History
The first goal when evaluating children with abdominal pain is to identify life-threatening conditions that require emergent interventions. Bilious vomiting in a neonate is considered malrotation with midgut volvulus until proven otherwise and warrants emergent surgical evaluation. Nonemergent causes of abdominal pain can be identified through deliberate evaluation, beginning with a careful history.
The typical symptoms of small bowel obstruction are abdominal pain, distention, and vomiting. A history of repetitive intermittent abdominal pain with vomiting suggests a chronic, partial small bowel obstruction. Other signs and symptoms that occasionally accompany small bowel obstruction include anorexia, diarrhea (sometimes early in the course of the obstruction), obstipation (common with complete obstructions), hematochezia, and fever (worrisome sign associated with bowel strangulation and necrosis).
Obtain as much history as possible from the child. Seek an accurate chronology of the events. Asking when the child was last completely healthy may help provide an accurate assessment of the child's pathophysiology. In young children, feeding intolerance is often the first change noted by caregivers. Caregivers may describe an infant or small child with abdominal pain as irritable or inconsolable. Pain from a small bowel obstruction is usually colicky. It is typically described as crampy and episodic, persisting for a few minutes at a time. A child with obstructive pain may be unable to remain immobile on the examining table. Constant pain may occur later in the disease course, when strangulation, perforation, or both have occurred. Vomiting caused by a proximal obstruction is usually of gastric content, or it is bilious if the obstruction is distal to the ampulla of Vater. In distal obstructions, vomiting may be feculent.
Obtain a complete past medical history, specifically including information on birth history and any history of trauma, malignancy, radiation, and abdominal surgery.
Additional details regarding the history for frequently encountered diagnoses are provided below.
Intussusception
Intussusception usually causes a sudden onset of severe colicky abdominal pain that often causes a child to draw up both legs. Children appear healthy between paroxysms of pain. As the intussusception progresses, the child becomes progressively more irritable and lethargic. Vomiting occurs in the early phase of the illness and is bilious in 30% of cases. Early in the course of the disease, stools are normal, but they become bloody and mucoid over time.
The classic triad described for intussusception (colicky abdominal pain, a sausage-shaped, palpable abdominal mass, and currant-jelly stools [see the following image]), is actually found in only 20% of cases. Postoperative intussusception occurs within 2-3 weeks after an extensive retroperitoneal dissection (Wilms tumor or neuroblastoma resection, etc). It is usually an ileoileal intussusception, and affected patients lack the palpable mass and rectal bleeding. Patients usually present with crampy abdominal pain, anorexia, bilious vomiting, abdominal distention, and irritability.
Pediatric Small Bowel Obstruction. The clinical photograph of a 5-month-old male patient reveals characteristic currant-jelly stools due to intussusception.
Hernia
An incarcerated hernia presents with signs and symptoms of intestinal obstruction (assuming the incarcerated organ is intestine), along with a tender and edematous mass at the site of herniation. A swollen, erythematous mass that becomes erythematous to violaceous and is exquisitely tender usually indicates a strangulated hernia. Fever and toxicity suggest necrosis of the incarcerated organ and possible perforation.
Internal hernias are usually asymptomatic, but when symptoms occur they are often vague. Repeated episodes of colicky abdominal pain and vomiting are common. These symptoms spontaneously subside when the hernia spontaneously reduces. Patients with incarcerated hernias have continuous pain, abdominal distention, fever, nausea, and vomiting. [35]
Malrotation with midgut volvulus
The hallmark of acute midgut volvulus is the sudden onset of bilious vomiting. A careful history may reveal prior feeding problems, with transient episodes of bilious vomiting or failure to thrive. Older children typically describe colicky abdominal pain. Stools are usually absent, but those that do occur yield positive results on guaiac tests. Bright red blood passed through the rectum implies intestinal ischemia.
Postoperative adhesions
Adhesive small bowel obstructions usually cause sudden onset of crampy abdominal pains, followed by anorexia, nausea, and bilious vomiting. Bowel movements and passage of flatus typically cease shortly after symptom onset.
