42 Maternal Anatomy and Physiology
SECTION 2
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 vaginocer- vicouterine septum is found (Darwish, 2009). Many septate uteri are identified during evaluation of infertility or recur- rent pregnancy loss. Although an abnormality may be identi- fied 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 abnor- mal 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 devel- oped uterus (see Fig. 3-3). Although some studies report no increased adverse associated outcomes, others have found exces- sive second-trimester losses, preterm labor, and malpresenta- tion (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 par- tial 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).
■ 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 identi- fiable 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 fal- lopian 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 preg- nancy, 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).
■ 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 embry- onic 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).
CHAPTER 3
not amenable to these simple procedures. In two women, lapa- roscopy 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).
■ Sacculation
Persistent entrapment of the pregnant uterus in the pelvis may lead to extensive lower uterine segment dilatation to accom- modate the fetus. An example of anterior sacculation is shown in Figure 3-4.In these extreme cases, sonography and MR imag- ing 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 pel- vis suggests a sacculation or an abdominal pregnancy. The Foley catheter is frequently palpated above the level of the umbili- cus! 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).
Friedman and associates (1986) described a rare case of pos- terior sacculation following aggressive treatment for intrauter- ine adhesions. Finally, uterine retroversion and a true uterine diverticulum have been mistaken for uterine sacculations (Hill, 1993; Rajiah, 2009).
■ 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 malpresenta- tion, 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 con- firmed preoperatively with MR imag- ing, which shows a twisted vagina that appears X-shaped rather than its normal H-shape (Nicholson, 1995).
As with uterine incarceration, dur- ing cesarean delivery, a severely dis- placed uterus should be repositioned anatomically before hysterotomy. In some cases, an inability to reposition may require that a poste- rior hysterotomy incision be done (Albayrak, 2011; De Ioris, 2010; Picone, 2006).
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