Williams Obstetrics, 24th Edition

CHAPTER 3. Congenital Genitourinary Abnormalities

GENITOURINARY TRACT DEVELOPMENT

MESONEPHRIC REMNANTS

BLADDER AND PERINEAL ABNORMALITIES

DEFECTS OF THE HYMEN

MÜLLERIAN ABNORMALITIES

MÜLLERIAN AGENESIS

VAGINAL ABNORMALITIES

CERVICAL ABNORMALITIES

UTERINE ABNORMALITIES

DIETHYLSTILBESTROL REPRODUCTIVE TRACT ABNORMALITIES

FALLOPIAN TUBE ABNORMALITIES

UTERINE FLEXION

Integral to successful reproduction is a normally functioning genital tract, both anatomically and physiologically. A number of developmental abnormalities can lead to infertility, subfertility, spontaneous abortion, or midpregnancy and preterm delivery. To care for affected women, it is imperative that the clinician have a working knowledge of genitourinary system development.

GENITOURINARY TRACT DEVELOPMENT

Embryologically in females, the external genitalia, gonads, and müllerian ducts each derive from different primordia and in close association with the urinary tract and hindgut. Abnormal embryogenesis of these is thought to be multifactorial and can lead to sporadic anomalies. Normal genitourinary development is summarized in Figure 3-1 and also discussed in Chapter 7 (p. 144).

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FIGURE 3-1 Embryonic development of the female genitourinary tract (A-F). (From Bradshaw, 2012, with permission.)

image Embryology of the Urinary System

Between the 3rd and 5th gestational weeks, an elevation of intermediate mesoderm on each side of the fetus–the urogenital ridge–begins development into the urogenital tract. This further divides into the gonadal or genital ridge, which will become the ovary, and into the nephrogenic cord, which is subsequently described. The müllerian ducts become the fallopian tubes, uterus, and upper vagina and derive from coelomic epithelium covering the nephrogenic cord. It is because of this separate gonadal and müllerian derivation that women with müllerian defects typically have functionally normal ovaries and are phenotypic females.

The urinary tract develops from the mesonephros or wolffian ducts situated within each nephrogenic cord and connects the mesonephric kidney to the cloaca (Fig. 3-1A). Recall that evolution of the renal system passes sequentially through the pronephric and mesonephric stages to reach the permanent metanephric system. Between the 4th and 5th weeks, each mesonephric duct gives rise to a ureteric bud, which grows cephalad toward its respective mesonephros (Fig. 3-1B). As each bud lengthens, it induces differentiation of the metanephros, which will become the final kidney (Fig. 3-1C). Each mesonephros degenerates near the end of the first trimester, and without testosterone, the mesonephric ducts regress as well.

The cloaca begins as a common opening for the embryonic urinary, genital, and alimentary tracts. By the 7th week it becomes divided by the urorectal septum to create the rectum and the urogenital sinus (Fig. 3-1D). The urogenital sinus is considered in three parts: (1) the cephalad or vesicle portion, which will form the urinary bladder; (2) the middle or pelvic portion, which creates the female urethra; and (3) the caudal or phallic part, which will give rise to the distal vagina and to the greater vestibular (Bartholin) and paraurethral (Skene) glands.

image Embryology of the Genital Tract

Development of the genital tract begins as the müllerian ducts, also termed paramesonephric ducts, form lateral to each mesonephros. These ducts extend downward and then turn medially to meet and fuse together in the midline. The uterus is formed by this union of the two müllerian ducts at approximately the 10th week (Fig. 3-1E). Fusion begins in the middle and then extends caudally and cephalad. With cellular proliferation at the upper portion, a thick wedge of tissue creates the characteristic piriform uterine shape. At the same time, dissolution of cells at the lower pole forms the first uterine cavity (Fig. 3-1F). As the upper wedge-shaped septum is slowly reabsorbed, the final uterine cavity is usually shaped by the 20th week. If the two müllerian ducts fail to fuse, then there are separate uterine horns. In contrast, resorption failure of the common tissue between them results in various degrees of persistent uterine septum.

As the distal end of the fused müllerian ducts contacts the urogenital sinus, this induces endodermal outgrowths termed the sinovaginal bulbs. These bulbs proliferate and fuse to form the vaginal plate, which later resorbs to form the vaginal lumen. This vaginal canalization is generally completed by the 20th week. However, the lumen remains separated from the urogenital sinus by the hymeneal membrane. This membrane further degenerates to leave only the hymeneal ring.

