N89: Other noninflammatory disorders of vagina

N89.7: Haematocolpos

The vagina is tubular and leads from the outside to the uterus. This lining of the uterus thickens at the start of each normal menstrual cycle. It is then expelled when you have your period. This process is controlled by various sex hormones.

Normally, menstrual blood can flow out through the vagina unhindered. If the vaginal opening is partially or completely blocked, the blood can back up in the vagina.