Amniotic band sequence and limb defects: data from a population-based study

Amniotic band syndrome and limb body wall complex in Europe 1980-2019

Amniotic band syndrome (ABS) and limb body wall complex (LBWC) have an overlapping phenotype of multiple congenital anomalies and their etiology is unknown. We aimed to determine the prevalence of ABS and LBWC in Europe from 1980 to 2019 and to describe the spectrum of congenital anomalies. In addition, we investigated maternal age and multiple birth as possible risk factors for the occurrence of ABS and LBWC. We used data from the European surveillance of congenital anomalies (EUROCAT) network including data from 30 registries over 1980-2019. We included all pregnancy outcomes, including live births, stillbirths, and terminations of pregnancy for fetal anomalies. ABS and LBWC cases were extracted from the central EUROCAT database using coding information responses from the registries. In total, 866 ABS cases and 451 LBWC cases were included in this study. The mean prevalence was 0.53/10,000 births for ABS and 0.34/10,000 births for LBWC during the 40 years. Prevalence of both ABS and LBWC was lower in the 1980s and higher in the United Kingdom. Limb anomalies and neural tube defects were commonly seen in ABS, whereas in LBWC abdominal and thoracic wall defects and limb anomalies were most prevalent. Twinning was confirmed as a risk factor for both ABS and LBWC. This study includes the largest cohort of ABS and LBWC cases ever reported over a large time period using standardized EUROCAT data. Prevalence, clinical characteristics, and the phenotypic spectrum are described, and twinning is confirmed as a risk factor.

Amniotic Band Syndrome With Pseudoarthrosis of Tibia and Fibula: A Case Report

Constriction of the lower limb by a congenital amniotic band has been proposed to explain the development of pseudoarthrosis of the tibia and fibula. We report a case of amniotic band syndrome in a preterm female infant with pseudoarthrosis of the tibia and fibula. She was born at 29 weeks of gestation with congenital amniotic bands and was noted to have a severely edematous left foot distal to the constricting band with rudimentary digits. The skin was pink and well perfused with palpable pulses. Radiography demonstrated pseudoarthrosis of the tibia and fibula. The limb deformities were managed with splints, positioning, and physiotherapy. She underwent Z-plasty with soft tissue release on the left lower leg on day 7 of life. At 36 weeks of postmenstrual age, a repeat radiograph showed markedly improved growth of the tibia and fibula with mature new bone formation, which avoided the need for further surgical intervention. During the follow-up period, she underwent left Syme's amputation at 18 months. At 29 months of age, the child was able to walk and run without support. The findings from our case confirm the potential for bone growth in patients with amniotic band syndrome, once the constricting band has been released. Simple release of the constriction band with Z-plasty resulted in growth of mature bone, replacing the pseudoarthrosis and, hence, the patient did not require surgical amputation. Thus, one should be cautious when deciding on surgical amputation, even in the presence of pseudoarthrosis, especially in preterm infants. Early limb-preserving surgery with release of the constricting band with an intention to salvage the limb appears appropriate.

The prevalence of amnion rupture sequence, limb body wall defects and body wall defects in Alberta 1980-2012 with a review of risk factors and familial cases

Prevalence rates of amnion rupture sequence, limb body wall defect, and body wall defects vary widely. Comparisons are difficult due to small case numbers and the lack of agreement of definition, classification, and pathogenesis. This study reports the prevalence of cases classified in five distinct categories. The Alberta Congenital Anomalies Surveillance System data on live births, stillbirths, and terminations of pregnancy (<20 weeks gestation) occurring between 1980 through 2012 with the ICD-10 Royal College of Paediatrics and Child Health Adaptation codes used for congenital constriction bands (Q79.80) and body wall complex (Q89.7) were reviewed. During the 33-year-study period, there were 153 eligible cases ascertained from 1,411,652 live births and stillbirths, giving a prevalence of 1.08/10,000 total births. There were more males (52%) than females (45%) and 3% were of unknown sex. The average maternal age, birth weight, and gestation was 27 years, 2,701 g, and 35 weeks, respectively. Limb deficiencies occurred in 78% of cases. Amniotic bands with limb deficiency was the most common phenotype (48%). Digital limb deficiency was the most frequent type (56%); however, cases with body wall defects had more severe types of limb deficiencies. The upper limbs only were affected more times (44%), and there was no side preference. Most cases are sporadic but a number of familial occurrences have been reported although some have insufficient documentation and others misdiagnosed. A review of putative risk factors gives conflicting results. © 2016 Wiley Periodicals, Inc.

