Uterine didelphys: diagnosis, management and pregnancy outcome

Abstract

This report addresses and discusses two cases of uterine didelphys in pregnancy. The first case describes the diagnosis, management and subsequent pregnancies in a 28-year-old woman, para 2, with known didelphys uterus, left-obstructed hemi-vagina and ipsilateral renal agenesis. This uterine anomaly was diagnosed at 13 years of age, after pelvic imaging identified a haematocolpos and two uteri. To drain this haematocolpos, a hymenectomy was performed. In the second case, an incidental finding of uterine didelphys and vaginal septum in a 28-year-old primigravida is described. Both patients delivered healthy male infants at term via emergency and planned lower segment caesarean sections, indicating women with major uterine anomalies can have successful obstetric outcomes.

Background

Congenital uterine anomalies arise from abnormal Mullerian duct formation, fusion or reabsorption during fetal life.¹ Complete fusion failure of bilateral Mullerian (paramesonephric) ducts results in uterine didelphys.¹ Morphologically uterine didelphys presents with two uteri, two cervices and a single or double vagina.¹ Bilateral Mullerian (paramesonephric) ducts begin to fuse at 6 weeks in utero and fusion continues until 14 weeks.² During embryogenesis, bilateral Mullerian ducts extend caudally and medially to unite together to form the uterus, cervix and vagina. This total fusion defect results in uterine didelphys. The population prevalence of didelphys uterus is reported to be between 0.3% and 5%.^{3 4} However, the true population prevalence is difficult to accurately determine, due to significant study heterogeneity, various diagnostic methods and no universally accepted classification system.

The presentation of such uterine anomalies can vary, ranging from incidental findings of isolated congenital uterine defects to complex uterine anomalies with genital and renal malformations. Furthermore, women with unification defects are at increased risk of preterm labour, growth restriction and fetal malpresentation.^5–8 Often the exact aetiology of these complications is unknown or multifactorial and unadjusted confounding factors may have further affected study findings.⁸ Moreover, unilateral renal agenesis may predispose women to pregnancy induced hypertension and preeclampsia.⁹ Despite these reported complications, women with uterine fusion defects who are asymptomatic or are diagnosed incidentally can have uncomplicated pregnancies.^{8 10–12}

We describe two cases of uterine didelphys in pregnancy. The first case describes the diagnosis, and subsequent pregnancies, in a woman with didelphys uterus, left obstructed hemi-vagina and ipsilateral renal agenesis. An incidental finding of uterine didelphys and vaginal septum in a primigravida is discussed in the second case. The diagnosis, management and pregnancy outcomes are addressed and discussed.

Case presentation

Case 1

The first case describes the diagnosis and pregnancy outcomes in a 28-year-old woman, para 2, with known uterine didelphys, left obstructed hemi-vagina and ipsilateral renal agenesis. At 13 years of age she presented with severe lower abdominal pain and distension. Pelvic ultrasonography identified a suspected haematocolpos, despite monthly menstruation. Pelvic MRI demonstrated a complete uterine septum, separating a larger left uterine horn with retained haemorrhage, from a smaller right uterine horn. Both images confirmed an absent left kidney and normal right kidney. Examination under anaesthesia (EUA) identified normal external genitalia, a left imperforate and a right poriferous hymen with two vaginas and cervices. Hymenectomy with a cruciate incision of the imperforate hymen was performed, and the collection was drained.

At 19 years of age, a further EUA confirmed two normal cervices, a right normal vagina, and a rudimentary left vagina. Double hysteroscopy identified two separate uterine cavities, each with a single tubal ostium. At laparoscopy, two fused uteri with a single fallopian tube from each cavity were visualised. Dye test confirmed a patent right fallopian tube, but the left fallopian tube contained a hydrosalpinx with an occluded phimotic fimbrial end.

