Gastrointestinal Emergencies in Infants in the First Year of Life

MALROTATION WITH AND WITHOUT VOLVULUS Volvulus is a major life-threatening complication of malrotation. 5 The complications of malrotation occur most commonly in the first year of life, although malrotation can give rise to symptoms at any time in a person's life. It is the most urgent of GI emergencies in infants and children because of consequent gangrene of the total midgut. The time interval from the first symptom to the development of total midgut gangrene may be only a few hours.

Pathophysiology During gestation, at approximately 6 weeks of age, the elongating intestines prolapse into the yolk sac. Upon reentry at 10 weeks, the midgut undergoes a 270° counterclockwise turn around the superior mesenteric artery. Usually, the duodenum and the cecum become fixed by peritoneal bands, and the small intestine has a broad mesenteric attachment along its base. Abnormal rotation and inadequate fixation can occur during gestation. Incomplete rotation or malrotation can leave the cecum high in the abdomen, with its peritoneal attachments crossing the duodenum in an obstructing manner. The mesentery fails to fan out, and the midgut is suspended and its entire vascular supply travels along a narrow pedicle.

Clinical Features The presenting symptoms are usually vomiting (ultimately becoming bilious), with or without abdominal distention, and streaks of blood in the stool. Infants with symptoms of obstruction or bilious vomiting must receive prompt surgical consultation and active resuscitation. The most dramatic presentation in newborns is the sudden onset of an acute abdomen and shock, with a rigid and discolored abdomen associated with bilious or bloody vomiting and bloody stools, indicating the presence of gangrenous bowel. On physical examination, such infants may appear pale and have grunting respirations, and approximately one-third of the infants will appear jaundiced. The vast majority of cases present within the first month of life. In older children, the pain is usually constant, not colicky. This symptom complex usually occurs in previously healthy children. However, there may have been minor episodes in the past of vomiting or abdominal discomfort. A child suspected of harboring a malrotation with possible midgut volvulus should have flat and upright abdominal x-rays. The presence of a loop of bowel overriding the liver is suggestive of the diagnosis. Occasionally, an upper GI examination may reveal an abnormal location of the ligament of Treitz.

Intussusception, duodenal stenosis, or atresia can produce a clinical picture similar to midgut volvulus.

Treatment An infant with systoms of obstruction or bilious vomiting must receive prompt surgical consultation, active resuscitation, and hospital admission. Intravenous fluid should be started immediately, and a nasogastric tube placed. Blood should be typed and crossmatched. A white blood cell count may identify early gut necrosis. Electrolytes and venous blood gases may identify sodium or potassium abnormalities or ongoing acidosis. Any child with vomiting or bloody stools who is identified as having an incompletely rotated bowel requires urgent laparotomy to prevent the development of midgut volvulus and total midgut gangrene.

INCARCERATED HERNIA Clinical Features An incarcerated hernia will not be detected unless the infant or child is totally undressed at the time of examination. The symptoms include irritability, poor feeding, vomiting, and an inguinal or scrotal mass. The differential diagnosis of an inguinal or scrotal mass most frequently includes hydrocele of the cord or the scrotum, undescended testicle, torsion of the testicle, torsion of the appendix testis, inguinal lymphadenopathy, inguinal node abscess, orchitis, and inguinal or scrotal trauma. The incidence of incarceration of inguinal hernias is highest in the first year of life. In both boys and girls, the incarcerated sac may contain small or large bowel. In girls, an ovary may be present in the sac.

Treatment In most instances, provided the child is examined gently and his or her confidence obtained, it is possible to achieve manual reduction of the incarcerated hernia (if it has been present for only a short period of time) without the use of sedation. When this maneuver is unsuccessful, most cases can be successfully reduced following the administration of intramuscular meperidine (up to 2 mg/kg of body weight in the first year of life). Quite often, as a result of the relaxation induced by the meperidine, the hernia spontaneously reduces. In the absence of spontaneous reduction, one should attempt to reduce the hernia. The few patients who do not respond to these maneuvers must undergo surgical reduction.

Once the hernia is reduced, the patient should be referred for surgical repair on an elective basis. Provisions are generally made for pediatric surgical consultation the next day. If it was a difficult reduction, the child should be admitted or observed for 6 to 12 h, and the pediatric surgeon consulted.

