Discordant amniotic band sequence in monozygotic twins

Area of Science:

• Perinatology
• Medical Genetics
• Developmental Biology

Background:

• Twin pregnancies present unique diagnostic and management challenges.
• Congenital anomalies require precise identification for appropriate counseling.
• Understanding placental membrane embryology is crucial for diagnosing conditions like amniotic band sequence.

Observation:

• Ultrasound at 16 weeks gestation identified multiple congenital anomalies in one fetus of an unsuspected twin pregnancy.
• Sonographic findings confirmed amniotic band sequence (ABS) and transient oligohydramnios in the affected fetus.
• The unaffected twin was erroneously diagnosed with ABS, complicating the clinical scenario.

Findings:

• Transient oligohydramnios supports the amnion rupture-leakage theory for ABS pathogenesis.
• Extensive craniofacial anomalies, including hydrocephalus, encephalocele, and facial clefts, were noted in the affected fetus.
• Misdiagnosis in the unaffected twin underscored the complexity of prenatal diagnosis.

Implications:

• Accurate prenatal diagnosis is critical for effective management and counseling in twin pregnancies with fetal anomalies.
• This case emphasizes the need for careful evaluation of placental membranes and fetal development.
• Discussion of selective termination procedures is essential in complex cases involving discordant fetal conditions.