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PubMed This is a summary of 18 peer-reviewed journal articles Updated
Gastroenterology

Recognizing the Signs: From Newborns to Adults

At a Glance

Annular pancreas causes symptoms by squeezing the small intestine. In newborns, it often presents as an emergency blockage with warning signs like green vomit and a swollen belly. In adults, symptoms may not appear for years and typically include chronic stomach pain, nausea, and early fullness.

Because annular pancreas is a structural issue, the symptoms it causes depend entirely on how tightly the ring of tissue is squeezing the duodenum (the first part of the small intestine) [1]. This explains why some people are diagnosed within hours of birth, while others may not know they have the condition until they are well into adulthood [2].

Neonatal Presentation: Signs in Infancy

In newborns, the ring of pancreatic tissue is often tight enough to cause a significant or total blockage of the intestine [2]. This is usually considered a surgical emergency because the baby cannot move milk or formula into the digestive tract [3].

  • Vomiting (A Critical Warning Sign): This is the most common sign. Doctors look closely to see if the vomit is bilious (green-colored, containing bile) or non-bilious [4].
    • Red Flag: Green/bilious vomit in a newborn is a medical emergency requiring immediate ER evaluation. It often indicates the blockage is located after the point where the bile duct empties into the intestine, and can be a warning sign for a life-threatening complication called midgut volvulus (twisted intestines) [5][6].
  • Abdominal Distension: The upper part of the baby’s stomach may look swollen or “full” as gas and fluid get trapped behind the blockage [4].
  • The “Double Bubble” Sign: On an X-ray, doctors often see two distinct air bubbles—one in the stomach and one in the first part of the duodenum—which is a classic indicator of a blockage in this area [4].
  • Feeding Intolerance: The baby may refuse to eat or become very fussy during and after feedings [3].

Adult Presentation: The “Silent” Anomaly

In adults, the ring is usually “incomplete” or loose enough that it doesn’t cause a total blockage during childhood [7]. However, as a person ages, other factors like pancreatitis (inflammation of the pancreas), the development of peptic ulcers, or natural scarring can narrow the passage further, finally triggering symptoms [8][9].

Adult symptoms are often “insidious,” meaning they come on slowly and can be intermittent for years [10]. Common signs include:

  • Chronic Epigastric Pain: A persistent or recurring ache in the upper middle part of the abdomen, often worse after meals [7][10].
  • Early Satiety: Feeling full after only a few bites of food because the stomach cannot empty efficiently [11].
  • Recurrent Pancreatitis: Repeated episodes of pancreatic inflammation can occur because the pancreatic ducts may be pinched or blocked by the unusual shape of the organ [12].
  • Nausea and Vomiting: Unlike infants, adult vomiting is frequently non-bilious, meaning it contains food but not green bile, because the narrowing in adults is often positioned before the bile duct’s entry point [7][6].

Why is it Often Misdiagnosed?

Because annular pancreas is so rare in adults, doctors may first look for more common conditions [13]. It is frequently confused with:

  • Peptic Ulcer Disease: The pain and vomiting can look identical to a severe stomach ulcer [13][14].
  • SMA Syndrome: A condition where the small intestine is “pinched” between two major blood vessels [6].
  • Malignancy: In older adults, doctors must carefully rule out tumors in the pancreas or duodenum that could be causing the blockage [13][15].
  • Gastritis: General inflammation of the stomach lining [16].

Because of these overlaps, doctors rely on advanced imaging like CT scans or MRI/MRCP to see the physical ring of tissue and confirm the diagnosis [17][18].

Common questions in this guide

What are the warning signs of annular pancreas in a newborn?
In infants, a tight ring of pancreas tissue can severely block the intestine. Key warning signs include vomiting (especially green or bilious vomit), a swollen belly, and refusing to feed. This is often a medical emergency requiring immediate evaluation.
Can you have an annular pancreas and not know it until adulthood?
Yes. In many adults, the ring of pancreatic tissue is loose enough that it doesn't cause a total blockage during childhood. Symptoms may only appear later in life when factors like inflammation, ulcers, or natural scarring narrow the passage further.
What does an annular pancreas feel like in adults?
Adult symptoms often come on slowly and include chronic pain in the upper middle stomach, feeling full after only a few bites of food, nausea, non-bilious vomiting, and recurrent episodes of pancreatic inflammation.
Why is an annular pancreas often misdiagnosed?
Because it is rare in adults, doctors may initially suspect more common stomach conditions that cause similar pain and nausea, such as peptic ulcers, gastritis, or SMA syndrome. Advanced imaging like an MRI or CT scan is necessary to confirm the diagnosis.
What does the double bubble sign mean on an X-ray?
The double bubble sign is a classic indicator seen on an X-ray when there is a blockage in the upper digestive tract. It shows two distinct air bubbles—one in the stomach and one in the small intestine—helping doctors pinpoint the location of the obstruction.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Is the obstruction occurring before or after the point where the bile duct enters the intestine?
  2. 2.Has the pancreas ring already caused any signs of chronic inflammation or scarring in the intestine?
  3. 3.Could my symptoms be caused by other conditions like SMA syndrome or a duodenal ulcer?
  4. 4.Does the imaging show any other variations, like pancreas divisum, that might be contributing to the pain?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (18)
  1. 1

    Exome sequencing findings in children with annular pancreas.

    Pitsava G, Pankratz N, Lane J, et al.

    Molecular genetics & genomic medicine 2023; (11(10)):e2233 doi:10.1002/mgg3.2233.

    PMID: 37635636
  2. 2

    Annular pancreas in neonates; Case series and review of literatures.