The close association of the mesonephric (wolffian) and paramesonephric (müllerian) ducts explains why there are commonly simultaneous abnormalities involving these structures. In an older study, Kenney and colleagues (1984) showed that up to half of females with uterovaginal malformations have associated urinary tract defects. Anomalies most frequently associated with renal defects are unicornuate uterus, uterine didelphys, and agenesis syndromes, whereas arcuate and bicornuate are less commonly linked (Reichman, 2010). When these are identified, the urinary system can be evaluated with magnetic resonance (MR) imaging, sonography, or intravenous pyelography (Hall-Craggs, 2013). Finally, in these cases, ovaries are functionally normal but have a higher incidence of anatomical maldescent into the pelvis (Allen, 2012; Dabirashrafi, 1994).

MESONEPHRIC REMNANTS

As discussed, the mesonephric ducts usually degenerate, however, persistent remnants may become clinically apparent. Mesonephric or wolffian vestiges can persist as Gartner duct cysts. These are typically located in the proximal anterolateral vaginal wall but may be found at other sites along the vaginal length. They can be further characterized by magnetic resonance (MR) imaging. Most are asymptomatic and benign, and although they may measure up to 7 cm in diameter, they usually do not require surgical excision. An infected cyst occasionally requires marsupialization.

Intraabdominal wolffian remnants in the female include a few blind tubules in the mesovarium—the epoöphoron—as well as similar ones adjacent to the uterus—collectively the paroöphoron (Moore, 2013). The epoöphoron or paroöphoron may develop into clinically identifiable cysts and are included in the differential diagnosis of an adnexal mass (Chap. 63p. 1226).

BLADDER AND PERINEAL ABNORMALITIES

Very early during embryo formation, a bilaminar cloacal membrane lies at the caudal end of the germinal disc and forms the infraumbilical abdominal wall. Normally, an ingrowth of mesoderm between the ectodermal and endodermal layers of the cloacal membrane leads to formation of the lower abdominal musculature and pelvic bones. Without reinforcement, the cloacal membrane may prematurely rupture, and depending on the extent of the infraumbilical defect, cloacal exstrophy, bladder exstrophy, or epispadias may result. Of these, cloacal exstrophy is rare and includes the triad of omphalocele, bladder exstrophy, and imperforate anus.

Bladder exstrophy is characterized by an exposed bladder lying outside the abdomen. Associated findings commonly include a widened symphysis pubis, caused by outward innominate bone rotation, and abnormal external genitalia. For example, the urethra and vagina are typically short, and the vaginal orifice is frequently stenotic and displaced anteriorly. The clitoris is duplicated or bifid, and the labia, mons pubis, and clitoris are divergent. At the same time, however, the uterus, fallopian tubes, and ovaries are typically normal except for occasional müllerian duct fusion defects.

Pregnancy with bladder exstrophy is associated with greater risk for antepartum pyelonephritis, urinary retention, ureteral obstruction, pelvic organ prolapse, and breech presentation. Due to the extensive adhesions from prior repair and altered anatomy typically encountered, some recommend planned cesarean delivery at a tertiary center (Deans, 2012; Greenwell, 2003).

Epispadias without bladder exstrophy includes anomalies that include a widened, patulous urethra; absent or bifid clitoris; nonfused labial folds; and flattened mons pubis. Vertebral abnormalities and pubic symphysis diathesis are also common.

Clitoral anomalies are unusual. One is clitoral duplication or bifid clitoris, which is rare and usually develops in association with bladder exstrophy or epispadias. With female phallic urethra, the urethra opens at the clitoral tip. Last, clitoromegaly noted at birth is suggestive of fetal exposure to excessive androgens (Chap. 7p. 148). In some preterm neonates, the clitoris may appear large, but then regresses as the infant grows. Other causes of newborn clitoromegaly include breech presentation with vulvar swelling, chronic severe vulvovaginitis, and neurofibromatosis (Dershwitz, 1984; Greer, 1981).

