Mullerian Anomalies in Pregnancy

1. What every clinician should know

How common are uterine anomalies?

Congenital anomalies of the uterus may be undiagnosed until a woman’s reproductive years. While often asymptomatic, patients may present with gynecologic and obstetric complaints such as dysmenorrhea, pelvic pain and pregnancy loss. Patients may also be incidentally diagnosed with a uterine anomaly after imaging or surgery.

The prevalence of uterine anomalies varies depending on the population studied. Rates in the general population are likely between 0.5-5.5%. Prevalence of uterine anomalies is much higher among women with various adverse pregnancy outcomes, with rates between 6-25%. Women with primary infertility have prevalence rates similar to that of the general population.

How do uterine anomalies form?

Anomalies are most likely sporadic, with some polygenic, multifactorial inheritance that has yet to be delineated. Women with first-degree relatives with a uterine anomaly may have a slightly greater frequency of anomalies than the general population. Most women with uterine anomalies have a normal 46XX karyotype.

The uterus and cervix are formed in a multistep process. The bilateral Müllerian ducts must develop by elongating, canalizing and migrating. The ducts then fuse, resulting in a uterus with a median septum by week 10. Ultimately, to form a single cavity, this septum is resorbed in a caudal to cranial procession between weeks 13-20. Errors in the various stages of the process lead to the wide array of Müllerian anomalies seen clinically.

How are uterine anomalies classified?

The American Fertility Society has made attempts to standardize the classification of Müllerian anomalies. Their chart provides pictorial testament to the varied abnormalities encompassed within the category of Müllerian anomalies. There are variations on these categories and the distinctions are at times blurred, so what is seen clinically may not fit easily into one of these categories. Ultimately, understanding the embryologic and anatomic defects guides our comprehension of the pathophysiology of obstetric complications and potential options for interventions and management.

Figure 13

Figure 14

Reports have varied in regard to prevalence of the various types of anomalies but are in the range of 10-46% bicornuate uterus, 25-50% uterine septum, 5-10% uterine didelphys, 4-20% unicornuate uterus and 3-10% Müllerian or vaginal agenesis. The variation likely stems from the inclusion criteria for any given study, as factors such as recurrent pregnancy loss, gynecologic symptoms and concurrent anomalies affect prevalence.

Agenesis and vertical fusion defects are less conducive to achieving pregnancy, and as a result are less likely to be encountered by the obstetrician. We will focus on the most common category of Müllerian anomalies affecting pregnancy – those resulting from defects of lateral fusion, including the unicornuate, didelphys, bicornuate and septate uterus.

2. Diagnosis and differential diagnosis

The diagnosis of a uterine anomaly can be suggested based on history (e.g. recurrent midtrimester pregnancy loss), physical exam (e.g. visualization of two cervices during a pelvic exam), surgical visualization or incidentally on imaging such as ultrasonography. When an anomaly is suspected, proceeding with various imaging modalities may be prudent to more fully characterize the genitourinary system.

Magnetic Resonance Imaging (MRI):Often considered the gold standard for the evaluation of uterine anomalies, MRI has proven efficacy for this purpose. It allows for evaluation of both the uterine cavity and contour without exposure to radiation. Signals vary between tissue types such as endometrium and myometrium so MRI can be used to differentiate between anomalies such as a functional rudimentary uterine horn or bicornuate versus septate uterus. Simultaneous evaluation of the renal system can be conveniently performed. MRI is a fairly costly technique and some patients have difficulty tolerating testing.

Ultrasound:Ultrasound is an imaging option that lends itself well to the investigation of uterine anomalies during pregnancy. It is noninvasive, relatively inexpensive and convenient, as most pregnant women undergo ultrasound testing routinely. The ability to accurately identify the nature of an anomaly becomes difficult as pregnancy progresses, but early in pregnancy three-dimensional ultrasound can be used to evaluate both the uterine contour and cavity. Although research is limited, studies note that ultrasound is comparable to MRI in its diagnostic efficacy with very good concordance (kappa index 0.880). Additionally, an evaluation of the kidneys and ovaries can be performed simultaneously.

