The document discusses 10 facts about amniotic constriction band: 1) It can cause limb constrictions, amputations, and finger fusions. Less commonly, it can cause cleft lip/palate and body wall defects. 2) There is no single consistent set of features and it is not a well-defined syndrome. 3) Theories for its cause include intrinsic developmental abnormalities, incomplete fusion of amniotic layers allowing bands to form, and disrupted blood flow due to trauma. It is likely caused by multiple factors.

1. 10 facts about amniotic constriction band
Ian Grant
1. Amniotic constriction band (ACB): arangeof associatedcongenital anomalies including
multiple annularlimb constrictions, oligodactyly, acrosyndactyly, andtalipesequinovarus 1
.
Less commonly cleft lip, cleft palate, craniofacial clefts 2
, and body-walldefects, andinternal
organabnormalities are seen in children bornwith amniotic constrictionband.
2. It is nota syndrome:thereare no consistently presentand defining features 3
.
There are numerousnames (34 reported) for the conditionincluding “Streeter’sdysplasia”, amniotic
rupturesequence, constrictionring syndrome, amniondisruptionsequence.
Amniotic constrictionbandcauses:
 disruptions (constrictionbands, amputations, andacrosyndactyly),
 deformations (oligohydramnios, pressureanddecreasedfoetal movementcan produce
talipes equinovarus, scolioisandjoint contractures), and
 malformations (an insultearly in gestationcan produce body wall defects, internal organ
abnormalitiesand craniofacial clefts.
3. The incidence of the condition
The figures for the incidence of amniotic constrictionbandvary from 1/1200 to1/15000. Between35
and50% of these children were bornprematurely, there is a higher incidence of gestationalproblems
suchas maternal haemorrhageor amniotic fluid leakage. Amniotic constrictionbandis almostalways
sporadic, the potentialfor recurrence is said to be negligible.
The initial consultationwith a family shouldinclude questionsregardingthe potential exposureto
limb teratogens (such as warfarin, phenytoin, valproicacid, misprostol, andcocaine), diagnosticand
therapeutic proceduresduring pregnancy. ACBcan be associatedwith in-vitro-fertilisation(IVF)4
Diagnosisto exclude includessymbrachydactly (oneaffected limb, with nubbins with nails or
invaginationsatthe end of the stump), and Adams-Oliversyndrome.
4. There are proposedaetiologies:
 The intrinsic theory
An intrinsic germline developmentalabnormality couldbe responsiblefor the features of amniotic
constrictionband 5
. This explains the associated craniofacial, body wall andinternal organ
abnormalities. A discrete lesion, at 26 daysafter conception, could cause multiple body wall andlimb
defects “the patternof the defects bear more resemblance to the embryonicproximity of the
affected structuresthat to the proximity in the mature body pattern.”
The theory does notexplain the bandingabnormalities. A germline defect, would arguably, be
expected toproduce more reproduciblepatternsof abnormality.
 The extrinsic theory
The inner amniotic cavity is lined by embryonic ectoderm expandswith the outerchorionic cavity.
After 12 weeks there is no space between the 2 layers. It is hypothesisedthatif thisfusion is
incomplete, the amniotic sac may ruptureallowing the foetus to passpartially or incompletely into
the chorionic cavity. Acellular fibrous bandsof ectoderm may then encircle or compressthe foetus.
Later rupturewould be expected to affect the limbs, earlier rupturewould be expected to cause
multiple limb andbody wall defects 6
.

2. 10 facts about amniotic constriction band
Ian Grant
 The vascular theory
A traumaticevent, for example amnionrupture, or exposure to a teratogenat 4-6 weeks after
gestationcould disruptthe bloodsupply tothe foetus causing haemorrhagicnecrosis 7
. The timing of
the insult woulddetermine the nature andextent of the abnormality.
5. Is there a single aetiology?
Amniotic constrictionbandcan be broadly sub-dividedintoclassic(constriction rings, acrosyndactyly,
oligodactyly andtalipes equinovarus)disruptionanddeformations, andthosepatientswith non
classic (cleft lip andor palate, body wall defects) malformation.
There is considerable overlapbetween these two, butno one hypothesisexplainsboth. Itseems likely
thata search for a unifying aetiology is a futile escapadeencouraged by the similar manifestationsof
two or more differing pathologies.
“So Einstein waswrong when he said, "God doesnotplay dice." Consideration ofblack holessuggests,
notonly thatGod doesplay dice, butthathe sometimesconfusesusby throwing themwherethey
can'tbe seen.”StephenHawking: “TheNatureof Spaceand Time”1996.
6. The site of involvement?
Amputationsandconstrictionstendto be transverse. They are more commonin the upperlimb that
the lower limb. They are more commondistally rather thanproximally with more than75% involving
the handand wrist. Upto80% ofpatientswill havenail deformity (hypoplasia, orabsence). Some
patientswill haveneurological impairmentdistal to the constriction.
7. Amniotic constriction bandlimb anomalies have beenclassified 8
:
 Type 1: extremities with constructionrings
 Type 2: constrictionring with distaldeformity
 Type 3: acrosyndactyly
 Type 4: amputation
8. Foetal sonography
More proximalamputationsandconstrictions(including the “Popeye”appearanceof the right foetal
forearm) havebeen detected at 15 weeks gestation. Colourdopplercan confirm bloodflow distalto a
constriction. Serial foetal sonography hasshownspontaneous resolutionofaconstriction:suggesting
thatamniotic bandscan rupturewith release of the limb.
Foetal surgery has been performed at about21-weeksof gestationwith reportedly successful lysis of
a constrictionband (usingscissors, or NdYAG or contactdiode laser) in 50-75% ofpatients. Small
numbersof cases are published, witheach individualcentre reporting at most5 patients. The
outcomesof surgery are difficult to judge, complicationsaffecting the motheror foetus are reported
in about25% of patients 9
.
9. Timing and planning surgery
For the majority, surgery can be postponedtill after 1 year of age. (Children with acrosyndactyly may
require initial separationof the finger tips at about6 months, andcompletionof surgery by 12
months. Childrenwith distal ischaemia andthreatened limb lossmay require early divisionof a
constriction). The manifestation of the conditionis uniqueto each child, the surgery is bespoke.
 Shallow constrictionscan be left (there will be some improvementwithgrowth).