DEFECTS OF THE HYMEN

Hymeneal anomalies include imperforate, microperforate, cribriform (sievelike), navicular (boatshaped), and septate hymens. They result from failure of the inferior end of the vaginal plate—the hymeneal membrane—to canalize. Their incidences approximate one in 1000 to 2000 females (American College of Obstetricians and Gynecologists, 2013). During the neonatal period, significant 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 occasionally they must be differentiated from a hymeneal cyst (Breech, 2009; Nazir, 2006). Problems with imperforate hymen are uncommon in neonates, and most become apparent during adolescence with classic findings of amenorrhea, cyclic abdominal pain, and a bulging bluish introital membrane.

MÜLLERIAN ABNORMALITIES

There are four principal deformities that arise from defective müllerian duct embryological steps: (1) agenesis of both ducts, either focally or along the entire duct length; (2) unilateral maturation of one müllerian 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 of these have been proposed, and shown in Table 3-1 is the one used by the American Fertility Society as derived by Buttram and Gibbons (1979). 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).

TABLE 3-1. Classification of Müllerian Anomalies

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Initially, müllerian anomalies may be suspected by symptoms or clinical findings. First, these defects are frequently identified during pelvic examination. Sonography is initially done to search for associated lesions. However, MR imaging is often required to more fully delineate anatomy, especially with obstructive lesions requiring surgery. Amenorrhea may be an initial complaint for those with agenesis of a müllerian component. For those with complete agenesis, karyotyping is typically indicated to exclude XY disorders of sex development, which were formerly termed male pseudohermaphroditism (Hughes, 2006). Last, pelvic pain due to occult blood accumulation may arise from functioning endometrium with outlet obstruction.

image Müllerian Agenesis

Class I segmental defects can be caused by müllerian hypoplasia or agenesis as shown in Figure 3-2. These developmental defects can affect the vagina, cervix, uterus, or fallopian tubes and may be isolated or may coexist with other müllerian defects.

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FIGURE 3-2 Classification of müllerian anomalies. (Redrawn from American Fertility Society, 1988.)

image Vaginal Abnormalities

In addition to vaginal agenesis, there are two types of congenital septa. One is a longitudinal septum, which arises from a fusion or resorption defect. The other, a transverse septum, results either from incomplete canalization or from vertical fusion failure between the down-growing müllerian duct system and the up-growing urogenital sinus. All of these defects may be isolated or associated with other müllerian anomalies. One example is the Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, in which upper vaginal agenesis is typically associated with hypoplasia or uterine agenesis. This syndrome may also display abnormalities of the renal, skeletal, and auditory systems. This triad is known by the acronym MURCS–llerian duct aplasia, renal aplasia, and cervicothoracic somite dysplasia (Duncan, 1979).

The obstetrical significance of vaginal anomalies depends greatly on the degree of obstruction. For example, complete vaginal agenesis, unless corrected operatively, precludes pregnancy by vaginal intercourse. With MRKH syndrome, a functional vagina can be created, but childbearing is impossible. In these women, however, ova can be retrieved for in vitro fertilization (IVF) in a surrogate mother.

With longitudinal septa, most are complete. When partial, they are high in the vagina. Septa are typically associated with other müllerian anomalies (Haddad, 1997). A complete longitudinal vaginal septum usually does not cause dystocia because the vaginal side through which the fetus descends dilates satisfactorily. An incomplete or partially obstructed longitudinal septum, however, may interfere with descent.

A transverse septum causes an obstruction of variable thickness, and it may develop at any depth within the vagina. Occasionally, the upper vagina is separated from the rest of the canal by a septum with a small opening. Gibson (2003) reported this in association with miscarriage and described dilatation of the septal opening to permit evacuation of products. In labor, such strictures may be mistaken for the upper limit of the vaginal vault, and the septal opening is misidentified as an undilated cervical os. If encountered during labor, and after the external os has dilated completely, the head impinges on the septum and causes it to bulge downward. If the septum does not yield, slight pressure on its opening usually leads to further dilatation, but occasionally cruciate incisions are required to permit delivery (Blanton, 2003). If there is a thick transverse septum, however, cesarean delivery may be necessary.