Hysterosalpingogram (HSG):By injecting radiopaque dye through the cervix and taking radiographic images, HSG can be used to evaluate the uterine cavity. It does not provide information about uterine contour. HSG is not useful for the obstetrician trying to make a diagnosis in pregnancy, but outside of pregnancy it is a safe, available and relatively inexpensive test.

Saline infusion sonohysterogram: Saline is instilled through the cervix to distend the uterine cavity enough to enhance visualization of the uterus during transvaginal ultrasound. As with HSG, this study cannot be performed during pregnancy, but it can help characterize the uterine cavity in non-pregnant women. It can be quite useful in delineating intracavitary pathology and was noted to have nearly 78% sensitivity in detecting uterine malformations.

Laparoscopy:Surgical exploration via laparoscopy allows for an evaluation of the uterine contour but does not provide information about the cavity. The addition of hysteroscopy addresses this limitation. This technique is not favored in pregnancy because of its invasive nature. Other imaging modalities are typically preferred, but incidental findings during laparoscopic or open surgery can be diagnostic of a Müllerian anomaly, especially when paired with a thorough pelvic examination.

What findings are associated with specific anomalies?

Unicornuate uterus (Type II):This anomaly results from a defect in one of the Müllerian ducts. There is a single cervix with a single uterine horn, accompanied by its fallopian tube. The affected Müllerian duct may not develop, or may be partially developed, resulting in a rudimentary horn with or without functional endometrium. Up to 75% of women with a unicornuate uterus have a rudimentary horn, many without a communicating channel to the cervix, vagina or contralateral hemiuterus. Unicornuate uterus is associated with fairly poor obstetrical outcomes. Live birth rates of less than 30% have been noted, but have ranged from 29-100% in case series. (See Figure 1, Figure 2 and Figure 3.)

Uterine didelphys (Type III):This anomaly results from failure of the Müllerian ducts to fuse, leaving duplication of the uterus and cervix. Clinically, two cervices will be noted along with two uterine horns, each with their own fallopian tube. A longitudinal vaginal septum is often present. Although complications are still common, uterine didelphys is associated with overall better pregnancy outcomes than other uterine anomalies. In one series, a 75% fetal survival rate was noted and 89% of women desiring pregnancy had at least one living infant. A larger review was not so optimistic, noting an averaged live birth rate of 55.9%. (See Figure 4, Figure 5 and Figure 6.)

Bicornuate uterus (Type IV):This anomaly results from incomplete fusion of the Müllerian ducts. A single cervix, with complete or partial division of the uterine body, results. The uterine contour will reveal an indentation of the fundus or two separate uterine horns. The upper portion of the cervix may also be duplicated, but a single cervix on pelvic exam will be noted. Obstetric complications are very common in women with bicornuate uteri with term delivery rates of 31-50% and live birth rates of 44-63%. (See Figure 7.)

Uterine septum (Type V):A septum results from incomplete resorption of the midline septum between the two Müllerian ducts. The uterine contour will be normal, but a two-sided endometrial cavity develops because of the midline tissue. The fibromuscular septum can vary in length and thickness. Although differences in anatomy are more subtle than those of many other Müllerian anomalies, uterine septum has been associated with the poorest pregnancy outcomes, with live birth rates ranging from 28-69%. (See Figure 8, Figure 9, Figure 10, Figure 11 and Figure 12.)

What other anomalies are associated with Müllerian defects?

Kidney and pelvic organ development is embryologically intertwined. As a result, urinary tract anomalies are common in women with Müllerian defects. 20-30% of patients with a uterine anomaly will have a concurrent renal anomaly. Prevalence is highest with unicornuate uterus, with 40.5% of women having a renal anomaly, most commonly renal agenesis ipsilateral to their Müllerian defect. Renal collecting system duplication, pelvic kidney and horseshoe kidney, among other variations, have also been noted. Women with uterine anomalies should be evaluated for urinary tract anomalies with renal ultrasound, IV pyelogram, MRI or CT.

Conversely, about 40% of women with renal agenesis have a Müllerian anomaly. The finding of renal agenesis should prompt a gynecologic evaluation. One specific pattern of associated anomalies is obstructed hemivagina with ipsilateral renal anomaly (OHVIRA), seen occasionally with uterine didelphys.

