The exact causes for uterine anomalies are not known, but it's generally thought that a combination of genetic and environmental causes are responsible. For example, a particular uterine anomaly characterized by a T-shaped uterus has been found in women whose mothers took the drug diethylstilbestrol (DES) during their pregnancy. Because few women with an irregularly shaped uterus also have close relatives with the same problem, the condition is not thought to run in families.
An incidence of uterine anomalies as low as 0.1% has been reported. Observations made at the time of delivery indicate an incidence of 2 to 3%. The most common uterine anomalies are the septate and bicornuate and didelphic uteruses. The unicornuate uterus is the least common type.
SymptomsIn many cases a uterine anomaly causes no problems and in fact may remain undetected until menstruation begins or pregnancy is attempted. If a uterine anomaly such as bicornuate uterus results in a rudimentary uterine horn with no outlet, menstrual outflow will be obstructed. This can result in pain and/or a mass similar to endometriosis that gets worse during periods. If untreated, blood collects in the uterus and may become infected.
A uterine anomaly may also be associated with dyspareunia and reproductive problems. These include:
- Ectopic pregnancy
- Recurrent miscarriage
- Premature delivery
- Intrauterine fetal growth restriction
- Abnormal fetal presentation – breech and transverse lies