Congenital limb deficiency disorders

Congenital limb deficiency disorders (LDDs) are birth defects characterized by the aplasia or hypoplasia of bones of the limbs. Limb deficiencies are classified as transverse, those due to intrauterine disruptions of previously normal limbs, or longitudinal, those that are isolated or associated with certain syndromes as well as chromosomal anomalies. Consultation with a medical geneticist is advisable. Long-term care should occur in a specialized limb deficiency center with expertise in orthopedics, prosthetics, and occupational and physical therapy and provide emotional support and contact with other families. With appropriate care, most children with LDDs can lead productive lives.

[Complex of amniotic deformities, adhesions, mutilations: Endless debate]

Amniotic deformities, adhesions, mutilations (ADAM) complex is a broad heterogeneous spectrum of congenital anomalies. ADAM complex is characterized by constriction rings, amputation of fingers or limbs and the presence of the amniotic band. However, it may also involve craniofacial disruptions, body wall defects and internal organ abnormalities. The aim of this review is to present the results found in regard to ADAM complex from its historical background, clinical manifestations, epidemiology, etc. In particular, our attention was focused on demonstrating the varying etiopathogenesis theories of ADAM complex and their contradictions. The study was conducted using the databases of PubMed, EBSCO host, Ovid, SpringerLink, Scopus, nature.com, JAMA and ScienceDirect with the following keywords for the search: "amniotic band syndrome", "amniotic band sequence", "Streeter dysplasia", "ADAM complex". In this study we used 22 full-text articles. Patients with ADAM complex require a complete pre- and postnatal evaluation to integrate the diagnosis and to decide on timely treatment. It is important for clinicians and surgeons to possess knowledge of this entity. Further research is necessary to establish a nosological basis.

The epithelial mesenchymal transition process may contribute to the pathogenesis of amniotic band syndrome

The etiology of the amniotic band syndrome is unknown, and has been subject of debate since the time of Hippocrates. The most accepted theories fail to cover all the abnomalities found in affected children. During organogenesis the epithelial-mesenchymal transition process (EMTP) participates in adequate formation of different organs from three embryo layers. Altered activation of EMTP occurs when the epithelial homeostasis is disturbed, the resulting myofibroblasts are able to secrete extracellular matrix proteins and deposit them on the tissues contributing to a fibrotic phenotype. If injury occurs during organogenesis, wound healing could be exaggerated and fibrotic response could be triggered. The molecule that regulates both of these processes (EMTP and fibrosis) is the transforming growth factor β (TGFβ); indeed null animals for TGFβ isoforms show similar defects than those seen in the amniotic band syndrome. Based on documented evidence this review intends to explain how the epithelial mesenchymal transition process may contribute to the pathogenesis of amniotic band syndrome.

Prenatal diagnosis of amniotic band syndrome - risk factors and ultrasonic signs

OBJECTIVE

The aim of this study was to describe our experience with amniotic band syndrome (ABS), define specific sonographic characteristics and common features.

METHODS

Patients diagnosed with ABS underwent detailed ultrasound evaluation at the time of diagnosis and during follow-up. Their ultrasound examinations and medical records concerning the current pregnancy and past medical records were analyzed.

RESULTS

Ten pregnancies were diagnosed with ABS. Most pregnancies were diagnosed at the beginning of the second trimester. Two cases were bichorionic twin pregnancies involving one of the fetuses and these were the only women who continued their pregnancies to term. The other eight cases with ABS chose to terminate their pregnancies. One pregnancy was conceived following trachelectomy. We found a significantly higher rate of prior uterine surgeries (p = 0.008) in patient with ABS compared to control. In three cases, all above 15 weeks of gestation, a small vestige at the distal part of the amputated limb was observed.

CONCLUSIONS

ABS diagnosed in early pregnancy can be a sporadic event. However, there is a higher risk of ABS in pregnancies preceded by uterine procedures. The ultrasonic vestige sign at the amputated limb may contribute to the diagnosis of ABS.

Complete calvarial agenesis in conjunction with a Tessier 1-13 facial cleft

Amniotic band sequence (ABS) is a condition in which rupture of the amniotic sac leads to the development of a broad spectrum of fetal anomalies. A newborn male presented at term with multiple craniofacial and skeletal anomalies, including attachment of the placenta to the head, a paramedian facial cleft, and multiple skeletal anomalies. The patient has undergone several operations to date. The initial operation was performed to remove the attached placenta off the underlying dura, which was with a collagen matrix bound to a silicone membrane. The patient subsequently underwent split-thickness skin grafting with complete survival of the graft.

