Major Duodenal Papilla

The major duodenal papilla is a small but critical anatomical structure located in the second part of the duodenum. It marks the opening where the common bile duct and the main pancreatic duct empty their contents into the gastrointestinal tract. This papilla is the site of the hepatopancreatic ampulla (ampulla of Vater) and is regulated by the sphincter of Oddi. Despite its small size, the major duodenal papilla plays a central role in digestive physiology and is a common site of disease processes, including choledocholithiasis, pancreatitis, and ampullary tumors. It also serves as a key target in endoscopic procedures such as ERCP (Endoscopic Retrograde Cholangiopancreatography).

Structure

The major duodenal papilla is a conical or dome-shaped elevation on the medial wall of the second portion of the duodenum. It is formed where the hepatopancreatic ampulla pierces the mucosa. Structurally, it contains the junction of the biliary and pancreatic systems and is surrounded by smooth muscle fibers constituting the sphincter of Oddi.

Anatomical Components

Component	Description
Common bile duct	Delivers bile from the liver and gallbladder
Main pancreatic duct (duct of Wirsung)	Delivers pancreatic enzymes
Hepatopancreatic ampulla (ampulla of Vater)	Fused terminal segment of both ducts just before entry into the duodenum
Sphincter of Oddi	Circular smooth muscle regulating the flow of bile and pancreatic juice

The ampulla may vary anatomically — in about 10–15% of people, the common bile duct and pancreatic duct enter the duodenum separately, without forming a true ampulla.

Dimensions

• Length: 1–1.5 cm (ampulla)
• Diameter of papilla: 2–5 mm protrusion into the duodenal lumen

Location

The major duodenal papilla is located in the posteromedial wall of the descending (second) part of the duodenum. It lies roughly halfway between the pylorus and the duodenojejunal flexure.

Topographic Details

• Region: Second (descending) part of the duodenum
• Level: Approximately at L2 vertebral level
• Medial to: The lumen of the duodenum
• Posterior to: The pancreas head and common bile duct
• Landmark: Located about 7–10 cm distal to the pylorus

It serves as a useful endoscopic landmark and is the primary access point for diagnostic and therapeutic procedures targeting the biliary and pancreatic ducts.

Function

The major duodenal papilla is the anatomical gateway for bile and pancreatic juice to enter the duodenum. These secretions are essential for digestion and pH regulation of chyme entering from the stomach.

Bile and Enzyme Delivery

• Bile: Emulsifies fats and aids in absorption of fat-soluble vitamins
• Pancreatic enzymes: Break down proteins, carbohydrates, and fats

Sphincter of Oddi Regulation

The flow through the papilla is controlled by the sphincter of Oddi, which has three distinct parts:

• Sphincter choledochus: Surrounds the terminal bile duct
• Sphincter pancreaticus: Surrounds the terminal pancreatic duct
• Sphincter ampullae: Surrounds the common ampullary chamber (if present)

These sphincters open in response to hormonal signals (like cholecystokinin) and vagal stimulation during digestion. During fasting, the sphincter remains closed, diverting bile into the gallbladder for storage.

Clinical Relevance

The major duodenal papilla is implicated in various pathological conditions and is a central focus in gastrointestinal and hepatobiliary interventions.

1. Choledocholithiasis

• Definition: Presence of gallstones in the common bile duct
• Impact: Stones may lodge at the ampulla, causing biliary obstruction
• Symptoms: Jaundice, biliary colic, cholangitis

2. Acute Pancreatitis

Obstruction or dysfunction at the level of the major papilla can lead to backflow of pancreatic secretions, triggering pancreatitis. This is especially true when gallstones obstruct the common channel shared by bile and pancreatic ducts.

3. Ampullary Tumors

• Ampullary adenoma or carcinoma: Tumors can arise directly from the epithelial lining of the papilla
• Presentation: Often causes painless jaundice due to bile duct compression
• Diagnosis: Endoscopic biopsy via ERCP or endoscopic ultrasound (EUS)
• Treatment: May require local resection or pancreaticoduodenectomy (Whipple procedure)

4. ERCP and Papillotomy

The major papilla is the access point for endoscopic retrograde cholangiopancreatography (ERCP), which is used to:

• Inject contrast into bile or pancreatic ducts
• Extract stones from the bile duct
• Place stents across narrowed ducts
• Perform a sphincterotomy (cutting the sphincter) to improve drainage

5. Sphincter of Oddi Dysfunction (SOD)

This functional disorder involves inappropriate or uncoordinated contraction of the sphincter, leading to:

• Biliary-type pain without stones
• Transient elevation in liver or pancreatic enzymes
• Diagnosed via manometry (pressure studies during ERCP)

It is treated with endoscopic sphincterotomy if conservative management fails.