Accessory bile ducts draining into ectopic sites were first reported in the 16th century by Vesarius (1543), and the first case report of common bile duct (CBD) drainage into the pylorus was published by Quintana and Labat.¹ Ectopic biliary drainage can be classified as either proximal or distal to the normal ampullary opening on the posteromedial wall of the second part of the duodenum. Distal ectopic sites include the third or fourth parts of the duodenum, while proximal sites encompass the duodenal bulb, pyloric channel, and gastric antrum. Bile stasis and the reflux of acidic gastric contents into the biliary tree predispose individuals to biliary complications. During endoscopic retrograde cholangiopancreatography (ERCP), the absence of the ampulla at its typical location should alert the clinician to the possibility of ectopic biliary drainage sites. A conventional forward-viewing gastroscope can aid in identifying the ectopic ampulla, and biliary interventions can be performed using either a therapeutic gastroscope or a standard duodenoscope. Endoscopic therapy is often the first line of management, with surgical options such as hepaticojejunostomy, ligation, or reinsertion of the accessory bile ducts into the duodenum reserved for patients with recurrent complications.

A 69-year-old man was referred to our facility by a general physician for ERCP. He had been experiencing right upper quadrant (RUQ) pain, fever, anorexia, nausea, and jaundice for the past week. His past medical, family, and social histories were unremarkable, with no history of chronic drug use. Upon admission, he presented with a fever of 38.6°C, tachycardia (with a heart rate of 101 beats per minute), a respiratory rate of 22 breaths per minute, and a blood pressure of 112/84 mmHg. Clinically, he appeared icteric and exhibited tenderness in the RUQ. Blood tests revealed neutrophilic leukocytosis of 28,000/mL (normal range: 4,000–11,000/mL) and abnormal liver biochemistry, including an elevated alanine transaminase level of 175 IU/mL (normal range: < 40 IU/mL), direct hyperbilirubinemia of 35 µmol/L (normal range: 1–15 µmol/L), and an alkaline phosphatase level of 396 IU/mL (normal range: < 140 IU/mL). Transabdominal ultrasonography indicated intrahepatic biliary radicle dilatation and a CBD diameter of 15 mm, along with multiple filling defects within the CBD. Contrast-enhanced computed tomography of the abdomen revealed a CBD diameter of 17 mm and multiple hyperdense rounded densities, suggestive of choledocholithiasis. An initial attempt at ERCP was unsuccessful due to difficulty in locating the papilla, prompting the use of magnetic resonance cholangiopancreatography (MRCP). MRCP revealed multiple stones in the mid-CBD and thickening of the CBD wall, indicative of cholangitis (Fig. 1). During a subsequent ERCP attempt, the ampulla of Vater was not visualized in the second portion of the duodenum. A small pool of bile was observed in the antropyloric region, but no bile was present in the duodenum. This finding, along with the absence of the papilla at its normal anatomical location, raised the suspicion of an ectopic biliary opening. Using a regular gastroscope, an ectopic biliary orifice was visualized in the pyloric channel (Fig. 2). The gastroscope was then exchanged with a duodenoscope to facilitate the passage of instruments. A sphincterotome with a 0.035-in wire was inserted into the orifice, which was draining bile, achieving deep cannulation of the CBD (Fig. 3A). A cholangiogram revealed a dilated CBD (< 15 mm) with multiple filling defects and a “hook-shaped” distal CBD (Fig. 4), consistent with an ectopic ampulla within the pylorus (Kanematsu type 1). A 3-mm limited sphincterotomy was performed at the ampullary orifice, followed by balloon dilation to 15 mm for 60 seconds under endoscopic and fluoroscopic guidance (Fig. 3B). Following dilation, no bleeding from the ampullary orifice was observed. The bile duct stones were successfully extracted using a balloon catheter (Fig. 3C), and a double pigtail plastic biliary stent was placed to treat the cholangitis (Fig. 3D). Following ERCP, the patient’s condition markedly improved, and his blood parameters normalized. He later underwent laparoscopic cholecystectomy, followed by biliary stent removal, and has been doing well throughout 3 months of follow-up.