Pattern recognition control of multifunction myoelectric prostheses by patients with congenital transradial limb defects: a preliminary study

BACKGROUND

Electromyography (EMG) pattern recognition offers the potential for improved control of multifunction myoelectric prostheses. However, it is unclear whether this technology can be successfully used by congenital amputees.

OBJECTIVE

The purpose of this investigation was to assess the ability of congenital transradial amputees to control a virtual multifunction prosthesis using EMG pattern recognition and compare their performance to that of acquired amputees from a previous study.

STUDY DESIGN

Preliminary cross-sectional study.

METHODS

Four congenital transradial amputees trained and tested a linear discriminant analysis (LDA) classifier with four wrist movements, five hand movements, and a no-movement class. Subjects then tested the classifier in real time using a virtual arm.

RESULTS

Performance metrics for the residual limb were poorer than those with the intact limb (classification accuracy: 52.1% ± 15.0% vs. 93.2% ± 15.8%; motion-completion rate: 49.0%± 23.0% vs. 84.0% ± 9.4%; motion-completion time: 2.05 ± 0.75 s vs. 1.13 ± 0.05 s, respectively). On average, performance with the residual limb by congenital amputees was reduced compared to that reported for acquired transradial amputees. However, one subject performed similarly to acquired amputees.

CONCLUSIONS

Pattern recognition control may be a viable option for some congenital amputees. Further study is warranted to determine success factors.

Facial Clefts and Associated Limb Anomalies: Description of Three Cases and a Review of the Literature

Facial clefts are rare congenital malformations. In the literature these are sometimes reported in combination with limb malformations, especially ring constrictions. This article describes three children with facial clefts and limb ring constrictions with various expressions. The first case has a lateral cleft with associated limb malformations. This combination has, to our knowledge, not yet been reported. The literature about facial clefting and the amniotic band syndrome and the possible etiology of clefting and constrictions in these cases are discussed.

Amniotic band syndrome and/or limb body wall complex: split or lump

Six cases of amniotic band syndrome/limb body wall complex were studied in respect to clinicopathologic characteristics. The diagnosis was based on two out of three of the following manifestations: cranio facial clefts; limb body wall defects and amniotic band attachment. Four cases were stillborn and associated with internal defects, including central nervous system. Two cases had facial and limb defects and were live born (3-5 years old at examination). Phenotypic features of the stillborn cases were craniofacial clefting, thoracoabdominoschisis, amputation, ring constriction, amniotic band adhesion, placental adhesions, and internal malformations. Histology of bands revealed fibroconnective tissue as well as flattened epithelial cells together with neuroectodermal elements. Umbilical cord section revealed an abnormal number of vessels. When analyzing the observed data in relation to their etiology, it was found that amniotic disruption, vascular disruption or genetic disruption could explain the amniotic band syndrome/limb body wall complexes, alone or in combinations. A brief review of literature in search of pathogenesis is offered along with an etiopathogenetic model.

Comparative study of clinical characteristics of amniotic rupture sequence with and without body wall defect: further evidence for separation

BACKGROUND

Amniotic rupture sequence (ARS) is a disruption sequence presenting with fibrous bands, possibly emerging as a result of amniotic tear in the first trimester of gestation. Our comparative study aims to assess whether there is a difference in the clinical pattern of congenital limb and internal organ anomalies between ARS with body wall defect (ARS-BWD) and ARS without BWD (ARS-L).

METHODS

Among 1,706,639 births recorded between 1998 and 2006, 50 infants with a diagnosis of ARS were reported to the Polish Registry of Congenital Malformations. The information on 3 infants was incomplete, thus only 47 cases were analyzed. These infants were classified into groups of ARS-L (38 infants) and ARS-BWD (9 infants).

RESULTS

The ARS-BWD cases were more frequently affected by various congenital defects (overall p < 0.0001), and in particular by urogenital malformations (p = 0.003). In both groups, limb reduction defects occurred in approximately 80% of cases; however, minor and distal limb defects (phalangeal or digital amputation, pseudosyndactyly, constriction rings) predominated in the ARS-L group (p = 0.0008). The ARS-L group also had a higher frequency of hand and upper limb involvement.

CONCLUSIONS

This observation suggests that amniotic band adhesion in ARS-L takes place at a later development stage. Although limited by a small sample size, our study contributes to the growing evidence that both ARS entities represent two nosologically distinct conditions.