Ectopic ovarian tissue may be present in women with uterine anomalies, most commonly occurring with unicornuate uterus. The affected ovary typically is ipsilateral to the missing or rudimentary horn and has been noted in varied locations from the upper abdomen to the inguinal canal.

Uterine anomalies have also been associated with gastrointestinal, cardiac, ophthalmologic and otologic abnormalities. Routine screening is not recommended because these findings are rare and the association has not been clearly outlined.

3. Management

Should surgical interventions be considered outside of pregnancy

In general, routine prophylactic surgical correction of the anomalous uterus is not indicated. One notable exception is in cases of unicornuate uterus with a rudimentary horn. Because of potential catastrophic obstetric outcomes of pregnancies with this anomaly, we recommend considering surgical removal of a rudimentary horn, particularly if it contains functional endometrium. Along with obstetric issues, women can have dysmenorrhea and severe endometriosis from retrograde menstruation if this horn has limited or no communication with the cervix.

Prophylactic removal of a uterine septum is controversial, but it may be prudent to consider surgery for patients with a history of poor pregnancy outcomes such as recurrent miscarriage or preterm birth. Because of comparable outcomes and the minimally invasive nature of hysteroscopic resection, it is favored over open techniques. Dramatic improvements in pregnancy outcomes have been noted in case series but no randomized studies with appropriate controls have been published to support these findings.

Patients with a poor obstetric history and uterine didelphys or bicornuate uterus also may seek surgical intervention. A small case series from Poland of 13 women with bicornuate uterus who underwent Strassman metroplasty noted increased fetal survival rates from 0-80%. Unfortunately, as with much of the data related to Müllerian anomalies, no randomized studies support the use of major uterine reconstruction to improve obstetric outcomes. Until more rigorous data are available, recommendations for major uterine reconstruction cannot be made.

4. Complications

What antepartum complications are associated with Müllerian anomalies?

Pregnancy complications associated with Müllerian anomalies can range from inconvenient to devastating for the patient and physician. Ectopic pregnancy, early and late miscarriage, cervical insufficiency, preterm delivery, hypertensive disorders, growth restriction and fetal demise are all antepartum issues more commonly faced by women with Müllerian anomalies. The risk of these complications varies with the type of uterine anomaly. Whether the diagnosis is made prior to or during pregnancy, patients should be counseled regarding the antenatal and intrapartum risks associated with their specific anomaly.

Ectopic pregnancy

Although the mechanism is unclear, women with Müllerian anomalies may have a higher rate of ectopic pregnancy. This risk may be related to an abnormal path that sperm, egg and embryo must traverse with the altered anatomy or possibly the higher rate of endometriosis seen with uterine anomalies. Reported ectopic pregnancy rates vary, with some studies citing rates as high as 20%. Most reviews note a prevalence more similar to the 1% seen in the general population.

Anomaly specific risks

Reports of anomaly-specific ectopic pregnancy prevalence also vary significantly, but ectopic rates of 1.2%, 1.3%, 0.3% and 0.6% for women with unicornuate, didelphys, bicornuate and septate uteri have been noted. One specific scenario that is often included within the category of ectopic pregnancy is pregnancy within a rudimentary uterine horn of a woman with unicornuate uterus. Transperitoneal migration of sperm can occur, resulting in fertilization and implantation of a pregnancy within a non-communicating rudimentary horn. This scenario poses particular risk to the woman because of the possibility of uterine rupture (see below).

Interventions/management

Early ultrasound confirmation of pregnancy location and viability should be considered.Surgical or medical management with methotrexate and potassium chloride injection may be undertaken as indicated by the particular scenario, with referral to an experienced gynecologic specialist for complicated cases.Because of the significant risk of rupture, when an early rudimentary horn pregnancy is diagnosed, pregnancy termination should be advised.

Surgical removal of a rudimentary horn that has functional endometrium should be strongly considered.

Miscarriage

Women with Müllerian anomalies commonly experience miscarriage and women with recurrent miscarriage are much more likely to have a uterine anomaly. In one study, 13% of women with recurrent pregnancy loss had a uterine malformation. The etiology is not delineated, but may be related to abnormal endometrium, uterine circulation or disruption of the pregnancy by abnormal intracavitary structures that diminish uterine capacity.