Enteric duplications
The presentation of duplication cysts primarily depends on the type of mucosal lining and cyst location. Some small intestine duplications contain gastric mucosa and manifest with peptic ulceration leading to gastrointestinal hemorrhage. Other cystic duplications may enlarge sufficiently to cause obstructive symptoms; in addition, these cysts may also act as the lead point for an intussusception.
Intestinal atresia and stenosis
Because most atresias (including duodenal atresias) are postampullary, bilious vomiting is the most common presentation. Abdominal distention may be notably absent in more proximal atresias; distention becomes more apparent in infants with more distal obstructions such as ileal atresia.
Necrotizing enterocolitis
The presenting clinical features of necrotizing enterocolitis (NEC) are nonspecific and variable; they include lethargy, temperature instability, feeding intolerance, and abdominal distention. Other common symptoms include bilious vomiting, gross or occult rectal bleeding, abdominal tenderness, and discoloration of the abdominal wall (see the image below). The Bell staging criteria are used to classify the severity of NEC using clinical and radiographic criteria. [36]
Pediatric Small Bowel Obstruction. This clinical image of a micro-premature baby boy shows discoloration on the right lower quadrant of the abdomen due to intestinal perforation secondary to necrotizing enterocolitis. An umbilical catheter is in place.
Meconium ileus
Infants with meconium ileus typically present with signs of a distal bowel obstruction (usually the terminal ileum), including vomiting (usually bile-stained), failure to pass meconium in the first 48 hours of life, and abdominal distention.
Physical Examination
On examination, children with small bowel obstructions frequently have abdominal distention. This finding may be notably absent, however, in more proximal obstructions. The abdomen may be tympanic to percussion. On auscultation, obstructions often produce active, high-pitched, and hyperactive bowel sounds with occasional rushes. In infants with thin abdominal walls, peristaltic waves within the bowel proximal to the obstruction can occasionally be visualized on the abdomen.
Abdominal tenderness varies but is typically not dramatic in the absence of compromised bowel. Patients who present late with necrotic bowel and/or perforation will develop signs of peritonitis on examination. In addition, these children may exhibit signs of inadequate perfusion, such as poor capillary refill, tachycardia, decreased urine output, mental status changes, and hypotension as a result of volume depletion from vomiting and third spacing of fluid into the bowel lumen.
Examination must include a careful assessment for signs of hernias that could be the culprit for the obstruction. Depending on the clinical scenario and level of concern for a very distal obstruction, a digital rectal examination may also be warranted.
With intussusception, physical examination occasionally reveals a tender, sausage-shaped mass. Because most intussusceptions are ileocolic, patients may also present with the Dance sign (empty or retracted right lower quadrant).
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Pediatric Small Bowel Obstruction. Small bowel obstruction is visible on a plain radiograph caused by intussusception in a 5-month-old patient.
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Pediatric Small Bowel Obstruction. This barium enema study reveals a coil spring appearance caused by the tracking of barium around the lumen of the edematous intestine in intussusception.
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Pediatric Small Bowel Obstruction. This image reveals small bowel obstruction caused by an incarcerated inguinal hernia in a 2-month-old infant with bilateral inguinal hernias as well as an umbilical hernia.
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Pediatric Small Bowel Obstruction. This radiograph depicts the double-bubble sign characteristic of duodenal atresia.
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Pediatric Small Bowel Obstruction. An upper gastrointestinal contrast study demonstrates a jejunal atresia with a proximal dilated atretic bowel and lack of passage of contrast material into the distal small bowel.
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Pediatric Small Bowel Obstruction. This is a surgical photograph of the patient in the previous image, depicting the proximal dilated atretic jejunum.
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Pediatric Small Bowel Obstruction. An upper gastrointestinal contrast study shows a malrotation with lack of a normal C-shaped duodenum and the small bowel "hanging" on the right side of the abdomen.
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Pediatric Small Bowel Obstruction. This imaged is a contrast enema study showing an abnormally located cecum in a patient with malrotation.
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Pediatric Small Bowel Obstruction. The surgical photograph shows necrotic bowel in a patient with midgut volvulus.
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Pediatric Small Bowel Obstruction. Necrotic bowel is shown after surgical reduction of an intussusception.
