Gastroschisis

A. Gastroschisis is a full-thickness paraumbilical abdominal wall defect usually associated with

evisceration of bowel and sometimes other abdominal organs
B. Clinical significance
1. Bowel herniation may lead to a variety of intestinal abnormalities because:
i. Mesenteric blood supply can become compromised
ii. Prolonged exposure of the bowel to the toxic environment of the amniotic fluid may
result in inflammatory changes in the bowel wall
2. In addition to bowel abnormalities, other common potential sequelae include:
i. Growth restriction
 Due to undernutrition from loss of protein and fluid across the exposed bowel
ii. Spontaneous preterm birth
iii. Fetal demise
 Related to growth restriction, cord compression
3. After birth, the newborn requires special care because of the exposed bowel
i. The defect must be closed
ii. However, the prognosis is generally very good
C. Pathogenesis
1. Defective formation or disruption of the body wall in the embryonic period, with
subsequent herniation of bowel:
i. Failure of mesoderm to form in the body wall
ii. Rupture of the amnion around the umbilical ring
iii. Abnormal involution of right umbilical vein leading to weakening of the body wall
iv. Disruption of the right vitelline artery with subsequent body wall damage
2. Gene polymorphisms that interact with environmental factors, such as smoking
3. The maternal immune response to new paternal (fetal) antigens may also play a role
4. Possible association with aspirin, ibuprofen, vasoconstrictive agents (pseudoephedrine)
D. Prevalence and epidemiology
1. Gastroschisis and omphalocele are the most common fetal abdominal wall defects
2. The incidence of gastroschisis is similar in male and female fetuses
3. Young women (under 20 years of age) have higher rate of offspring with gastroschisis
E. Laboratory markers
1. An increased possibility of gastroschisis, as well as other fetal anomalies, should be
considered in pregnancies with an elevated maternal serum alpha fetoprotein (MSAFP)
level as almost all cases of gastroschisis are associated with this finding
2. An elevated MSAFP is an indication for thorough ultrasonographic examination of the
fetus for anatomic abnormalities
F. Prenatal diagnosis
1. Prenatal detection rates are high
 2. Ultrasound findings
i. Small (typically 2 to 5 cm) paraumbilical abdominal wall defect, usually to the right
of the midline, with visceral herniation
ii. Umbilical cord insertion site is adjacent to and separate from the defect and is normal
iii. Usually, the intestine is the only herniated organ, but the liver and stomach may also
herniate; other intra-abdominal organs rarely pass through the defect
iv. The stomach is usually malpositioned, even when intra-abdominal
v. The intestinal mass lacks a covering membrane and floats freely in the amniotic fluid
vi. The exteriorized bowel appears cauliflower-like
3. Associated anomalies and findings
i. Associated GI anomalies and problems (malrotation, atresia, stenosis, perforation,
necrosis, volvulus) occur in up to 25% of cases
ii. Disruption of the superior mesenteric artery, for example, may lead to volvulus or to
"apple peel" jejunal-ileal lesions
iii. Meckel's diverticulum and gallbladder atresia also occur but are less common
iv. Oligohydramnios > Polyhydramnios
4. Differential diagnosis — Omphalocele is the major differential diagnosis
i. The membranous sac helps to distinguish omphalocele from gastroschisis; however,
membranes occasionally rupture in utero
ii. If the membrane ruptures, the locations of the liver and cord vessels and insertion site
can help to differentiate an omphalocele from gastroschisis
iii. Omphalocele is often associated with an extracorporeal liver, while the liver is
typically intracorporeal in gastroschisis
iv. The cord insertion site is into the umbilical sac in omphalocele and paraumbilical
onto an otherwise intact abdominal wall in gastroschisis
v. If the sac ruptures, the cord vessels traverse the amniotic remnant in omphalocele and
enter the abdomen in the suprapubic region
vi. Gastroschisis is associated with a lower rate of associated defects than omphalocele
Other major abdominal wall defects in differential diagnosis (ectopia cordis, limb-
body wall complex, cloacal exstrophy, and urachal cyst
vii. Omphalocele and body-stalk defects are connected to the cord, ectopia cordis
develops above and bladder exstrophy below the cord insertion, and gastroschisis is
paraumbilical
G. Clinical findings
1. The characteristic clinical finding in newborns is a full-thickness paraumbilical
abdominal wall defect, often associated with evisceration of bowel
2. Located to the right of the umbilical cord insertion site and tends to be <4 cm in diameter
3. There is no covering membrane
