O30.013

Clinical Causes: Conception of identical twins resulting from the splitting of a fertilized egg later than usual, leading to sharing of the same chorion and amniotic sac. Genetic factors that may influence the timing of the split, although precise causes are not fully understood. Random biological variation, as the exact trigger for this specific twin arrangement remains unknown.

Key Symptoms: In many cases, there are no specific symptoms, and the condition is identified during routine ultrasound scans. Potential signs include rapid growth of the gravid uterus or discrepancies in growth between the twins observed during ultrasound. Complications such as polyhydramnios (excess amniotic fluid) may arise, indicated by increased abdominal girth and discomfort in the mother. Observation of umbilical cord entanglement during ultrasounds, which can be a concern in monoamniotic twins.

Diagnosis Path: Ultrasound showing a single chorionic sac and a single amniotic sac encompassing both fetuses. Detection of two fetuses with a single placental mass, confirming shared chorion. Assessment of umbilical cord entanglement or cord loops during imaging. Serial ultrasounds to monitor fetal growth, amniotic fluid levels, and potential complications throughout the third trimester.

Treatment Protocols: Frequent ultrasounds to assess fetal well-being, amniotic fluid levels, and cord status. Non-stress tests and biophysical profiles to evaluate fetal health as the pregnancy advances. Early hospitalization may be considered in the later stages of the third trimester for close observation. Timing of delivery is critical, often recommended around 32 to 34 weeks, to minimize risks related to cord entanglement and other complications. Delivery by cesarean section is often preferred due to the increased risk of cord accidents.