Both pregnancies were spontaneously conceived in the right uterine horn. In the first pregnancy, spontaneous onset of labour occurred at term, and this was augmented with intravenous oxytocin. At 6 cm cervical dilation, intravenous oxytocin was stopped due to the presence of variable decelerations on the cardiotocography. Vaginal examination, 2 hours later, noted full cervical dilation with the vertex at −1. However, the vaginal septum obstructed fetal descent. Since cardiotocography had improved, intravenous oxytocin was recommenced. A further 2 hours later vaginal examination remained unchanged. A live male infant, weighing 3330 g, was delivered via a category two lower segment caesarean section. Apgar scores were normal; 9 and 10 at 1 and 5 min. Second pregnancy, 3 years later, was uncomplicated. Routine ultrasounds were reassuring, demonstrating a healthy foetus with normal umbilical dopplers and liquor volume. At term, an elective lower segment caesarean section was planned (figure 1). A live male infant weighing 3680 g, with Apgar scores of 9 and 10 at 1 and 5 min, was delivered.

Figure 1.

Case 1—didelphys uterus at caesarean section.

Case 2

A healthy 28-year-old primigravida, who presented for pregnancy dating ultrasound at 12 weeks gestation, was incidentally diagnosed with a didelphys uterus. Transabdominal ultrasound identified a viable intrauterine pregnancy in the right horn and both uteri were confluent with a single cervix (figure 2). Both kidneys were present and appeared normal. Body mass index was elevated at 34 kg/m². Medical, surgical and gynaecological history were unremarkable, although her maternal grandmother had two uteri.

Figure 2.

Case 2—didelphys uterus with pregnancy in the right uterine horn.

Antenatal course was uneventful. Ultrasound showed a well-grown foetus with normal umbilical dopplers and liquor volume. At 39 weeks gestation, induction of labour was planned for reduced fetal movements. Cardiotocography was reassuring, but limited fetal movement was noted on ultrasound. After 6 mg of prostin, vaginal examination demonstrated two cervices and two vaginas separated by a thin longitudinal vaginal septum. The left cervix was closed and soft, but the right cervix was 1 cm long and 2 cm dilated with bulging membranes. Spontaneous rupture of membranes occurred, and intravenous oxytocin was commenced.

After 8 hours of intravenous oxytocin, the right cervix remained unchanged and a non-reassuring cardiotocography was recorded. A category two lower segment caesarean section was performed, confirming two individual uteri, each with one fallopian tube and ovary, extending to the vagina. A flat male infant weighing 3110 g was delivered. Apgar scores were 2, 6 and 9, at 1, 5 and 10 min. Resuscitation was successful.

Outcome and follow-up

Although both patients required emergency and planned lower segment caesarean sections, both women and their infants had uneventful postnatal recoveries. Since the patient in case 1, has had two previous caesarean sections, contraception is important. Prior to conceiving, the combined contraceptive pill was prescribed for dysmenorrhoea and this was recommenced 3 weeks post-delivery. The patient discussed in case 2 has two functioning vaginas, vaginal delivery after caesarean section is an option for future deliveries. While contraceptive method was not confirmed before discharge, one intrauterine conceptive will need to be inserted in each uterus for effective contraception.

Discussion

Both cases represent complex Mullerian duct fusion anomalies. Confirming the diagnosis of uterine didelphys with obstructed left hemi-vagina and unilateral renal agenesis was particularly challenging, given imperforate hymen is typically seen in primary amenorrhoea.² Fusion of the Mullerian ducts forms the uterus and upper vagina, while, the inferior vagina is formed from the urogenital sinus.¹³ Wolffian (mesonephric) ducts induce both kidney formation and lateral fusion of the caudal Mullerian ducts with the urogenital sinus.¹³ Mullerian duct fusion failure results in double uteri, and this combined with a lateral fusion defect results in obstructive hemi-vagina with ipsilateral renal anomaly.¹⁴ This triad of uterine didelphys, obstructed hemi-vagina and ipsilateral renal agenesis known as Herlyn-Werner-Wunderlich-Syndrome was described in the 1980s.¹⁵ In 2007, the acronym OHVIRA (obstructed hemivagina and ipsilateral renal agenesis) was devised to allow inclusion of other uterine anomalies.¹⁴ Our first case report described left-sided obstructed hemi-vagina and ipsilateral renal agenesis, meeting the criteria for OHVIRA. Interestingly, left-sided urogenital anomalies are rarely reported, with studies finding 66.9%–80% of women with uterine didelphys had a right-sided obstructed hemi-vagina with ipsilateral renal agenesis.^{13 16 17} While the exact aetiology is uncertain, disturbed embryogenesis compounded by sporadic environmental or genetic factors likely account for this discrepancy.

