[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Embryology](https://durgical.com/en/embryology/) › [Digestive system](https://durgical.com/en/embryology/#a-digestive) › Duodenal atresia and stenosis [Embryology](https://durgical.com/en/embryology/) · [Digestive system](https://durgical.com/en/embryology/#a-digestive) # Duodenal atresia and stenosis - Malformation The duodenum stays closed or very narrow because it never regains its lumen in embryonic life; the newborn vomits within hours. Updated 2026-11-01 **See it in 3D:** [Duodenum](https://durgical.com/en/anatomy/duodenum/) · [Stomach](https://durgical.com/en/anatomy/stomach/) · [Pancreas](https://durgical.com/en/anatomy/pancreas/) ## Key points - Cause: failed recanalization of the duodenum, not a vascular accident as in jejunoileal atresia. - Prenatal: polyhydramnios and a fluid-filled double bubble on ultrasound. - After birth: vomiting within hours, bilious if the block is distal to the major papilla, which is the usual case. - X-ray: double bubble (stomach and proximal duodenum) with no distal gas. - About one third of children with duodenal atresia have Down syndrome. - Other associations: annular pancreas, malrotation, heart defects, VACTERL and other atresias. ## What it is It is a congenital complete (atresia) or partial (stenosis) obstruction of the duodenum, almost always in its second part. It happens because the lumen, temporarily plugged by epithelium in the embryonic period, fails to recanalize. It is a classic marker of Down syndrome and gives the radiographic double bubble sign. ## Embryological cause - In the second month the duodenal epithelium proliferates and temporarily plugs the lumen. - Normally vacuoles form and coalesce, recanalizing the tube by the end of the embryonic period. - If recanalization fails, a membrane, a fibrous cord or a complete gap remains (atresia); if it is incomplete, a stenosis or a perforated web remains. - Annular pancreas can cause a similar obstruction by external compression. ## How it presents - Early, large-volume vomiting on the first day, usually bilious. - Distended upper abdomen with a flat lower abdomen. - History of polyhydramnios; often preterm birth. - Associations: Down syndrome, annular pancreas, malrotation, congenital heart disease, VACTERL. ## Diagnosis - Prenatal ultrasound: polyhydramnios and two fluid-filled structures in the upper abdomen (double bubble). - Abdominal X-ray: double bubble sign, with no distal gas in atresia and some distal gas in stenosis. - Work-up for associations: echocardiogram and karyotype. ## Memory aid Two bubbles and nothing more: the air is trapped in the stomach and duodenum because the door that closed in the embryo never reopened. ## Test yourself Think of the answer, then tap the question to see it. ## Which embryonic error causes duodenal atresia? Failure to recanalize the duodenal lumen, which the epithelium had temporarily plugged during the embryonic period. ## Which prenatal finding suggests duodenal atresia? Polyhydramnios, because the fetus cannot absorb the amniotic fluid it swallows, together with a double bubble on ultrasound. ## Which chromosomal disorder is most strongly associated? Trisomy 21: about one third of children with duodenal atresia have Down syndrome. ## Why is the vomit usually bilious? Because the obstruction is usually distal to the major papilla, where bile has already entered the duodenum. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/embryology/duodenal-atresia-and-stenosis/) ## See it in 3D The structures of Durgical's 3D anatomy where it is found. - [Duodenum](https://durgical.com/en/anatomy/duodenum/) - [Stomach](https://durgical.com/en/anatomy/stomach/) - [Pancreas](https://durgical.com/en/anatomy/pancreas/) ## Related - [Foregut: esophagus, stomach rotation and duodenum](https://durgical.com/en/embryology/foregut-esophagus-stomach-rotation-and-duodenum/) - [Annular pancreas and pancreas divisum](https://durgical.com/en/embryology/annular-pancreas-and-pancreas-divisum/) - [Malrotation and midgut volvulus](https://durgical.com/en/embryology/malrotation-and-midgut-volvulus/) - [Jejunal and ileal atresia](https://durgical.com/en/embryology/jejunal-and-ileal-atresia/) - [Amniotic fluid: polyhydramnios and oligohydramnios](https://durgical.com/en/embryology/amniotic-fluid-polyhydramnios-and-oligohydramnios/) - [Meiosis and nondisjunction: where trisomies come from](https://durgical.com/en/embryology/meiosis-and-nondisjunction-where-trisomies-come-from/) - [Hypertrophic pyloric stenosis](https://durgical.com/en/embryology/hypertrophic-pyloric-stenosis/) ## Related conditions - [Down syndrome (trisomy 21)](https://durgical.com/en/conditions/down-syndrome/) [← All of embryology](https://durgical.com/en/embryology/) Educational content on embryonic development; not a guide to prenatal diagnosis or to medicines in pregnancy and no substitute for a health professional's advice. No doses are given. Sources: [Duodenal Atresia and Stenosis](https://www.ncbi.nlm.nih.gov/books/NBK470548/) (StatPearls Publishing (NCBI Bookshelf), 2023); [Duodenal atresia](https://medlineplus.gov/ency/article/001131.htm) (MedlinePlus, U.S. National Library of Medicine, 2025). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/embryology/duodenal-atresia-and-stenosis/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/embryology/duodenal-atresia-and-stenosis/