7\ Uterine Disorders

7.1\ Müllerian Duct Anomalies

If other causes of infertility are excluded, uterine anomalies may be suggested as a cause of infertility. On the other hand, unknown numbers of

uterine anomalies may escape detection since reproductive ability is often unaffected or not noticeably affected (Rock 1997).

Müllerian duct anomalies (MDAs) exhibit a prevalence of approximately 3%. Infertility issues are encountered in 25% of such women. Presenting symptoms vary depending on the

specific anomaly. Amenorrhea is seen with imperforate hymen, vaginal atresia, uterine anomalies, Mayer-Rokitansky-Küster-Hauser syndrome, and Wünderlich syndrome. In the first two conditions, primary amenorrhea presents as cryptomenorrhea, in which menstrual blood cannot be extruded and patients commonly complain of periodic abdominal pain. MR imaging clearly demonstrates the point of obstruction, as well as the presence or absence of hematoceles, which includes hematometra, hematosalpinx, or blood in the rudimentary uterus (Javitt 1997; Togashi et al. 1987). In addition, MR imaging allows evaluation of urinary tract abnormalities which are commonly associated, since embryologically, the müllerian and mesonephric ducts are closely related.

Müllerian duct anomalies may be depicted by HSG; however, the complex situation of the various classes of anomalies seems to be better defined by sonography or MR imaging.

Classification of MDAs according to the system adapted by the American Fertility Society can be readily achieved based on MR findings (Carrington et al. 1990). In one comparative

study, MR imaging attained 100% accuracy for diagnosis of uterine anomalies, as compared with 92% for ultrasound and <20% for HSG (Nicolini et al. 1987). In the evaluation of uterine cavity deformation, highly accurate diagnosis of submucosal leiomyomas is easily established on MR imaging, readily differentiating the lesions from adenomyosis and endometrial polyps.

The most basic classification of müllerian duct defects consists of agenesis and hypoplasia, defects of vertical fusion, and defects of lateral fusion. In 1979, Buttram and Gibbons (Buttram and Gibbons 1979) proposed a classification of müllerian duct anomalies that was based on the degree of failure or normal development, and they separated these anomalies into classes that demonstrate simi-

in 1988 by the American Society of Reproductive Medicine, the classification remains the most widely accepted schematization and addresses uterovaginal anomalies (Fig. 16, Scheme anomalies).

7.1.1\ Class I: Hypoplasia or Agenesis

Failure of normal development of the müllerian ducts causes uterine agenesis or hypoplasia. Patients present with primary amenorrhea in adolescence. Agenesis or hypoplasia of any part of the genital tract (vagina, cervix, uterus, tubes) may occur either in isolation or more common in combination. This relatively uncommon class of anomalies accounts for approximately 5% of müllerian duct anomalies. Vaginal agenesis is the most common subtype, and is often accompanied by uterine agenesis.

It is necessary to document whether a functioning uterine corpus and cervix are present.

Mayer-Rokitansky-Küster-Hauser syndrome is a malformation of this category. The typical form of this syndrome is characterized by congenital absence of the uterus and upper vagina. The ovaries and fallopian tubes are usually normal. The atypical form of the syndrome includes associated abnormalities of the ovaries and fallopian tubes and renal anomalies (Strübbe et al. 1993) (Fig. 17).

Women with acquired uterine hypoplasia due to drugs, pelvic irradiation, or ovarian failure may have a disproportionately small uterine corpus. In these patients the ratio of the uterine body to the cervix is reduced to less than the normal 2:1, similar to a premenarchal uterus.

Fig. 17  Class I: uterine agenesis. Sagittal midline sonogram shows normal vagina, small (curved arrows) cervix (straight arrow), and absent uterus

7.1.2\ Class II: Unicornuate

This MDA consists of one normally developed müllerian duct, with the contralateral duct either hypoplastic (subtypes 2a–c) or absent (subtype 2d). Types 2a–c comprise approximately 90% of cases (Heinonen et al. 1982; Rock 1997) (Fig. 18a–c).

Agenesis of a unilateral müllerian duct causes a single banana-shaped uterus with a single fallopian tube. If the rudimentary horn is either noncommunicating or lacks a cavity, it will not be detected by hysterosalpingography. Sonographic findings which are often subtle and easily overlooked include a small uterine cavity, an asymmetric ellipsoid fundal shape, and lateral deviation of the uterus. If the rudimentary horn is present without a cavity, it may be mistaken for a fibroid or the broad ligament.

MRI findings are similar to those seen with ultrasound, but cavity detection in the rudimentary horn can be facilitated by using heavily T2W imaging sequences. Normal zonal anatomy is observed in a small uterus.

If the rudimentary horn is noncommunicating endometrial tissue expelled retrogradely through the fallopian tube during menstruation results in an increased frequency of endometriosis (Brody et al. 1998).

Spontaneous abortion and premature labor may occur in pregnancies with unicornuate uterus, and the poorest fetal survival among all uterine anomalies has been reported (Rock 1997). A potentially lethal complication is uterine rupture which can occur if a pregnancy implants in a rudimentary horn.

7.1.3\ Class III: Didelphys

Complete failure of fusion of the two müllerian ducts results in two complete uteri, each with its own cervix (Fig. 19a–c). A longitudinal sagittal vaginal septum is usually, but not always, observed. Among all uterine anomalies, uterus didelphys is associated with the highest successful pregnancy rate, except for arcuate uterus (Rock 1997). Uterus didelphys is the least common of uterine duplication anomalies. HSG will clearly delineate the two separate uterine cavities if each cervix can be cannulated. In a small percentage of cases the vaginal septum may prevent

Fig. 18  Class II: left unicornuate uterus: HSG shows uterine cavity deviated toward left side with patent left fallopian tube (a). Axial T2W MRI in this patient shows

no rudimentary horn on the right side (b). In another patient HSG shows right unicornuate uterus with hydrosalpinx (c)

cannulation of one cervical canal, leading to the appearance of a unicornuate uterus.

Sonographic images reveal two widely spaced uterine fundi with myometrium and a deep cleft separating the two endometrial cavities. Two separate cervices may not be visible, since endocervical echoes are less prominent than endometrial echoes, but transvaginal imaging can demonstrate these findings better. Sonography is also useful for demonstrating hematocolpos, hematometra, and endometriosis in cases missed by HSG owing to an obstructing vaginal septum. Uterus didelphys with an obstructed hemivagina is termed Wünderlich syndrome (Fig. 19a–c) and is usually associated with ipsilateral renal agene-

sis. Several series have noted a tendency for the right hemi-uterus to obstruct, in association with right renal agenesis (Imaoka et al. 2003).

MRI is best performed with multiplanar scans. To improve visualization of the fundal contour, coronal images should be obtained in a plane parallel to the tubal ostia and internal os. MR findings are similar to those of sonography, with a deep separating cleft (>3 cm) between the two uterine fundi. The widely spaced uterine horns have an obtuse intercornual angle (>110°), although occasional overlap with a bicornuate anomaly exists. Separate cervices and a vaginal septum (if present) can be demonstrated by caudal axial T2-weighted sections.

Fig. 19  Class III: Wünderlich syndrome: on ultrasound (a) an obstructed hemivagina is seen in an 11-year-old girl presenting with unilateral renal agenesis (not documented). Axial T2W MR images at different levels (b) as well as coronal and sagittal images (c) show two separate

uteri (arrows) and two cervices, all of which have normal zonal anatomy indicating an uterus didelphys. In addition, a hematocele (H) due to obstruction of the right hemivagina is depicted. B (urinary bladder)