1. Definitions: Omphalocele and gastroschisis represent two major congenital abdominal wall defects that are similar in presentation and appearance in the neonatal period, yet they have distinct differences that will affect treatments/outcomes. a. Omphalocele: an anterior abdominal wall defect at the base of the umbilical cord with herniation of abdominal contents through the umbilical ring. The herniated organs are covered by the peritoneal sac, amnion and Wharton’s jelly. With the large variation in sizes, the defect may involve the liver and other organs.
Omphalocele is associated with a high incidence (up to 0 percent) of other congenital/chromosomal defects and syndromes (e. g. , Beckwith-Wiedemann syndrome, trisomies 18, 13, 21, Turner syndrome, Klinefelter syndrome; cardiac/GI/ genitourinary/musculoskeletal/neural tubal anomalies). (7; 20; 24; 56) b. Gastroschisis: a full thickness abdominal wall defect that causes the evisceration of uncovered abdominal contents into the amniotic cavity. It usually occurs to the right of the umbilical cord and is never enclosed in a peritoneal sac. Typical defect size ranges from 2 to 5 cm.
The umbilicus is normally developed and in the correct position. The large and/or small intestine(s) are usually the only organs that eviscerate outside the abdominal wall, but a small percent may involve the liver or spleen. Gastroschisis may be accompanied by intestinal atresia that will complicate the pathology and treatment. (7; 20; 24; 55; 56) c. Diagnosis: Differentiation of omphalocele and gastroschisis is based on the presence or absence of the umbilical ring, identification of an intact sac or sac remnants and the site of the umbilical insertion.
Correct identification is important before cutting the umbilical cord to avoid injury to the iscera; therefore definitive diagnosis is usually made shortly after birth. Exam by ultrasound may diagnose abdominal wall defects in utero as well as a maternal serum alpha-fetoprotein level. Early diagnosis during pregnancy allows preparation for maternal transport to a tertiary care facility where appropriate resources are available for infant and mother. Correct diagnosis leads to early detection and intervention of associated anomalies. (55)
B. POTENTIAL PROBLEMS: 1. Bowel Compromise: (26; 32; 56; 63) a. Paralytic ileus (pseudo-obstruction): nonmechanical temporary paralysis; potentially leading to necrotizing nterocolitis (NEC) b. Malrotation/volvulus: mechanical obstruction resulting from twisting, kinking or knotting of the intestine; can lead to ischemia and necrosis with sudden onset of bilious vomiting, bloody diarrhea, abdominal distension, shock. c. Necrotizing enterocolitis (NEC): necrosis of the mucosal/submucosal wall of the bowel (sudden or insidious). d. Intestinal atresia/stenosis: an absence or narrowing of the opening of the intestine.
e. Abdominal compartment syndrome: increased intra-abdominal pressure causing compromise to the blood supply of the bowel or major vessels supplying the body. Occurs secondary to torsion and volvulus of exterior bowel or after primary or staged repair associated with increased intra- abdominal pressure leading to compromised blood flow. This causes a decrease in 02 supply to the intestines leading to bowel ischemia leading to necrosis. Increased intra-abdominal pressure caused by surgical correction of the defect can lead to edema of legs and oliguria from direct compression of kidneys and inferior vena cava.
This can lead to bowel obstruction, ischemia and necrosis. (26; 56) f. Amniotic fluid exposure: intestines are thickened and matted resulting in altered unctionality/tissue compromise, leading to ischemia and necrosis. (56) 2. Electrolyte Imbalance: a. Sodium The primary action is located in extracellular fluid and balance is maintained by the kidneys. (35; 37) b. Potassium: regulated by the kidneys, primarily in intracellular fluid but also in extracellular fluid. Serum levels are not indicative of body stores.
Potassium maintains cell volume, pH, enzyme function, protein synthesis and cell growth. The amount of body potassium is proportional to muscle mass and body weight. Depending on severity of the deficit, treatment may include oral upplements and IV replacements. (35; 37) c. Magnesium: primarily located in intracellular fluid and regulated by Gl tract, kidney and bone. Serum level is not a good indicator of body stores. Magnesium is involved in many enzymatic reactions including metabolism, neuromuscular transmission, cardiovascular function and muscle contraction.
IV supplementation may be used to treat moderate to severe deficits. (35; 37) d. Phosphorus: most abundant intracellular anion, primarily located in the bone and soft tissue. Serum levels are not an indicator of body stores. Phosphorus has many mportant functions including a component in adenosine triphosphate (ATP) production, glucose utilization, glycolysis, neurological and muscular function. (35; 37) e. Calcium: vast majority in the bone and teeth, but also found in extracellular fluid. Calcium is regulated by parathyroid hormone (PTH), vitamin D and calcitonin.
