The septate uterus is not only the most common Müllerian anomaly, it is the uterine malformation associated with the poorest reproductive outcomes, including recurrent pregnancy loss, preterm labor, malpresentation, and probably infertility. Although many patients with a uterine septum are asymptomatic and conceive and deliver without any difficulty, those who do have poor outcomes can benefit from transection of the septum.
The simplicity of hysteroscopic septoplasty, with its low rates of intraoperative complications and postoperative sequelae, provides experienced gynecologic surgeons with the opportunity to remarkably improve reproductive and obstetric outcomes for their patients with this anomaly.
By Dr. Megan Daw
The procedure has proven to be safe and effective for women with a history of recurrent miscarriage and other poor reproductive outcomes. Although a causal relationship between the septate uterus and infertility remains unproven, encouraging findings from numerous retrospective and observational studies are supporting the procedure’s use in patients with unexplained primary infertility as well.
Incidence and Effects
Müllerian anomalies are an embryologic phenomenon of the female reproductive tract. The anomalies are the result of a defect in the elongation, fusion, canalization, or septal reabsorption of the Müllerian/paramesonephric ducts.
Normally, at approximately 9 weeks’ gestation, these steps occur without incident and result in the creation of a single unified uterine cavity. In some cases, however, incomplete or failed reabsorption of the intervening partition of Müllerian products results in a persistent fibromuscular uterine septum. The extent of the septum varies; usually, it partially affects the uterine cavity rather than completely dividing it.
The septate uterus, the most common type of Müllerian anomaly, has been estimated to occur in 3%-7% of the general population. Its clinical sequelae include increased rates of spontaneous abortion, preterm delivery, intrauterine growth restriction, and malpresentation, compared with rates in women without a septum, as well as a higher rate of cesarean delivery.
Estimates of pregnancy rates in patients with a septate uterus have ranged from 5% to 40%, and miscarriage rates of 70%-90% have been reported. Thus, live birth rates in this population are poor.
Although uterine septa are closely related to recurrent miscarriage, the effect of the septate uterus on fertility is controversial. Some experts have proposed that the septate uterus may at least contribute to otherwise unexplained infertility by adversely affecting implantation. The endometrium overlying the septum may be different from the neighboring endometrium within the uterine cavity, it is believed, although this relationship is not yet directly correlated with primary infertility.
Dr. Luigi Fedele and his colleagues in Milan reported ultrastructural changes in biopsy sites from the septum, compared with the sites in the lateral uterine wall, using scanning electron microcopy. These histological factors included reductions in the number of glandular ostia, an irregular distribution of glandular ostia, incomplete ciliogenesis, and reductions in the ciliated cell ratio. The authors further concluded that septal tissue had decreased sensitivity to steroid hormones (Fertil. Steril. 1996;65:750-2).
Indications for Surgery
Currently, indications for surgical correction of a uterine septum include pelvic pain, endometriosis, an obstructing phenomenon, recurrent miscarriage, and history of preterm delivery.
Infertility is a controversial indication for surgery, as its association with the septate uterus has not been demonstrated by randomized studies. Several observational studies, however, have shown promising results with postoperative pregnancy rates of 25%-70% in patients with primary infertility, and there is consequently a movement to expand the use of hysteroscopic septoplasty to this subset of patients.
In one systematic review of 18 studies (including one retrospective cohort study of 64 women conducted by the review’s authors), the overall pregnancy rate after hysteroscopic septoplasty was 60% and the overall live birth rate was 45% (Reprod. Biol. Endocrinol. 2010;8:52-60).
A more recently published prospective study of women with unexplained primary infertility yielded remarkable results. Of 88 patients who underwent septoplasty, 48% conceived within a mean time to conception of approximately 7 months. Nearly 80% of these women conceived spontaneously, and more than 80% had live births. Approximately 71% of the deliveries were vaginal.
The only identifiable factor associated with reproductive failure in this study was a uterine septum. Patients had unexplained primary infertility for at least 48 months, and the study excluded patients with any history of miscarriage, abortion, or other factors that could contribute to infertility, such as endometriosis (Eur. J. Obstet. Gynecol. Reprod. Biol. 2011;155:54-7).
Diagnosis
Many imaging modalities have been used in the diagnosis of a uterine septum, including hysterosalpingogram (HSG), 2D and 3D ultrasound, saline infusion sonohysterography, and MRI. Müllerian anomalies may be paired with anomalies of the urinary tract, although the correlation with uterine septa is present less frequently than with other uterine anomalies. Nevertheless, evaluation of the urinary tract should be performed as part of the diagnostic work-up in patients with anomalies and thus may influence the diagnostic approach.