Threatened lower extremity in a neonate from a severely constricting amniotic band: a case for limb salvage after a 6-year functional follow-up

A child presented at birth with a threatened lower limb from severe constriction band. Limb salvage was performed by emergency z-plasty reconstructions and subsequent sural nerve grafting to a fibrotic segmental deficit in the sciatic nerve. Follow-up over a 6-year period enables us to provide a favorable outlook with regard to functional use of the extremity and absence of chronic lymphedema, but she does have a significant limb length discrepancy. There is virtually no information on long-term functional outcome of such cases, although textbook teaching advises one to attempt emergency salvage of an extremity that is threatened by a severely constricting congenital amniotic band. Follow-up of our patient equips us with outcome information so that we can now better inform parents when once again faced with this problem in the neonate.

Obstetric US: watch the fetal hands

Hand anomalies are difficult to diagnose and are often overlooked during prenatal ultrasonography (US). The spectrum of malformations varies from subtle finger deformities to the complete amputation of limbs. Malformations of the hand can be classified, according to the predominant anomaly, among the following categories: alignment abnormalities (clenched hand, camptodactyly, clinodactyly, hypokinesia, clubhand, phocomelia), thumb anomalies, abnormal size (macrodactyly, trident hand), abnormal echogenicity (abnormal calcifications), abnormal number (polydactyly, syndactyly, ectrodactyly), and constriction band sequence. A fetal hand anomaly has important diagnostic and prognostic implications as well as functional consequences. Malformation may be isolated but often is associated with a syndrome or karyotype anomaly. Classification and characterization of the anomaly help to narrow the differential diagnosis: Some malformations (clenched hand, hitchhiker thumb) are highly suggestive of a specific diagnosis. The detection of a fetal hand malformation warrants a complete work-up, including complete fetal and cardiac US examinations, as well as genetic counseling to determine whether familial inquiry and karyotype analysis are necessary.

Congenital placental-cerebral adhesion: an unusual case of amniotic band sequence. Case report

Amniotic band sequence is a disruption sequence having a broad spectrum of clinical manifestations ranging from partial amputations to major craniofacial and limb-body wall defects. Most reported cases of placental-cerebral adhesion pertain to patients with severe craniofacial defects who were either stillborn or who died a few hours after birth. The authors present a case of a male infant born with a placental-cerebral adhesion through a cranial defect. This adhesion was separated at birth, and duraplasty and primary scalp closure were performed. A detailed examination of the placenta revealed the presence of multiple amniotic bands. The case demonstrates that survival and normal early post-natal development are possible if the condition is treated promptly.

Pre- and postnatal diagnosis of limb anomalies: A series of 107 cases

This is a 3-year retrospective study of 107 cases presenting with limb anomalies detected either on prenatal ultrasound scan, or after birth. These limb malformations are developmental anomalies, and can be isolated, syndromic, or associated with multiple malformations. Cases were ascertained through the prenatal diagnosis center, the pediatrics department, and the feto-pathology department. Several criteria were analyzed including sex ratio, prenatal diagnosis, karyotype, termination of pregnancies, clinical or pathological examination, pediatric or surgical and/or genetic assessment, and whether or not a diagnosis was made. Positional deformities and syndactyly were excluded. Limb anomalies were detected prenatally in 45% of the cases, and a diagnosis was made in 78%, including isolated, syndromic, or chromosomal anomalies. Sixty-one per cent of the infants had follow-up, either pediatric, surgical, or genetic. Prenatal multidisciplinary assessment is fundamental to assist with counseling, as is the post-natal follow-up of the infant. The diagnosis, if made, will obviously influence the information that will be given to the parents and the management of the malformation. If the pregnancy is terminated, feto-pathological examination is essential to help make a diagnosis, and guide recurrence risks. We are currently undertaking a prospective study, and we will develop a protocol of investigations in the future, depending on the type of the malformation identified.

Recording congenital differences of the upper limb

Consistent classification of congenital differences of the upper limb is of paramount importance for the study of the pathogenesis. To overcome the inconsistencies of present classifications, a non-classifying recording method has been developed. This method records individual aberrations, including bone and soft-tissue defects. Between 1996 and 1998, a prospective study was performed to validate the method. Two hundred and thirty-one patients with upper limb differences were assessed, and all individual aberrations were recorded. These data can be transferred to any classification. It is concluded that the presented method will allow consistent grouping of patients without losing details about simple and complex differences.