Anomaly specific risks

Miscarriage incidence varies widely, with rates of 12-67% for unicornuate uterus, 25-69% for uterine didelphys, 28-46% for bicornuate uterus and 25-67% for uterine septum being noted in the literature.

Intervention/management

  • No specific interventions during pregnancy have been shown to improve the miscarriage rate in women with Müllerian anomalies.

  • Study findings vary in regard to the usefulness of uterine septum characterization in predicting obstetric complications. Some reports note higher rates of obstetric complications with shorter, vascularized septa, while others show no correlation with length or thickness. We do not recommend trying to measure or otherwise evaluate the septum at this time.

  • Review the signs and symptoms of miscarriage as well as bleeding precautions with the patient.

  • Patients who experience recurrent pregnancy loss should undergo evaluation for a uterine anomaly.

Cervical insufficiency

Cervical incompetence has been diagnosed in 30% of women with uterine anomalies in one study, possibly related to the abnormal fusion event resulting in dysfunctional cervical tissue composition. A greater ratio of muscular fibers to connective tissue has been noted. This may significantly contribute to the high preterm delivery rate seen in women with Müllerian anomalies.

Anomaly specific risks

Women with bicornuate uteri were found to have the highest rate of cervical insufficiency (38%) in a study of 98 women.

Intervention/management

Historically, cerclage was often recommended for women with uterine anomalies. Case series have reported dramatic decreases in late miscarriage and preterm delivery from 50-21% with the use of cerclage. Increased rates of term deliveries from 26-63% were noted with its use in patients with cervical insufficiency.

Term delivery rates also were improved in patients without a history of early delivery attributed to cervical incompetence (96% vs 64%) when they received a cerclage. Unfortunately, the data is far from robust, no randomized trials have been performed and cerclage use has not been supported by more recent experience. Based on existing data, the use of cerclage to prevent or treat cervical insufficiency among women with Müllerian anomalies is not uniformly recommended.

Preterm delivery

Patients with uterine anomalies have higher rates of preterm delivery and the greatest contributor to neonatal morbidity and mortality associated with Müllerian anomalies is likely preterm delivery. Cervical insufficiency and decreased myometrial mass have been theorized as etiologies of the association with prematurity, but the mechanism has not been elucidated.

Anomaly specific risks

Preterm delivery rates vary widely. Unicornuate uterus has a preterm delivery rate of about 20%. This may be related to diminished musculature and abnormal uterine vasculature with a one-sided blood supply (one set of uterine and utero-ovarian arteries). Uterine didelphys, bicornuate uterus and uterine septum have had preterm delivery rates of 17-53%, 22-25% and 9-33% respectively.

Interventions/management

Patients should be counseled regarding the signs and symptoms of preterm delivery. A lower threshold for prompting an evaluation should be considered.

The use of cervical length ultrasound to stratify patients at greatest risk of preterm delivery is routinely used in other high-risk obstetric populations and may prove beneficial in women with uterine anomalies. Using a cervical length threshold of 25mm between 14-24 weeks, one study noted 71% sensitivity, 91% specificity and 96% negative predictive value for predicting delivery prior to 35 weeks. An additional study using similar criteria found good negative predictive value in cervical length ultrasound but noted that it might not be as predictive in women with uterine didelphys. What has not been elucidated is what to do with patients found to have a short cervix.

Consideration for ultrasound indicated cerclage may be made, but this intervention has not been well studied in women with Müllerian anomalies. In one small series of six patients with uterine anomalies who received therapeutic cerclage, two delivered prior to 35 weeks despite cerclage.

Vaginal progesterone has been reported to reduce the risk of preterm birth among women with a sonographically short cervix. Women with Müllerian anomalies were excluded from the trial of Hassan et al and were not excluded from the trial of Fonseca et al. It is reasonable to offer vaginal progesterone to reduce the risk of preterm birth among women with Müllerian anomalies and sonographic short cervix less than 15 mm.

While 17 alpha-hydroxyprogesterone caproate (17OHPC) was shown to be effective at reducing the risk of recurrent preterm birth, women with Müllerian anomalies were excluded from the study. As a result, we know little of its efficacy in women with a history of preterm birth possibly related to a uterine anomaly. 17OHPC may be offered to these patients, but the limited applicability of the data from the original trial should be reviewed with patients and individual decisions regarding 17OHPC made.