4. Inflammation and fibrosis from chronic exposure to amniotic fluid result in:
i. Thickening and matting of the intestines
ii. Decreased bowel motility
 iii. Possibly luminal obstruction
H. Delivery room care
1. Neonatal fluid losses are 2.5 times that of a healthy newborn in the first 24 hours of life
2. Neonate is at risk for insensible heat and fluid losses from exposure of eviscerated bowel
i. In addition, third space fluid deficits from sequestration of intestinal fluid
3. The initial approach to management of these newborns includes:
i. Wrapping the bowel with sterile saline dressings covered with plastic wrap →
 Preserves body heat
 Minimizes insensible fluid loss
 Protects the bowel
ii. Inserting an orogastric tube to decompress the stomach
iii. Placement of peripheral IV access to provide fluids and broad-spectrum antibiotics
that cover maternal vaginal flora (ampicillin and gentamicin)
iv. Ensuring a patent airway
v. Keeping the neonate in a thermoneutral environment
vi. Providing respiratory support, if required
4. Synopsis of surgical management
i. Primary closure, when feasible, is performed within a few hours of birth
ii. In the operating room, the bowel is decompressed by aspirating stomach contents and
evacuating the large bowel through the rectum
iii. Size of the defect is increased 1-2 cm to minimize trauma to bowel during reduction
iv. The abdominal wall is manually stretched, and the bowel is replaced, taking care to
avoid creating intra-abdominal pressure that is too high
v. Primary closure is successful in 70% of cases
 If primary closure is not feasible because of thickened, distended intestinal loops,
a staged closure with a silastic silo can be used as in omphalocele cases
 A preformed silo with a spring-loaded ring can be placed at the bedside to cover
the herniated intestine quickly without suturing
vi. Prolonged postoperative dysmotility is common and interferes with enteral feeding
5. Prognosis
i. Gastroschisis has the most favorable prognosis of the abdominal wall defects because
most cases are not complicated by concomitant non-GI anomalies or aneuploidy
ii. Gastroschisis in infants can be categorized as "simple" or "complex" based on the
absence or presence of intestinal atresia, stenosis, perforation, necrosis, malrotation,
or volvulus, but this distinction is often not possible to discern prenatally
I. Recurrence risk
1. There is an increased risk of recurrence in families with a child with gastroschisis, which
suggests that genetic factors play a role in causation

Omphalocele
A. Introduction
1. Midline abdominal wall defect of variable size at the base of the umbilical cord
2. The defect is covered by a three-layer membranous sac consisting of:
i. Amnion
ii. Wharton's jelly
iii. Peritoneum
3. The cord/umbilical vessels insert at the apex of the sac, which typically contains
herniated abdominal contents
4. Omphaloceles are categorized as either
i. Non-liver-containing (containing bowel loops)
ii. Liver-containing
B. Embryology and pathogenesis
1. Fetal wall defects result from disturbances in organogenesis during embryonic period
2. Normal embryologic development of the abdominal wall
i. During the fourth to fifth week of development, the flat embryonic disk folds in four
directions and/or planes: cephalic, caudal, and right and left lateral
ii. Each fold converges at site of the umbilicus, thus obliterating extraembryonic coelom
 The lateral folds form the lateral portions of the abdominal wall, and the cephalic
and caudal folds make up the epigastrium and hypogastrium
iii. Rapid growth of the intestines and liver also occurs concurrently
iv. During the sixth week of development (or eight weeks from the last menstrual
period), the abdominal cavity temporarily becomes too small to accommodate its
contents, resulting in protrusion of the midgut into the residual extraembryonic
coelom at the base of the umbilical cord
v. This temporary herniation involves 90 degrees of counterclockwise rotation of the
midgut around superior mesenteric pedicle and called physiologic midgut herniation
vi. Reduction of the hernia involves further rotation to 270 degrees in the abdominal
cavity and normally occurs by the 12th postmenstrual week; thus, midgut herniation
is no longer physiologic beyond the 12th week
vii. In contrast to the fetal bowel, the liver does not undergo physiologic migration
outside of the abdominal cavity during development
 Therefore, the liver is never present in physiologic midgut herniation
3. Pathogenesis
i. Extraembryonic gut fails to undergo the obligatory 270-degree counterclockwise
rotation back into the abdomen, resulting in a simple, small, midline omphalocele
ii. Failure of the left and right lateral folds to close normally creates a large abdominal
