You are in: eMedicine Specialties > Radiology > PEDIATRICS Duodenal AtresiaArticle Last Updated: Aug 28, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 7
  Author: Gerald Mandell, MD, Consulting Staff, Department of Radiology, Phoenix Children's Hospital Gerald Mandell is a member of the following medical societies: American Academy of Pediatrics, American College of Angiology, American College of Nuclear Medicine, American College of Nuclear Physicians, American College of Radiology, American Medical Association, Society for Pediatric Radiology, and Society of Nuclear Medicine Editors: Lori Lee Barr, MD, Adjunct Associate Professor of Radiology, Department of Radiology, University of Texas Health Science Center San Antonio; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; David A Stringer, MBBS, FRCR, Clinical Professor, National University of Singapore; Clinical Director, Diagnostic Imaging, National University Hospital; Head, Diagnostic Imaging, KK Women's and Children's Hospital, Singapore; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; John Karani, MBBS, FRCR, Consulting Staff, Department of Radiology, King's College Hospital, London Author and Editor Disclosure Synonyms and related keywords: duodenal stenosis, duodenal membrane, duodenal diaphragm, duodenal web INTRODUCTIONSection 2 of 7
  BackgroundDuodenal atresia represents complete obliteration of the duodenal lumen. A duodenal diaphragm (or duodenal web) is thought to represent a mild form of atresia. Duodenal stenosis (incomplete obstruction of the duodenal lumen) is discussed with duodenal atresia because the 2 disorders together represent a spectrum of similar intrauterine events. Annular pancreas occurs when pancreatic tissue surrounds the second portion of the duodenum. If the encirclement is complete, it may be associated with complete or incomplete duodenal obstruction. Since duodenal atresia or duodenal stenosis occurs in all cases of annular pancreas, the anomalous pancreas should be considered a secondary change rather than a primary cause of duodenal obstruction. PathophysiologyThe etiology of duodenal atresia and stenosis is unknown. Failure of recanalization of the duodenal lumen remains the favored theory, compared with intrauterine vascular ischemia. During the third week of embryonic development, the second portion of the duodenum, at the junction of the foregut and midgut, forms biliary and pancreatic buds, which are derived from endoderm. During the next 4 weeks, these buds differentiate into the hepatobiliary system, with the development and subsequent fusion of the 2 pancreatic anlagen. Concurrently, the epithelium of the duodenum undergoes active proliferation, which, at times, completely obliterates the duodenal lumen. Vacuolization, followed by recanalization, reestablishes the hollow viscus. The second part of the duodenum is the last to recanalize. The early forming biliary system consists of 2 channels arising from the embryonic duodenum. This structure creates a narrow segment of bowel, approximately 0.125 mm in length, that is interposed between the 2 biliary channels. This narrow region is the area most prone to problems, with recanalization and with atresia formation. The ampulla of Vater usually is immediately adjacent to or traverses the medial wall of the diaphragm. The presence of a bifid biliary system, or the insertion of 1 duct above the atresia and 1 duct below it, is rare, occurring when both biliary duct anlagen remain patent. The presence of bile above and below the atresia indicates a bifid biliary system. FrequencyUnited StatesThe incidence of duodenal atresia is 1 per 6000 births. Intrinsic congenital duodenal obstruction constitutes two thirds of all congenital duodenal obstructions (duodenal atresia, 40-60%; duodenal web, 35-45%; annular pancreas, 10-30%; duodenal stenosis, 7-20%). InternationalThe incidence in Finland of congenital obstruction (intrinsic, extrinsic, combined) is 1 per 3400 live births. Mortality/MorbidityIf duodenal atresia or significant duodenal stenosis is left untreated, the condition rapidly becomes fatal as a result of electrolyte loss and fluid imbalance.