Women with Müllerian anomalies should not be excluded from interventions routinely employed in the management of preterm labor, such as betamethasone administration and magnesium for fetal neuroprotection.

Uterine rupture

Cases of uterine rupture in women with various Müllerian anomalies have been reported, although the prevalence of this complication is difficult to ascertain. Rupture may be related to diminished uterine mass and higher rates of ectopic pregnancy. When uterine rupture occurs it often happens earlier in pregnancy, prior to the onset of labor.

Anomaly specific risk

Most reports of uterine rupture have occurred in women with unicornuate uteri with pregnancies in a rudimentary horn. These women are noted to have a 50% rupture rate. Rupture can occur anytime during pregnancy, but about 80% occur prior to the third trimester. Rupture usually occurs without antecedent symptoms. Regardless of timing, uterine rupture can lead to catastrophic outcomes with maternal mortality of 5.7%.

Interventions/management

If an advanced uterine horn pregnancy is diagnosed, the use of tocolytics can be considered, with plan for early delivery once the risk of prematurity for the fetus is diminished.

Growth restriction

Further characterization of the risk of intrauterine growth restriction in women with Müllerian anomalies is needed. Diminished musculature and abnormal uterine vasculature have been speculated as possible etiologies, particularly when the pregnancy is supplied primarily by a single set of uterine/utero-ovarian arteries. One study found that 2/3 of women with uterine anomalies had a completely lateralized placenta, were more likely to have abnormal systolic/diastolic ratios in the contralateral uterine artery and had higher rates of fetal growth restriction.

Anomaly specific risk

Anomalies such as unicornuate uterus or uterine didelphys are more likely to have unilateral vascular supply to a pregnancy and may be associated with greater risk of fetal growth restriction. Case series have noted fetal growth restriction in 10% of women with unicornuate uterus and 11% of women with uterine didelphys. Similarly, women with a uterine septum or bicornuate uterus that leads to complete lateralization of the placenta and pregnancy may also have increased rates of fetal growth complications.

Interventions/management

  • Fundal heights should be assessed and followed closely throughout the second half of pregnancy.

  • Obtaining serial growth ultrasounds every 3-4 weeks in the third trimester may be considered.

Hypertensive disorders of pregnancy

Hypertensive disorders are more likely to develop in pregnancies of women with uterine anomalies. Limited research has reported pre-eclampsia in 3-18% of women with uterine anomalies. Pre-eclampsia was found to be twice as common in women with uterine anomalies. A mechanism has not been elucidated, but additional pre-eclampsia risk factors associated with uterine anomalies have been outlined. Specifically, in one study 42% of women with renal agenesis and a uterine anomaly had a pregnancy complicated by gestational hypertension or pre-eclampsia. The relative risk for these complications was 2.33 compared to women with an anomalous uterus but without a renal anomaly.

Anomaly specific risk

The anomalies such as unicornuate uterus, which are most commonly associated with renal agenesis, may be at greatest risk for developing pre-eclampsia. One study found that 13% of women with uterine didelphys were diagnosed with pre-eclampsia. Regardless of the uterine anomaly, women found to have an associated renal anomaly are likely at risk for hypertensive complications.

Interventions/management

  • If not done prior to pregnancy, patients with a uterine anomaly should have renal imaging to note the presence of bilateral kidneys. This may be conveniently performed during a first trimester or anatomy ultrasound.

  • Consider obtaining baseline labs such as creatinine and urine protein evaluation which may prove helpful if evaluating a patient for pre-eclampsia later in pregnancy.

  • The signs and symptoms of pre-eclampsia should be reviewed with the patient.

Intrauterine fetal demise

Possibly related to several of the antepartum complications such as pre-eclampsia and intrauterine growth restriction noted previously, women with Müllerian anomalies may be at increased risk for intrauterine fetal demise. Further characterization of this risk is needed.

Anomaly specific risk

Limited data notes a fetal demise rate of 10.5% rate in women with unicornuate uterus and a 3.5% risk in women with uterine didelphys.

Interventions/management

⇒ Antenatal surveillance with non-stress tests or biophysical profiles in the third trimester can be considered, and should be performed in pregnancies complicated by hypertensive disorders or growth restriction.

