This is a newborn infant male born to a 25 year old G1P1A0 mother at 36 weeks gestation via vaginal delivery. Mother received appropriate antenatal care throughout her pregnancy. The pregnancy was remarkable for polyhydramnios. The baby looked normal at birth, however, at 1 day of age (day 2 of life), the infant begins to vomit bilious material and appears jaundiced. Physical exam of the infant is remarkable only for jaundice. A pertinent negative finding is the absence of a distended abdomen.
A plain abdominal radiograph reveals a "double-bubble sign." His symptoms along with the radiographic findings are suggestive of duodenal atresia. Initial treatment consists of insertion of a nasogastric tube along with IV fluid replacement. An echocardiogram and radiographic studies of the spine are performed to evaluate for other congenital abnormalities. No other abnormalities are found and the patient is referred to surgery for surgical evaluation and treatment.
Atresia, by definition, is the absence of an opening of a hollow visceral organ, resulting in a complete obstruction (1). There are several types of atresias: esophageal atresia with and without tracheoesophageal fistula, duodenal atresia, jejunal atresia and ileal atresia.
Esophageal Atresia
Esophageal atresia (EA) occurs in 1/3,000-4,500 live births. Approximately one third of infants with esophageal atresia are born prematurely (2). EA occurs as a result of the failure of the primitive foregut to recanalize (3). An overwhelming majority of EAs are accompanied by a fistula between the trachea and the distal esophagus. These tracheoesophageal fistulas (TEF) occur due to the failure of the lung bud to separate from the foregut (3). An EA with a TEF can be distinguished from an EA without a TEF by the presence of a gas in bowel. EA without TEF does not permit any passage of gas into the bowel, but a TEF permits a pathway from the trachea to the distal esophagus and the stomach.
In rare instances, infants have a tracheoesophageal fistula without an esophageal atresia. This is known as an H-type TEF (the connection between the esophagus and trachea looks like an H). It usually presents with recurrent coughing along with aspiration pneumonia. H-type TEF is commonly diagnosed in childhood or sometimes adulthood by esophageal instillation of methylene blue followed by bronchoscopy to look for dye entering the trachea. Once identified, H-type TEFs require surgical correction.
Esophageal atresias should be suspected if any one of the following is present: maternal polyhydramnios (from inability of the fetus to swallow and absorb amniotic fluid); excessive oral secretions in the newborn; cyanosis, choking, regurgitation or coughing occurring with the first feeding. If suspected, the diagnosis of an esophageal atresia can be confirmed by inability to pass the nasogastric tube into the stomach and by a chest radiograph, which shows the coiling of the tube in the proximal esophageal pouch. Injection of 1mL of contrast into the obstructed esophageal segment can also assist with the diagnosis (3).
One half of infants with esophageal atresia have other associated abnormalities. For example, the VACTER association includes vertebral defects, anal atresia, cardiac anomalies, tracheoesophageal fistula with esophageal atresia, radial upper limb hypoplasia and renal defects (2).
Newborns with EA are at risk for pulmonary aspiration, so nasogastric (actually nasoesophageal) suctioning of the esophageal pouch should be implemented once the diagnosis is confirmed. Also, patients should be placed in the prone position to minimize the flow of gastric contents into the lungs (stomach to distal esophagus through the TEF into the lungs). Postoperatively, an esophagogram should be performed before feeding is resumed to determine the integrity of the anastomosis of the two ends of the esophagus. Prognosis is determined by the extent of pulmonary aspiration. Patients with EA commonly have structural malformations of the trachea such as degeneration of elastic, cartilage and connective tissue of the trachea (tracheomalacia). However, tracheal development is normal if the EA presents in the absence of a fistula. Other complications of the disease are failure to thrive, slow feeding, esophageal stenosis, recurrent aspiration pneumonia, reactive airway disease, severe gastroesophageal reflux, coughing and choking (2).
Intestinal Atresias
Intestinal atresias (duodenal, jejunal and ileal) are common and account for approximately one third of all cases of neonatal intestinal obstruction, but colonic atresias are rare. Distribution of atresias within the small intestine is as follows: 50% in the duodenum, 36% in the jejunum and 14% in the ileum. Other congenital abnormalities are more common with duodenal and jejunal atresias as compared to ileal atresia. Atresias affect males and females equally (3).
