Bowel obstruction occurs when normal flow of intraluminal contents is interrupted and can be either attributed to functional (ie, abnormal intestinal physiology) or mechanical causes. In infants and children, gastrointestinal (GI) obstruction can be categorized as congenital or acquired. It may be divided based on age of presentation and onset of symptoms. These broad categories are not mutually exclusive, but categorizing them in this fashion helps with identifying the etiology of the obstruction. For example, congenital lesions of the intestine such as an enteric duplication or Meckel diverticulum may not cause obstruction until later in life. Congenital anatomic defects and acquired disorders of the intestine presenting in the first 30 days of life are characterized as neonatal intestinal obstruction.
Functional obstruction may be due to defective peristalsis, neuromuscular disorders, or pseudo-obstruction. Mechanical obstruction may be extrinsic, intrinsic, or luminal in origin and is either partial or complete. Progressive accumulation of the luminal contents results in dilatation of the proximal bowel while the distal bowel is empty and collapsed. Irrespective of the cause, bowel obstruction results in abdominal distention and emesis changing from gastric to bilious and progressing to feculent. Swallowed air, saliva, GI secretions, and loss of intestinal absorption will increase the distention and ultimately lead to bowel wall edema, ischemia, and perforation.
CLINICAL FEATURES AND DIFFERENTIAL DIAGNOSIS
Neonatal Intestinal Obstruction
Neonatal intestinal obstruction is characterized by a neonate presenting with failure to pass meconium within the first 24 to 48 hours of life and is associated with feeding intolerance, abdominal distention, and persistent vomiting or the aspiration of more than 20 mL of gastric secretions. Prenatally, these babies will present with polyhydramnios in the third trimester. Proximal obstructions usually result in earlier manifestation of polyhydramnios, which is a consequence of disrupted amniotic fluid dynamics. Figure 384-1 demonstrates an algorithm for approaching the neonate presenting with intestinal obstruction, along with the most common differential diagnoses. The anatomic conditions that present with neonatal intestinal obstruction and their diagnostic features are summarized in Table 384-1. Accurate diagnosis of neonatal intestinal obstruction relies on a thorough history, careful examination, and directed radiological studies. In a newborn infant, postprandial nonbilious emesis or, more commonly, regurgitation, or spitting up, is quite common and does not require urgent evaluation. In contrast, neonatal intestinal obstruction usually is a serious condition and will need to be addressed expeditiously. Bilious emesis is most frequently a consequence of mechanical intestinal obstruction, and prompt evaluation is necessary to exclude life-threatening conditions such as volvulus or necrotizing enterocolitis. The history provides clues to the potential etiology of intestinal obstruction, but history and physical examination alone may be insufficient, as much of the findings are nonspecific. Thoughtful consideration of the specific situation can narrow the differential diagnosis. For example, a 3-week-old infant with bilious emesis who has passed meconium and previously tolerated feeding is unlikely ...