image Cervical Abnormalities

Developmental abnormalities of the cervix include partial or complete agenesis, duplication, and longitudinal septa. Uncorrected complete agenesis is incompatible with pregnancy, and IVF with gestational surrogacy is an option. Surgical correction by uterovaginal anastomosis has resulted in successful pregnancy (Deffarges, 2001; Fedele, 2008). There are significant complications with this corrective surgery, and the need for clear preoperative anatomy delineation has been emphasized by Rock (2010) and Roberts (2011) and their colleagues. For this reason, they recommend hysterectomy for complete cervical agenesis and reserve reconstruction attempts for carefully selected patients with cervical dysgenesis.

image Uterine Abnormalities

From a large variety, a few of the more common congenital uterine malformations are shown in Table 3-1. Accurate population prevalences of these are difficult to assess because the best diagnostic techniques are invasive. The reported population prevalence ranges from 0.4 to 5 percent, and rates in women with recurrent miscarriage are significantly higher (Acién, 1997; Byrne, 2000; Chan, 2011b). In a review of 22 studies with more than 573,000 women who were screened for these malformations, Nahum (1998) reported the distribution of uterine anomalies as follows: bicornuate, 39 percent; septate, 34 percent; didelphic, 11 percent; arcuate, 7 percent; unicornuate, 5 percent; and hypo- or aplastic, 4 percent.

Müllerian anomalies may be discovered at routine pelvic examinations, cesarean delivery, during laparoscopy for tubal sterilization, or during infertility evaluation. Depending on clinical presentation, diagnostic tools may include hysterosalpingography, sonography, MR imaging, laparoscopy, and hysteroscopy. Each has limitations, and these may be used in combination to completely define anatomy. In women undergoing fertility evaluation, hysterosalpingography (HSG) is commonly selected for uterine cavity and tubal patency assessment. That said, HSG poorly defines the external uterine contour and can delineate only patent cavities. It is contraindicated during pregnancy.

In most clinical settings, sonography is initially performed. Transabdominal views may help to maximize the viewing field, but transvaginal sonography (TVS) provides better image resolution. For this indication, the pooled accuracy for TVS is 90 to 92 percent (Pellerito, 1992). Saline infusion sonography (SIS) improves delineation of the endometrium and internal uterine morphology, but only with a patent endometrial cavity. Also, SIS is contraindicated in pregnancy. Three-dimensional (3-D) sonography is more accurate than 2-D sonography because it provides uterine images from virtually any angle. Thus, coronal images can be constructed, and these are essential in evaluating both internal and external uterine contours (Olpin, 2009). Both 2-D and 3-D sonography are suitable for pregnancy. In gynecological patients, these are ideally completed during the luteal phase when the secretory endometrium provides contrast from increased thickness and echogenicity (Caliskan, 2010).

Several investigators have reported very good concordance between 3-D TVS and MR imaging of müllerian anomalies, although MR imaging is currently preferred for imaging such defects (Bermejo, 2010; Ghi, 2009). MR imaging provides clear delineation of both the internal and external uterine anatomy and has a reported accuracy of up to 100 percent in the evaluation of müllerian anomalies (Fedele, 1989; Pellerito, 1992). Moreover, complex anomalies and commonly associated secondary diagnoses such as renal or skeletal anomalies can be concurrently evaluated. Precautions with MR imaging in pregnancy are discussed in Chapter 46 (p. 934).

In some women undergoing an infertility evaluation, hysteroscopy and laparoscopy may be selected to assess for müllerian anomalies; screen for endometriosis, which is often coexistent; and exclude other tubal or uterine cavity pathologies (Puscheck, 2008; Saravelos, 2008). However, hysteroscopy is contraindicated in pregnancy.

Unicornuate Uterus (Class II)

With this anomaly, the underdeveloped or rudimentary horn may be absent. If present, it may or may not be communicating and may or may not contain an endometrium-lined cavity (see Fig. 3-2). General population estimates cite that a unicornuate uterus develops in 1 in 4000 women (Reichman, 2009). It may be detected during fertility evaluation by HSG. Although this study can define the primary cavity contour, noncommunicating or noncavitary rudimentary horns may not fill with dye. Conventional sonography may be difficult for less-experienced sonographers as the smaller size and lateral deviation of an isolated unicornuate uterus or a rudimentary horn may not be appreciated. If suspected, 3-D sonography increases diagnostic accuracy, but MR imaging is often preferred (Fig. 3-3). Importantly, 40 percent of affected women will have renal anomalies, and evaluation for these is indicated (Fedele, 1996a).

