Abnormal uterine bleeding
| Dysfunctional uterine bleeding | |
|---|---|
| Classification and external resources | |
| Specialty | gynaecology |
| ICD-10 | N93.8 |
| ICD-9-CM | 626.8 |
| MedlinePlus | 000903 |
| eMedicine | article/795587 |
| MeSH | D008796 |
Dysfunctional uterine bleeding (DUB) is abnormal genital tract bleeding based in the uterus and found in the absence of demonstrable structural or organic disease. It is usually due to hormonal disturbances: reduced levels of progesterone cause low levels of prostaglandin F2alpha and cause menorrhagia (abnormally heavy flow); increased levels of tissue plasminogen activator (TPA) (a fibrinolytic enzyme) lead to more fibrinolysis.
Diagnosis must be made by exclusion, since organic pathology must first be ruled out.
AUB can be classified as ovulatory or anovulatory, depending on whether ovulation is occurring or not. It is usually a menstrual disorder, although abnormal bleeding from the uterus is possible outside of menstruation.
Some sources state that the term "dysfunctional" implies a hormonal mechanism. Use of the term "abnormal uterine bleeding" is preferred in today's medicine.
10% of cases occur in women who are ovulating, but progesterone secretion is prolonged because estrogen levels are low. This causes irregular shedding of the uterine lining and break-through bleeding. Some evidence has associated Ovulatory DUB with more fragile blood vessels in the uterus.
It may represent a possible endocrine dysfunction, resulting in menorrhagia or metrorrhagia. Mid-cycle bleeding may indicate a transient estrogen decline, while late-cycle bleeding may indicate progesterone deficiency.
About 90% of DUB events occur when ovulation is not occurring (Anovulatory DUB). Anovulatory menstrual cycles are common at the extremes of reproductive age, such as early puberty and perimenopause (period around menopause). In such cases, women do not properly develop and release a mature egg. When this happens, the corpus luteum, which is a mound of tissue that produces progesterone, does not form. As a result, estrogen is produced continuously, causing an overgrowth of the uterus lining. The period is delayed in such cases, and when it occurs menstruation can be very heavy and prolonged. Sometimes anovulatory DUB is due to a delay in the full maturation of the reproductive system in teenagers. Usually, however, the mechanisms are unknown.
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