⇒ Patients may be instructed to monitor fetal activity and counseled to present for evaluation if concerns arise.

What intrapartum complications are associated with Mullerian anomalies?
Malpresentation

Malpresentation is very common among women with all types of uterine anomalies, with reports of 23-38% of fetuses presenting non-vertex at time of delivery. Higher rates of malpresentation may be related to the abnormal uterine cavity that inhibits rotation of the fetus to cephalic presentation and to more frequent preterm deliveries, when the fetus is more likely to be breech.

Women who have pregnancies complicated by malpresentation may face it as a recurrent issue. One study noted that women with Müllerian anomalies and a history of cesarean section for malpresentation had significantly higher rates of repeat cesarean section for breech than women with normal uteri (59.3 vs 14.4%).

Anomaly specific risk

Limited studies note a particularly elevated risk of malpresentation with uterine septum, with a 35-53% rate of breech presentation.

Intervention/management

⇒ Confirming fetal presentation by pelvic examination or ultrasound is essential when a patient presents in labor or prior to labor induction.

⇒ Breech presentations are typically delivered by cesarean section.

⇒ Unfortunately no data on efficacy, risk or outcomes are available to guide the consideration of external cephalic version (ECV) in women with Müllerian anomalies. Success rates are likely much lower, and in most cases we advise against attempted ECV in this population.

Uterine rupture

Previously discussed as an antepartum risk, cases of uterine rupture during spontaneous labor and labor induction have been reported. Data on overall risk of rupture and outcomes are lacking.

Anomaly specific risk

Uterine rupture has occurred in spontaneous labor and during labor induction in pregnancies within rudimentary horns. The nearly 50% risk of rudimentary horn rupture does not vary whether or not the rudimentary horn communicates with the cervix, vagina or hemiuterus. Case reports of uterine rupture following hysteroscopic septum removal have also been noted, but this appears to be rare, with one event in a series of 180 term pregnancies. Hysteroscopic procedures likely confer a significantly lower risk of rupture and do not necessitate a cesarean delivery. Any woman who has undergone open or laparoscopic uterine metroplasty is at increased risk for uterine rupture.

Intervention/management

⇒ Women with uterine anomalies should be monitored in labor.

⇒ Patients who have had a hysterotomy for uterine metroplasty should be delivered by cesarean section prior to the onset of labor.

⇒ Pregnancies within a rudimentary horn should be delivered by cesarean section prior to the onset of labor once the risk of prematurity for the fetus is diminished.

Labor dystocia

While noted in early reviews of uterine anomalies and associated complications, limited data exist on the risk of labor dystocia in pregnancies complicated by Müllerian anomalies. Abnormal uterine musculature and insufficient forces generated by abnormal myometrium may lead to labor dystocia and an increased rate of operative delivery.

Anomaly specific risk

Several anomalies pose particular risks for labor dystocia. A rudimentary horn can obstruct descent of the fetal presenting part even if the pregnancy is located in the unicornuate horn. Additionally, women with uterine didelphys frequently have a longitudinal septum that can occasionally obstruct labor progress.

Intervention/management

Labor progress should be monitored and evaluation for factors contributing to dystocia such as vaginal septum or suboptimal fetal presentation should be performed.

Prophylactic resection of a longitudinal vaginal septum is generally not recommended, as the tissue often distends and moves aside because of the fetal presenting part. Controlled surgical resection with maneuvers to obtain hemostasis may be considered if a vaginal septum seems likely to bleed heavily with spontaneous disruption.

Attention must be paid to a patient’s specific anomaly and pregnancy location when undertaking maneuvers to assess and augment labor. In particular, women with uterine didelphys should have the appropriate cervix identified when performing cervical exams and placing a foley bulb or pressure monitor.

Cesarean delivery

Cesarean delivery is common in women with uterine anomalies. Malpresentation is the most common indication for cesarean delivery, but it is likely that increased rates of pre-eclampsia, labor dystocia and growth restriction also contribute to the cesarean section rate. More research is needed to determine the risks and complications of cesarean section specific to this population.