Calcium has an important role in blood coagulation, neuromuscular transmission and smooth muscle contraction. Fifty percent of calcium is bound to albumin. Serum calcium levels can be misleading if hypoalbuminemia exists. (35; 37) f. Maintaining electrolyte balance is crucial. Acute bnormality is generally associated with symptoms and all electrolytes should be reviewed. Rarely is there just one electrolyte abnormality. Acute illness, current medical condition/ status, procedures/surgeries, medications, IV fluids, NGT losses and nutrition support can affect electrolyte balance. 35; 37)
g. Etiology: malabsorption, fever, diarrhea, vomiting, multiple medications, draining wounds, excessive rapid breathing, hemorrhaging, inadequate or excessive nutrient intake, NPO status and duration. 3. Fluid Imbalance: (8; 16; 36; 45) a. Water is the medium that dissolves the body’s solutes and is ital to homeostasis. If water or electrolyte levels rise or fall beyond normal limits, many bodily functions fail to proceed at their normal rates. Water is retained in the body, remains relatively constant and is freely exchanged among all body fluid compartments.
Maintenance of water balance requires that intake be about equal to the fluid losses (e. g. , insensible, urine, stool, evaporation). All types of fluid imbalances are accompanied by changes in the electrolyte concentrations. b. Dehydration: loss of pure water that results in volume depletion and hypernatremia. c. Fluid volume deficit: loss of body fluids (e. g. water, electrolytes and bodily fluids), caused by deficient intake or excessive excretion (e. g. sweating, vomiting, diarrhea, fistulas, fever, hemorrhage, third space fluid shifts). 45; 62)
d. Hypovolemia/volume depletion: Extracellular fluid deficit that occurs when circulating blood volume decreases. Usually accompanied by loss of sodium and water, leading to imbalances of osmolarity and acid-base. If inadequate tissue perfusion is untreated organ dysfunction may occur. e. Overhydration: excess water in the body resulting from xcessive fluid retention/increased fluid intake that exceeds the body’s ability to excrete. This leads to excess water moving into cells resulting in tissue edema and decreased sodium levels. (50)
f. Fluid volume excess: excess in fluids or sodium. This can be caused when excretion is reduced (e. g. renal/heart/liver failure, third space fluid shifts) or when there is excessive sodium or fluid intake/administration. (45; 62) g. Hypervolemia/volume overload: increased extracellular fluid that can occur when renal excretion of sodium and water is reduced, with excessive dministration of hypertonic IV solutions or with mobilization of third-space fluids. h. Infants/young children have higher total body water, higher basal metabolic rates and a higher daily turnover of water.
They are also subject to greater rapid water loss and reduced ability to adjust to increased/decreased intake produced by illness/disease process (e. g. , vomiting, diarrhea, increased insensible water losses, burns, major surgery, renal disease, congestive heart failure) which can result in critical fluid imbalances. i. Fluid requirements vary with age (decrease with ge), sex, body weight, disease process and insensible losses. Infants have higher total body water, basal metabolic rates and daily turnover of water.
4. Hypothermia: (8; 31; 36) a. Decreased core temperature. Hypothermia results when heat loss (e. g. , conduction, convection, radiation and evaporation) exceeds heat production (e. g. , chemical thermogenesis). Hypothermia/cold stress is due to a disturbance in the net regulation of heat production and heat loss that can result from defective homeostatic regulation, reduced metabolism (e. g. , diminished cellular metabolism) or ncreased loss from exposure to extreme cold. (31) Exposure to cold stimulates the hypothalamus through afferent fibers of cold receptors and via cold circulating blood.
Hypothalamic response includes immediate stimulation of autonomic nervous system and delayed endocrine, behavioral and skeletal muscle responses (the neonate is not developmentally able to shiver to increase heat production). Initial effects mimic intense sympathetic stimulation (e. g. , tremulousness, vasoconstriction, increased oxygen consumption, accelerated heart rate, increased minute ventilation). Mild hypothermia reduces latelet aggregation leading to bleeding. Rapid rewarming results in metabolic acidosis; rewarming shock can occur.
b. The neonate is at risk for hypothermia due to the exposure of abdominal contents, their large body surface area-to-mass ratio and having less subcutaneous fat for heat production. Hypothermia may be present regardless of temperature, if common signs and symptoms of hypothermia are present. (44; 60) 5. Hypoxia/Hypoxemia: a. Hypoxia: occurs when oxygenation of the body is inadequate to meet the metabolic demands of the tissues.
