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Defects in Uterine Fusion and Resorption
By Eric Daiter, M.D.

The incidence of congenital uterine fusion defects is not well established since these defects are not readily apparent without radiologic imaging (or the equivalent). Therefore, the incidence rates in the literature have a potential selection bias, since they reflect a selected group of women (that is, a population selected to have the testing required for diagnosis). Understanding this, the available reports generally cite incidences of about 1 in 200 to 1 in 600 women. Therefore, these defects are not common but also not rare. About 1 in 4 women with a congenital anomaly of the uterus due to a fusion defect will have significant difficulty with reproduction, possibly including recurrent pregnancy loss.

Mullerian duct abnormalities include :

  • septate uterus: a partial lack of resorption of the poorly vascularized tissue within the uterine cavity. The remaining tissue creates a wedge shaped septum in the fundus (top) of the uterine cavity. Implantation of an embryo onto this septum, and within a septate uterus, has a markedly greater chance of spontaneous abortion (miscarriage) compared with a normally developed uterus. There is also an increase in preterm labor and delivery as well as abnormal fetal lie or presentation (such as breech). Fortunately, the repair of the septate uterus is fairly straightforward and usually very effective, requiring an outpatient surgical procedure (hysteroscopy). Reportedly, repair of a septate uterus will improve the miscarriage rate from about 80-90% if untreated to about 10-15% following treatment.

  • unicornuate uterus: failure in development of 1 of the Mullerian ducts most likely due to a failure in the migration (movement) of the duct to the proper location prior to its time for fusion (resulting in its loss). The resulting unicornuate or half uterus has connection to only 1 fallopian tube since the other tube was to be formed from the "lost" Mullerian duct. The caliber (size) of the cavity in the unicornuate uterus is very important in determining the likelihood of reproductive success. Generally, a unicornuate uterus is associated with the highest rate of loss of any of the congenital abnormalities of uterine fusion. Unfortunately there is no accepted benefit for the treatment of these uterine defects. The unicornuate uterus is associated with renal abnormalities (renal agenesis, lack of a kidney, on the side of the missing Mullerian structures) and other reproductive problems (abnormal lie or presentation, intrauterine growth retardation, preterm labor and delivery, incompetent cervix). An incompetent cervix is essentially a "weak" cervix that tends to open without contractions during the course of pregnancy and can result in the delivery of a markedly premature baby or a nonviable fetus (miscarriage).

  • bicornuate uterus: a partial lack of fusion of the Mullerian ducts resulting in a single cervix and two uterine cavities in a "heart shaped" partially unified uterus. Reproductive outcome may be normal so no treatment is indicated unless reproductive problems are identified. Reports suggest an increase in spontaneous abortion (miscarriage), preterm labor and delivery, and abnormal presentation (breech). The patient with recurrent pregnancy loss, a bicornuate uterus, and treatment for all other identified causes for the losses may reasonably consider repair of the uterus. The treatment is surgical repair requiring a laparotomy with unification of the uterine cavities. The laparotomy requires a lengthy (few weeks) postoperative recovery period. Success with this surgery is generally quite good, improving the miscarriage rate from about 90-95% if untreated (and the cause for the recurrent losses) to about 25-30% if treated.

  • didelphic uterus: a complete lack in fusion of the Mullerian ducts with duplication of the uterus and cervix so that the patient has 2 cervices and two uteruses (each smaller than normal). Commonly also associated with a vaginal septum so that there are 2 separate vaginal canals at the top of the vaginal vault. Occasionally, one of the sides will become obstructed and result in pain as blood accumulates in the obstructed hemiuterus. There is an association with abnormal lie or presentation as well as preterm labor and delivery.

  • rare abnormalities: there are an entire host of intermediate or somewhat unique problems associated with abnormal development of the Mullerian structures. Isolated endometrial (lining of the uterus) or cervical agenesis (lack of development) are rare. Communicating and noncommunicating uterine horns that failed to fuse and canulate properly are possible.

Dr. Eric Daiter graduated from the University of Pennsylvania, where he was awarded an academic scholarship and was enlisted into the University Scholar's Program and the Benjamin Franklin Scholar's Program.

Dr. Daiter graduated medical school at Temple University Medical School in Philadelphia and completed the Obstetrics and Gynecology residency program at Albert Einstein College of Medicine in New York. He completed his Reproductive Endocrinology and Infertility fellowship at the Hospital of the University of Pennsylvania. He has considered a career as a physician scientist in research medicine and has published several articles on molecular events that occur during the human embryo's implantation into the uterus. Dr. Daiter entered private practice in 1994, where he joined a successful referral based infertility practice and further developed his clinical skills. Dr. Daiter emphasizes the basic principles of infertility patient care, including the importance of highly personalized, cost considerate, state of the art, one on one care for his patients. He specializes in all aspects of In Vitro Fertilization, with a patient success rate among the highest in the state. He has performed several hundred advanced operative laparoscopic and hysteroscopic surgeries, utilizing the most modern laser techniques.

Dr. Daiter opened his Edison, NJ office in 1997. The office continues to support the highest level of professional care for infertile couples. Extended office hours are available for patient convenience.

Eric Daiter, M.D.
34-36 Progress Street
Suite B-4
Edison, New Jersey, 08820

Web Site URL:
Phone: (908) 226-0250
Fax: (908) 226-0830

The information presented in these articles are offered for informational purposes only. These pages have been written by Dr. Eric Daiter, yet are not intended to replace the medical advise offered by your personal physicians or healthcare professionals.

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