Amniotic band syndrome (ABS) comprises of a wide spectrum of abnormalities which result from entrapment of various fetal parts from a disrupted amnion. Due to the randomness of entrapment, each affected individual has the potential to form a very unique deficit.
The phenomenon is estimated to occur in ~1:1200-1300 live births 1,8.
The exact pathogenesis is not well known although several theories have been proposed.
An early disruption of the amnion allows the embryo or fetus to enter the chorionic cavity and contact the chorionic side of the amnion leading to fibrous bands, which entrap the fetal body components.
Occurs as a result of vascular compromise with mesoblastic strings not being a causal agent 4.
The vast majority of cases have a sporadic occurrence 8. In rare situations, it may be associated with:
There is a massive spectrum of abnormalities depending on what part gets entrapped and at what time of gestation. Features are often asymmetrical. Observable features according to position include:
Limb defects tend to be the commonest 7:
- variable levels of limb amputation
- variable levels of limb constriction +/- atrophy
- lymphoedema distal to the level of the band constriction
- club feet
- phocomelia 2
In addition to these defects, actual background amniotic bands may also be detected on ultrasound.
Treatment and prognosis
The prognosis is extremely variable dependent on the part that gets entrapped. This can range from normal life expectancy at one extreme in the case of a minor distal limb entrapment to in-utero death if there is anencephaly from head entrapment. There is no recognised recurrence risk for future pregnancies.
The differential is extremely variable dependent on the type of deficit and is best left for individual features.
- 1. Burton DJ, Filly RA. Sonographic diagnosis of the amniotic band syndrome. AJR Am J Roentgenol. 1991;156 (3): 555-8. AJR Am J Roentgenol (citation) - Pubmed citation
- 2. Bromley B, Benacerraf B. Abnormalities of the hands and feet in the fetus: sonographic findings. AJR Am J Roentgenol. 1995;165 (5): 1239-43. AJR Am J Roentgenol (abstract) - Pubmed citation
- 3. Inubashiri E, Hanaoka U, Kanenishi K et-al. 3D and 4D sonographic imaging of amniotic band syndrome in early pregnancy. J Clin Ultrasound. 36 (9): 573-5. doi:10.1002/jcu.20528 - Pubmed citation
- 4. Sentilhes L, Verspyck E, Patrier S et-al. [Amniotic band syndrome: pathogenesis, prenatal diagnosis and neonatal management] J Gynecol Obstet Biol Reprod (Paris). 2003;32 (8 Pt 1): 693-704. - Pubmed citation
- 5 Walter JH, Goss LR, Lazzara AT. Amniotic band syndrome. J Foot Ankle Surg. 37 (4): 325-33. - Pubmed citation
- 6. Ross MG. Pathogenesis of amniotic band syndrome. Am. J. Obstet. Gynecol. 2007;197 (2): 219-20. doi:10.1016/j.ajog.2007.03.079 - Pubmed citation
- 7. Moran SL, Jensen M, Bravo C. Amniotic band syndrome of the upper extremity: diagnosis and management. J Am Acad Orthop Surg. 2007;15 (7): 397-407. J Am Acad Orthop Surg (full text) - Pubmed citation
- 8. Entezami M, Albig M, Knoll U et-al. Ultrasound Diagnosis of Fetal Anomalies. Thieme. (2003) ISBN:1588902129. Read it at Google Books - Find it at Amazon
- 9. Merz E, Bahlmann F. Ultrasound in obstetrics and gynecology. Thieme Medical Publishers. (2005) ISBN:1588901475. Read it at Google Books - Find it at Amazon