INTESTINAL OBSTRUCTION Clinical Features Intestinal obstruction presents in infants and young children in the classic manner, with symptoms of pain (manifested by irritability); vomiting; abdominal distention; and, later, absence or diminution of bowel movements. The differential diagnosis of intestinal obstruction in newborns and infants includes intestinal atresia or stenosis, meconium ileus (newborns only), incarcerated inguinal hernia, intussusception, malrotation, malrotation with volvulus, volvulus around a congenital intraabdominal band, duplication cysts of the intestinal tract, imperforate anus, and Hirschsprung disease.

Diagnosis and Treatment Flat and upright films of the abdomen show dilated loops of bowel with air-fluid levels ( Fig 123-1). Such an appearance on the plain x-ray film warrants a barium enema examination with a Hirschsprung catheter, which helps to differentiate between Hirschsprung disease, malrotation, and colonic stenosis and also separates lower large bowel obstruction from upper small bowel obstruction.

Tube Bowel Obstruction

Once intestinal obstruction has been diagnosed, the patient should be prepared for surgical intervention by having an intravenous line and a nasogastric tube placed and should be admitted.

PYLORIC STENOSIS The infant with a history of nonbilious projectile vomiting must be considered to have pyloric stenosis. The disorder affects approximately 1 in 150 male and 1 in 750 female patients. It occurs more frequently in firstborn males, and a familial incidence is noted in approximately 50 percent of patients. It is caused by diffuse hypertrophy and hypoplasia of the smooth muscle that narrows the antrum of the stomach to a small channel that can be easily obstructed.

Clinical Features Onset is rare before the age of 1 week, and the disorder usually begins in the second or third week of life. It seldom develops after the third month of life. Initially, the infant may only regurgitate small amounts of milk, making it difficult to distinguish the cause of vomiting from simple regurgitation, gastric reflux, or milk intolerance. Vomiting usually becomes projectile within a week of onset of symptoms, and the vomitus is never bile stained although it may occasionally have streaks of blood. Vomiting occurs just after or near the end of feeding, and afterward the infant will refeed hungrily unless the child has become malnourished or dehydrated.

Vomiting eventually becomes projectile. Constipation usually is noted because the infant is not retaining enough formula and becomes dehydrated.

Physical examination usually demonstrates a hungry infant who has failed to gain weight over the past several weeks or has lost weight. Jaundice occurs in 1 to 2 percent of cases. If one undresses and then feeds the infant, peristaltic waves can sometimes be seen passing from left to right across the upper abdomen, just prior to an episode of vomiting. Palpation of a pyloric tumor—the "olive"—is pathognomonic. If it is present, one can be sure of the diagnosis. The olive is usually felt near the lateral margin of the right rectus muscle just below the liver edge. Palpation of the olive is very dependent on the amount of hypertrophy of the pylorus and the skill of the clinician.

In advanced cases, the physical examination will reveal dehydration and lethargy. The child may appear moribund, with sunken eyes, decreased elasticity of the skin and loss of subcutaneous tissue.

Diagnosis If the olive is palpated, further studies are not necessary. If no olive is palpated, abdominal ultrasonography is recommended. Accuracy depends on the use of a high-resolution machine and an experienced sonographer. Although false positives are rare, false negatives can occur in up to 20 percent of cases, often due to bowel gas interference. If the diagnosis is highly suspected and the findings on ultrasonography are normal, an upper GI series can be performed. This usually demonstrates delayed gastric emptying and indentation of the antrum by the pyloric olive. The pyloric channel is narrowed and appears like a "string." If pyloric stenosis is not noted, the radiographer can evaluate the infant for gastroesophageal reflux. The major risk from the upper GI series is the potential for aspiration. The barium should be removed after the x-ray to prevent aspiration.

Treatment Once the diagnosis of pyloric stenosis has been confirmed or is highly suspected, surgical consultation should be obtained. Surgery is the treatment of choice, and the procedure is very safe.

Oral intake should be restricted and an intravenous line started. Dehydration and electrolyte abnormalities must be corrected before surgery. Much of the reduced morbidity and mortality from surgery for this disease can be attributed to improved preoperative status. Extensive and protracted vomiting in pyloric stenosis may lead to hypokalemia and hyponatremia. More striking decreases occur in chloride concentration and an increase in pH and carbon dioxide content. This constitutes the characteristic changes of hypochloremic alkalosis. Initial administration of 5% dextrose in normal saline or normal saline to which potassium chloride is added gradually and successfully replaces the calculated deficits of potassium chloride and sodium.

INTUSSUSCEPTION Intussusception occurs when a portion of the alimentary tract is telescoped into another segment. It is the most common cause of intestinal obstruction between 3 months and 6 years of age and is rare under 3 months of age. The male/female ratio is 4:1.