Epidemiology of limb loss and congenital limb deficiency: a review of the literature

OBJECTIVE

To examine the state of research on population-based studies of the incidence of limb amputation and birth prevalence of limb deficiency.

DATA SOURCES

A total of 18 publication databases were searched, including MEDLINE, CINAHL, and the Cochrane Library.

STUDY SELECTION

The search was performed by using a hierarchical process. Articles were reviewed for inclusion by 3 reviewers. Inclusion criteria included defined catchment area, calculation of population-based incidence rates, defined etiology of limb loss, and English language. Review articles, animal studies, case reports, cohort studies, letters, and editorials were excluded.

DATA EXTRACTION

Figures on the estimated incidence of amputation and birth prevalence of congenital limb deficiency were gleaned from selected reports and assembled into a table format by etiology.

DATA SYNTHESIS

The studies varied in scope, quality, and methodology, making comparisons between studies difficult. Incidence rates of acquired amputation varied greatly between and within nations. Rates of all-cause acquired amputation ranged from 1.2 first major amputations per 10,000 women in Japan to 4.4 per 10,000 men in the Navajo Nation in the United States between 1992 and 1997. Consistent among all nations, the risk of amputation was greatest among persons with diabetes mellitus.

CONCLUSIONS

Surveillance of congenital limb deficiency exists in much of the developed world. Existing studies of acquired amputation suffer from a host of methodologic problems. Future efforts should be directed toward the application of standardized measures and methods to enable trends to be evaluated over time and comparisons to be made within and between countries.

Clinical and epidemiological studies of amniotic deformity, adhesion, and mutilation (ADAM) sequence in a South American (ECLAMC) population

Amniotic deformity, adhesion, and mutilation (ADAM) sequence is a heterogeneous condition, with a broad spectrum of anomalies, where intrinsic causes, as defect of germ plasm, vascular disruption, and disturbance of threshold boundaries of morphogens during early gastrulation, alternate with extrinsic causes as amniotic band rupture to explain the condition. This study aimed to identify which phenotypes could be considered as ADAM sequence, determine the prevalence rate, and disclose risk factors for this sequence. We identified 270 cases defined as having some skin evidence of constriction band, plus those having limb defects suggestive of ADAM sequence, among 3,020,896 live and stillborns in the years 1982 to 1998 in ECLAMC (Latin American Collaborative Study of Congenital Malformations). Half of the cases presented mutilation (reduction), and deformity (ring constriction) affecting distal parts of fingers or toes bilaterally, without associated defects. Acrania, cephalocele, typical or atypical facial clefts, eyelid coloboma, and celosomia were also observed being significantly associated with the skin lesion. One affected infant in every 11,200 births, was found with stable trends during the last 17 years. There was an excess of cases in populations living at high altitude, stillborns, and neonatal infant dead. Among ADAM cases there was an excess of mothers with a prenatal history of febrile acute illness, medication drug use, or vaginal bleeding during the first trimester of pregnancy. Higher than expected frequencies of first-born child, premature birth, low birth weight for gestational length, and non-cephalic fetal presentation were also found. The observed geographic difference in birth prevalence could be a useful indication to study specific genetic and environmental candidate factors to ADAM susceptibility.

Atypical presentation of amniotic band sequence

Amniotic Band Sequence (ABS) is a disruption sequence that results in a variable group of abnormalities secondary to the disruption process and subsequent deformations. The incidence of ABS ranges from 1:1,200 to 1:15,000 live-born, and is even higher in still-born [Froster and Baird, 1993: Am J Med Genet 46:497-500]. The pathophysiology of ABS remains controversial, but a close look to critical periods of embryogenesis and/or organogenesis has helped in understanding pathogenetic mechanisms leading to the ABS disruption. The abnormalities are typically limited to external structures; however, associated internal malformations as seen in the case reported here may occur [Hunter and Carpenter, 1986: Am J Med Genet 24:691-700]. The prognosis depends on the severity of the abnormalities and the involvement of internal organs [Froster and Baird; 1993: Am J Med Genet 46:497-500; Levy, 1998: Ped Rev 19:249].

