Management of a twin pregnancy in a didelphys uterus: one fetus in each uterine cavity

Background

A uterine didelphys is a congenital anomaly due to the failure of fusion of the Müllerian ducts, leading to the development of two uterine bodies, each with its own cervix, fallopian tube and often a septate vagina.1 The prevalence of this anomaly is approximately 0.3%; however, the prevalence is increased in women with adverse reproductive outcomes and infertility.2 3 Twin pregnancy in a uterine didelphys with one twin in each horn is rare; however, the exact rate of occurrence is unknown as the data on such cases are only represented in a small number of case reports.1 One such case report quotes the incidence to be 1 in 1 million pregnancies.4 This rare occurrence poses multiple risk factors for the woman and the fetuses.1 5 The risks include preterm labour and birth, intrauterine fetal growth restriction, malpresentation and caesarean delivery.5 We present the case of a woman with a known uterine didelphys. She presented with spontaneous conception of a twin pregnancy with one fetus in each uterine cavity. Her pregnancy was complicated by intrauterine growth restriction necessitating preterm delivery and mild postpartum pre-eclampsia.

Case presentation

A fit-and-well 35-year-old nulliparous female patient was diagnosed with a complete uterine didelphys (two uteri, two cervices and a vaginal septum) as an adolescent (figure 1). She had the vaginal septum resected at age 29 and subsequently conceived spontaneously. She was referred at 12 weeks’ gestation with a twin pregnancy. She had no other significant medical disease or family history of pre-eclampsia, uterine anomalies or twin pregnancies. Her ethnicity is Eurasian. Initial ultrasound at 8 weeks’ gestation identified the twin pregnancy with one fetus in each uterine cavity. Her referral was forwarded to the tertiary hospital’s dedicated preterm birth clinic due to the increased risk of preterm delivery.

Investigations

Initial assessment in the preterm birth clinic included an ultrasound performed by a maternal–fetal medicine specialist. This confirmed a live fetus in both the right and left horns of the uterine didelphys. (figures 2 and 3). Placentae were situated on the posterior wall of each uterine cavity and fetal growth was concordant with gestational age. Routine transvaginal cervical length assessment was performed with the left cervix measuring 38 mm and the right measuring 35 mm (in closed length) (figure 4) and progesterone supplementation was not required, as per local guidelines, for preterm birth prevention. Routine aneuploidy screening was performed with normal results (low risk for trisomy 21, 13 and 18). She was screened for pre-eclampsia at each antenatal visit with routine blood pressure measurements and urinalysis, all of which were normal.

Serial ultrasound monitoring (including transvaginal cervical length) in the preterm birth clinic was performed every 2–3 weeks until 23 weeks’ gestation. Cervical length remained stable between 35 and 43 mm for both cervices until viable gestation. Fetal anatomy was reviewed at 19 weeks and 6 days gestation, and was reported as normal (within limitation of ultrasound). Presentation of both twins was assessed with each ultrasound and remained breech-breech from 23 weeks’ gestation onwards.

Serial growth scans were performed at 28, 32 and 36 weeks’ gestation. Measurements were plotted on local population-based growth charts derived from data obtained in the Raine Study.6 Intrauterine growth restriction of twin 2 was identified at 36 weeks’ gestation. The abdominal circumference for twin 2 crossed from the 50th percentile to the 3rd percentile across a 4-week period. The umbilical artery and middle cerebral artery dopplers were normal for both twins; however, delivery was planned for 36+3 weeks given static growth of twin 2.

Treatment

Discussion with the patient regarding mode of delivery began at 28 weeks’ gestation. Consideration for vaginal delivery as an option was discussed with the patient. In the case of the presenting twin remaining in breech presentation, a caesarean delivery was to be recommended.

Given the persistent breech presentation of both fetuses at 36 weeks, a caesarean delivery was recommended. Given the intrauterine growth restriction of the male fetus, timing of delivery was brought forward and an elective caesarean section was booked for 36 weeks and 3 days.

A Pfannenstiel skin incision was made with routine abdominal entry. A transverse incision was made on the lower segment of the left uterus, and a live male infant was delivered. Assessment of the right uterus revealed a relatively narrow and poorly formed lower segment, a classical (vertical) incision was made and a live female infant delivered (figure 5). Placentae were removed one by one with controlled cord traction and both uterine wounds were sutured in two layers (figures 6 and 7).

Outcome and follow-up

Both male and female infants were born alive and well, no resuscitation was required and both infants had Apgar scores of 9 at 1 and 5 min. The male infant weighed 2440 g and the female infant weighed 2730 g. The patient’s postoperative recovery was complicated by pre-eclampsia immediately post delivery requiring one dose of antihypertensives and blood pressure monitoring in the high-dependency unit. She had a raised urine protein:creatinine ratio of 59 mg/mmol, her platelet count dropped to 104×10⁹/L, and she had a mildly raised lactate dehydrogenase at 346. She was discharged from the postnatal ward after 5 days without further complication and she neither required magnesium sulfate nor ongoing antihypertensive therapy.