From the Guidelines
Monoamniotic twins with umbilical cord entanglement require intensive management to minimize morbidity and mortality, with a recommended delivery via cesarean section at 32-34 weeks gestation. The pathophysiology of monoamniotic twins involves both twins floating freely within one amniotic cavity without a separating membrane, allowing their cords to intertwine during fetal movement, which can lead to compression of umbilical vessels, restricting blood flow and oxygen delivery to one or both fetuses 1.
Diagnosis
Diagnosis is primarily made through detailed ultrasound examination, which can visualize cord entanglement as early as the first trimester, with color Doppler ultrasound being particularly useful in showing characteristic crossing patterns of the umbilical cords 1.
Management
Management requires intensive fetal surveillance starting at 24-26 weeks gestation with daily or twice-daily fetal heart rate monitoring to detect early signs of compromise, and hospitalization is often recommended from 24-28 weeks until delivery 1. Antenatal corticosteroids (betamethasone 12mg IM, two doses 24 hours apart) should be administered at 24 weeks to accelerate fetal lung maturity.
Complications
Major complications include sudden fetal death (occurring in 10-20% of cases despite monitoring), preterm birth complications, and acute intrapartum complications during delivery such as cord prolapse or acute cord compression 1. The mortality rate has significantly improved with modern management but remains higher than in other twin pregnancies, emphasizing the need for care at specialized centers with experience in managing these high-risk pregnancies.
Some key points to consider in the management of monoamniotic twins with umbilical cord entanglement include:
- Intensive fetal surveillance starting at 24-26 weeks gestation
- Hospitalization from 24-28 weeks until delivery
- Administration of antenatal corticosteroids at 24 weeks
- Planned delivery via cesarean section at 32-34 weeks gestation
- Monitoring for complications such as sudden fetal death, preterm birth, and acute intrapartum complications.
From the Research
Pathophysiology
- Monoamniotic twin pregnancies are high-risk pregnancies with a unique set of challenges, including a high risk of intrauterine fetal demise due to co-morbid conditions such as congenital anomalies and umbilical cord entanglement 2.
- Umbilical cord entanglement is a severe complication in monoamniotic multiple pregnancies, which can lead to intrauterine death of one or both twins 3, 4.
- The presence of superficial artery-to-artery and vein-to-vein anastomoses and deep arteriovenous shunts in the placenta can also contribute to the pathophysiology of monoamniotic twin pregnancies 3.
Diagnosis
- Early prenatal diagnosis of cord entanglement in monoamniotic multiple pregnancies is feasible using color Doppler and pulsed Doppler velocimetry, and can be detected as early as 10 weeks of gestation 3.
- Ultrasound examination is essential for establishing chorionicity and amniocity in twin pregnancy, and for diagnosing cord entanglement in monoamniotic twin pregnancy 4.
- Intensive fetal monitoring, including regular antepartum fetal heart trace monitoring and serial sonograms with umbilical artery Doppler flow study, is crucial for managing monoamniotic twin pregnancies 5.
Management
- The management of monoamniotic twin pregnancies relies primarily on retrospective studies and expert consensus, with a focus on early diagnosis, intensive fetal monitoring, and timely delivery 2.
- Inpatient hospitalization at viability, administration of corticosteroids for fetal lung maturity, and vigilant fetal monitoring can improve outcomes in monoamniotic twin pregnancies 2.
- Planned delivery in uncomplicated monoamniotic twin pregnancies can be considered at around 33 weeks of gestation, with cesarean section being the preferred mode of delivery 6, 5.
Complications
- Monoamniotic twin pregnancies are associated with high antenatal and perinatal morbidity and mortality, including cord entanglement, congenital anomalies, twin-twin transfusion syndrome, intrauterine growth retardation, and preterm delivery 5.
- Umbilical cord entanglement can lead to intrauterine death of one or both twins, and is a major contributor to the high perinatal mortality rate in monoamniotic twin pregnancies 3, 4.
- Prematurity and congenital anomalies are also significant contributors to the high perinatal mortality rate in monoamniotic twin pregnancies 6.