COMMENTARY

Congenital Uterine Anomalies Associated With Adverse Pregnancy Outcomes

Peter Kovacs, MD, PhD

Disclosures

February 09, 2015

Clinical Implications of Congenital Uterine Anomalies: A Meta-analysis of Comparative Studies

Venetis CA, Papadopoulos SP, Campo R, Gordts S, Tarlatzis BC, Grimbizis GF
Reprod Biomed Online. 2014;29:665-683

Background

The uterus, tubes, and upper vagina develop from the Müllerian ducts in the absence of anti Müllerian hormone. This development requires the prior existence of mesonephric ducts that will give rise to the renal system. The fusion of the Müllerian ducts will form the tubes, uterus, and upper vagina around the tenth week of gestation. Subsequent canalization will form the cavity, and the absorption of the dividing septum will result in the final, normal anatomy by midgestation.[1]

Congenital uterine anomalies can be detected in about 5% of women. The rate is lower in the general population, higher among infertile women, and the highest in women with recurrent pregnancy losses (10%).[2] Lack of fusion of the ducts, lack of absorption of the dividing septum, or lack of connection with the urogenital sinus may result in various types of anomalies. Uterine anomalies are classified into seven groups by the American Society for Reproductive Medicine (ASRM; formerly known as the American Fertility Society).[3]

Congenital anomalies of the uterus have been associated with infertility and adverse pregnancy outcomes. Anomalies that are not associated with outflow tract obstruction are asymptomatic and can only be detected on vaginal exam or imaging studies. There are multiple imaging modalities that can be used to specify the problem. Ultrasound is typically used as a first step, but hysterosalpingogram, sonohysterogram, 3D ultrasound, MRI, and hysteroscopy/laparoscopy can all be used to establish the correct diagnosis.

Anomalies that are associated with outflow tract obstruction are typically associated with cyclic pain around the time of menstruation and, therefore, require surgical treatment. Anomalies that do not produce symptoms do not necessarily require treatment unless they are associated with adverse reproductive outcomes. Prior to recommending routine surgical correction, one has to assess the impact of the various anomalies on reproduction and the potential benefits of surgery.

The Study

The authors have performed a meta-analysis based on the results of 25 studies (4 prospective, 21 retrospective). They have included comparative studies only where women with uterine anomalies were compared with women without such anatomic defects. The chance to achieve a pregnancy, the risk for pregnancy loss, preterm delivery, delivery of low-birth-weight infant, and third trimester pregnancy complications were evaluated. The ASRM classification was used to categorize anomalies.

The chance to achieve a natural pregnancy was negatively influenced by a uterine septum, but with the other anomalies there was no difference from control women. During assisted reproduction, there was no difference in the chance to achieve a pregnancy with or without anomalies.

The presence of an arcuate uterus, didelphys uterus, or a unicornuate uterus had no impact on first trimester pregnancy loss rates. The rate was, however, increased among women with a septated (relative risk [RR]: 2.65; 95% confidence interval [CI]: 1.39-5.06) or a bicornuate uterus (RR: 2.32; 95% CI: 1.05-5.13). The risk for second trimester loss was not affected by the presence of didelphys or unicornuate uterus but was increased with an arcuate, septated, or bicornuate uterus.

All types of anomalies were associated with preterm delivery before the 37th week of gestation, though the association was only marginally significant in the case of arcuate uterus. Very premature delivery before the 28th week of gestation was significantly associated only with bicornuate uterus. All anomalies were associated with an increased risk for malpresentation at delivery (transverse lie or breech presentation).

The delivery of a low-birth-weight (<2500 g) infant was significantly associated with a didelphys, bicornuate, or unicornuate uterus. An increased risk for intrauterine growth restriction was seen with all anomalies except for the arcuate uterus. Premature rupture of membranes was found not to be more common among women with uterine anomalies, but the risk for placental abruption was increased with arcuate and septated uterus. The risk for perinatal mortality was two- to threefold increased with septated and bicornuate uterus.

The chance to achieve a pregnancy did not improve following hysteroscopic removal of the uterine septum, but the risk for first trimester miscarriage was reduced by more than 60% (RR: 0.37; 95% CI: 0.25-0.55). According to this report, the risk for preterm delivery was not affected by the removal of the septum.

The authors concluded that certain types of congenital uterine anomalies are associated with certain adverse reproductive events. The removal of a uterine septum is associated with a lower risk for spontaneous pregnancy loss.

Viewpoint

Intact anatomy is required for successful reproduction, not just the ability to produce embryos and achieve implantation but a pregnancy that progresses to term and results in the delivery of a healthy child. Congenital anomalies of the Müllerian ducts affect between 5% and 10% of women, depending on the type of population evaluated.[2] The anomalies range from the absence of a uterus to a slight indentation in the fundal area resulting in an arcuate uterus.

Congenital anomalies of the uterus may be suspected based on the medical history (primary amenorrhea, dysmenorrhea, recurrent pregnancy loss), may be found during pelvic exam (vaginal septum, double cervix, etc.) or can be diagnosed during imaging studies. A 2D ultrasound may raise the suspicion. 3D ultrasound, saline sonohysterogram, or hysterosalpingogram could further aid the proper diagnosis. Pelvic MRI or laparoscopy/hysteroscopy may be required to establish the correct diagnosis. Because the genital and urinary tracts develop simultaneously and are in close proximity, the anomaly of one system should prompt an evaluation of the other.

Congenital uterine anomalies do not necessarily require treatment, and there are anomalies that cannot be corrected surgically. Because these types of anomalies are often found in women of reproductive age, their association with poor obstetric outcome and the potential of benefits with surgical correction need to be evaluated.

Various invasive and noninvasive surgical procedures have been proposed for the correction of the different anomalies. Some, however, seem to do more harm than good (eg, surgical correction of a bicornuate uterus) and, therefore, are no longer performed routinely. Based on the findings of this paper, surgical removal of a uterine septum is associated with a reduced risk for pregnancy loss and should be offered particularly to those with recurrent pregnancy loss.

It is important to establish the correct diagnosis once a uterine anomaly is suspected and to discuss the risks associated with the given anomaly. According to the currently available evidence, the removal of a uterine septum should be offered to those with this type of anomaly, but there is no sufficient scientific support for surgical correction of other types of anomalies. More research should evaluate the full impact of the anomalies and their surgical treatments on reproductive outcome.

Abstract

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