Duodenal atresia is a congenital malformation characterized by complete (atresia) or partial (stenosis) obstruction of the duodenum. Incidence is approximately 1/5000-10000 live births. It has strong association with Down syndrome (trisomy 21) — 25-40% of infants with duodenal atresia have Down syndrome. Pathogenesis is related to failure of recanalization of the duodenum during embryonic development. Typical presentation begins with bilious or non-bilious vomiting in early postnatal hours. On abdominal radiograph (AXR), the double bubble sign is pathognomonic — gas accumulation in the stomach and proximal duodenum appears as two large air bubbles. Absence (or paucity) of gas in distal bowel indicates complete atresia; presence of distal gas suggests incomplete obstruction such as stenosis or annular pancreas. The double bubble sign can also be detected on prenatal ultrasound and polyhydramnios frequently accompanies. Treatment is surgical — duodenoduodenostomy (diamond-shaped anastomosis) is the standard surgery.
Age Range
0-0
Peak Age
-
Gender
Equal
Prevalence
Rare
Duodenal atresia results from failure of recanalization of the duodenal lumen during 8-10 weeks of embryonic development. In normal development, the duodenum at the foregut-midgut junction transforms from a solid cell cord to a luminated tubular structure — this process is called recanalization. When recanalization fails, the lumen is completely (atresia — Type I: membranous web, Type II: fibrotic cord, Type III: gap atresia) or partially (stenosis: narrow lumen) obstructed. Obstruction is generally at or just distal to the ampulla of Vater — therefore vomiting may be bilious (green) if obstruction is distal to the ampulla or non-bilious if proximal. Annular pancreas is an extrinsic cause of duodenal obstruction — pancreatic tissue encircles the duodenum ring-like and narrows the lumen. Down syndrome association is explained by genes on chromosome 21 affecting gastrointestinal development — trisomy 21 increases duodenal atresia risk 300-fold. Physical basis of double bubble sign: stomach and proximal duodenum fill with air but air cannot pass beyond the obstruction → two separate air collections form → appear as two separate radiolucent (black) bubbles on upright or supine film.
Two large air bubbles seen in the stomach and proximal duodenum on abdominal radiograph. The larger bubble on the left reflects the stomach filling with air, the smaller bubble on the right reflects the proximal duodenum filling with air. Absence of gas in distal bowel confirms complete duodenal obstruction (atresia). This sign is pathognomonic for duodenal obstruction and was first described in the 1930s. On prenatal US, the same finding is seen as fluid-filled structures.
Two large radiolucent (black) air bubbles are seen on AXR — the larger bubble on the left is the stomach (gastric bubble), the smaller bubble on the right is the proximal duodenum (duodenal bubble). On upright film, air-fluid levels are seen beneath both bubbles. A pyloric band (opacity created by the pyloric muscle) is seen between the two bubbles — separating them. Absence of gas in distal bowel indicates complete atresia, while small amount of gas suggests stenosis or annular pancreas. The double bubble sign almost always indicates duodenal obstruction and is practically not seen in other diagnoses.
Report Sentence
Double bubble sign (gas in stomach and proximal duodenum) is seen on AXR with absent/decreased gas in distal bowel; findings are consistent with duodenal atresia/obstruction; chromosomal analysis for Down syndrome is recommended.
Prenatal ultrasound reveals two anechoic (fluid-filled) bubbles in the fetal abdomen — the larger is the stomach, the smaller is the proximal duodenum. Polyhydramnios frequently accompanies because the fetus cannot swallow adequate amniotic fluid. Prenatal double bubble sign is generally detectable from mid-second trimester (24-28 weeks). Down syndrome markers (increased nuchal translucency, absent nasal bone, short femur) should be evaluated together.
Report Sentence
Two anechoic bubbles (double bubble sign) and polyhydramnios are seen in the fetal abdomen on prenatal US; consistent with duodenal atresia and chromosomal analysis for Down syndrome is recommended.
Postnatal ultrasound reveals dilated, fluid-filled stomach and proximal duodenum. Stomach wall thickness is normal. Proximal duodenum is dilated and fluid-filled — no passage beyond the obstruction site. Fluid flow from pylorus to duodenum can be observed in real-time. US may be helpful for evaluating annular pancreas presence — pancreatic tissue is seen encircling the duodenum ring-like. SMA-SMV relationship should be evaluated by upper GI fluoroscopy or US for exclusion of malrotation.
