History and Physical Examination
Infants with intestinal obstruction are unable to feed; hence, their problem is immediately apparent.
Infants with pyloric stenosis vomit gastric content: milk or mucus. If there is associated gastritis, the emesis may be rust colored.
Bilious (green) gastric aspirate or emesis indicates that the intestines are obstructed below the ampulla of Vater.
An infant who was eating well but who suddenly vomits bile (green fluid) has malrotation/volvulus until proven otherwise by upper gastrointestinal (GI) studies. [8]
Surprisingly, a survey of 175 knowledgeable people (pediatricians, neonatologists, nurses, midwives, and parents) determined that most respondants (75%) did not know that the color of "bilious emesis" is green. [18]
Important observations to make in examining an infant with intestinal obstruction include the following:
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Is the baby's abdomen scaphoid or distended?
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Is there a palpable mass (usually the obstructed loop of intestine)?
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Does the abdomen have rippled appearance? Do the waves feel ropey (dilated intestine)?
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Are bowel sounds present or absent or hyperactive?
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Is the abdomen tender?
Peritonitis is an ominous sign, suggesting bowel ischemia or necrosis, sepsis, and multisystem organ failure. Closely monitor for the following signs:
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Hypotension and tachycardia
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Prolonged capillary filling and pallor
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Hematochezia (intussusception, necrotizing enterocolitis)
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Thrombocytopenia and Coagulopathy
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Respiratory failure
Duodenal atresia/stenosis
Vomiting and right upper quadrant fullness complement the radiologic "double-bubble sign" in duodenal atresia. This fullness may disappear upon placement of an orogastric tube. In 85% of patients, the obstruction is distal to the ampulla of Vater, and these patients have bilious vomiting. Patients with duodenal atresia should be evaluated for trisomy 21.

Malrotation/volvulus
Babies with malrotation/volvulus present with sudden onset of bilious vomiting. Initially, the abdomen is scaphoid. Midgut volvulus begins as an incomplete closed-loop obstruction; however, with the passage of time, the obstruction becomes complete and the baby's abdomen becomes increasingly distended. Obtain an urgent upper GI onstrast study.

Jejunal atresia
Infants with jejunal atresia usually present with bilious vomiting. If the atretic proximal intestine is dilated and bulbous, the baby may also have abdominal distention and a palpable mass.
Ileal atresia
Infants with distal bowel obstruction present with abdominal distention, delayed passage of meconium, and absent transitional stools. Bowel sounds may be hypoactive or absent (fatigue in chronic obstructions).
Meconium ileus and plug syndrome
Meconium ileus usually presents with abdominal distention and obstipation.
Meconium plug syndrome is a relatively benign condition, usually occurring in healthy-appearing term infants. Abdominal distention and failure to pass meconium within the first 24 hours of life are the presenting signs.
Hirschsprung disease
Babies with Hirschsprung disease usually have distended abdomens and are intolerant of feedings; often, passage of meconium is delayed. A contrast enema study may be diagnostic (delay digital rectal examination until after the radiologic study) and therapeutic (initiating a bowel movement). Some neonates with Hirschsprung disease may be managed with rectal dilatation and irrigations and undergoing a primary pull-through procedure. Infants with enterocolitis, however, should be treated with diversion (a "leveling colostomy").
Strangely, some babies with Hirschsprung disease present later in life, perhaps because breast milk has so little residue. Later, when additional foods are added to the baby's diet, symptoms of constipation develop. [19]

Imperforate anus
A diagnosis of imperforate anus is imediately obvious upon inspection of the newborn's perineum. Anorectal malformations range from anterior displacement of the anal opening to an absent patent anus. Infants with imperforate anus (see the following image) may have abnormalities of the sacrum; boys with high imperforate anus will have a rectourinary tract fistula, which may be demonstrated by the presence of meconium in the urine.

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Intestinal obstruction in the newborn. Malrotation/volvulus. Note the spiral twist and the partial obstruction.
