Amniotic Band Syndrome:
Information for Healthcare Professionals

Amniotic band syndrome (ABS) is a sporadic condition that occurs in approximately 1:1200 to 1:15000 live births. Although the exact cause of the syndrome is not known, early rupture of the amnion resulting in bands that insert on the body of the fetus is the most accepted view. The bands may lead to amputations, constrictions and other deformities of the fetus.

Although at the time of diagnosis most cases of ABS show congenital anomalies beyond surgical repair (e.g., amputations, eccentric encephaloceles), some fetuses may show an isolated constriction of an extremity without amputation. In these cases, it has been speculated that the limb constriction can lead to subsequent amputation or significant functional impairment of the extremity.

Natural History of ABS

Knowledge of the natural history of amniotic bands is still not exactly known, there is evidence to suggest that limb amputation may result from constricting bands that progressively interfere with blood flow and result in distal necrosis. Why some fetuses show amputations early in pregnancy and others in more advanced gestational ages is unknown. Perhaps those seen early result from tighter bands or mesodermic disruptions, while those seen later may still allow blood flow distal to the obstruction until amputation of the extremity results from relative growth of the extremity without concomitant growth of the band. From pediatric surgical literature, it is known that the bands may be snipped after birth, or that staged band excision and Z‑plasty closure may be required. All tissue layers may be affected, but the majority of cases show a superficial involvement.

Diagnosis

Assessment of fetuses with amniotic band syndrome for in utero therapy

In utero therapy is usually limited to fetuses with amniotic band syndrome with constriction of a fetal extremity. The presence of other complex anomalies is ruled out by ultrasound. Doppler studies of the extremity are carried out to determine the degree of impairment to the circulation of the extremity. Measurements of the diameter of both extremities proximal and distal to the obstruction are made for comparison. Genetic testing is required or performed at the time of surgery.

Treatment of ABS

Constricting amniotic bands, although not lethal by definition, (except for a few case reports where the band may compromise the umbilical cord) purportedly may result in amputation of the extremity or significant functional impairment. In these cases, and provided the maternal and fetal risks of surgery are small, surgical intervention may be proposed to avoid amputation or permanent damage to the extremity.

Surgical Technique

The bands are either lysed or released from the affected limbs.

Prognosis

Surgical release of ABS in utero is aimed at preventing spontaneous limb amputations. However, functional sequelae including neurological paresis, contractures or hypoplasia may not be averted with surgery. This is important for counseling, as parents need to be aware of the possible need for postnatal rehabilitation and additional surgery to achieve the best results. Other defects, including severe craniofacial defects that may occur with ABS require complex surgical procedures to address them, often with the participation of different pediatric surgical subspecialties.

Referrals

For further information, feel free to contact us.

Phone Toll Free: 1-877-FETAL-77
Phone: 813-259-8513

Fax: 813- 259-0839

E-mail: sdzabel@tgh.org 

 

References

1. Bagatin M, Der Sarkissian R, Larrabee WF, Jr. Craniofacial manifestations of the amniotic band syndrome. Otolaryngol Head Neck Surg 1997;116:525-8.
2. Crombleholme T, Dirkes K, Whitney T, Alman B, Garmel S, Connelly R. Amniotic band syndrome in fetal lambs. I: Fetoscopic release and morphometric outcome. J Pediatr Surg 1995;30:974-8.
3. Evans MI, Drugan A, Manning FA, Harrison MR. Fetal surgery in the 1990s. AJDC 1989;143:1431-36.
4. Higginbottom MC, Jones KL, Hall BD, Smith DW. The amniotic band disruption complex: Timing of amniotic rupture and variable spectra of consequent defects. The Journal of Pediatrics 1979;95:544-549.
5. Hill L, Kislak S, Jones N. Prenatal ultrasound diagnosis of a forarm constricition band. J Ultrasound Med 1988;7:293-295.
6. Kanayama MD, Gaffey TA, Ogburn PL , Jr. Constriction of the umbilical cord by an amniotic band, with fetal compromise illustrated by reverse diastolic flow in the umbilical artery. A case report. J Reprod Med 1995;40:71-3.
7. Quintero R, Reich H, Puder K, al. e. Operative fetoscopy: a new frontier in fetal medicine. Am J Obstet Gynecol - abstract 1994;179 (1, part 2):297.
8. Torpin R. Amniochorionic mesoblastic fibrous strings and amnionic bands. Am J Obstet Gynecol 1965;91:65-75.
9. Weinzweig N, Barr A. Radial, ulnar, and median nerve palsies caused by a congenital constriction band of the arm: single-stage correction. Plast Reconstr Surg 1994;94:872-6.
10. Weinzweig N. Constriction band-induced vascular compromise of the foot: classification and management of the "intermediate" stage of constriction-ring syndrome. Plast Reconstr Surg 1995;96:972-7.