Gastroschisis is a

birth defect A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can ...

in which the baby's

intestines The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans ...

extend outside of the

abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...

through a hole next to the

belly button The navel (clinically known as the umbilicus, commonly known as the belly button or tummy button) is a protruding, flat, or hollowed area on the abdomen at the attachment site of the umbilical cord. All placental mammals have a navel, although ...

. The size of the hole is variable, and other organs including the

stomach The stomach is a muscular, hollow organ in the gastrointestinal tract of humans and many other animals, including several invertebrates. The stomach has a dilated structure and functions as a vital organ in the digestive system. The stomach i ...

and

liver The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...

may also occur outside the baby's body. Complications may include feeding problems, prematurity, intestinal atresia, and

intrauterine growth restriction Intrauterine growth restriction (IUGR), or fetal growth restriction, refers to poor growth of a fetus while in the womb during pregnancy. IUGR is defined by clinical features of malnutrition and evidence of reduced growth regardless of an infant's ...

. The cause is typically unknown. Rates are higher in babies born to mothers who smoke, drink alcohol, or are younger than 20 years old.

Ultrasound Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...

s during pregnancy may make the diagnosis. Otherwise diagnosis occurs at birth. It differs from

omphalocele Omphalocele or omphalocoele also called exomphalos, is a rare abdominal wall defect. Beginning at the 6th week of development, rapid elongation of the gut and increased liver size reduces intra abdominal space, which pushes intestinal loops out of ...

in that there is no covering membrane over the intestines. Treatment involves surgery. This typically occurs shortly after birth. In those with large defects the exposed organs may be covered with a special material and slowly moved back into the abdomen. The condition affects about 4 per 10,000 newborns. Rates of the condition appear to be increasing.

Signs and symptoms

There are no signs during pregnancy. About sixty percent of infants with gastroschisis are born prematurely. At birth, the baby will have a relatively small (<4 cm) hole in the abdominal wall, usually just to the right of the belly button. Some of the intestines are usually outside the body, passing through this opening. In rare circumstances, the

and

may also come through the abdominal wall. After birth these organs are directly exposed to air.

Causes

The cause of gastroschisis is not known. There may be genetic causes in some cases, and there may be environmental factors to which the mother is exposed during pregnancy. Risk factors include the mother being young, and use of alcohol or tobacco.

Pathophysiology

During the fourth week of

human embryonic development Human embryonic development, or human embryogenesis, is the development and formation of the human embryo. It is characterised by the processes of cell division and cellular differentiation of the embryo that occurs during the early stages of de ...

, the lateral body wall folds of the embryo meet at the midline and fuse together to form the anterior body wall. However, in gastroschisis and other anterior body wall defects, this fails to occur by either one or both of the lateral body wall folds not moving properly to meet with the other and fusing together. This incomplete fusion results in a defect that allows abdominal organs to protrude through the abdominal wall, and the intestines typically herniate through the

rectus abdominis The rectus abdominis muscle, ( la, straight abdominal) also known as the "abdominal muscle" or simply the "abs", is a paired straight muscle. It is a paired muscle, separated by a midline band of connective tissue called the linea alba. It exte ...

muscle, lying to the right of the umbilicus. The forces responsible for the movement of the lateral body wall folds are poorly understood, and a better understanding of these forces would help to explain why gastroschisis occurs mostly to the right of the umbilicus, while other ventral body wall defects occur in the midline. At least six hypotheses have been proposed for the pathophysiology: # Failure of

mesoderm The mesoderm is the middle layer of the three germ layers that develops during gastrulation in the very early development of the embryo of most animals. The outer layer is the ectoderm, and the inner layer is the endoderm.Langman's Medical E ...

to form in the body wall # Rupture of the amnion around the umbilical ring with subsequent herniation of bowel # Abnormal involution of the right umbilical vein leading to weakening of the body wall and gut herniation # Disruption of the right vitelline (yolk sac) artery with subsequent body wall damage and gut herniation # Abnormal folding of the body wall results in a ventral body wall defect through which the gut herniates # Failure to incorporate the yolk sac and related vitelline structures into the umbilical stalk The first hypothesis does not explain why the mesoderm defect would occur in such a specific small area. The second hypothesis does not explain the low percentage of associated abnormality compared with omphalocele. The third hypothesis was criticized due to no vascular supplement of anterior abdominal wall by umbilical vein. The fourth hypothesis was commonly accepted, but it was later shown that the right vitelline artery (right omphalomesenteric artery) did not supply the anterior abdominal wall in this area. More evidence is needed to support the fifth hypothesis.

Diagnosis

In the developed world, around 90% of cases are identified during normal ultrasound screens, usually in the second trimester. Distinguished from other ventral body wall defects such as

, there is no overlying sac or peritoneum, and the defect is usually much smaller in gastroschisis.

Treatment

Gastroschisis requires surgical treatment to return the exposed intestines to the abdominal cavity and close the hole in the abdomen. Sometimes this is done immediately but more often the exposed organs are covered with sterile drapings, and only later is the surgery done. Affected newborns frequently require more than one surgery, as only about 10% of cases can be closed in a single surgery. Given the urgent need for surgery after birth, it is recommended that delivery occur at a facility equipped for caring for these high-risk neonates, as transfers to other facilities may increase risk of adverse outcomes. There is no evidence that cesarean deliveries lead to better outcomes for babies with gastroschisis, so cesarean delivery is only considered if there are other indications. The main cause for lengthy recovery periods is the time taken for the infant's bowel function to return to normal. After surgery infants are fed through IV fluids and gradually introduced to normal feeding.

Prognosis

If left untreated, gastroschisis is fatal to the infant; however, in adequate settings the survival rate for treated infants is 90%. Most risks of gastroschisis are related to decreased bowel function. Sometimes blood flow to the exposed organs is impaired or there is less than the normal amount of intestine. This may put infants at risk for other dangerous conditions such as

necrotizing enterocolitis Necrotizing enterocolitis (NEC) is a devastating intestinal disease that affects premature or very low birth weight infants.Gephart S.M., Quinn M. A call to action to fight for equity and end necrotizing enterocolitis disparities. ''Adv. Neonata ...

. Also, because their intestines are exposed, infants with gastroschisis are at increased risk for infection, and must be closely monitored. After surgery a child with gastroschisis will have some degree of

intestinal malrotation Intestinal malrotation is a congenital anomaly of rotation of the midgut. It occurs during the first trimester as the fetal gut undergoes a complex series of growth and development. Malrotation can lead to a dangerous complication called volvulus. ...

. About 1% of children will experience a midgut

volvulus A volvulus is when a loop of intestine twists around itself and the mesentery that supports it, resulting in a bowel obstruction. Symptoms include abdominal pain, abdominal bloating, vomiting, constipation, and bloody stool. Onset of symptoms ma ...

after surgery.

Epidemiology

As of 2015 the worldwide incidence was about 2 to 5 per 10 000 live births, and this number seemed to be increasing. As of 2017 the

CDC The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georgi ...

estimates that about 1,871 babies are born each year in the United States with gastroschisis.

References

External links

{{Congenital abdominal wall defects Congenital disorders of musculoskeletal system Autosomal recessive disorders Genetic disorders with OMIM but no gene Wikipedia medicine articles ready to translate