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Intestinal obstruction in the newborn. Malrotation with volvulus of the proximal small intestine coiled around the superior mesenteric vessels.
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Intestinal obstruction in the newborn. Partial duodenal obstruction: duodenal stenosis or malrotation/volvulus? Note the "double bubble" sign and narrowing of the second portion of the duodenum; however, the duodenum does cross the midline and it is not twisted.
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Intestinal obstruction in the newborn. Jejunal atresia. Note the sharp transition between the proximal dilated jejunum and the distal unused intestine at the point of the atresia.
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Intestinal obstruction in the newborn. Jejunal atresia. Ischemic compromise of the proximal segment is noted.
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Intestinal obstruction in the newborn. Meconium plug syndrome. Contrast enema shows a dilated colon proximal to the meconium plug. If the enema elicits an evacuation, the obstruction may be relieved.
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Intestinal obstruction in the newborn. Baby with a high imperforate anus; note the indistinct perineum ("rocker bottom"). Compare this photograph with the low imperforate anus photograph in the section "Surgical Relief of Obstruction," in which "pearls" of meconium along the scrotal raphe can be seen.
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Intestinal obstruction in the newborn. This diagram is a sample algorithm for the diagnosis of neonatal intestinal obstruction.
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Intestinal obstruction in the newborn. Operative photograph of hypertrophic pyloric stenosis. The pylorus is thickened and elongated.
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Intestinal obstruction in the newborn. Operative photograph of jejunal atresia with a mesenteric gap and discontinuous bowel segments.
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Intestinal obstruction in the newborn. Meconium ileus. Intraluminal intestinal obstruction from thick, tenacious meconium.
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Intestinal obstruction in the newborn. Colonic atresia. The hugely dilated colon will never function satisfactorily; therefore, it is resected, leaving a cuff of cecum to preserve the ileocecal valve.
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Intestinal obstruction in the newborn. Operative photograph of midgut volvulus. Note the transverse orientation of the colon (look for the appendix).
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Intestinal obstruction in the newborn. Omphalomesenteric duct (Meckel diverticulum) attached to the umbilicus.
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Intestinal obstruction in the newborn. Colon pull-through for Hirschsprung disease.
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Intestinal obstruction in the newborn. Midgut volvulus. Necrosis of the midgut is the the most feared complication of malrotation/volvulus.
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Intestinal obstruction in the newborn. Malrotation volvulus. Note the partial duodenal obstruction. The distal duodenum does not cross the midline (over the vertebral column) and the "curly Q" twist.
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Intestinal obstruction in the newborn. Gastrografin enema. Note the tiny, unused colon and the dilated (by swallowed air) proximal, obstructed intestine.
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Intestinal obstruction in the newborn. Midgut volvulus. The bowel is eviscerated and the entire midgut is twisted counterclockwise, effecting reduction of the volvulus.
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Intestinal obstruction in the newborn. The midgut volvulus is reduced.
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Intestinal obstruction in the newborn. Photograph of neonatal intestinal perforation. Note the aneurysmal dilatation of the (perforated) intestine proximal to the obstructed (by inspissated stool) distal ileum.
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Intestinal obstruction in the newborn. The contrast enema in a baby with Hirschsprung disease; the rectum is small and the sigmoid colon is dilated.
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Intestinal obstruction in the newborn. Operative photograph showing dilatation of the sigmoid colon and a small caliber rectum.
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Intestinal obstruction in the newborn. When the proximal mesentery is destroyed in jejunal atresia, the ileum may derive its blood supply from the ileocolic vessels and wraps around these vessels, creating the appearance of a "Christmas tree" or "apple peel."
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Intestinal obstruction in the newborn. Operative photograph showing proximal esophageal atresia and distal tracheoesophageal fistula.
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Intestinal obstruction in the newborn. Contrast enema in a baby with a small left colon and meconium plug syndrome.
