Abdominal wall defects (AWDs) correspond to a wide spectrum of congenital defects,
these affect 6.3/10,000 pregnancies.
They represent a heterogeneous group of malformations that share a common feature: the herniation of one or more viscera through the anterior abdominal wall.
Omphalocele and gastroschisis are the most frequent abnormalities,
nevertheless there are less frequent and more complex pathologies,
such as bladder exstrophy,
cloacal exstrophy,
body stalk anomaly,
pentalogy of Cantrell and abdominoschisis due to amniotic bands.
Abdominal wall defects are associated with other congenital abnormalities that have important prognostic and management implications,
such as timing and mode of delivery,
as well as an adequate parent counseling,
all of these affecting pregnancy outcomes.
Embryology
In the 3rd week of embryonic life,
a trilaminar disk has developed with the ectoderm facing the amnion,
the endoderm facing the yolk sac and a mesoderm “sandwich” lying in between,
except for both ends where the ectoderm and endoderm are in contact,
these contact points are: at the cranial end,
the oropharyngeal membrane (mouth),
and at the caudal end,
the cloacal membrane (urogenital and anal orifices).
In the 4th week the trilaminar disk starts to fold,
both craniocaudally and laterally,
this gives rise to a tube (gut) within a tube (body tube).
The craniocaudal fold gives the typical C-shaped appearance seen in ultrasound,
the lateral folds close the abdominal wall.
Alterations during the aforementioned process can result in an abdominal wall defect,
excluding omphalocele.
The allantois,
a ventral diverticulum,
projects from the caudal end (cloaca) towards the connecting stalk (body stalk),
which attaches the embryo to the chorion,
this will eventually become the umbilical cord.
During the 6th week,
physiologic gut herniation into the umbilical cord results secondary to insufficient space in the abdominal cavity for the rapidly growing midgut,
around 11th and 12th weeks,
the midgut rotates 270° counterclockwise and returns to the abdomen.
Failure in the return of this physiologic gut herniation gives rise to an omphalocele.
Epidemiology
According to the European Surveillance of Congenital Anomalies from 2012 to 2016,
there were a total of 2185 cases of abdominal wall defects.
With a prevalence of 6.47 per 10,000 pregnancies Table 1.