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FIGURE 3-3 Three-dimensional transvaginal sonographic images. A. A nongravid septate uterus characteristically has a flat external fundal contour but a deep cleft that separates the hyperechoic endometrial cavities. B. This gravid unicornuate uterus illustrates the classic “banana” configuration. (A & B modified from Moschos, 2012, with permission.) C. A nongravid arcuate uterus characteristically has a flat external fundal contour and a shallow indentation into the hyperechoic endometrial cavity. (Modified from Werner, 2012, with permission.)

This müllerian anomaly carries significant obstetrical risks, including first- and second-trimester miscarriage, malpresentation, fetal-growth restriction, fetal demise, prematurely ruptured membranes, and preterm delivery (Chan, 2011a; Hua, 2011; Reichman, 2009). Abnormal uterine blood flow, cervical incompetence, and diminished cavity size and muscle mass of the hemiuterus are postulated to underlie these risks (Donderwinkel, 1992).

Rudimentary horns also increase the risk of an ectopic pregnancy within the remnant, which may be disastrous. This risk includes noncommunicating cavitary rudiments because of transperitoneal sperm migration (Nahum, 2004). In a report of 70 such pregnancies, Rolen and associates (1966) found that the rudimentary uterine horn ruptured prior to 20 weeks in most. Nahum (2002) reviewed the literature from 1900 to 1999 and identified 588 rudimentary horn pregnancies. Half had uterine rupture, and 80 percent did so before the third trimester. Of the total 588, neonatal survival was only 6 percent.

Imaging allows an earlier diagnosis of rudimentary horn pregnancy so that it can be treated either medically or surgically before rupture (Edelman, 2003; Khati, 2012; Worley, 2008). If diagnosed in a nonpregnant woman, most recommend prophylactic excision of a horn that has a cavity (Fedele, 2005; Rackow, 2007).

Uterine Didelphys (Class III)

This interesting müllerian anomaly arises from a complete lack of fusion that results in two entirely separate hemiuteri, cervices, and usually two vaginas (see Fig. 3-2). Most women have a double vagina or a longitudinal vaginal septum (Heinonen, 1984). Uterine didelphys may be isolated or part of a triad that has an obstructed hemivagina and ipsilateral renal agenesis (OHVIRA), also known as Herlyn-Werner-Wunderlich syndrome (Smith, 2007; Tong, 2013). Didelphys derives from the Greek di—two + delphus—uterus. The term was once used to refer to all marsupials, but now only to one genus that includes the American possum—Didelphys virginiana—one of several mammalian species in which the female has a double uterus, cervix, and vagina.

These anomalies may be suspected on pelvic examination by identification of a longitudinal vaginal septum and two cervices. During HSG for fertility evaluation, contrast shows two separate endocervical canals. These open into separate noncommunicating fusiform endometrial cavities that each ends with a solitary fallopian tube. In women without fertility issues, sonography is a logical initial imaging tool, and separate divergent uterine horns with a large intervening fundal cleft are seen. Endometrial cavities are uniformly separate. MR imaging may be valuable in cases without classic findings.

Adverse obstetrical outcomes associated with uterine didelphys are similar but less frequent than those seen with unicornuate uterus. Increased risks include miscarriage, preterm birth, and malpresentation (Chan, 2011a; Grimbizis, 2001; Hua, 2011). Metroplasty for either uterine didelphys or bicornuate uterus involves resection of intervening myometrium and fundal recombination. These are uncommon surgeries and chosen for highly selected patients with otherwise unexplained miscarriages. Unfortunately, there is no evidence-based support to confirm efficacy of such surgical repair.

Bicornuate Uterus (Class IV)

This relatively common anomaly forms as lack of fundal fusion results in two hemiuteri, with only one cervix and vagina (see Fig. 3-2). As with uterine didelphys, a coexistent longitudinal vaginal septum is not uncommon. Radiological discrimination of bicornuate uterus from the septate uterus can be challenging. However, it is important because septate uterus can be treated with hysteroscopic septal resection. Widely diverging horns seen on HSG may suggest a bicornuate uterus. An intercornual angle greater than 105 degrees suggests bicornuate uterus, whereas one less than 75 degrees indicates a septate uterus. However, MR imaging is necessary to define fundal contour. With this, an intrafundal downward cleft measuring 1 cm or more is indicative of bicornuate uterus, whereas a cleft depth less than 1 cm indicates a septate uterus. Use of 3-D sonography also allows internal and external uterine assessment.