Anomaly specific risk

Delivery by cesarean section is most common in women with uterine didelphys with a reported rate of 84%. Of note, about 3/4 of these pregnancies will be located in the right uterus – something to consider when orienting to the uterus and important structures prior to making a hysterotomy.

Intervention/management

Awareness of the patient’s specific anomaly at time of surgery is important. Knowing landmarks that may or may not be present because of altered anatomy can be extremely helpful when negotiating a rotated, scarred or otherwise abnormal uterus. Special attention should be paid to locating the uterine vessel(s) and bladder prior to making the hysterotomy. Additionally, closely inspecting the lower uterine segment to assess its adequacy for a low transverse incision is advised, as it is not uncommon to need a classical incision to deliver the fetus. Orienting yourself to the patient’s anatomy can be even more essential should operative maneuvers such as hysterectomy be required to manage hemorrhage.

Post-partum hemorrhage

Bleeding complications can occur following delivery, most commonly associated with incomplete expulsion of the placenta, which occurs more frequently in women with Müllerian anomalies. Women with a vaginal septum in conjunction with a uterine anomaly are at risk for septum laceration. Data is limited regarding frequencies of these complications.

Intervention/management

  • Consider active management of the third stage of labor.

  • The placenta should be inspected after delivery and ultrasound should be available to evaluate for retained products.

  • A thorough inspection of the perineum and vagina should be performed with repair of a vaginal or septum laceration as indicated.

Trial of labor after cesarean (TOLAC)

Given the high rate of cesarean delivery in women with uterine anomalies, the question of attempting a vaginal birth after cesarean (VBAC) is frequently faced. One early study noted an 80% successful VBAC rate along with an 8% rate of uterine rupture. While concerning, both cases of uterine rupture occurred in women who underwent prostaglandin induction, which is no longer standard practice.

Additionally, researchers found higher rates of urgent cesarean section for fetal tracing concerns, operative vaginal delivery and cord prolapse. A more recent and larger retrospective study noted no cases of uterine rupture among women electing for TOLAC. The most common indication for the primary c-section was malpresentation. This was a recurrent complication for 58% of the women who had desired a TOLAC. For all women who intended to VBAC, success rates were significantly lower for women with a uterine anomaly (37.6%) versus those with normal uterine anatomy (50.7%).

Considering only women with cephalic fetuses, success rates were comparable between women with and without a uterine anomaly (57.4% vs 54.2%).

Intervention/management

The appropriateness of TOLAC is specific to each patient, her uterine anomaly, as well as her additional obstetric and medical history. Women should be counseled on their individual risks, benefits and likelihood of successful TOLAC, and consideration made for motivated women if appropriate.

Uterine torsion

Torsion of one uterine horn is a very rare complication reported with uterine didelphys that is most often encountered in labor . Patients may present with pain, labor dystocia or fetal distress. Resultant uterine ischemia and fetal compromise often requires emergent cesarean delivery.

Intervention/management

Women with uterine anomalies should be monitored on a labor suite capable of emergent cesarean delivery if significant fetal compromise is noted that is unresponsive to conservative measures.

Evaluating and comparing the placental location in a non-emergent scenario can help illuminate the etiology of pain or dystocia. Specifically, an ultrasound on the labor suite may note an anterior placenta when previous ultrasounds documented a posterior placenta.

6. What is the evidence for specific management and treatment recommendations

Simon, C. “Mullerian defects in women with normal reproductive outcome”. Fertil Steril. vol. 56. 1991. pp. 1192-3. (Study of 679 patients with normal reproductive outcomes to investigate the prevalence of various mullerian anomalies.)

Raga, F. “Reproductive impact of congenital Mullerian anomalies”. Hum Reprod. vol. 12. 1997. pp. 2277-81. (Retrospective longitudinal study of 3181 women attempting conception to determine the incidence and reproductive impact of uterine malformations. The population analysed included fertile, infertile and sterile patients, so the study allows an investigtion into the differential rates of mullerian anomalies in these populations. The overall frequency of uterine malformations was 4.0%. Infertile patients (6.3%) had a higher incidence of Müllerian anomalies, in comparison with fertile (3.8%) and sterile (2.4%) women.)

Acien, P. “Incidence of Mullerian defects in fertile and infertile women”. Hum Reprod. vol. 12. 1997. pp. 1372-6.