Pathophysiology The causes of most intussusceptions are unknown. There is a seasonal incidence that seems to follow peak viral illness seasons. In some patients, recognizable causes for intussusception are found, such as Meckel's diverticulum, intestinal polyp, duplication, lymphosarcoma, or as a complication of Henoch-Schonlein purpura, but are rarely found in infants under 2 years of age. Rarely, tumors or foreign bodies may cause intussusception. Ileocolic intussusceptions are the most common. The upper portion of the bowel invaginates into the lower portion, bringing the mesentery with it. Constriction of the mesentery obstructs venous return with engorgement of the intussusceptum. With edema and bleeding, there may be bloody stools, with mucus giving rise to the characteristic "currant jelly" stool.

Clinical Features The classic patient is a robust, 6- to 18-month-old infant without prior difficulty. Suddenly, the child appears to be in pain. The youngster may be playing quietly in the playpen and suddenly stop playing, begin to cry, and even roll around in discomfort. Just as suddenly, the pain ceases, and the child appears to be as happy and content as before the onset of pain. Episodes may recur at more frequent intervals, with the duration of the painful attacks increasing. Some children become very still, listless, and pale, and appear to be in a shocklike state due to the visceral pain. Vomiting is rare in the first few hours but usually develops after 6 to 12 h. The classic "currant jelly" stool associated with intussusception is a late manifestation of the disease complex and is present in only 50 percent of cases. 6 Its absence should not delay evaluation for intussusception in the patient. However, a positive stool guaiac test is present in almost every case. Fever can occur and even rise to 41°C (106°F). Respirations may be shallow and grunting in nature.

Apathy or lethargy may be the only presenting sign of intussusception in up to 10 percent of cases. Because of this, some infants will receive a lumbar puncture and other diagnostic studies, thus delaying the diagnosis and management of the child's illness. 78

Examination between attacks may reveal the often-described sausage-shaped tumor mass of intussuscepted bowel in the right side of the abdomen. If this mass is felt in the epigastrium, the long axis is usually horizontal. At least one-third of patients do not have a palpable mass, but the absence of a mass must not delay further investigation. An ileoileal intussusception may have a less typical presentation, with symptoms and signs suggestive of intestinal obstruction.

Diagnosis and Management The presumptive diagnosis of intussusception is made on the basis of the history and may be seriously considered as a result of a telephone description of a child's problem by the caregiver. The apparent well-being of a child in the absence of clinical findings should not mislead the physician. An x-ray examination of the abdomen may show a mass or filling defect in the right upper quadrant of the abdomen ( Fig, 12.3.-2.^.). Even in the presence of normal plain x-ray films (which can be 30 percent of cases), the history described demands a barium enema examination, which demonstrates the classic "coiled spring" ( Fig

123-2B). The barium enema examination is not only a diagnostic tool in the management of this disease, but is frequently curative. 7 If it is obtained in the first 12 to 24 h of the developing intussusception, up to 80 percent of cases can be corrected by barium enema alone. When barium enema does not resolve the intussusception, surgical intervention is indicated. If the barium enema reduces the intussusception, the parents should be warned of a 5 to 10 percent recurrence rate, usually within the first 24 to 48 h following barium enema reduction.

Intussusception Plain Film

FIG. 123-2. Intussusception. A. Plain film with loss of bowel pattern in the right upper quadrant. B. With barium enema, showing a "coiled spring" in the ascending colon.

Recently, air insufflation is being used by radiologists more frequently than barium to diagnose and manage intussusception. This is a safer method particularly if there is a possibility of perforation, since the peritoneum would not be contaminated by barium. It may be as effective as barium and enables better control over colonic pressure used for the reduction.9 In most hospitals, protocol calls for notification of the pediatric surgeon prior to radiologic reduction of intussusception.

Once reduction occurs, the child should be observed to watch for any recurrence of symptoms or for complications from the reduction. Reliability of the parents or caretaker and other pediatric social concerns may affect length of observation.

A barium enema reduction is contraindicated if there is free peritoneal air on plain films or if the infant has signs of peritonitis or sepsis. The surgeon and emergency physician should provide intravenous fluid replacement for hypovolemia (due to vomiting, poor intake, and third spacing of fluids) and provision of antibiotics is essential in such a patient.

The recurrence rate after barium enema reduction ranges from 5 to 10 percent and usually occurs within the first 24 to 48 h following reduction. A second attempt at barium reduction can be considered and is usually successful. If another episode of intussusception occurs, then an exploratory laparotomy is necessary.

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