There are increased risks for adverse obstetrical outcomes with bicornuate uterus that include miscarriage, preterm birth, and malpresentation. As discussed earlier, surgical correction by metroplasty is reserved for highly selected patients.

Septate Uterus (Class V)

This anomaly is caused when a resorption defect leads to a persistent complete or partial longitudinal uterine cavity septum (see Fig. 3-2). In rare cases, a complete vaginocervicouterine septum is found (Darwish, 2009). Many septate uteri are identified during evaluation of infertility or recurrent pregnancy loss. Although an abnormality may be identified with HSG, MR imaging or 3-D sonography is typically required to differentiate this from a bicornuate uterus (see Fig. 3-3).

Septate anomalies are associated with diminished fertility as well as increased risks for adverse pregnancy outcomes that include miscarriage, preterm delivery, and malpresentation. The poorly vascularized uterine septum likely causes abnormal implantation or defective early embryo development and miscarriage (Fedele, 1996b). Hysteroscopic septal resection has been shown to improve pregnancy rates and outcomes (Grimbizis, 2001; Mollo, 2009; Pabuçcu, 2004). From their metaanalysis, Nouri and colleagues (2010) reported a 60-percent pregnancy rate and 45-percent live birth rate in those so treated.

Arcuate Uterus (Class VI)

This malformation is a mild deviation from the normally developed uterus (see Fig. 3-3). Although some studies report no increased adverse associated outcomes, others have found excessive second-trimester losses, preterm labor, and malpresentation (Chan, 2011a; Mucowski, 2010; Woelfer, 2001).

Treatment with Cerclage

Some women with uterine anomalies and repetitive pregnancy losses may benefit from transvaginal or transabdominal cervical cerclage (Golan, 1992; Groom, 2004). Some women with partial cervical atresia or hypoplasia may also benefit (Hampton, 1990; Ludmir, 1991; Mackey, 2001). Candidacy for cerclage is determined by the same criteria used for women without such defects, which is discussed in Chapter 18 (p. 361).

image Diethylstilbestrol Reproductive Tract Abnormalities (Class VII)

During the 1960s, a synthetic nonsteroidal estrogen–diethylstilbestrol (DES)–was used to treat pregnant women for threatened abortion, preterm labor, preeclampsia, and diabetes. The treatment was remarkably ineffective. In addition, it was later discovered that women exposed as fetuses had increased risks of developing a number of specific reproductive-tract anomalies. These included vaginal clear cell adenocarcinoma, cervical intraepithelial neoplasia, small-cell cervical carcinoma, and vaginal adenosis. A fourth of affected women had identifiable structural variations in the cervix and vagina to include transverse septa, circumferential ridges, and cervical collars. Even more anomalies were smaller uterine cavities, shortened upper uterine segments, T-shaped and other irregular cavities, and fallopian tube abnormalities (see Fig. 3-2) (Barranger, 2002).

These women also had fertility issues that included impaired conception rates and higher rates of miscarriage, ectopic pregnancy, and preterm delivery, especially in those with structural abnormalities (Goldberg, 1999; Palmer, 2001). Now, more than 50 years after DES use was proscribed, most affected women are past childbearing age, but higher rates of earlier menopause and breast cancer have been reported in exposed women (Hatch, 2006; Hoover, 2011).

image Fallopian Tube Abnormalities

The fallopian tubes develop from the unpaired distal ends of the müllerian ducts. Congenital anomalies include accessory ostia, complete or segmental tubal agenesis, and several embryonic cystic remnants (Woodruff, 1969). The most common is a small, benign cyst attached by a pedicle to the distal end of the fallopian tube—the hydatid of Morgagni (Zheng, 2009). In other cases, benign paratubal cysts may be of mesonephric or mesothelial origin. Last, in utero exposure to DES has been associated with various tubal abnormalities. Of these, short, tortuous tubes or ones with shriveled fimbria and small ostia have been linked to infertility (DeCherney, 1981).