Report Sentence
Dilated stomach and proximal duodenum are seen on US with no fluid passage distally; findings are consistent with duodenal obstruction.
Upper GI contrast study (UGI) definitively determines the level and type (complete/incomplete) of obstruction. Barium or water-soluble contrast is administered orally/via NG tube. Stomach and proximal duodenum fill but contrast does not pass beyond the obstruction site (complete atresia) or passes as a thin stream (stenosis). In annular pancreas, narrowing due to extrinsic compression is seen in the duodenal lumen ('napkin ring' appearance). UGI also evaluates malrotation (position of duodenojejunal junction) and Ladd bands.
Report Sentence
On upper GI contrast study, contrast stops at the proximal duodenum with no/minimal passage distally; findings are consistent with complete duodenal atresia/incomplete obstruction.
Duodenal atresia may be a component of VACTERL association — vertebral anomalies (hemivertebra, butterfly vertebra), 13-rib pair anomalies, and cardiomegaly should be sought on chest/abdominal radiograph. Situs inversus and other symmetry disorders should also be evaluated. Other anomalies associated with Down syndrome (cardiac defects — AV canal defect most common) should be screened by echocardiography.
Report Sentence
Vertebral anomaly is/is not seen on abdominal/chest radiograph; comprehensive evaluation for VACTERL association and anomalies accompanying Down syndrome is recommended.
Criteria
Thin membrane/web in duodenal lumen causes obstruction, duodenal continuity preserved, most common type (80%)
Distinct Features
Web may be perforated (windsock deformity) → incomplete obstruction, thin passage on contrast study, surgical web excision
Criteria
Proximal and distal duodenal ends connected by fibrous cord, short gap
Distinct Features
Complete obstruction, gasless distal bowel, surgical duodenoduodenostomy
Criteria
Completely separate segments between proximal and distal duodenum, variable gap distance, mesenteric interruption may be present
Distinct Features
Complete obstruction, most difficult surgical type, anastomotic tension may occur, malrotation frequently accompanies
Criteria
Pancreatic tissue encircles duodenum ring-like, extrinsic obstruction, 30% combined with intrinsic web
Distinct Features
Pancreatic tissue around duodenum seen on US/CT, complete or incomplete obstruction, pancreatic tissue cannot be divided (pancreatitis risk), surgical bypass (duodenoduodenostomy)
Distinguishing Feature
Midgut volvulus may also give double bubble appearance but generally not as distinct; in malrotation the duodenojejunal junction is located on the right on UGI (absent Treitz); volvulus is surgical emergency, 'corkscrew sign' seen
Distinguishing Feature
Jejunal atresia shows triple bubble sign (three bubbles — stomach, duodenum, jejunum); air reaches more distally; distal bowel is gasless; no double bubble sign
Distinguishing Feature
Hypertrophic pyloric stenosis shows single bubble (stomach), no double bubble; pyloric muscle thickness >3 mm and length >15 mm; typically in 3-6 week old infants (duodenal atresia at birth); US differentiation is definitive
Urgency
emergentManagement
surgicalBiopsy
Not NeededFollow-up
specialist-referralDuodenal atresia requires surgery but is not emergent per se (cases presenting with bilious vomiting need rapid evaluation — volvulus must be excluded). Preoperative management: nasogastric decompression, IV fluids and electrolyte balance. Surgery: diamond-shaped duodenoduodenostomy is the standard — Kimura technique with anastomosis between transverse proximal and longitudinal distal duodenum. In annular pancreas, pancreatic tissue is not divided — bypass performed. Karyotype analysis for Down syndrome is mandatory (25-40% incidence). Long-term prognosis with surgical technique is excellent (survival >95%); prognosis depends on associated anomalies.
Duodenal atresia requires surgical repair — duodenoduodenostomy (diamond-shaped anastomosis). Down syndrome screening (chromosomal analysis) and associated anomaly evaluation (echocardiography, vertebral imaging) are mandatory. Associated malrotation is corrected with Ladd procedure during surgery. With early surgery, prognosis is excellent (>95% survival).