Hypoxia is a life- threatening condition. There may be several different causes, including tissue perfusion alteration (e. . , increased intraabdominal pressure leading to diaphragm being held in a high fixed position, decreased cardiac output, vascular occlusion), decreased 02 tension in the blood (e. g. , high altitude), decreased 02-carrying capacity (e. g. , anemia), compromise of regional blood flow (e. g. , vascular occlusion due to abdominal contents compressing abdominal blood flow, stasis or hypertension), compromised perfusion from the capillaries to the tissues (edema) or impaired utilization of O2 at the cellular level. 8; 25; 36)
b. Hypoxemia: failure of the respiratory system to oxygenate arterial blood caused by low inspired 02 (e. g. , gas blender failure), increased diffusion barriers, hypoventilation (e. g. , postoperative patients, pain, opioid overdose, increased intra-abdominal pressure), ventilation-perfusion mismatch (e. g. , pneumonia) and shunt or venous admixture (e. g. , heart defects). (8; 25; 36) 6. Infection: a. Microorganisms may contain/produce toxins that increase their ability to invade a host (abdominal contents at great risk due to exposure), damage the host or survive on or in host tissue.
Infection occurs when microorganisms invade healthy tissue and proliferate to the point of overwhelming the host’s immune response. Infection is viewed as a continuum of injury, from local infection to bacteremia leading to sepsis, then severe sepsis-induced hypotension leading finally to multiple organ dysfunction syndrome. Glycemic control is imperative for infection prevention. The exposed abdominal content places the infant at high risk for infection, as normal barriers are absent. In addition, the abdominal contents may be irritated from prolonged exposure to amniotic fluid in utero causing tissue compromise. 9; 40; 56)
b. Etiology:Transmission of infection requires three elements: • A source of infectious agents • A susceptible host with a portal of entry receptive to the agent • A mode of transmission of the infectious agent. C. Several classes of pathogens cause infection (e. g. , bacteria, fungi, viruses, prions); modes of transmission vary by type of organism. (58) 7. Situational Response: a. An unanticipated medical event/illness/injury to a child during which coping mechanisms of the child and their parent/ guardian are temporarily compromised. (11) 8. Undernutrition (17; 36)
a. Undernutrition (protein-energy malnutrition) is the biochemical and/or physical consequence of long-term inadequate intake and lack of sufficient calories/protein/ micronutrients to meet the body’s metabolic demands. This may result from refusal to eat, inability to swallow, malabsorption, increased metabolic demands due to illness/disease/stress, increased nutrient losses, chronic illness. Associated with poor clinical outcomes, immunosuppression, decreased ability to heal, poor functional status, frequent hospitalizations, increased length of stay and death.
Primary malnutrition: results from inadequate nutrition intake (may include healthcare-associated malnutrition). • Secondary malnutrition: results from increased nutrient needs, decreased nutrient absorption and/or increased nutrient losses. • Micronutrients include vitamins A, B and C, folate, zinc, calcium, iodine, iron. C. ADDITIONAL INFORMATION: 1. Initial management: involves preservation of body heat, decompression of exposed abdominal content, protection against infection and hemodynamic stabilization. Clinical management of omphalocele and gastroschisis are similar.
2. Delivery room/presurgical care: a. Place infant’s trunk and legs in a sterile plastic “bowel bag” or cover with saline-soaked gauze dressing and transparent plastic film to reduce risk of heat loss, contamination and tissue trauma. (7; 56) b. Place under preheated radiant warmer or other external heat source to prevent cold stress and hypothermia. (7;56) c. IV placement/fluid resuscitation with isotonic solutions (e. g. , normal saline, Ringer’s lactate) until urine output normalizes and/or acid-base balance is normal. Increased fluid needs may be necessary due to excessive losses from exposed bowel. ; 56)
d. Urinary catheter is placed to monitor urine output and measure bladder pressures. (48) e. Place naso/orogastric tube to low intermittent suction to provide Gl decompression and prevent decreased blood flow to the bowel; prevent emesis/aspiration. Observe for signs of ischemia/necrosis. (7; 56) f. Position neonate on their right side in a lateral decubitus position, if able, to promote venous blood return from the gut and decreased the risk of poor perfusion caused by compression or kinking of mesenteric vessels. (7;56)
g. Prophylactic antibiotic therapy may be given. (7;56) h. Assess pain status and provide pharmacologic/ nonpharmacologic pain and comfort measures. (7) 3. Surgical repair: (7; 24; 55; 56) Surgical correction is based on three factors. First the size of the defect, secondly the accompanying anomalies/syndromes and finally the neonate’s clinical status/ ability to tolerate the procedure. a. Three methods are used: • Primary closure: This is the preferred method and involves complete reduction of the herniated viscera into the abdominal cavity.