Chan, YY. “The prevalence of congenital uterine anomalies in unselected and high-risk populations: a systematic review”. Hum Reprod Update. vol. 17. 2011. pp. 761-71. (Systematic review evaluating the prevalence of congenital uterine anomalies in unselected populations and in women with infertility, a history of miscarriage, or a history of preterm delivery.)

Grimbizis, GF. “Clinical implications of uterine malformations and hysteroscopic treatment results”. Hum Reprod Update. vol. 7. 2001. pp. 161-74. (Clinical review of mullerian anomalies and their impact on fertility and pregnancy outcomes.)

Lin, PC. “Female genital anomalies affecting reproduction”. Fertil Steril. vol. 78. 2002. pp. 899-915. (Clinical review of mullerian anomalies, including embryologic origins and a summary of the studies that look at the impact of anomalies on a woman’s fecundity. Surgical therapies to potentially improve fertility are also reviewed.)

“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. vol. 49. 1988. pp. 944-55. (Most commonly used classification system for mullerian anomalies, depicted visually including subclassifications.)

Bermejo, C. “Three-dimensional ultrasound in the diagnosis of Mullerian duct anomalies and concordance with magnetic resonance imaging”. Ultrasound Obstet Gynecol. vol. 35. 2010. pp. 593-601. (Study of 65 women with mullerian anomalies who underwent both 3D ultrasound and MRI noted comparable diagnostic efficacy and very good concordance.)

Soares, SR, Barbosa dos Reis, MM, Camargos, AF. “Diagnostic accuracy of sonohysterography, transvaginal sonography, and hysterosalpingography in patients with uterine cavity diseases”. Fertil Steril. vol. 73. 2000. pp. 406-11. (Descriptive prospective study of 65 infertile women to evaluate the diagnostic accuracy of sonohysterography versus HSG and in uterine cavity diseases in infertile patients, comparing its results with those of hysterosalpingography (HSG) and transvaginal sonography (TVS). )

Nahum, GG. “Uterine anomalies, induction of labor, and uterine rupture”. Obstet Gynecol. vol. 106. 2005. pp. 1150-2. (Editorial on mullerian anomalies and risk of uterine rupture with labor induction.)

Reichman, D, Laufer, MR, Robinson, BK. “Pregnancy outcomes in unicornuate uteri: a review”. Fertil Steril. vol. 91. 2009. pp. 1886-94. (An excellent review article of pregnancy outcomes in women with unicornuate uteri.)

Heinonen, PK. “Clinical implications of the didelphic uterus: long-term follow-up of 49 cases”. Eur J Obstet Gynecol Reprod Biol,. vol. 91. 2000. pp. 183-90. (One of the larger retrospective studies (49 cases) of uterine didelphys and the impact on pregnancy outcomes.)

Oppelt, P. “Female genital malformations and their associated abnormalities”. Fertil Steril. vol. 87. 2007. pp. 335-42. (Study of 211 women with mullerian anomalies to evaluate the type and frequency of associated anomalies.)

Li, S. “Association of renal agenesis and mullerian duct anomalies”. J Comput Assist Tomogr. vol. 24. 2000. pp. 829-34.

Fedele, L. “Urinary tract anomalies associated with unicornuate uterus”. J Urol. vol. 155. 1996. pp. 847-8.

Heinonen, PK. “Gestational hypertension and preeclampsia associated with unilateral renal agenesis in women with uterine malformations”. Eur J Obstet Gynecol Reprod Biol. vol. 114. 2004. pp. 39-43.

Reichman, DE, Laufer, MR. “Congenital uterine anomalies affecting reproduction”. Best Pract Res Clin Obstet Gynaecol. vol. 24. 2010. pp. 193-208.

Pinsonneault, O, Goldstein, DP. “Obstructing malformations of the uterus and vagina”. Fertil Steril. vol. 44. 1985. pp. 241-7.

Hunter, RH. “Tubal ectopic pregnancy: a patho-physiological explanation involving endometriosis”. Hum Reprod. vol. 17. 2002. pp. 1688-91.

Heinonen, PK. “Unicornuate uterus and rudimentary horn”. Fertil Steril. vol. 68. 1997. pp. 224-30.

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