Diagnosis of uterine anomalies, while dependent on imaging and surgical findings, is often subjective. Although two-dimensional ultrasound is commonly utilised, it is considered the least accurate imaging investigation,¹⁸ likely due to difficulties visualising the external uterus.¹⁹ Compared with hysteroscopy, two-dimensional ultrasound has a sensitivity of 56% and specificity of 100%, indicating it is useful for screening in conjunction with other imaging modalities.¹⁸ Furthermore, women who experience infertility or recurrent miscarriages are more likely than the general population to undergo extensive investigation, potentially identifying a higher incidence of uterine anomalies in this group.¹⁹ In the second case, transabdominal ultrasound showed both uterine horns were confluent with a single cervix indicating potential bicornuate-unicollis (single cervix). Although it can be difficult to differentiate a non-fused bicornuate uterus from a didelphys uterus, imaging combined with clinical examination ensures correct diagnosis and subsequent appropriate management.

Women with major uterine fusion defects are at increased risk of adverse obstetric outcomes including: preterm labour, fetal malpresentation and caesarean section.^{3 5–8} Studies were retrospective with inherent bias and clinical heterogeneity, limiting causation of these findings. In all studies uterine didelphys was the rarest uterine anomaly, but was significantly associated with preterm labour <37 weeks gestation in 33.3%–56% of women.^6–8 The aetiology of preterm labour is often unknown or multifactorial.⁸ Furthermore studies were uncontrolled, and unadjusted risk factors may have influenced results.^6–8 Distorted anatomy limiting uterine capacity or cervical incompetence may increase the risk of preterm labour in this group.⁵ A short cervical length with known uterine anomaly is a good predictor for preterm labour.²⁰ Other than uterine anomaly, both our patients had no other known risk factors for preterm labour and breech presentation. Both women delivered healthy infants at term, in the vertex presentation, indicating women with major uterine anomalies can have successful obstetric outcomes.

In comparison to the general population, women with Mullerian uterine anomalies are more likely to undergo caesarean section.^5–8 Studies report up to 82.3% of women with uterine anomalies required caesarean sections, irrespective of the clinical indication.^{5 7} From this cohort, 43.6%–65.8% of caesarean sections were indicated for non-vertex presentation, and 28.4%–53.8% of caesarean sections were completed for repeat caesarean section.^{5 7 21} However, these studies did not differentiate uterine didelphys from other major uterine anomalies, thus the risk of caesarean section is not clear for this subgroup. Furthermore, women undergoing trial of labour did not have a higher risk of caesarean section in comparison to the general population.^{5 6 21} Given the high rate of caesarean sections and fetal malpresentation in this group, less women were likely to labour. Both our patients required emergency caesarean sections for failure to progress in the first and second stages of labour. The presence of a vaginal septum may cause soft tissue dystocia, mechanically limiting fetal descent.¹⁰ It is not clear whether suboptimal myometrium contraction or decreased uterine muscle mass due to abnormal embryonic development contributed to labour dystocia.¹⁰ Irrespective of uterine anomaly, each clinical situation must be assessed and managed individually. The decision to proceed with an emergency caesarean section is often based on clinical indicators of maternal and fetal distress, where clinical benefit outweighs risk of adverse events.

Given the rate of fetal malpresentation is higher in women with uterine anomalies,^{3 5–8} it is more likely these women will require planned caesarean sections. Consequently, family planning is especially important for this group. Depending on risk factor profile and patient preference, a long-acting contraceptive may be the method of choice. Although significant uterine distortion is considered a contraindication to intra-uterine contraceptive device insertion, several case reports describe successful insertion of an intra-uterine device in each uterus.^{8 22–24} Essentially, patient choice, desire for further pregnancies and medical history must be considered when planning future fertility.

Learning points.

• Uterus didelphys can present incidentally or with significant symptoms, and there are often concurrent renal and genital anomalies.

• As demonstrated by our case reports, women with uteri didelphys can have good obstetric outcomes, despite increased risk of caesarean section for fetal malpresentation and history of previous caesarean section.

• Available studies are clinically heterogenous, retrospective and vary methodologically influencing prevalence rates and study results.