Also known as:
* ADAM Complex (Amniotic Deformity, Adhesions and Mutilations).
* Amniotic band disruption complex or sequence.
* Amniotic bands and sheets.
* Annular constriction bands.
* Congenital ring constriction.
* Congenital transverse defects.
* Constriction band syndrome.
* Intrauterine amputation.
* Limb-body Wall Complex
* Streeter Anomaly.
* TEARS (The Early Amnion Rupture Spectrum).
Learning Objectives:
• Briefly define amniotic band syndrome.
• Discuss the prevalence of ABS and the
• Describe current theories of the etiology of ABS.
• Is there a genetic component to ABS?
• Describe the role of preconception counseling with regard to ABS.
• Discuss the role of ultrasound and perinatal diagnoses of ABS.
Pretest Questions:
1. During a late 3 rd trimester ultrasound the ultrasound tech notices the fetus is missing it's right hand. All of the following are possible causes for this anomaly except:
- Throughout the pregnancy the mother took thalidomide for morning sickness.
- Up until the last month the mother lived in Chernobyl Russia .
- A tight amniotic band constricted the babies wrist preventing it's hand from forming.
- The mother took 1mg of folic acid everyday since the day she found out she was pregnant.
- The mother is a recovering heroin addict and has been on Methadone maintenance throughout the pregnancy.
2. When during pregnancy do most birth defects occur?
- Weeks 1-13
- Weeks 14-26
- Weeks 27-38
3. True or false. There is an association between Clubfeet and ABS.
4. What type of error in morphogenesis of the developing fetus is ABS?
- malformation
- disruption
- deformation
- sequence
- syndrome
Answers: 1. D, 2. A, 3. True (32% of ABS babies have clubfeet). 4. B
Malformations represent primary errors of morphogenesis, in other words there is an intrinsically abnormal developmental process.
Disruptions result from secondary destruction of an organ or body region that was previously normal in development; thus, in contrast to malformations, disruptions arise from an extrinsic disturbance in morphogenesis. Amniotic bands, denoting rupture of amnion with resultant formation of "bands" that encircle, compress, or attach to parts of the developing fetus, are the classic example of a disruption.
Deformations, like disruptions, also represent an extrinsic disturbance of development rather than an intrinsic error of morphogenesis. Fundamental to the pathogenesis of deformations is localized or generalized compression of the growing fetus by abnormal biomechanical forces, leading eventually to a variety of structural abnormalities. The most common underlying factor responsible for deformations is uterine constraint.
A sequence is a pattern of cascade anomalies. A good example of a sequence is the oligohydramnios(or Potter) sequence
A syndrome is a constellation of congenital anomalies, believed to be pathologically related, that, in contrast to a sequence, cannot be explained on the basis of a single, localized, initiating defect.
Case:
Mr. and Mrs. T are expecting their first baby. At 22 weeks gestation the excited couple goes to their ob/gyn to get an ultrasound to find out the gender of their baby. Incidentally during this exam the doctor notices an amniotic band floating in the amniotic fluid. At 37 weeks gestation Mrs.T goes into labor and you are the medical student on call and you are offered the chance to observe the delivery of your first baby. The resident safely delivers the baby and it is whisked off by the nurse to the warming table where he will be assessed. You are busy delivering the placenta when the pediatric nurse notes that the newborn is missing his 3 rd , 4 th and 5th digits on his right hand and that he is missing his right foot altogether.
Family History: Mr. T's paternal Grandmother had one foot that turned slightly and she walked with a limp. Mr. T's 2 nephews were both born with a mild clubfoot that was easily corrected without surgery. There was no family history of birth defects on Mrs. T's side.
Questions:
What is Amniotic Band Syndrome?
Amniotic Band Syndrome is a set of congenital birth defects caused believed to be caused by entrapment of fetal parts (usually a limb or digits) in fibrous amniotic bands while in utero. No two cases of ABS are exactly alike. There are several features that are relatively consistent: syndactyly (webbed digits), distal ring constrictions, deformity of the nails, stunted growth of the small bones in the digits, limb length discrepancy, distal lymphedema (swelling), congenital band indentations and severe defects of the head, face spine and umbilical cord and body wall.
What causes amniotic band syndrome?
There are several theories as to the cause of ABS. The most widely accepted is a rupture of the amnion early ingestation. When the amnion ruptures, this exposes the baby to fibrous sticky tissue (bands) of the placenta. The chorion portion of the placenta is made up of fibrous tissues, which can float in the waters of the uterus, these fibrous tissues can entangle the baby and cause multiple anomalies as well as limb anomalies and amputations. The timing of the rupture is believed to occur between 28 days after conception to 18 weeks of gestation. However, late bands can occur and present at birth with multiple abnormalities of limbs, even after a normal sonogram earlier in gestation. This can be observed following any form of intervention such as amniocentiesis or fetal surgery.
 Image from the fetalcarecenter.com
What is the incidence of ABS?
ABS affects 1:1200 to 1:1500 live births. In 50% of the ABS cases the baby does not survive. It is believed to be the cause of 178 in 10,000 miscarriages. It was once thought to be a rare anomaly but recent literature supports that the incidence occurs more often than once thought.
Who is at risk for ABS?
The only known risk factor is young maternal age. The risk for ABS actually decreases as women age. There have been some reports of methadone dependent mothers having ABS but these are rare. There has been some epidemiological studies that suggest that young maternal age, low maternal education, unplanned pregnancy, and non-white/non-Hispanic race/ethnicity might increase the risk of abdominal wall defects caused by amniotic bands in offspring.
How is ABS diagnosed?
The earliest that amniotic bands have been detected is at 12 weeks gestation, by vaginal ultrasound. Bands may difficult to detect by ultrasound. The bands are more often diagnosed by the effect they have on the fetal anatomy, as in the case of missing or misshapen limbs.
Is there any treatment for ABS?
In utero surgery has been done for life threatening conditions such as constriction of the umbilical cord. However, there has been some success of in utero surgery for threatened limb amputation due to amniotic band constriction.
Is there a genetic component to ABS?
The general consensus on ABS is that there is no clear or simple genetic basis for it. There are sparse case reports of ABS occurring in families but overall no genetic link has been identified.
What web based resources and support groups are available for this family?
1. Amniotic Band Syndrome Website: This site was started by a mother with a son with amniotic band syndrome. Contains many stories from families with children that have survived and died from ABS. http://www.amnioticbandsyndrome.com/
2. International Amniotic Band Meet-up Day: http://abs.meetup.com/
3. The fetal care center of Cinncinati: http://www.fetalcarecenter.org
4. Birth Disorder Information Directory: http://www.bdid.com/
Hyperlinks:
1.Online Mendelian Inheritance in Man (OMIM): http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=OMIM
2. National Center on Birth Defects and Developmental disabilities from the CDC: http://www.cdc.gov/ncbddd/bd/default.htm
Reference articles and textbooks:
1.Behrman: Nelson Textbook of Pediatrics, 17th ed., Copyright © 2004 Elsevier
2. Kumar: Robbins and Cotran: Pathologic Basis of Disease, 7th ed., Copyright © 2005 Elsevier Retrieved from MDConsult.. www.mdconsult.com
3. Sentilhes L. Amniotic band syndrome: pathogenesis, prenatal diagnosis and neonatal management. J Gynecol Obstet Biol Reprod ( Paris ) - 01-DEC-2003; 32(8 Pt 1): 693-704
4. Werler MM. Louik C. Mitchell AA. Epidemiologic analysis of maternal factors and amniotic band defects. Birth Defects Research. 67(1):68-72, 2003 Jan
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