Retained Menses – Causes of Restricted Menstrual Blood Flow

What is Retained Menstruation?

Retained menstruation occurs when a woman has normal periods but the menstrual blood is unable to flow out due to an obstruction in the tract. This occurrence is also known as cryptomenorrhea. In medical terms, accumulation of menstrual blood in the vagina is known as hematocolpos. When there is accumulation of menstrual blood in the uterus, it is known as hematometra (“hemato” referring to blood and “colpos” meaning vagina). There may be the monthly period pain but the woman will present with amenorrhea (no period). In most cases, the condition may be corrected by surgery.

Pathophysiology of Genital Tract Outflow Obstruction

The lower two thirds of the vagina develop from the urogenital sinus, while the upper vagina, cervix, uterus, fallopian tubes, and ovaries develop from the Mullerian duct system. During development of the embryo, if there is failure of the two systems to fuse vertically, it results in cervical stenosis or atresia, vaginal atresia, transverse vaginal septum, and imperforate hymen. These malformations are rare and are usually accompanied by other abnormalities, especially related to the kidneys, urinary tract, and bones.

Causes of Retained Menstruation


1. Imperforate Hymen

Hematocolpos or accumulation of menstrual blood in the vagina  occurs most frequently due to an imperforate hymen. The hymen is a membrane situated at the entrance to the vagina, which partially occludes the vaginal opening. In some cases, the hymen completely occludes the vagina, leading to retention of menstrual blood within the vagina.

This congenital (present at birth) abnormality may be detected in a newborn baby but is more frequently detected soon after menarche. Signs of puberty such as breast development will be present but the girl will present with a history of primary amenorrhea. There may be cyclic menstrual pain each month but no menstrual flow. A painless mass may be felt at the lower abdomen, and urinary problems such as dysuria (painful urination) and frequency (frequent urination) may be complained oreportedf.

Under general anesthesia, a stab incision in the center of the imperforate hymen is likely to yield a large amount of chocolate-colored fluid (altered blood) flowing out of the vagina. The incision on the hymen may be extended in a cruciate manner to drain all the fluid, following which the abdominal lump will be seen to disappear.

2. Transverse vaginal septum

This is a congenital condition which may lead to retained menses. Excision of vaginal septum is the treatment of choice.

3. Severe labial adhesions

Labial adhesions usually form due to vaginal inflammation, local irritation, trauma, or childhood sexual abuse. Surgery may be needed in severe cases.

4. Vaginal atresia and agenesis

These are congenital defects of the female reproductive system where the vagina partially or completely fails to form. Vaginal reconstruction may be contemplated in suitable cases.

Causes of Hematometra

1. Proximal transverse vaginal septum

This is a congenital defect due to an embryological abnormality meaning that it arises during during fetal development.

2. Cervical stenosis or atresia

Stenosis is narrowing of the endocervical canal which could be due to a number of causes including trauma, recurrent vaginal infections (vaginitis), cervical cancer, menopause or exposure to radiation. It can also be congenital – present since birth. With atresia, the cervical canal is absent and has to be surgically reconstructed.

Complications of Retained Menstruation

  • Hematocolpos – blood retained in the vagina.
  • Hematometra – blood retained in the uterus.
  • Hematosalpinx – blood retained in the fallopian tubes.
  • Retrograde menstruation or back flow of menstrual blood.
  • Endometriosis
  • Peritonitis
  • Urinary retention

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