    Ali Almoamin HH, Kadhem SH, Saleh AM

    African journal of paediatric surgery : AJPS 2022; (19(2)):97-101 doi:10.4103/ajps.AJPS_180_20.

    PMID: 35017379
  3. 3

    Annular Pancreas Presenting with Intermittent Duodenal Obstruction in Early Childhood: A Diagnostic Masquerade.

    Rogalidou M, Papagiannis G, Galina P, et al.

    Reports (MDPI) 2026; (9(1)) doi:10.3390/reports9010026.

    PMID: 41562824
  4. 4

    Annular pancreas as a cause of neonatal duodenal obstruction, a case report.

    Gutiérrez-González JA, González De La Torre E, Armijo-Borjón EA, et al.

    Journal of surgical case reports 2023; (2023(7)):rjad407 doi:10.1093/jscr/rjad407.

    PMID: 37489161
  5. 5

    The diagnostic accuracy of ultrasound and upper gastrointestinal contrast studies for locating atresia/stenosis and intestinal malrotation and detecting annular pancreas in pediatric patients with duodenal atresia/stenosis.

    Hosokawa T, Tanami Y, Sato Y, et al.

    Journal of medical ultrasonics (2001) 2022; (49(2)):299-309 doi:10.1007/s10396-021-01176-1.

    PMID: 34988762
  6. 6

    Annular Pancreas in a 13-Year-Old Boy: A Delayed Clinical Presentation of a Congenital Anomaly Highlighting Challenges of Diagnosis.

    Mohamed SS, Mead AO, Nur AO

    International medical case reports journal 2025; (18()):1153-1158 doi:10.2147/IMCRJ.S549637.

    PMID: 40933584
  7. 7

    The Epidemiology of Annular Pancreas in the United States: A Population-based Study.

    Alkhayyat M, Bachour S, Abou Saleh M, et al.

    Journal of clinical gastroenterology 2022; (56(2)):186-191 doi:10.1097/MCG.0000000000001531.

    PMID: 33769394
  8. 8

    From duodenitis to stricture: Decoding the impact of partial annular pancreas over years.

    Alok H, Bansal L, Prasad A

    Abdominal radiology (New York) 2026; (51(4)):1765-1769 doi:10.1007/s00261-025-05194-2.

    PMID: 41369896
  9. 9

    "Partial Annular Pancreas Causing Obstruction of the First Part of the Duodenum: An Exceedingly Rare Conundrum-A Rare Case Report and Comprehensive Literature Review".

    Jha S, Luitel S, Kushwaha N, et al.

    Clinical case reports 2025; (13(7)):e70614 doi:10.1002/ccr3.70614.

    PMID: 40642593
  10. 10

    Adult-Onset Annular Pancreas: When to Intervene?

    Ali IM, Reddy M VS, Shetty V

    Cureus 2024; (16(8)):e67728 doi:10.7759/cureus.67728.

    PMID: 39318953
  11. 11

    A rare cause of vomiting: annular pancreas.

    Şahin Y, Doğan Y, Civan HA, et al.

    Turk pediatri arsivi 2017; (52(4)):236-239 doi:10.5152/TurkPediatriArs.2017.3394.

    PMID: 29483805
  12. 12

    Annular pancreas causing pyloric stenosis in a 66-year-old patient treated with gastrojejunostomy: a case report.

    Patel P, Diko S, Kulkarni S, et al.

    Journal of surgical case reports 2021; (2021(4)):rjab125 doi:10.1093/jscr/rjab125.

    PMID: 33927863
  13. 13

    Annular Pancreas: A Rare Cause of Upper Gastrointestinal Bleeding in Adults.

    Kweun JA, Kang HM, Kim JE, Park SJ

    The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi 2022; (79(4)):182-186 doi:10.4166/kjg.2022.012.

    PMID: 35473777
  14. 14

    [A Case of Surgical Resection of Advanced Gallbladder Cancer with Adult Annular Pancreas].

    Saito T, Matsuo Y, Aoyama Y, et al.

    Gan to kagaku ryoho. Cancer & chemotherapy 2023; (50(4)):520-522.

    PMID: 37066474
  15. 15

    Imaging spectrum of non-neoplastic and neoplastic conditions of the duodenum: a pictorial review.

    Del Toro C, Cabrera-Aguirre A, Casillas J, et al.

    Abdominal radiology (New York) 2023; (48(7)):2237-2257 doi:10.1007/s00261-023-03909-x.

    PMID: 37099183
  16. 16

    A Case of Robot-Assisted Pylorus-Preserving Pancreatoduodenectomy for Branch-Duct Intraductal Papillary Mucinous Neoplasms Complicated With an Annular Pancreas.

    Hayasaki A, Kuriyama N, Usui M, et al.

    Asian journal of endoscopic surgery 2025; (18(1)):e70022 doi:10.1111/ases.70022.

    PMID: 39799733
  17. 17

    Investigation of annular pancreas through multiple detector spiral CT (MDCT) and MRI.

    Zhou Y, Li X

    Journal of applied clinical medical physics 2022; (23(1)):e13487 doi:10.1002/acm2.13487.

    PMID: 34845829
  18. 18

    Adult annular pancreas and its classification under endoscopic ultrasonography.

    Fang L, Zhang L, Hou S

    Revista espanola de enfermedades digestivas 2023; (115(5)):270-271 doi:10.17235/reed.2022.9103/2022.

    PMID: 36148679

This page explains the symptoms of annular pancreas for educational purposes only. Always seek immediate emergency medical care if a newborn exhibits green, bilious vomiting or severe abdominal swelling.

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