Congenital Gynecologic Defects and Müllerian Anomalies Flashcards
What are the two primary categories of congenital gynecologic defects?
Obstructive and non-obstructive. “Obstructive” lesions are those which completely or partially block obstruction of menstrual outflow and / or prevent or impede vaginal intercourse. Obstructive lesions include transverse vaginal septum. “Non-obstructive” lesions include everything else, including a bicornuate uterus.
What are the four steps in Mullerian development?
1) elongation of the ducts 2) fusion of the ducts 3) canalization of the ducts 4) septal resorption between the ducts.
What must the Mullerian system unite with in the process of development?
Müllerian system (cephalad) must unite with urogenital sinus (caudad) and the resulting plane of fusion must resorb.
How is abnormal development of the mullerian system associated with renal abnormalities?
The mesonephric and para-mesonephric ducts develop in tandem. The ureters, renal calyces and collecting tubules arise from the ureteral buds, which arise from the mesonephric ducts and induce the formation of the kidneys. Many of the embryolic defects of the Mullerian system, especially the lateral fusion defects, therefore co-evolve with the renal system. Therefore, abnormal differentiation of the mesonephric and paramesonephric ducts may be also predictive of abnormal renal development.
What is the typical clinical presentation of a transverse vaginal septum and what are the conditions that may result?
A transverse vaginal septum classically presents in a young woman with no menses and periodic lower abdominal pain. The pain stems from the accumulation of blood and menstrual tissue above the level of the obstruction and is known as a hematocolpos. This accumulation may lead to a growing abdomino-pelvic mass. If sufficiently large, the mass can even cause urinary retention. Physical exam reveals a blind vaginal pouch, most commonly in the upper vagina, as opposed to introital with the imperforate hymen.
How is a transverse vaginal septum treated?
If the patient’s pain is sufficient, surgical treatment is indicated. MRI is critical in order to assess the septal thickness. Most transverse septi are relatively thin, less than a centimeter. If the septum is thicker, i.e. greater than 2 cm, then a skin graft will be necessary in order to prevent strictures of the vagina and to allow for good mucosal healing.
What are the seven classes of Mullerian anomalies?
I - Hypoplasia/agenesis II - Unicornuate III - Didelphus IV - Bicorunate V - Septate VI - Arcuate VII - DES Drug Related
What causes Mullerian agenesis and what class of mullerian anomaly is it?
Failure of elongation of the ducts. Can be bilateral or unilateral. When both ducts fail to develop, the diagnosis of Mullerian agenesis is made. These patients are categorized as Class I: Agenesis / Hypoplasia. Among the class I or hypoplasia disorders, the most common is the combined disorder where the uterus, upper vagina and cervix are all missing, although a small distal segment of fallopian tube is found on each side.
What causes unicornuate uterus, what is it’s classification, and what consequences are highly associated with it?
When one duct elongates correctly and the other does not, the end result is known as a unicornuate uterus. Class II abnormality. Only about 35% of unicornuate uteri are isolated. Renal agenesis on the same side as the missing duct occurs in about 40% of cases. Probably because of poor vascularity, reproductive potential of the unicornuate uterus is especially poor with a spontaneous abortion rate of about 50%.
How do rudimentary horns form and characteristics might they have?
In many cases of unicornuate uterus, a unilateral elongation defect is only partial, giving rise to what is known as a rudimentary horn. Rudimentary horns differ from each other in two key characteristics: 1) whether or not they are cavitary, and 2) whether or not they communicate with the properly formed horn.
What are the risks of a cavitary rudimentary horn, and what is the treatment?
Rudimentary horns that are cavitary contain functioning endometrium. Pregnancies can implant in these horns, even if they do not communicate directly with the normal horn. These are vulnerable to catastrophic rupture and maternal death in the first or second trimester of pregnancy, and therefore should be removed. A cavitary horn which does not communicate with the normally formed horn can accumulate blood and lead to obstructive symptoms. If there is functioning endometrium, the uterine horn should probably be excised to prevent either of these outcomes.
What conditions result from defects in the lateral fusion of the left and right ductal systems?
Lateral fusion defects between the right and left ductal systems can be complete or partial. Total failure of fusion results in two different systems with the uterine horns not communicating at all. LONGITUDINAL VAGINAL SEPTUM: Fusion defects at the level of the vagina result in a longitudinal vaginal septum, which may or may not be obstructive. A longitudinal vaginal septum will be associated with two cervices (bicolis), one on either side of the septum. DIDELPHYS: Failure of fusion at the level of the cervix leads to two uterine horns (didelpys) and two cervices. DIDELPHYS: Failure of fusion above the level of the cervix leads to two uterine horns (didelpys).
What are the reproductive outcomes for uterus didelphys and what treatments are available?
Uterus didelphys has reasonably good reproductive outcomes. This is likely because of improved vascularity as compared with the unicornuate uterus. Fetal survival rates are quite reasonable at >55%, which makes this the most reproductively benign of the lateral fusion defects. While surgical procedures to unify the two cavities exist, they are rarely performed and only in cases of recurrent poor reproductive outcomes.
How does the bicornuate uterus differ from the didelphyc uterus and what are its reproductive outcomes and treatment?
As opposed to the didelphic uterus, the bicornuate uterus has communicating endometrial cavities. Reproductive outcomes are reasonably good, with a spontaneous abortion rate of 30% and fetal survival of 60%. Rates tend to be better in women with partial than complete bicornuate uterus. As with uterus didelphys, surgery is rarely indicated and only in women with previous poor reproductive outcomes. In order to be deemed bicornuate on MRI, a cleft or indentation of at least 1.0 cm must be seen.
What does a defect in the canalization of the ducts result in?
Vaginal agenesis
What does a defect in the lateral fusion of the ducts result in?
Longitudinal vaginal Septum (with 2 cervices) Didelphys uterus (May completely divide into 2 cervices) Bicornuate uterus (septum remains, but is not as severe as Didelphys)
What does a defect in the septal resorption between the ducts result in?
Septate uterus Arcuate uterus
What are the reproductive outcomes in a septate uterus and what treatments are available?
The septate uterus has an extremely high rate of first trimester pregnancy loss, up to 65% pregnancy loss rate. Resection of the intrauterine septum has reduced pregnancy wastage rates to as low as 6%. Hysteroscopic resection therefore may be considered in patients with repeated pregnancy wastage
What are the reproductive outcomes and treatment for arcuate uterus?
The arcuate uterus reflects only minimal non-resorption of the septum and as such, most clinicians feel that there is no adverse reproductive outcome associated with the condition.
What uterine malformations are associated with DES?
Specific uterine malformations that are seen include T-shaped uterus (the most common anomaly) small hypo plastic uterus constriction bands widened lower uterine segment narrowed fundal segment of the endometrium irregular endometrial margins intraluminal filling defects. Fallopian tube abnormalities are also seen, probably accounting for some of the increase in ectopic pregnancy risk. Cervical incompetence leading to early pregnancy loss is often seen.