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Intestinal obstruction in the newborn. Upright radiograph in a patient with complete intestinal obstruction. Note the air-fluid levels and absence of air in the colon.
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Intestinal obstruction in the newborn. Jejunal obstruction caused by a mucosal web.
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Intestinal obstruction in the newborn. Multiple atresias have a"string of sausages" appearance.
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Intestinal obstruction in the newborn. In babies with meconium ileus, the contrast enema shows an unused microcolon.
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Intestinal obstruction in the newborn. Operative photograph of jejunoileal atresia. The bowel is obstructed but in continuity.
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Intestinal obstruction in the newborn. Operative photograph of meconium ileus. The dilated, meconium-laden loop of intestine may be resected and an anastomosis performed.
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Intestinal obstruction in the newborn. Pull-through procedure for Hirschsprung disease. Note the biopsy site in the dilated bowel.
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Intestinal obstruction in the newborn. The contrast enema shows an unused microcolon in babies with meconium ileus.
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Intestinal obstruction in the newborn. Pyloromyotomy: carefully cutting and spreading apart the hypertrophied muscle layer without penetrating the mucosa.
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Intestinal obstruction in the newborn. Mother and daughter both had pyloric stenosis. Pyloric stenosis is more common in males, but if the mother had pyloric stenosis, her offspring are more likely to be affected than if the father had it. Pyloric stenosis cases occur in clusters, indicating an environmental trigger, but there is most likely a complicated interaction of heredity and environment.
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Intestinal obstruction in the newborn. An enteric duplication may cause twisting (volvulus) of a loop of intestine.
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Intestinal obstruction in the newborn. Volvulus of a loop of intestine. The intestine is obstructed at both ends, creating a "closed loop."
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Intestinal obstruction in the newborn. Initial radiograph during hydrostatic reduction of intussusception.
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Intestinal obstruction in the newborn. Radiograph when hydrostatic reduction is almost complete.
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Intestinal obstruction in the newborn. Operative photograph of intussusception.
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Intestinal obstruction in the newborn. A baby with esophageal atresia and tracheoesophageal fistula, who has right upper lobe atelectasis and pneumonia. Note the abdominal distention prior to gastrostomy tube placement, and resolution of the distention and atelectasis after placement of the gastrostomy tube.
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Intestinal obstruction in the newborn. Operative photograph of midgut volvulus. Note the transverse orientation of the colon (look for the appendix).
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Intestinal obstruction in the newborn. Baby with an incarcerated inguinal hernia causing intestinal obstruction. The viability of the testicle is also at risk.
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Intestinal obstruction in the newborn. Operative photograph of midgut volvulus, after its reduction by rotating the entire midgut in a counter-clockwise direction. Next, adhesions between the duodenum and the colon will be divided, exposing the superior mesenteric vessels.
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Intestinal obstruction in the newborn. Operative photograph of malrotation/volvulus diagnosed too late to save the midgut, which is gangrenous.
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Intestinal obstruction in the newborn. A stricture of the small intestine, following necrotizing enterocolitis, causing intestinal obstruction.
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Intestinal obstruction in the newborn. In a baby with jejunal atresia and extensive loss of the distal small bowel, the bulbous, dilated proximal jejunum may be narrowed and lengthened utilizing the STEP (serial transverse enteroplasty) procedure.
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Intestinal obstruction in the newborn. Anastomosis between the dilated proximal duodenum (left) and the smaller caliber distal duodenum.
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Intestinal obstruction in the newborn. Baby with a low imperforate anus. Note the "pearls" of meconium along the scrotal raphe. Low imperforate anus is amenable to repair during the neonatal period.
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Intestinal obstruction in the newborn. The obstructed proximal jejunum is dilated, bulbous; and its motility (peristalsis) is poor. If the baby has an adequate length of distal intestine, this segment is resected; however, if there is limited distal intestine, the STEP (serial transverse enteroplasty) procedure may convert this short dilated segment to a longer, narrower segment.