Amniotic band syndrome: the association between rare facial clefts and limb ring constrictions

The pathologic cause of both rare craniofacial clefts and congenital limb ring constrictions is the subject of some debate. Uncommon though these two conditions are, they have often been anecdotally reported in association. This study sought to determine the frequency of congenital limb anomalies in general and limb ring constrictions in particular amongst a population of patients with rare craniofacial clefts. Eighty-five cases of nonsyndromal, rare, craniofacial cleft were identified from a population of 280 patients assessed at the Women's and Children's Hospital, North Adelaide, with a diagnosis of rare craniofacial cleft classifiable by the Tessier system. Twenty-two patients (25.9 percent) displayed congenital limb anomalies. Eleven of these (12.9 percent) showed evidence of limb ring constrictions, a frequency much greater than in the general population. The group with limb ring constrictions demonstrated a significantly greater complexity of involvement with craniofacial clefting than the non-limb ring constriction group (4.27 clefts/patient versus 2.3 clefts/patient, p < 0.01). The distribution of craniofacial cleft locations in patients with evidence of limb ring constrictions was found to differ significantly from those with other or no limb anomalies (p < 0.01). The clefts in cases in which limb ring constrictions coexist are largely restricted to the paramedian 2-12, 3-11, 412 axes. This study confirms an association between rare craniofacial clefts and limb ring constrictions. The two conditions may therefore possess common etiology.

Maternal smoking during pregnancy and limb reduction malformations in Sweden

OBJECTIVE

This study was undertaken to investigate a possible connection between different types of limb reduction defects and maternal smoking during pregnancy.

METHODS

With the use of the Swedish health registries, 610 cases of limb reduction malformations were selected from among 1 109 299 infants born between 1983 and 1993 with known smoking exposure in early pregnancy. Confounders such as maternal age and parity were controlled for with the use of the Mantel-Haenszel technique.

RESULTS

The odds ratio for any maternal smoking among all cases of limb reductions was 1.26 (95% confidence interval = 1.06, 1.50). The main subgroups of limb reduction defects showed similar odds ratios, but in longitudinal reduction defect, only unilateral cases showed an association with maternal smoking.

CONCLUSIONS

This study supports an association between maternal smoking and limb reduction malformations, but further work is needed before a causal inference can be made.

Chorionic villus sampling safety. Report of World Health Organization/EURO meeting in association with the Seventh International Conference on Early Prenatal Diagnosis of Genetic Diseases, Tel-Aviv, Israel, May 21, 1994

Accumulated experience of 138,996 cases of chorionic villus sampling shows that chorionic villus sampling is a safe procedure with an associated fetal loss rate comparable to that of amniocentesis. The chorionic villus sampling registry shows that chorionic villus sampling is currently performed primarily between 9 and 12 weeks' gestation and carried no increased risk of limb reduction defects: the overall incidence of limb reduction defects after chorionic villus sampling is 5.2 to 5.7 per 10,000, compared with 4.8 to 5.97 per 10,000 in the general population. Analysis of the pattern distribution of limb defects after chorionic villus sampling revealed no difference from the pattern in the general population. This applies specifically to transverse limb defects. Together with the overall incidence of limb reduction defects, these data provide no evidence for any risk for congenital malformation determined by chorionic villus sampling. Because chorionic villus sampling is currently performed generally after 8 completed weeks of pregnancy, few data are available for analysis of complications related to earlier procedures. Avoiding early chorionic villus sampling also excludes sampling in cases of early fetal death, which can be diagnosed reliably by ultrasonography at 9 weeks of pregnancy.

Limb defects and chorionic villus sampling: results from an international registry, 1992-94

BACKGROUND

Several reports of limb defects occurring among infants exposed to chorionic villus sampling (CVS) during pregnancy resulted in concern about the safety of this procedure for prenatal diagnosis. To avoid publication bias and evaluate the true risk of limb defects in a CVS cohort, the World Health Organization initiated international registration of post-CVS limb defects in 1992.

METHODS

From May, 1992, to May, 1994, 77 infants or fetuses with limb defects from 138 996 pregnancies having CVS were reported to the WHO CVS Registry. These cases were analysed by standardised methods-ie, exclusion of syndromes, inherited disorders, and defects occurring in previable fetuses. The included limb deficiencies were studied by pattern analysis.

FINDINGS

Defects of the upper limbs were reported in 64.6%, of the lower limbs in 12.5%, and of both upper and lower limbs in 20.8% of cases. These figures are in agreement with the distribution of limb defects in several large population-based studies. Transverse limb defects occurred in 40.8% and longitudinal defects in 59.2%, compared with 42.7% and 57.3% in an unexposed population.

INTERPRETATION

The analysis of this cohort did not show any differences from the background population in the overall frequency or pattern distribution of limb deficiencies. There was also no correlation between gestational age at CVS and severity of defects. Therefore these results do not indicate any increased risk of limb defects after CVS.

Amniotic band sequence in child of thalidomide victim

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