ABDOMINAL WALL DEFETCTS
Omphalocele is a congenital defect of the peri-umbilical abdominal wall in which the coelomic cavity is covered only by peritoneum and amnion (membrane covering).
There are two kinds of omphalocele: fetal and embryonic.
Fetal omphalocele is a small abdominal defect (< 4 cm wide) with herniation of bowel into a sac of amnion that has the umbilical vessels located at the apex of the sac. This is due to failure in development of the periumbilical periumbilical abdominal wall after the first 8 weeks of gestation. Other anomalies are present in less than 10% of these patients. About 15% of congenital abdominal wall defects are fetal omphaloceles.
CONGENITAL UMBILICAL HERNIA Definition -Fascial defect at the umbilicus is frequently present in the newborn, particularly in premature infants. Pathology The defect may have invagination of the intestines or omentum with an overlying skin covering Its size may actually increase with increase in intra-abdominal pressure. Protrusion of bowel through the umbilical defect rarely results in incarceration in childhood most dangerous defects are less than 2cm. Etiology-Unknown Etiology-Unknown Incidence -Incidence thus decreases with age as the natural tendency is to close spontaneously. -Is very common 1; 1000 -Majority .50 % are small defects less than 1cm in size-belly button umbilical hernia in those < 2years.
Race -The incidence is highest in blacks. Clinical presentation -Most as ymptomatic. ymptomatic. -Omentum trapped in the hernia causes reflex vomiting without intestinal obstruction. -Classical presentation is reducing mass in the umbilical area with or without vomiting associated with intermittent abdominal pain. -the hernia may become obstructed, strangulated and present as acute abdomen. Course
In most children, the umbilical ring progressively diminishes in size and eventually closes. closes . Fascial defects less than 1 cm in diameter close spontaneously by 5 years of age in 95% of cases. When the fascial defect is greater than 1.5 cm in diameter, it seldom closes spontaneously. spontaneously. Surgical repair is indicated when
1) 2)
The intestine becomes incarcerated
Symptomatic hernia. 3) when the fascial fascial defect defect is greater greater than 1 cm, in girls girls over over 2 years 4) All All chil childr dren en ove overr 4 year years s of age age.. 5) Cosmesis In girls must be repaired because the defect may worsen in pregnancy. some patients with umbilical defects develop acquired umbilical hernia due to increase in abdominal pressure due to ascites
Mortality/Morbidity -Intestinal obstruction and infection -2-12% recurrence after the corrective operation. operation.
It is characterized by a wide abdominal wall defect, usually greater than 4 cm in width, width , in which the amnion does not protrude far beyond the abdomen, and the umbilical cord joins the abdominal wall at the perimeter of the defect rather than at the apex. Liver as well as bowel is herniated. Multiple anomalies are present in 50% of these cases, such as Congenital heart defects (20%) (tetralogy of Fallot; atrial septal defect) Trisomies 21, D, and E; Diaphragmatic hernia Renal anomalies.
Pentalogy of Cantrell -omphalocele is is epigastric in position and there is a defect in the diaphragm and pericardium, allowing pericardial herniation of bowel, a split or shortened lower sternum, ventricular septal defect, and diverticulum from the heart--and a small thorax which may result in pulmonary hy poplasia
Beckwith-Wiedemann syndrome, in which a midabdominal omphalocele is associated with a baby who is large for gestational age and who has macroglossia, visceromegaly of the kidneys, adrenal glands, and pancreas, h ypoglycemia in early infancy, and a high frequency of hepatoblastoma, Wilms' tumor, or adrenocortical carcinoma; and
Hypogastric omphalocele associated with cloacal exstrophy and spinal dysraphism.
Treatment
Omphaloceles with small abdominal defects can be treated by excising the omphalocele sac and reapproximating reapproximating the linea alba and skin.
Acute management of omphalocele of omphalocele involves covering the defect with a sterile dressing soaked with warm saline to prevent fluid loss.
A nasogastric tube should be placed on suction to minimize intestinal distention and allow decompression Intravenous fluids and glucose, and antibiotics A central venous catheter is required to monitor central venous pressure and blood gases in anticipation of postoperative hypovolemia from third space losses and for TPN.
OMPHALOCELE
Introduction
JUDY WAWIRA GICHOYA YR 2007
Embryonic omphalocele is due to failure of abdominal wall closure in the embryonic stage of development (before the eighth week).
An umbilical artery catheter can catheter can be maintained without interfering with the repair. A bladder catheter can be used to monitor intraabdominal pressure.
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Most large embryonic omphaloceles cannot be closed without staging the procedure which gradual reduction of the omphalocele contents into the abdominal cavity and a secondary closure. Without removing the amniotic sac, a silicone rubber sheet is formed into a tube (silastic silo), which is sutured to the skin at the perimeter of the omphalocele membrane. The silo is progressively compressed to invert the amniotic sac and its contents into the abdomen and to bring the edges of the linea alba together by stretching the abdominal wall muscles. This requires a number of days. Postoperatively, Postoperatively, third-space fluid losses may be extensive; fluid and electrolyte therapy, therefore, must be carefully monitored.
As edema and shaggy membrane of the protuberant intestine are absorbed, the bowel will readily reduce into the abdominal cavity. A gastrostomy is valuable in postoperative care of the baby, because gastrointestinal function is often slow to return. The death rate for infants with gastroschisis has been greatly reduced by this technique. Poor gastrointestinal function and episodes of sepsis, presumably from compromised bowel, may occur. Total parenteral nutrition may be necessary for several weeks.
NB. Diagnosis may be done in utero of the last 2 disorders by doing an U/S-at 16 and 32 weeks -Alpha fetal protein raised in both cases. -Cytology on the amniotic fluid for other associated disorders.
GASTROSCHISIS Introduction
Gastroschisis is a defect in the abdominal wall that usually is to the right of a normal insertion of the umbilical cord. There is no membrane or sac and no liver or spleen outside the abdomen. Gastroschisis is associated with no anomalies except intestinal atresia. The herniation is thought to occur as a rupture through an ischemic portion of the abdominal wall. It is probably produced by rupture of an embryonic omphalocele sac in utero. The remnants of the amnion are usually reabsorbed. The skin may continue to grow over the remnants of the amnion, and there may be a bridge of skin between the defect and the cord. The small and large bowel herniate through the abdominal wall defect. Having been bathed in the amnionic fluid, and with compression of the blood supply at the abdominal defect, the bowel wall has a very thick, shagg y membrane covering it. The loops of intestine are usually matted together, and the intestine appears to be abnormally short. The membrane thickens during delay in surgical closure and compromises the outcome
Complications Since the bowel has not been contained intra-abdominally, the abdominal cavity fails to enlarge, and it frequently cannot accommodate the protuberant bowel. Over 70% of the infants are premature, but associated anomalies occur in less than 10% of cases. Nonrotation of the midgut is present. Intestinal atresia occurs frequently, because segments of intestine that have herniated through the defect become infarcted in utero. Treatment & Prognosis
Small defects may be closed primarily after manually stretching the abdominal cavity. cavity.
Frequently, a staged approach is required.
Initially, the bowel should be covered b y forming a tube from silicone-coated fabric and incorporating the protuberant bowel into the tube (silo). The end of the tube is tied off.
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