivagina with a longitudinal septum. A renal ultrasound at diagnosis identifies a missing or abnormal kidney that changes surgical and follow-up planning.
How is imperforate hymen treated?
Imperforate hymen is treated surgically by incising or excising the membrane, draining the retained blood and keeping the opening patent. Early drainage prevents infection and reduces the risk of endometriosis from trapped menstrual blood.
Does imperforate hymen affect future fertility?
Imperforate hymen does not usually affect future fertility when drained early, because the uterus and ovaries are normal. Delayed drainage carries risks of infection and endometriosis that may impair later fertility.