Duodenal Atresia in a Neonate

HISTORY

The patient is a female neonate who weighed 2210 g at birth. The mother is an 18-year-old Mexican American (gravida 1, para 0, rapid plasma reagin-nonreactive, rubella-immune, and hepatitis B surface antigen-negative) who has had no regular prenatal care. She was admitted via the emergency department to labor and delivery after spontaneous rupture of fetal membranes at home.

The infant was delivered in vaginal vertex presentation (the mother had epidural anesthesia). Apgar scores were 9 at 1 minute and 9 at 5 minutes. The patient was admitted to the transitional nursery for observation. Her initial blood glucose levels were normal. The infant was moderately growth-retarded (eighth percentile for weight). Her gestational age was 38 weeks.

PHYSICAL EXAMINATION

Soon after admission, the infant was noted to have excessive salivation with intermittent episodes of vomiting of bile-stained fluid mixed with mucus. Nasogastric suctioning yielded about 100 mL of fluid. Within a few minutes of admission, the infant was assessed by the attending physician, who observed moderate abdominal distention. Bowel obstruction was suspected, and an abdominal radiograph was obtained.

"WHAT'S YOUR DIAGNOSIS?"

Answer on Next Page

ANSWER: BOWEL OBSTRUCTION

From the abdominal radiograph, the diagnosis of bowel obstruction was made. Surgical intervention was immediately planned after abdominal decompression and appropriate hydration. There was some doubt about the exact level of bowel obstruction. The radiologist suggested intrinsic duodenal obstruction or annular pancreas. The surgical preoperative diagnosis was "probable jejunal obstruction." Surgical exploration revealed intrinsic duodenal obstruction below the ampulla of Vater. The obstruction was resected, and a diamond-shaped flap duodeno-duodenostomy was performed. There were no postoperative complications, and no additional abnormality was detected.

Of particular interest in this case is the finding from the abdominal radiograph: severe gaseous distention of the stomach and proximal duodenum reaching to the midpelvic region. Imminent gastric perforation was feared, but decompression was rapidly accomplished after the abdominal radiograph was reviewed.

DUODENAL ATRESIA

Duodenal atresia is the most common congenital GI obstruction. It occurs in about 1 of 5000 pregnancies and is responsible for more than half of all cases of duodenal obstruction. The atresia is complete in 40% to 60% of patients. It is commonly associated with prematurity (46%), maternal polyhydramnios (33%), Down syndrome (24%), annular pancreas (33%), and malrotation (28%).¹

Intrinsic duodenal atresia occurs either above (34%) or below (66%) the opening of the bile duct. It is probably caused by the failure of recanalization of the intestinal tract during the second month of fetal life. The development of the intestinal tract is completed by the 10th week of intrauterine life. Until the fifth week of fetal life, the intestinal tract is a hollow tube, but there is a proliferation of the intestinal mucosa that appears to occlude the lumen. While this is occurring, the midgut is increasing in length. This--with vacuolization of the epithelium--leads to a restoration of the lumen.

One theory holds that intestinal atresias result from a failure of the vacuolization of the intestinal epithelium. More recent observation suggests that vascular insufficiency of the developing fetal intestine is the primary cause of bowel atresias.²

The duodenum may be partially obstructed by a perforate membrane or stenosis or completely obstructed by an imperforate membrane or atresia. Intrinsic obstruction is often associated with other congenital defects; this supports the hypothesis that the obstruction occurs early in intrauterine life.

Duodenal atresia may be detected by fetal ultra- sonography as early as 18 weeks' gestation. Antepartum ultrasonography also permits early recognition of polyhydramnios, as well as dilatation of the proximal duodenum and the antrum of the fetal stomach (prepyloric region); these areas of dilatation result in the classic "double bubble" sign of duodenal atresia. Jejunal or ileal atresia produces proximal dilatation, which appears as multiple echolucent areas. Using dynamic ultrasound imaging, one can observe marked preobstruction peristalsis.

Karyotyping is required in all fetuses with duodenal atresia because trisomy 21 is present in up to 30% of those who are affected.

Postnatally, excessive salivation and frequent vomiting are common. However, abdominal distention may not be present or it may be confined to the high epigastric areas. Generalized abdominal distention may indicate gastric perforation. Obstruction beyond the ampulla of Vater is characterized by bilious vomiting. All infants with bilious vomiting, or those from whom more than 15 mL of bilious gastric fluid is removed after passage of a nasogastric tube, require an immediate workup to rule out midgut volvulus. Conditions within this group include duodenal atresia, duodenal webs, annular pancreas, malrotation, jejunoileal atresia, and meconium ileus. Duodenal obstruction above the ampulla of Vater with nonbilious vomiting may delay the diagnosis.

Abdominal radiography is the most helpful test for defining the cause and, perhaps, the level of bowel obstruction. Duodenal obstructions caused by atresia, annular pancreas, preduodenal portal vein, and malrotation all can occur with a "double bubble" sign caused by the dilatation of the duodenum and stomach. In a complete duodenal obstruction, there is no intestinal air below the level of the obstruction, as in the case presented here. Early diagnosis of duodenal obstruction, decompression of the dilated stomach and duodenum, and appropriate fluid and electrolyte therapy are required.

The long-term outcome depends on the infant's condition before and immediately after surgery and on the associated congenital and chromosomal anomaly.

OUTCOME OF THIS CASE

After a few days of parenteral nutrition therapy, the patient was gradually introduced to oral feeding, which she tolerated well. She was discharged home on the 11th day of life in apparently good condition and was monitored in the pediatric surgical clinic until she was 6 months old. She did not experience any feeding difficulty and was discharged from surgical follow-up.

References:

REFERENCES:

1. Fanaroff AA, Martin RJ. The neonatal gastrointestinal tract, part 4: intestinal obstruction. In:

Neonatal-Perinatal Medicine: Diseases of the Fetus and Infant. 7th ed. St Louis: Mosby; 2002:1279.
2. Ziegler MM, Azizkhan RG, Weber TR. Intestinal atresia. In: Operative Pediatric Surgery. New York: McGraw-Hill; 2003:589.

FOR MORE INFORMATION:

Atwell JD. Neonatal intestinal obstruction. In: Paediatric Surgery. New York: Oxford University Press; 1998:200.

Creasy RK, Resnik R, Iams JD. General principles and application of ultra- sonography: abnormalities of the gastrointestinal tract. In: Maternal-Fetal Medicine: Principles and Practice. 5th ed. Philadelphia: WB Saunders Co; 2004:340.

Rodeck CH, Whittle MJ. Gastrointestinal abnormalities: duodenal obstruction. In: Fetal Medicine: Basic Science and Clinical Practice. New York: Churchill Livingstone; 1999:704.

Rowe MI. Duodenal obstruction. In: Essentials of Pediatric Surgery. St Louis: Mosby; 1995:486.