Is Prophylactic Hysteroscopic Metroplasty for the Septate Uterus Justified?

Introduction

Septate uterus is a common congenital malformation. Although clinical studies have shown poor obstetric outcomes in patients with septate uteri, the significance of this finding and its effect on fertility remain controversial. ¹ Operative hysteroscopy is the preferred method of treatment in patients presenting with recurrent abortions or poor obstetric histories; however, choosing to perform prophylactic metroplasty when a septum is incidentally diagnosed in an otherwise healthy patient is controversial. During uterine formation, either interruption or dysregulation of any of the dynamic processes of Müllerian-duct differentiation, migration, fusion, or canalization can lead to a wide spectrum of morphologic anomalies. ² The occurrence of congenital uterine malformations has a polygenic multifactorial inheritance, and may represent one component of a multiple malformation syndrome.^3–5

The septate uterus is graded class V according to the classification system originally proposed by Buttram and Gibbons and revised in 1988 by the American Fertility Society, now the American Society of Reproductive Medicine.^6,7 The septum, located in the midline fundal region, is composed of poorly vascularized fibromuscular tissue. ⁸ Morphologically, there are numerous variations, including a complete septum that extends from the fundus to the internal cervical os (dividing the endometrial cavity) and that is frequently associated with a longitudinal vaginal septum. ⁹ A partial septum, however, does not extend to the os, and in variants of this disorder, some septa may be segmental, permitting limited communication between the endometrial cavities. ¹⁰ This review outlines the clinical importance of a septate uterus, techniques of diagnosis and surgical treatment, and the reproductive outcome after metroplasty, with a focus on data supporting prophylactic hysteroscopic metroplasty.

Clinical Significance of the Septate Uterus

The presence of a malformed uterus might impair reproductive performance by increasing the risks of early or late abortion as well as preterm delivery and premature rupture of membranes. It is likely that different types of septa will have different impacts on pregnancy outcomes. ¹¹ There is difficulty in defining the prevalence of uterine anomalies, because most affected women will not experience reproductive problems and will remain undiagnosed. In a review of five studies collating nearly 3000 cases, the mean overall prevalence of a uterine malformation in the general population of fertile women was 4.3%, which included septate uteri in 34.9% of the cases. ¹¹ By contrast, the mean incidence of Müllerian defects in infertile women was 3.4%, which would suggest that the presence of such defects does not affect fertility significantly, although the presence of a septate uterus might delay natural conception in a patient with secondary infertility.

A later retrospective longitudinal study by Raga et al., ¹² which examined 3181 patients using a combination of hysterosalpingography (HSG) and laparoscopy/laparotomy to establish uterine morphology, found a higher incidence of Müllerian anomalies among infertile women, compared with fertile cohorts (6.3%, 3.8%, and 2.4%, respectively). In this study, the prevalence of septate uteri was similar in both infertile and fertile patients (2.0% versus 1.5%, respectively). The prevailing belief is that a septate uterus produces the poorest reproductive outcomes of all uterine malformations. In this respect, the mean overall prevalence of Müllerian defects in patients with recurrent pregnancy loss is 12.6%, a substantial increase over that of the general population, in whom failure to treat uterine malformations may impair pregnancy outcome significantly.^12–14 With respect to this concern, a review of 198 patients with a untreated septate uteri and a total of 499 pregnancies showed a 44.1% abortion rate, a 22.3% preterm delivery rate, a 32.9% term delivery rate, and a 50% live birth rate. ¹¹

Diagnosis of a Septate Uterus

There are six methods available for diagnosing a septate uterus, including HSG, transvaginal ultrasound (TVUS) with or without color Doppler imaging, hysterosonography, three-dimensional ultrasound (3D-US), magnetic resonance imaging (MRI), and hysteroscopy. In a study by Kupesic and Kurjac that compared the diagnostic accuracy of the different modalities, TVUS and color Doppler imaging were performed in all 420 patients prior to hysteroscopy, whereas hysterosonography and 3D-US were used in 76 and 86 patients, respectively. The sensitivity of TVUS and 3D-US with color Doppler imaging for the diagnosis of septate uteri was 95.0% and 99.3%, respectively, whereas the sensitivity of hysterosonography and 3D-US was 100.0% and 93.6%, respectively. Although all congenital uterine malformations were predicted by 3D-US, this modality was unable to differentiate septate uteri from other fusion malformations. ¹⁵ A fibrous septum is demonstrated by a low signal intensity on T2-weighted MRIs, whereas a septum composed of abundant muscular tissue shows intermediate signal intensity. The external uterine contour appears normally convex, flat, or minimally indented by <1 cm. ¹⁶

Surgical Treatment of the Septate Uterus

Hysteroscopic metroplasty is the preferred and most commonly performed surgical procedure for resection of the uterine septum. Some perform combined laparoscopy–hysteroscopy operations—first to distinguish a septate from a bicornuate uterus and, second, to avoid damage to the uterine fundus. Currently, following advanced imaging, many surgeons perform hysteroscopic metroplasty without laparoscopic assistance. Hysteroscopic metroplasty can be performed by using a resectoscope or scissors or by utilizing laser energy with no clear advantage of any of these techniques. Operative hysteroscopy can be performed either by bipolar or monopolar electrosurgery, with bipolar electrosurgery requiring a distention medium. ¹⁷