Duodenal atresia is similar to esophageal atresia in that it also results from a failure of recanalization. In the case of duodenal atresia, the failure occurs after the solid phase of intestinal development during week 4 and 5 of gestation. It may also be caused by local ischemia and may have a genetic component. Duodenal atresia occurs in 1/10,000 live births. Approximately 50% of infants with duodenal atresia are born prematurely (4). Duodenal atresias occur most frequently distal to the ampulla of Vater (3). There are three types of duodenal atresia: Type I is a mucosal web with normal muscular wall. Type II describes a short, fibrous cord that connects two ends of the atretic duodenum. Type III represents complete separation of the atretic ends. Type I is the most common and type III is the least common (5). Other conditions are associated with duodenal atresia: Down syndrome, malrotation, esophageal atresia, annular pancreas, renal anomalies, congenital heart disease and imperforate anus. Bilious vomiting without abdominal distention on the first day of life is the hallmark of duodenal atresia. Other manifestations include polyhydramnios which is present in 50% of cases, jaundice and intolerance to feeding. Radiographically, duodenal atresia is suggested by the presence of the "double-bubble sign" which results from accumulation of gas in the stomach and proximal duodenum. Because of the atresia, bowel gas does not enter the remainder of the bowel until after the first day of life. Duodenal atresia can be diagnosed prenatally by fetal ultrasonography. Initial treatment consists of nasogastric or orogastric decompression in conjunction with IV fluid replacement to correct fluid and electrolyte derangements. Prior to surgical correction of duodenal atresia, an evaluation for associated life-threatening congenital abnormalities should be performed. Duodenal atresia is usually repaired by duodenoduodenostomy which bypasses the obstruction. Long term prognosis is determined by the patient's associated congenital abnormalities (5).
Unlike esophageal and duodenal atresias, jejunal and ileal atresias are not caused by failure to recanalize the intestinal lumen. Instead it is thought that their etiology is an intrauterine ischemic event of the bowel such as intussusception, volvulus, malrotation, arterial occlusion, internal hernia or strangulation due to an abdominal wall defect such as an omphalocele or in gastroschisis (5). This may result in a focal infarction resulting in an atretic portion of bowel. These atresias are also associated with meconium ileus which occurs in newborns with cystic fibrosis. Similarly to other atresias, a quarter of patients with jejunoileal atresia have a history of polyhydramnios (4).
Jejunal atresias are more common than ileal atresias (5). Isolated jejunal atresia has a higher prevalence in twins and infants with low birth weight. Also, patients with isolated jejunal atresia are more likely to have other unrelated congenital abnormalities (3). There are four different types of jejunal and ileal atresias. Type I is mucosal obstruction that is caused by an epithelial intraluminal membrane, but the proximal and distal ends of the bowel are intact. In type I, which accounts for 20% of jejunal and ileal atresias, the bowel wall and the mesentery of the intraluminal membrane are both intact. Type II is characterized by the connection of the blind ends of the bowel by a fibrous cord and constitutes 35% of intestinal atresias. Type III is subdivided into Type IIIa and IIIb. In type IIIa, the blind ends of the bowel are completely separated by a mesenteric defect that is V-shaped. It accounts for 35% of all atresias. Type IIIb, also known as "apple peel" or "Christmas tree" deformity, describes a loss of the normal blood supply to the distal bowel and is associated with a significant mesenteric defect. It appears that there is a genetic predisposition to Type IIIb (3,5). Type IV comprises 5% of all bowel atresias and is characterized by multiple bowel atresias which resemble a string of sausages (4,5).
Jejunoileal atresia can be diagnosed by prenatal ultrasound. The majority of newborns with jejunoileal atresia exhibit clinical symptoms during the first day of life. Symptoms are characterized by abdominal distention, bilious emesis or bilious gastric aspirate. Other symptoms include jaundice and failure to pass meconium. However, the passage of meconium does not rule out intestinal atresia because a third of infants with jejunoileal atresia will pass meconium prior to development of obstructive symptoms (3). Air-fluid levels or peritoneal calcifications may be seen on plain abdominal radiographs. In the differential of jejunoileal atresia are: Hirschsprung's disease, meconium ileus and meconium plug. These diseases can be distinguished from jejunoileal atresia by contrast studies of the upper and lower bowel which will pinpoint the level of obstruction (4). Definitive treatment requires resection of the atretic portion of the bowel with an end-to-end anastomosis. Postoperatively, nutritional support is provided by parenteral hyperalimentation until bowel function is restored (5). Prognosis is determined by the length and function of the remaining bowel. Long-term complications include malabsorption, feeding intolerance and bacterial overgrowth (3). Multiple atretic segments may result in a short gut syndrome with insufficient or marginal total bowel nutrition absorptive capacity.
Intestinal Duplications
Intestinal duplications are rare congenital abnormalities that consist of tubular or spherical structures with gastrointestinal epithelium. These structures are attached to the intestine and are located on the mesenteric border. The lumen of the normal intestine usually is not continuous with that of the duplication. Usually the duplication and the normal intestine share vascular supply and a fraction of the muscular layer. There are three categories of intestinal duplications. The first category is localized duplications. These duplications are most common in the jejunum and the ileum, although they may occur in other areas of the GI tract. Localized duplications are usually tubular or cystic. Their exact etiology is unknown, although it is thought that defects in the recanalization of the intestinal lumen after the solid stage of embryologic development, may contribute to the development of these duplications. The second category is duplications that are associated with spinal cord or vertebral abnormalities such as hemivertebra or anterior spina bifida. A possible cause of these duplications may be the separation of the notochord during embryologic development. The last category is duplication of the colon. This duplication is commonly associated with abnormalities of the genitals or the urinary tract. In general, duplications tend to be symptomatic and present during the first year of life as a palpable mass or they may cause intestinal obstruction, volvulus or intussusception. Other symptoms include vomiting, abdominal pain, constipation, diarrhea and acute GI hemorrhage. Duplications may be diagnosed with ultrasound, MRI or CT of the abdomen. Undiagnosed intestinal duplications may undergo malignant transformation. Definitive treatment includes complete resection of the duplication with an end-to-end anastomosis (3,7).