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Pediatric Small Bowel Obstruction. The surgical photograph depicts a transition zone in a patient with small bowel obstruction.
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Pediatric Small Bowel Obstruction. An incarcerated left inguinal hernia is noted.
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Pediatric Small Bowel Obstruction. This photograph reveals a mesocolic hernia.
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Pediatric Small Bowel Obstruction. The surgical image depicts a laparotomy on a 7-month-old girl with ileocolic intussusception.
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Pediatric Small Bowel Obstruction. The surgical image depicts a laparotomy on a 2-day-old female patient with congenital small bowel obstruction. A type I jejunal atresia without mesenteric gap and a grossly dilated proximal intestine is seen.
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Pediatric Small Bowel Obstruction. A barium enema study on a 1-year-old male patient depicts an ileocolic intussusception.
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Pediatric Small Bowel Obstruction. The clinical photograph of a 5-month-old male patient reveals characteristic currant-jelly stools due to intussusception.
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Pediatric Small Bowel Obstruction. The plain abdominal film on a 3-day-old newborn depicts the classic double-bubble sign for duodenal atresia.
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Pediatric Small Bowel Obstruction. This contrast-enhanced upper gastrointestinal film shows a duodenal atresia in a 2-day-old newborn.
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Pediatric Small Bowel Obstruction. The surgical photograph is that of a 3-year-old male patient with an obstructive, noncommunicating ileal duplication.
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Pediatric Small Bowel Obstruction. This plain abdominal film was obtained in a 6-year-old male patient with MRCP (mental retardation and cerebral palsy) and an organo-axial gastric volvulus. Note the grossly dilated and obstructed stomach. A gastrostomy feeding tube can be seen in place. Surgical staples from a previous laparoscopic fundoplication are seen near the diaphragmatic crura.
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Pediatric Small Bowel Obstruction. This is a surgical photograph of an 8-month-old patient with ileocolic intussusception.
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Pediatric Small Bowel Obstruction. The plain abdominal film of a premature baby born at 28 weeks of gestation reveals necrotizing enterocolitis. Note the "railroad sign" (pneumatosis intestinalis) in the hepatic flexure and "soap bubbles" in the descending colon.
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Pediatric Small Bowel Obstruction. This clinical image of a micro-premature baby boy shows discoloration on the right lower quadrant of the abdomen due to intestinal perforation secondary to necrotizing enterocolitis. An umbilical catheter is in place.
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Pediatric Small Bowel Obstruction. A plain abdominal film of a premature baby girl with necrotizing enterocolitis is shown. Note the air in the biliary tree and the grossly dilated bowel.
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Pediatric Small Bowel Obstruction. This is a surgical photograph of a 1-year-old male patient who previously underwent a right radical nephrectomy for Wilms tumor. He presented to the emergency department with signs of a mechanical small bowel obstruction. A transition zone is clearly seen at the point where the small bowel is trapped on an internal hernia through a mesenteric gap.
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Pediatric Small Bowel Obstruction. This sonogram reveals intussusception in a 9-month-old male patient.
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Pediatric Small Bowel Obstruction. The surgical photograph was obtained in an 8-month-old boy with intussusception. The surgeon's finger is inserted into the intussusceptum, and the intussuscipiens is seen entering the distal bowel. No lead point was identified.
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Pediatric Small Bowel Obstruction. The surgical photograph depicts loops of bowel passing through a mesenteric defect. The bowel segment proximal to the obstruction is dilated, purplish, distended, and hypoperistaltic. The bowel distal to the obstruction is decompressed and normal-looking.
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Pediatric Small Bowel Obstruction. The surgical photograph was obtained in a newborn with a type IIIa jejunal atresia. Note the dilated proximal bowel pouch, the mesenteric V-shaped defect, and the thin, nondilated distal jejunum.
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Pediatric Small Bowel Obstruction. The surgical photograph depicts a Meckel diverticulum.
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Pediatric Small Bowel Obstruction. This surgical photograph was obtained from a newborn with type IIIb (“apple peel” or “Christmas tree”) atresia. Note the shortened distal small bowel coiled around its mesentery.
