Amniotic band syndrome (ABS) consists of a wide spectrum of congenital malformations depending on the affected body part(s).

There are two hypotheses on the formation of amniotic bands and ABS. The “extrinsic model” theory explains the rupture of the amnion without the rupture of the chorion which leads to transient oligohydramnios due to loss of amniotic fluid through the initially permeable chorion. The fetus passes to the extra embryonic coelom through the defect and comes in contact with ‘sticky’ mesoderm on the chorionic surface of the amnion resulting in entanglement of fetal parts and skin abrasions. Entanglement of fetal parts by amniotic bands causes constriction rings and amputations, whereas skin abrasions can lead to disruption defects, such as cephaloceles and swallowing of the bands will cause asymmetric clefts on the face. The “intrinsic model” by Streeter suggests that the anomalies and the fibrous bands have a common origin, caused by a perturbation of developing germinal disc of the early embryo. Most cases of ABS are not of genetic origin, and occur sporadically with no recurrence in siblings or children of affected adults. Maternal trauma, teratogenic insult, oophorectomy during pregnancy, intrauterine contraceptive device, amniocentesis and familial incidence of connective tissue disorders (Ehler-Danlos syndrome) are some of the implicated aetiopathological factors. [1]

It affects both sexes equally with an incidence of 1 in 1,200 to 15,000 live births [2] and 1 in 70 stillbirths. [3]

Due to possibility of different combinations of anomalies, there are no two identical cases of ABS. Children with ABS have very polymorphic clinical findings:

Craniofacial defects: vertical and oblique facial cleft, cleft lip and palate, orbital defects (anophthalmos, microphthalmos, enophthalmos), corneal abnormalities, microtia, central nervous system malformations (anencephaly, encephalocele, asymmetric meningocele) and calvaria defect.[4]

Truncal defects: chest wall defect with heart extrophy, lung hypoplasia, scoliosis, abdominal wall defect, abdominal organs extrophy, umbilical cord strangulation with often lethal outcome. [5]

Limb defects: constriction rings, lymphoedema of the digits, shortening of the limbs or intrauterine limb amputation, amputation of the digits (most often 2nd, 3rd and 4th fingers) and toes, syndactyly, hypoplasia of the digits, club foot, pseudarthrosis, hip dislocation, peripheral nerve palsy.

Other anomalies: gastroschisis, small intestinal atresia, renal agenesis, Patau syndrome, Septo-optic dysplasia.

In 1961, Patterson described a classification [6] that is still relevant today:

1. a) Simple ring constrictions;
2. b) Ring constrictions accompanied by deformity of the distal part with or without lymphoedema;
3. c) Ring constrictions accompanied by fusion of distal parts ranging from mild to severe acrosyndactyly and
4. d) Intrauterine amputations.

ABS is often difficult to diagnose before birth. Prenatal ultrasound can help in visualization of amniotic bands attached to a fetus with restriction of motion, constriction rings on extremities and irregular amputations of fingers and/or toes with terminal syndactyly. Recently 3D and 4D ultrasound techniques contribute to more sensitive prenatal diagnostics of ABS. Foetal MRI can be helpful in complicated cases. Doppler study of the constricted limb could be of use in the diagnosis of in-utero amputation as well as to take decisions regarding in-utero treatment. Physical examination is the main way of postnatal diagnosis of ABS, with a search to establish potential malformations of different organs and body parts. Ultrasound, echocardiography, and x-ray films may help to diagnose or rule out other associated anomalies.

Management strategy of ABS depends on the extent of the associated anomalies. Treatment is mostly surgical with an individual approach to every single case. Most references recommend the use of Z-plasty or W-plasty after the excision of the constriction band, in one- or two-stage approach. Termination of pregnancy is usually proposed at the time of the diagnosis of severe craniofacial and visceral abnormalities, whereas minor limb defects can be repaired with postnatal surgery. Lately, there have been some attempts of prenatal ABS treatment – foetoscopic laser cutting of amniotic bands, before their compression on the foetus makes malformations.[7] Patterson in his study of 52 patients of congenital constriction rings had reported only two cases of below knee amputations in addition to other musculoskeletal defects.[6] In 1983, Zych et al. reported a case of involvement of congenital bands, pseudarthrosis and impending gangrene of leg, which was salvaged with multiple Z-plasty.[8] Greene et al. had advised a one-stage release for circumferential congenital constriction bands which was performed in all four extremities.[9] In 2006, Samra et al. reported a case of severe constricting amniotic band with a threatened lower extremity in a neonate, which was salvaged with multiple Z-plasties over a 6-year functional follow up.[10] Recently, Choulakian et al. has described a two-staged approach of direct closure after excision of the constriction band.[11] So, the outcome of the disease depends on the gravity of the malformation associated with it.