UTERINE FLEXION

image Anteflexion

This is defined by anterior flexion of the uterine fundus relative to the cervix in the sagittal plane. Mild or moderate flexion is typically without clinical consequence, but congenital or acquired extremes may lead to pregnancy complications. Exaggerated degrees of anteflexion usually pose no problem in early pregnancy. Later, however, particularly when the abdominal wall is lax such as with diastasis recti or ventral hernia, the uterus may fall forward. This may be so extreme that the fundus lies below the lower margin of the symphysis. Sometimes this abnormal uterine position prevents proper transmission of labor contractions, but this is usually overcome by repositioning and application of an abdominal binder.

image Retroflexion

This is posterior uterine fundal flexion in the sagittal plane. A growing retroflexed uterus will occasionally become incarcerated in the hollow of the sacrum. Symptoms include abdominal discomfort, pelvic pressure, and voiding dysfunction that may include urinary frequency or retention. On bimanual pelvic examination, the cervix will be anterior and behind the symphysis pubis, whereas the uterus is appreciated as a mass wedged in the pelvis. Sonography or MR imaging may be necessary to confirm the clinical diagnosis (Gardner, 2013; Grossenburg, 2011; van Beekhuizen, 2003).

The incarcerated uterus must be repositioned to its normal anatomical position. After bladder catheterization, the uterus can usually be pushed out of the pelvis when the woman is placed in the knee-chest position. Often, this is best accomplished by digital pressure applied through the rectum. Conscious sedation, spinal analgesia, or general anesthesia may be necessary. Following repositioning, the catheter is left in place until bladder tone returns. Insertion of a soft pessary for a few weeks usually prevents reincarceration. Lettieri and colleagues (1994) described seven cases of uterine incarceration not amenable to these simple procedures. In two women, laparoscopy was used at 14 weeks to reposition the uterus using the round ligaments for traction. Alternatively, in two case series, colonoscopy was used to dislodge an incarcerated uterus (Dierickx, 2011; Seubert, 1999).

image Sacculation

Persistent entrapment of the pregnant uterus in the pelvis may lead to extensive lower uterine segment dilatation to accommodate the fetus. An example of anterior sacculation is shown in Figure 3-4. In these extreme cases, sonography and MR imaging are typically required to define anatomy (Gottschalk, 2008; Lee, 2008). Cesarean delivery is necessary when there is marked sacculation, and Spearing (1978) stressed the importance of identifying the distorted anatomy. An elongated vagina passing above the level of a fetal head that is deeply placed into the pelvis suggests a sacculation or an abdominal pregnancy. The Foley catheter is frequently palpated above the level of the umbilicus! Spearing (1978) recommended extending the abdominal incision above the umbilicus and delivering the entire uterus from the abdomen before hysterotomy. This will restore correct anatomical relationships and prevent inadvertent incisions into and through the vagina and bladder. Unfortunately, this may not always be possible (Singh, 2007).

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FIGURE 3-4 Anterior sacculation of a pregnant uterus. Note the markedly attenuated anterior uterine wall and atypical location of the true uterine fundus.

Friedman and associates (1986) described a rare case of posterior sacculation following aggressive treatment for intrauterine adhesions. Finally, uterine retroversion and a true uterine diverticulum have been mistaken for uterine sacculations (Hill, 1993; Rajiah, 2009).

image Uterine Torsion

It is common during pregnancy for the uterus to rotate to the right side. Rarely, uterine rotation exceeds 180 degrees to cause torsion. Most cases of torsion result from uterine leiomyomas, müllerian anomalies, fetal malpresentation, pelvic adhesions, and laxity of the abdominal wall or uterine ligaments. Jensen (1992) reviewed 212 cases and reported that associated symptoms may include obstructed labor, intestinal or urinary complaints, abdominal pain, uterine hypertonus, vaginal bleeding, and hypotension. Both maternal and fetal complications were more common with early gestation and with greater degrees of torsion.

Most cases of uterine torsion are found at the time of cesarean delivery. In some women, torsion can be confirmed preoperatively with MR imaging, which shows a twisted vagina that appears X-shaped rather than its normal H-shape (Nicholson, 1995). As with uterine incarceration, during cesarean delivery, a severely displaced uterus should be repositioned anatomically before hysterotomy. In some cases, an inability to reposition may require that a posterior hysterotomy incision be done (Albayrak, 2011; De Ioris, 2010; Picone, 2006).

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