Amniotic Band Sequence

Lincoln Medical and Mental Health Center, Bronx, NY

This full-term baby was born with malformations of the upper and lower extremities. The mother, a 21-year-old primigravida, had a normal spontaneous vaginal delivery and no prenatal or perinatal complications. A prenatal ultrasound examination at 32 weeks’ gestation was reported as unremarkable.

The newborn physical examination findings included a stubbed left fifth finger with no distal interphalangeal joint, a right clubfoot with missing toes (except for a vestigial third toe), and a soft tissue nodule in place of the right ankle. The left lower leg appeared as if a rubber band had been tightly wrapped around it. The infant also had a large umbilical granuloma, an unrelated finding.

The deformities were attributed to amniotic band sequence, also known as amniotic band syndrome. This comprises a broad clinicalspectrum of congenital defects caused by amniotic bands that include disruptions, deformations, and malformations of developing structures.1 The estimated incidence ranges from 1:1234 to 1:15,000 live births. The condition affects both sexes equally. The pathogenesis, although not completely established, may be linked to early amniotic rupture and the release of loose strands that adhere to the fetus. This results in mechanical or vascular constriction of a limb or digits (eg, clubfoot), the body wall
(eg, thoracoschisis, gastroschisis), or the head (eg, facial cleft, encephalocele).2

The condition may be detected by prenatal ultrasonography. In most cases, the bands are not visualized by this method; however, the fetal abnormality is often evident.3 In utero treatment with fetoscopic laser transection of amniotic bands performed between 20 and 28 weeks’ gestation has been attempted.3

This infant was referred to a pediatric orthopedic surgeon for evaluation and future surgical correction and treatment, if required for cosmetic reasons or
ambulation. A genetic evaluation for associated underlying disorders, including genetic diseases that may mimic amniotic band sequence (eg, Adams-Oliver syndrome, which has an autosomal dominant pattern of inheritance), was also recommended.