RaceNo racial predilection exists. SexThe incidence of duodenal atresia and duodenal stenosis is approximately equal in males and females. AgeInfants with duodenal atresia present with vomiting in their first few hours of life, but patients with duodenal stenosis present at various ages. The clinical findings depend on the degree of stenosis. Occasionally, with duodenal web or duodenal stenosis, presentation occurs in adulthood. AnatomyIn most cases, duodenal atresia occurs below the ampulla of Vater. In a very few cases, the atresia occurs proximal to the ampulla. Clinical DetailsBile-stained vomit in neonates aged 24 hours or younger is the typical presentation of atresia or severe stenosis. Minimal duodenal obstruction in mild stenosis or duodenal membrane may have few symptoms. In a few cases, the atresia is proximal to the ampulla of Vater and the vomit is free of bile. A few familial cases have been reported. Preferred ExaminationPlain radiographs that demonstrate a double-bubble appearance with no distal gas are characteristic of duodenal atresia. Distal bowel gas indicates stenosis, incomplete membrane, or a hepatopancreatic ductal anomaly. Occasionally, a radiograph must be obtained with the patient in the erect or the decubitus position to delineate the duodenal component. If a combination of esophageal atresia and duodenal atresia is present, ultrasonography is preferred. Limitations of TechniquesNo oral contrast materials are necessary in the evaluation of complete duodenal obstruction. Occasionally, a small amount of positive contrast material can be instilled through a feeding tube into the distal stomach and duodenum to differentiate the diaphragm from a long stenosis. Occasionally, barium enema examination is suggested as an adjunct study in the evaluation of duodenal atresia. Barium enema findings can demonstrate a malpositioned cecum, but this is not always diagnostic of malrotation and volvulus. In addition, if a microcolon is demonstrated, the presence of additional, more distal atresias can be suggested. Succus entericus may be prevented from reaching the colon because of the additional area of bowel obstruction. Multiple atresias are present in approximately 15% of patients. However, most surgeons can determine the presence of malrotation and additional atresias at the time of surgery. To the author's knowledge, in only 1 instance was the addition of the barium enema examination beneficial to the preoperative examination of a patient with trisomy 21. This case involved the coexistence of Hirschsprung disease. (The presence of trisomy 21 makes the likelihood of Hirschsprung disease in a patient 15-fold greater.) If these conditions are known prior to surgery, the surgeon can create a temporizing colostomy at the time of duodenojejunostomy and spare the child from undergoing additional anesthesia. DIFFERENTIALSSection 3 of 7
Abdominal Aortic Aneurysm, Rupture Midgut Volvulus Other Problems to Be ConsideredAnnular pancreas
RADIOGRAPHSection 4 of 7
FindingsThe double-bubble sign represents dilatation of the stomach and duodenum. This configuration most commonly occurs with duodenal atresia and an annular pancreas. An annular pancreas is almost always associated with duodenal atresia. In a few cases of duodenal atresia, air can be observed distal to the area of obstruction. The anomalous hepatopancreatic ducts permit movement of air through a Y-shaped ductal system, with 1 limb proximal to the obstruction and 1 limb distal to the atresia. When duodenal atresia is combined with esophageal atresia, no air is observed in the stomach. Because the stomach is obstructed at both ends, the infant presents with a large, opaque upper midabdominal mass. If esophageal atresia exists along with a distal fistula, air is found in the stomach and duodenum. Duodenal obstruction in the neonate may be partial or complete, and it may be secondary to intrinsic or extrinsic abnormalities. The duodenal bulb may be larger in duodenal atresia than in obstructions of the duodenum. Increased intramural pressure in duodenal obstruction can result in gastric pneumatosis. Degree of ConfidenceOnce the radiographic finding of a double-bubble sign without distal gas is determined, the diagnosis of duodenal atresia is evident, and usually, no additional, contrast-enhanced studies are needed. False Positives/NegativesDuodenal atresia that is associated with a Y-shaped biliary duct connection can have air distal to the point of duodenal atresia. This finding may suggest stenosis rather than atresia. ULTRASOUNDSection 5 of 7
FindingsA finding of 2 echo-free fluid collections in the upper abdomen suggests duodenal atresia in association with esophageal atresia. Esophageal atresia without a fistula does not permit air to reach the stomach and duodenum. Degree of ConfidenceThese findings do not require confirmation with additional procedures. MULTIMEDIASection 6 of 7
REFERENCESSection 7 of 7
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