wall defect through which contents of abdominal cavity (including the liver) can
herniate
4. Prevalence and epidemiology
 i. Omphalocele and gastroschisis are the most common fetal abdominal wall defects
ii. More common in offspring of women at the extremes of reproductive age
iii. Associations with maternal obesity and in utero SSRI exposure
iv. Omphalocele has also been associated with male sex and multiple births
C. Prenatal (fetal) diagnosis
1. Over 90% are diagnosed prenatally
2. Prenatal diagnosis of a non-liver-containing omphalocele can be made reliably after 12
postmenstrual weeks; prior to this time, unless large, it can be difficult to differentiate
from physiologic midgut herniation
3. Prenatal diagnosis of liver-containing omphalocele can be made by transvaginal
sonography as early as 9 to 10 postmenstrual weeks if a homogenous mass measuring
greater than 5 to 10 mm in diameter suggestive of liver is imaged within the area of
physiologic midgut herniation
4. The sonographic diagnosis of a liver-containing omphalocele can be made before the
12th postmenstrual week because herniated liver is never a normal developmental finding
5. Findings on ultrasound
i. Midline abdominal wall defect of variable size in the area of the umbilicus, covered
by a membranous sac consisting of amnion as the outer layer, peritoneum as the inner
layer, with Wharton's jelly in between, and containing abdominal contents (typically
bowel but often liver and occasionally stomach or bladder)
ii. The cord inserts into the apex of the sac
iii. Ascites may be seen in the sac or the abdomen
iv. Eighty percent of omphaloceles contain part of the liver
v. The location of the liver is important, in part because the smallest omphaloceles are
those that are bowel only, non-liver-containing omphaloceles
vi. These small omphaloceles are commonly associated with a fetal aneuploidy, while
the larger liver-containing omphaloceles are usually associated with euploid fetuses
vii. The term "giant omphalocele" has been used to describe omphaloceles that contain
most (>75 percent) of the liver or have a very large size (absolute size typically ≥5 cm
or large size relative to the fetal abdomen)
6. Associated abnormalities
i. Structural
 Associated structural anomalies are common
 Associated abnormalities occurring with increased frequency include additional
gastrointestinal abnormalities, cardiac defects, genitourinary anomalies, orofacial
clefts, neural tube defects, and diaphragmatic defects
ii. Chromosomal abnormalities
 Omphaloceles containing only small bowel (the liver is intracorporeal) are
associated with a high frequency of fetal aneuploidy particularly trisomy 18 or 13
iii. Amniotic fluid volume – Polyhydramnios is common
 iv. Fetal growth – An increased frequency of growth restriction
7. Syndromes associated with omphalocele
i. Beckwith-Wiedemann syndrome
ii. Trisomy 13
iii. Trisomy 18
iv. Trisomy 21
8. Differential diagnosis
i. Gastroschisis – Gastroschisis is the major disorder to consider in differential
diagnosis of omphalocele. The membranous sac of an omphalocele helps to
distinguish it from gastroschisis, which is characterized by loops of bowel free
floating in amniotic fluid. However, omphalocele membranes occasionally rupture in
utero, particularly in giant omphaloceles. In such cases, an extracorporeal liver and/or
an umbilical defect site suggest an omphalocele, while an intracorporeal liver and a
paraumbilical defect suggest gastroschisis
ii. Umbilical cord hernia – In an umbilical cord hernia, the umbilical cord inserts
normally into the umbilical ring, which is surrounded by intact skin and is typically
<2 cm in diameter, whereas in an omphalocele, the cord inserts into a membranous
sac that covers a large abdominal wall defect occupying the area of the umbilical ring
[46-48]. Like an omphalocele, umbilical cord hernias can contain bowel, but in
contrast to omphaloceles, they are not associated with an increased risk for anomalies
or genetic syndromes. Pathogenesis is also probably different. Omphalocele is either
a rotational abnormality or a primary failure of the four body folds to form a normal
midabdominal wall, whereas in umbilical cord hernia, the body folds develop
normally, but physiologic midgut herniation may persist and result in a simple hernia.
iii. Other major abdominal wall defects in differential diagnosis, such as ectopia cordis,
limb-body wall complex, cloacal exstrophy, and urachal cyst, are rare (prevalence of
each less than 1 in 100,000 births). They can be differentiated by their location
(upper, middle, or lower abdomen), cord insertion, and associated abnormalities
(table 2). Omphalocele and body stalk defects are both connected to the cord, but
body stalk anomaly is also associated with scoliosis and a short umbilical cord.
