Limb body wall complex (LBWC) is a rare and severe syndrome of congenital malformations involving craniofacial and abdominal anomalies. LBWC emerges during early fetal development and is fatal. The cause of LBWC is unknown.
| Limb body wall complex | |
|---|---|
| Other names | Body stalk anomaly Cyllosomus and pleurosomus Congenital absence of umbilical cord |
| Specialty | Neonatology |
| Usual onset | Early fetal development |
| Prognosis | Incompatible with life |
| Frequency | 1 in 15,000 pregnancies[1] |
Diagnosis and classification
Traditionally, LBWC is diagnosed by the presence of at least two of the three Van Allen criteria:[2]
- Exencephaly or encephalocele with facial clefts
- Abdominal wall defects: thoracoschisis and/or abdominoschisis
- Limb defects
As a component of the abdominal wall defect, the umbilical cord is shortened or absent with the fetus being directly attached to the placenta, a key feature in its prenatal diagnosis by ultrasound.[3]
Several systems have been proposed to classify LBWC cases phenotypically. Russo et al. (1993) proposed two types distinguished by the presence or absence of craniofacial defects.[4] Sahinoglu et al. (2007) proposed three types based on the anatomical location of defects:[5]
- Type 1: Craniofacial defect and intact thoracoabdominal wall; rarely, placenta or umbilical cord attachment to cranial structures
- Type 2: Supraumbilical thoracoabdominal wall defect with abdominal organ eventration into the amniotic sac; defective umbilical cord
- Type 3: Infraumbilical abdominal wall defect with broad placenta attachment and abdominal organ eventration into the gestational sac; malformed or absent cloacal structures
In all types of LBWC, some of the fetus's organs develop outside of its body,[6] and the placenta will adhere to the affected body structure (cranium, thorax, or abdomen).[7] The umbilical cord is significantly shortened. As a consequence, the developing spine and limbs are contorted, leading to scoliosis and limb defects.[1]
LBWC can be diagnosed by prenatal ultrasound as early as gestational week 11.[8] Elevated alpha-fetoprotein levels in maternal serum may suggest the possibility of LBWC or another anomaly, motivating ultrasound follow-up.[7] Due to LBWC's extremely poor prognosis, termination of the pregnancy is typically recommended.[1][5][7]
Prevalence
LBWC is estimated to occur in 1 in 15,000 pregnancies, with the majority of cases ending in intrauterine death.[1][2] Its incidence at birth is estimated to be 0.32 in 100,000.[2] Infants with LBWC which survive to term die during or shortly after birth.[7]
Causes
The etiology of LBWC is unknown.[7] Several hypotheses have been proposed: defective blastodisc development, vascular disruption during early embryonic development, and early amniotic membrane rupture resulting in mechanical damage to the fetus.[5] Case reports have reported associations between LBWC and placental trisomy 16, maternal uniparental disomy 16, mosaic trisomy 13, cocaine usage, and continued use of oral contraceptives during early gestation.[5]
References
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