Reproductive Outcome After Hysteroscopic Metroplasty

The reproductive outcomes following hysteroscopic metroplasty are inconsistent and are based on retrospective studies. Nouri et al. collected data from 18 retrospective studies investigating the effect of hysteroscopic metroplasty on reproductive outcome in 1501 patients. ¹⁷ The overall pregnancy and live birth rates after hysteroscopic metroplasty were 60.1% and 45%, respectively. Mollo et al. ¹⁸ performed the only prospective controlled trial comparing 44 patients with septate uteri and otherwise unexplained infertility, with 132 patients with unexplained infertility but without uterine septa. All patients with septate uteri underwent hysteroscopic metroplasty. After 1 year of follow-up, the pregnancy and live birth rates were significantly higher in patients who underwent removal of uterine septa than in the group with unexplained infertility and no uterine septa (38.6% versus 20.4%, and 34.1% versus 18.9%, respectively).

Complications of Hysteroscopic Metroplasty

The likelihood of complications following a hysteroscopic metroplasty depends upon the operative procedure and the operator's skills, although most complications are relatively rare. Sui et al. performed 447 hysteroscopic metroplasties with 1 (0.22%) uterine perforation; 6 cases (1.34%) of blood loss >50 mL, and 2 cases of blood loss (0.45%)>100 mL. ¹⁹ In this study, there were 3 cases (0.67%) of postoperative pelvic infection, 5 cases (1.1%) of urethral infection, and 2 cases (0.45%) of bradycardia. In the pooled analysis of Nouri et al., ¹⁷ repeat operations were required in 6% of the patients. A late complication of uterine rupture during a subsequent pregnancy in which a prior operative hysteroscopy was performed is rare, but has been described by Sentilhes et al. in a review of 14 such case reports. ²⁰ Uterine perforation and/or the use of electrosurgery increased the risk of uterine rupture but neither were independent risk factors.

Is Prophylactic Hysteroscopic Metroplasty Justified?

Controversy exists in the literature concerning the reproductive outcome after uterine metroplasty, mainly because of the retrospective nature of observational studies in which a prospective, randomized trial that compared metroplasty to expectant management would be considered unethical. Despite this, hysteroscopic metroplasty is a common practice in many countries in women with recurrent miscarriage, based on its presumptive effectiveness; however, studies are biased favoring patients with an intention-to-treat basis because of their poor reproductive outcomes. ²¹

It is suggested that counseling for metroplasty should depend on the patient's personal medical and obstetric history, in which, despite the fact that the presence of a uterine septum does not contribute clearly to infertility per se, the septum might delay natural conception and increase the risk of adverse pregnancy outcomes even during the patient's first pregnancy. As stated, untreated septate uteri are associated with increased abortion and preterm delivery rates and with reduced term delivery and live birth rates. ¹¹ It is intuitive to consider—but as yet unproven—that prophylactic hysteroscopic metroplasty is beneficial.

An unanswered question is the indication for metroplasty in the presence of a uterine septum in a patient who has had only one abortion. Because operation-related complications are rare, and the psychosocial burden to the patient increases with every additional abortion, the current authors believe that it is appropriate to perform a metroplasty in such cases. The retrospective data already referred to reported by Mollo et al. ¹⁸ in patients with unexplained infertility who underwent routine metroplasty for septate uteri showed higher pregnancy and live birth rates in this group, and would suggest endorsement for prophylactic metroplasty. The more challenging question is whether or not to perform prophylactic metroplasty when a septum is incidentally diagnosed in an otherwise healthy patient. Regarding this question, Acien et al. studied the pregnancy outcomes of patients with untreated Müllerian defects. The group of 31 patients with septate uteri included 24 first pregnancies and 65 recurrent pregnancies. The abortion rate was 21% versus 23%; the preterm delivery rate was 8% versus 23%; and the term delivery rate was 71% versus 54% in the first- and the recurrent-pregnancies groups, respectively. By comparison, data on 28 patients with normal uteri included 26 first pregnancies and 47 recurrent pregnancies. In this group, the abortion rate was 12% versus 8%; the preterm delivery rate was 8% versus 6%; and the term delivery rate was 81% versus 85%, respectively, ²² suggesting that prophylactic uterine metroplasty might decrease the abortion rate and increase the term delivery rate, but would not affect the preterm delivery rate.

Conclusions

Hysteroscopic metroplasty is a safe procedure with few complications; thus it has the potential to be offered more widely even if a septate uterus has been diagnosed incidentally. It is generally accepted that metroplasty is indicated in patients with septate uteri and a poor obstetric histories. In women with reproductive histories of 2 or more fetal losses during the first or second trimester of pregnancy, hysteroscopic metroplasty offers a chance for a favorable prognosis with a considerable decrease in miscarriage risk.^1,22,23 In a patient presenting with a single spontaneous abortion or in patients with infertility, hysteroscopic metroplasty might prove beneficial, and is therefore advised, although some researchers advocate a conservative approach, given the relatively high delivery rate in subsequent pregnancies. ¹ Although hysteroscopic metroplasty is controversial, the current authors suggest that this prophylactic treatment could include patients who have not yet experienced any potential obstetrical problems, particularly in patients >age 35 with predicted declining fecundity, in those with unexplained infertility, and prior to using assisted reproductive techniques.