3. 10 facts about amniotic constriction band
Ian Grant
 Deep constrictionsof the fingers can be excised, sidewall subcutaneousfatadvanced, and
then closed with Z-plasty (toprevent an hour-glasscircular scar).
 Narrow proximalconstrictionscan potentially be excised and directly closed without Z-plasty.
 Surgery for proximallimb constrictionmay need to be combinedwith fasciotomies.
Individualsurgeonswill need tojudge how much todo at any one sitting in a child with multiple limb
anomalies, andmultiple involved digits. Forconstrictionsinvolvingthe entire circumference of the
digit, surgery can be staged.
Parental expectationsneed to be managed(disappointmentisthegap between expectation and
reality). There will be persistent cosmetic deformity, there will be residualskeletal reductionor
malformation.
Children may need further surgery. I have carried out “Colemanfat” injection in adolescents with
amniotic constrictionbandof the lower limb.
When consideringmicrovasculartransfer of digits be mindfulof potentialdisruptionof the normal
expected vascularanatomy proximalto an amnioticconstriction band.
10. Amniotic constriction band surgery and acrosyndactyly
The distal elements of the fingers are fused, butthere is always a communicationbetween the palmar
anddorsal surface between the fingers. There may associatedamputations. Thefingers may be stiff.
This mightbe bilateral. The presumptionisthat ulceration occurs at the constrictionring causing
subsequentfusion. Fingersare commonly joinedside to side butcan be “stacked”or “crossed”.
Planninglocal flaps, particularly aroundthe sinusbetween the fingers, is difficult. Surgery is often
stagedwith separationof the finger tips at 6 monthsof age, removal of any “ballooned” and bulbous
finger tips, anddeepening of the web-space(as far proximally as possible)ideally before 1-year. Skin
grafts are usually needed andcan be split - or full - thickness.
The fingers are often stiff, andshort, with some residual angulation. Secondary surgery, asa teenager,
is often required.
References
1 Koskimies, E., Syvanen, J., Nietosvaara, Y., Makitie, O. &Pakkasjarvi, N. Congenitalconstriction
bandsyndromewith limb defects. J PediatrOrthop 35, 100-103,
doi:10.1097/BPO.0000000000000206 (2015).
2 Coady, M. S., Moore, M. H. & Wallis, K. Amniotic bandsyndrome:theassociationbetween
rare facial clefts andlimb ring constrictions. PlastReconstrSurg 101, 640-649 (1998).
3 Goldfarb, C. A., Sathienkijkanchai, A. & Robin, N. H. Amniotic constrictionband:a
multidisciplinary assessmentof etiology and clinical presentation. J BoneJointSurg Am 91
Suppl 4, 68-75, doi:10.2106/JBJS.I.00339 (2009).
4 Patel, M. I. A., Laing, T. & Grant, I. Amniotic constrictionbandin infants conceived by in vitro
fertilization: a reportof two consecutivecases. J Hand Surg EurVol, 1753193420979227,
doi:10.1177/1753193420979227 (2021).
5 Bamforth, J. S. Amniotic bandsequence: Streeter's hypothesisreexamined. Am J Med Genet
44, 280-287, doi:10.1002/ajmg.1320440304(1992).
6 Kim, J. B., Berry, M. G. & Watson, J. S. Abdominalconstrictionband:A rare location for
amniotic bandsyndrome. J PlastReconstrAesthetSurg 60, 1241-1243,
doi:10.1016/j.bjps.2006.10.015 (2007).

4. 10 facts about amniotic constriction band
Ian Grant
7 Van Allen, M. I. Fetal vasculardisruptions:mechanismsandsomeresultingbirth defects.
PediatrAnn 10, 219-233 (1981).
8 Patterson, T. J. Congenitalring-constrictions. BrJ PlastSurg 14, 1-31 (1961).
9 Iqbal, C. W., Derderian, S. C., Cheng, Y., Lee, H. & Hirose, S. Amniotic band syndrome:asingle-
institutionalexperience. FetalDiagn Ther 37, 1-5, doi:10.1159/000358301 (2015).