Ectopia cordis (and the Pentalogy of Cantrell) has at least a portion of the heart
outside of the body cavity and is the classic upper midline abdominal wall defect.
Bladder exstrophy develops below the cord insertion and is the classic lower midline
abdominal wall defect
9. Associated maternal findings
i. The mother is asymptomatic
ii. If a maternal serum alpha-fetoprotein concentration has been performed as part of
screening for neural tube defects, it may be elevated
D. Post-diagnostic fetal evaluation
1. After an omphalocele is diagnosed, further evaluation of the fetus may include:
i. Genetic studies
 ii. Testing for Beckwith-Wiedemann syndrome (BWS)
iii. Echocardiogram
E. Approach to the neonate
1. Delivery room — In the delivery room, the key is to avoid clamping the umbilical sac.
(In umbilical cord hernias, it is important to avoid clamping the proximal part of the
umbilical cord, which may contain occult herniated bowel.)
2. The immediate care of the newborn with omphalocele involves:
i. Sterile wrapping of the bowel to preserve heat and minimize insensible fluid loss
ii. Insertion of an orogastric tube to decompress the stomach
iii. Stabilizing the airway to ensure adequate ventilation
iv. Establishing peripheral intravenous access
v. Positioning left-side down right-side up if low blood pressure, tachycardia, or dusky
bowel appearance suggesting vascular compromise
3. One approach is to place gauze dressings soaked in warm sterile saline and cover the
dressing with clear plastic wrap
4. Excessively wet and circumferential dressings should be avoided because they can
macerate the omphalocele sac and cause the newborn's temperature to drop
5. Circumferential abdominal wall wraps also should be avoided, as they have the potential
to compromise blood flow
6. Intravenous fluids and broad-spectrum antibiotics are administered
7. Cardiorespiratory and fluid status should be monitored closely and a thorough physical
examination performed to identify additional malformations
8. The neonate should be maintained in a thermoneutral environment
F. Synopsis of surgical management
1. The priority for abdominal wall repair is preservation of intestinal blood flow
2. In all cases, the size of the abdominal wall defect must be balanced with right of domain
(anteroposterior depth of abdominal cavity)
3. In general, small defects (2 to 3 cm) can be repaired in the first 24 to 72 hours of life by
primary closure of both fascia and skin
4. The remaining spectrum of defects usually involves some type of silo in the first 24 hours
of life and delayed closure
5. The silo can be reduced gradually over three to seven days in the intensive care unit, after
which the infant is returned to the operating room for final closure of the abdominal wall
6. Reducing a large defect or one that contains an anatomically kinked liver can be done
with Doppler ultrasound guidance to ensure the vena cava and hepatic outflow are not
compromised during the silo reduction
7. Giant omphaloceles (>5 cm defects with >75 percent liver out) may be managed by a
combination of silo, acellular dermal patch, and skin graft or by promoting formation of
an amniotic sac eschar by application of a sclerosing solution (topical povidone-iodine),
with delayed hernia repair
 8. After omphalocele reduction, the neonate may require prolonged mechanical ventilation
because of respiratory difficulties and caval compression
9. Postoperative increase in intra-abdominal pressure required to restore intestinal right of
domain must be carefully monitored through urine output, pulse rate, and blood pressure
10. Infants with very large omphaloceles containing most of the liver may require multiple
reconstructive procedures and have the potential for long-term morbidity
11. Nutritional status, associated anomalies, and pulmonary hypoplasia all play major roles in
determining whether the child will have a good long-term outcome

Gastroschisis
A. Abdominal wall defect, not involving umbilicus, through which intestinal contents herniate
B. Bowel is not covered by peritoneum or amniotic membrane
C. As a result, prolonged contact with the amniotic fluid typically causes a thick, exudative
covering (a “peel”) on the exposed bowel
D. Not associated with extraintestinal anomalies, but segments of intestinal atresia are common
E. After surgical reduction of the defect, return of normal bowel function may be slow and
requires prolonged parenteral nutrition for infants with long atretic segments (short-bowel
syndrome) and infants with a thick peel
Omphalocele
A. Abdominal wall defect through the umbilicus caused by failure of the intestine to return to
the abdomen during fetal life
B. Bowel is within the umbilical cord and covered by peritoneum and amniotic membranes
C. Associated with other congenital anomalies, especially cardiac defects, Beckwith-
Wiedemann syndrome, and intestinal complications
D. Treatment is surgical closure, which sometimes must be performed in stages to fit the bowel
into a congenitally small abdominal cavity