This method is done when hemodynamic or respiratory compromises are not anticipated; however, prolonged ventilatory support and muscular paralysis may be needed, as well as monitoring of intra-abdominal pressures. • Staged/Silo repair: This method is utilized when the defect is large or contains other organs and the abdominal cavity does not have sufficient space to accept the eviscerated contents all at once. Staged repair requires placement of a Silastic silo for gradual reduction of abdominal contents with secondary closure occurring at a later time.
The silo is sutured to the abdominal musculature forming a tubular structure around the exposed viscera. Silo reduction is done 1 to 2 times daily over 7 to 10 days. Several methods are used for silo reduction (e. g. , tape ties, sutures, clamps, staples). Slow reduction reduces the risk of abdominal compartment syndrome. • Skin flap closure: This repair is done on infants with complicated pathology and associated congenital anomalies that interfere with ventral wall closure. A skin flap is used to cover the exposed viscera without repair of the abdominal wall. This allows for more immediate problems to be addressed.
Final repair may be delayed for 6 to 12 months allowing the abdominal cavity to grow. 4. Postoperative care: Goal is to restore and maintain fluid and electrolyte balance; monitor for respiratory complications, signs/ symptoms of infection and abdominal compartment syndrome. a. Maintain IV access [e. g. , central line, peripherally inserted central catheter (PICC), peripheral IV line] to administer fluids, antibiotic therapy and total parenteral nutrition (TPN), until third spacing resolves and bowel function returns. (7; 55; 56) b. Monitor for respiratory complications and intervene as needed (e. g. , O2, intubation, ventilator support). ;55)
c. Maintain abdominal decompression (e. g. , patent NGT to low intermittent Suction, ileus evaluation, positioning, frequent circulation assessments). (7; 55; 56) d. Maintain neutral-thermal environment and monitor temperature (e. g. , radiant warmer, incubator). (7; 55) e. Continuous infection surveillance. (7; 55) f. Monitor for cholestasis. (44) g. Continuous nutritional surveillance; monitor for signs of returning bowel function and ability to begin enteral feedings (e. g. , return of bowel sounds, stooling, decreased NG output). (7; 55) h. Provide pain/comfort measures (e. g. , medications/ sedation, positioning). )
i. Constant wound surveillance and aseptic dressing changes to decreased risk of infection. (7; 55; 56)j. Provide family care (e. g. , keep informed of patient status, involve in caregiving as appropriate, encourage verbalization of fears/concerns). (7) 5. Miscellaneous: a. Ultrasound diagnosis should not be performed before the 14th week of gestation as the intestines are extra-abdominal until the 11th week of gestation. (7; 56) b. Delivery usually occurs between 34 to 36 weeks gestation. The preferred method is cesarean section, although studies have been done to show vaginal delivery is safe as well. (24; 56)
c. Etiology of gastroschisis is uncertain but the incidence has been rising for the last two decades (10/100,000 births or 70/100,000 births for mothers aged less than 20 years live births). There is little gender predilection. Omphalocele occurs in 25/100,000 births and is more common in males. (7; 64) d. Once gut motility returns, it is important to initiate enteral feedings as soon as possible; beginning with small volumes and advancing as tolerated. TPN is usually decreased as feedings are increased. Median time in days to initiate enteral feedings is 15 days with primary closure and 30 days with a silo procedure.
Target daily calorie requirement is 90 to 100cal/kg, 3 to 4g/kg lipids and 3g/kg of protein. (30; 56) e. NEC occurs in up to 20 percent of infants with gastroschisis. f. The use of topical agents to promote eschar formation and epithelialization is controversial and varies from organization to organization. (56) g. lleus can last for up to 2 to 4 weeks. Those neonates with primary closure may experience less ileus time. (38) h. Follow-up care is important for monitoring and management of nutritional status, growth and development, feeding difficulties, changes in bowel status. 4)
i. Discharge criteria include weight gain, receiving adequate enteral feedings without IV nutrition and regular intestinal functioning. (44)j. New methods of assessing presurgical bowel perfusion include placing an 02 saturation probe postductal proximal and distal to the abdomen to evaluate the difference in readings or placing an 02 probe on a distal extremity and on the surface of the transparent silo to detect the difference in readings. These methods, in combination with clinical assessment, have shown promise with detecting bowel perfusion. (26; 34)
