Amniotic band syndrome
Updates to Article Attributes
Amniotic band syndrome (ABS) comprises of a wide spectrum of abnormalities which results fromresult 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.
Epidemiology
The phenomenon is estimated to occur in ~1:1200-1300 live births 1,8.
Pathology
The exact pathogenesis is not well known although several theories have been proposed.
Exogenous theory
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.
Endogenous theory
Occurs as a result of vascular compromise with mesoblastic strings not being a causal agent 4.
Associations
The vast majority of cases have a sporadic occurrence 8. It rareIn rare situations, it may be be be associated with:
Radiographic features
There is a massive spectrum of abnormalities depending on what part gets entrapped and at what point in time of gestation. Features are often asymmetrical. Observable features according to position include:
Head/face entrapment
Truncal entrapment
Extremity entrapment
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
- pseudosyndactylity
- 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.
Differential diagnosis
The differential is extremely variable dependent on the type of deficit and is best left for individual features.
See also
-<p><strong>Amniotic band syndrome (ABS)</strong> comprises of a wide spectrum of abnormalities which results from entrapment of various fetal parts from a disrupted <a href="/articles/amnion">amnion</a>. Due to the randomness of entrapment, each affected individual has the potential to form a very unique deficit. </p><h4>Epidemiology</h4><p>The phenomenon is estimated to occur in ~1:1200-1300 live births <sup>1,8</sup>.</p><h4>Pathology</h4><p>The exact pathogenesis is not well known although several theories have been proposed. </p><h6>Exogenous theory</h6><p>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.</p><h6>Endogenous theory </h6><p>Occurs as a result of vascular compromise with mesoblastic strings not being a causal agent <sup>4</sup>.</p><h5>Associations</h5><p>The vast majority of cases have a sporadic occurrence <sup>8</sup>. It rare situations it may be be associated with:</p><ul>- +<p><strong>Amniotic band syndrome (ABS)</strong> comprises of a wide spectrum of abnormalities which result from entrapment of various fetal parts from a disrupted <a href="/articles/amnion">amnion</a>. Due to the randomness of entrapment, each affected individual has the potential to form a very unique deficit. </p><h4>Epidemiology</h4><p>The phenomenon is estimated to occur in ~1:1200-1300 live births <sup>1,8</sup>.</p><h4>Pathology</h4><p>The exact pathogenesis is not well known although several theories have been proposed. </p><h6>Exogenous theory</h6><p>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.</p><h6>Endogenous theory </h6><p>Occurs as a result of vascular compromise with mesoblastic strings not being a causal agent <sup>4</sup>.</p><h5>Associations</h5><p>The vast majority of cases have a sporadic occurrence <sup>8</sup>. In rare situations, it may be associated with:</p><ul>