Microcolon
Microcolon is a rare congenital cause of intestinal obstruction. The microcolon generally results from intrauterine underutilization of the colon, which would include conditions in which intestinal contents are not passed into the colon during gestation. This would include ileal atresia, but this would not include duodenal atresia, because duodenal atresia is in the proximal small bowel, such that the middle and distal small bowel continue to shed epithelial tissue (meconium precursors) distally into the colon during gestation. Microcolon is also part of a megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS). MMIHS is a genetic disorder with an autosomal recessive pattern of inheritance. This syndrome affects primarily female infants. Infants with MMIHS present with bilious vomiting, delayed passage of meconium and abdominal distention. Dilation of the bladder and the small bowel causes abdominal distention. Physical exam reveals thin musculature of the anterior abdominal wall. Diagnosis is confirmed by ultrasound, upper GI contrast study and an enema which shows a nonobstructed microcolon (7,8). This syndrome is usually lethal within the first year of life (9).
Questions
1. The double-bubble sign on plain abdominal radiograph is diagnostic of what kind of atresia?
2. How could you distinguish between an esophageal atresia with tracheoesophageal fistula (TE) from an esophageal atresia without TE fistula?
3. What other abnormalities are associated with an esophageal atresia?
4. How does an esophageal or duodenal atresia differ etiologically from a jejunal or an ileal atresia?
5. What makes undiagnosed intestinal duplication potentially life threatening?
References
1. Schofield DS, Cotran RS. Chapter 11 - Diseases of Infancy and Childhood. In: Cotran RS, Kumar V, Collins T (eds). Robbins Pathologic Basis of Disease, sixth edition. 1999, Philadelphia: W. B. Saunders Company, pp. 459-491.
2. Herbst JJ. Chapter 319 - Atresia and Tracheoesophageal Fistula. In: Behrman RE, Kliegman RM, Jenson HB (eds). Nelson Textbook of Pediatrics, sixteenth edition. 2000, Philadelphia: W. B. Saunders Company, pp. 1122-1123.
3. Keljo DJ, Squires RH. Chapter 84 - Anatomy and Anomalies of the Small and Large Intestines. In: Feldman M, Scharschmidt BF, Sleisenger MH, Klein S (eds). Sleisenger & Fordtran's Gastrointestinal and Liver Disease Pathophysiology / Diagnosis / Management, sixth edition. 1998, Philadelphia: W. B. Saunders Company, pp. 1423-1431.
4. Wyllie R. Chapter 330 - Intestinal Atresia, Stenosis, and Malrotation. In: Behrman RE, Kliegman RM, Jenson HB (eds). Nelson Textbook of Pediatrics, sixteenth edition. 2000, Philadelphia: W. B. Saunders Company, pp. 1133-1136.
5. Engum SA, Grosfeld JL. Chapter 67 - Pediatric Surgery. In: Townsend CM, Beauchamp RD, Evers BM, Mattox, KL (eds). Sabiston Textbook of Surgery, sixteenth edition. 2001, Philadelphia: W. B. Saunders Company, pp. 1466-1471.
6. Wyllie R. Chapter 331 - Intestinal Duplications, Meckel Diverticulum, and Other Remnants of the Omphalomesenteric Duct. In: Behrman RE, Kliegman RM, Jenson HB (eds). Nelson Textbook of Pediatrics, sixteenth edition. 2000, Philadelphia: W. B. Saunders Company, pp. 1137-1138.
7. Loening-Baucke V, Kimura K. Failure to pass meconium: diagnosing neonatal intestinal obstruction. Am Fam Physician 1999; 60(7):2043-2050.
8. Paterson A, Sweeney L. Chapter 54 - Paediatric gastrointestinal radiology. In: Grainger RG, Allison DJ, Adam A, Dixon AK (eds). Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging, fourth edition. 2001, Philadelphia: Churchill Livingstone, pp. 1199-1236.
9. White SM, Chamberlain P, Hitchcock R et al. Megacystis-microcolon-intestinal hypoperistalsis syndrome: the difficulties with antenatal diagnosis. Case report and review of the literature. Prenat Diagn.2000;20(9):697-700.
Answers to questions
1. Duodenal atresia.
2. Esophageal atresia with tracheoesophageal fistula results in a gas within the bowel, esophageal atresia without tracheoesophageal fistula does not.
3. VACTER association; includes vertebral defects, anal atresia, congenital cardiac anomalies, tracheoesophageal fistula with esophageal atresia, radial upper limb hypoplasia and renal defects.
4. Esophageal or duodenal atresias result from failure of the lumen to recanalize. A jejunal or ileal atresia results from an intrauterine ischemic event.
5. Undiagnosed intestinal duplications may cause a bowel obstruction or may undergo malignant transformations in adults.