As noted, the hymen marks the embryological boundary between structures derived from the miillerian and urogenital sinus. Hymeneal anomalies include imperforate, microperforate, cribriform (sievelike), navicular (boat-shaped), and septate hymens. They result from failure of the inferior end of the vaginal plate-the hymeneal membrane-to canalize. Their incidences approximate 1 in 1000 to 2000 females (American College of Obstetricians and Gynecologists, 2016). During the neonatal period, signiicant amounts of mucus can be secreted due to maternal estrogen stimulation. With an imperforate hymen, secretions collect to form a bulging, translucent yellow-gray mass, termed hydro-or mucocolpos, at the vaginal introitus. Most are asymptomatic and resolve as mucus is reabsorbed and estrogen levels decrease, but rarely can cause perinatal urinary retention from their mass efects Gohal, 2009).
Four principal deformities arise from defective miillerian duct embryological steps: (1) agenesis of both ducts, either focally or along the entire duct length; (2) unilateral maturation of one mullerian duct with incomplete or absent development of the opposite side; (3) absent or faulty midline fusion of the ducts; or (4) defective canalization. Various classifications have been proposed, and Table 3-3 shows the one from the American Fertility Society (1988). It separates anomalies into groups with similar clinical characteristics, prognosis for pregnancy, and treatment. It also includes one for abnormalities associated with fetal exposure to diethylstilbestrol (DES). Several other classiication systems have been crafted, but this one is the most widely used (Acien, 2011; Di Spiezio Sardo, 2015; Oppelt, 2005).
Mullerian anomalies may be suspected by symptoms or physical findings such as vaginal septa, blind-ending vagina, or duplicated cevix. Amenorrhea may be an initial complaint for those with agenesis of a mullerian component. In those with outlet obstruction, pelvic pain from occult blood that accumulates and distends the vagina, uterus, or fallopian tubes may arise from functioning endometrium. Endometriosis and its associated dysmenorrhea, dyspareunia, and chronic pain are also frequent with outlet obstruction.
Class I segmental defects are caused by mullerian hypoplasia or agenesis as shown in Figure 3-5. These developmental defects can afect the vagina, cervix, uterus, or fallopian tubes and may be isolated or may coexist with other mullerian defects.
TABLE 3-3. Classification of MU"erian Anomalies
I. Segmental mullerian hypoplasia or agenesis ab. Vaginal . Cervical c.
d.
e.
II. Unicornuate uterus a.
b.
c.
d.
III. Uterine didelphys
IV. Bicornuate uterus a.
Complete-division to internal os b.
V. Septate uterus a.
Complete-septum to internal os b.
VI. Arcuate
VII. Diethylstilbestrol related
Data from American Fertility Society: The American Fertility Society classifications of adnexal adhesions, distal tubal occlUSion, tubal occlusion secondary to tubal ligation, tubal pregnancies, Mullerian anomalies and intrauterine adhesions, Fertil Steril 1988 Jun;49(6):944-955.