Figure 1. MRCP 3D reconstruction displaying central IHBRD and calculi within the mid-CBD (dotted circle). Note the hook-shaped configuration of the most distal portion of the CBD (arrow). MRCP, magnetic resonance cholangiopancreatography; 3D, three-dimensional; IHBRD, intrahepatic biliary radicle dilatation; CBD, common bile duct.

Figure 2. Endoscopic image of the pre-pyloric region. An ectopic ampullary opening (dotted circle) is evident just proximal to the pylorus (arrow), with an adjacent linear ulcer (star).

Figure 3. (A) Cannulation of the ectopic ampulla in the stomach using a standard sphincterotome. (B) CRE balloon dilation of the ectopic ampullary opening. (C) Retrieval of large bile duct stones and sludge via balloon trawling. (D) Placement of a plastic double pigtail biliary stent through the distal stomach. CRE, controlled radial expansion.

Figure 4. (A) Cholangiogram displaying the characteristic hook-shaped configuration of the distal bile duct (arrows) and multiple filling defects within the mid-CBD. (B) Cholangiogram following balloon sweep. CBD, common bile duct.

Informed consent was obtained for this case report. Institutional and ethical approval was not required for this case report.

Ectopic biliary drainage is characterized by the termination of the ampulla of Vater at aberrant sites, including the stomach, pyloric canal, duodenal bulb, and the third or fourth portion of the duodenum.² A retrospective study of 6,133 ERCPs in Taiwan revealed an incidence of 0.13% for this condition,² while a Turkish study by Disibeyaz et al³ involving 12,158 ERCPs reported an incidence of 0.43%. In Korea, an analysis of 16,541 ERCPs found the incidence to be 0.10%.⁴ Two case series by Lee et al⁴ and Lee et al⁵ demonstrated a clear male predominance in the fourth and fifth decades of life. The exact etiology of this congenital anomaly is not fully understood, but it is thought to result from an abnormality during the embryonic developmental period. In the fourth week of development, the liver begins to form as a ventral bud known as the hepatic diverticulum, emerging from the caudal part of the foregut. This bud extends into the septum transversum, separating into two parts: the smaller caudal portion becomes the gallbladder, and the stalk of the diverticulum forms the cystic duct. The stalk that connects the hepatic and cystic ducts to the duodenum evolves into the bile duct, which opens on the ventral aspect of the duodenum.⁶ Also during the fourth week, a projection forms on the ventral wall of the primitive midgut at the level of the primitive duodenum. The cranial bud of this projection develops into two lobes of the liver, while the caudal bud gives rise to the gallbladder and the extrahepatic biliary tree. It is theorized that an earlier division of the hepatic diverticulum into the pars hepatica and pars cystica, as proposed by the Boyden⁷ theory, could cause the CBD to empty into locations other than its usual site. The most frequent site of ectopic biliary drainage into the stomach is the corpus, followed by the antrum and cardia. Ectopic drainage into the third and fourth parts of the duodenum is exceedingly rare and has been associated with conditions such as pancreatic divisum and long common channel anomaly.⁸ Congenital anomalies associated with ectopic drainage of the biliary tract are further categorized into four types according to the Kanematsu classification (Table 1).⁹

Table 1 . Kanematsu classification⁹.

Kanematsu type	Anatomical anomaly
Type 1	Single septated duct draining into the stomach
Type 2	Division of the CBD into 2 junctions: a normal papillary position and a second position with an opening in the stomach
Type 3	Two independent ducts draining into the normal papilla and stomach
Type 4	Two independent ducts draining into the normal papilla and stomach, along with intercommunications

CBD, common bile duct.

The differential diagnosis for this condition includes fistula secondary to peptic ulcer disease or choledocholithiasis. Additionally, spontaneous or iatrogenic surgical fistula and surgical choledochoenteric diversion should be excluded.¹⁰ Problems associated with ectopic biliary drainage include an elevated risk of choledocholithiasis due to anomalous bile drainage and the hook-shaped configuration of the distal CBD.¹¹ A lack of sphincter control can facilitate the reflux of gastric contents into the biliary tree, leading to biliary tree injury or cholangitis. Pancreatobiliary secretions can also cause mucosal damage and ulcer formation.¹¹ The clinical presentation may include gallstones, choledocholithiasis, obstructive jaundice, cholangitis, pancreatitis, and peptic ulcer. Additionally, bile reflux gastritis, atrophic gastritis, and (rarely) gastric adenocarcinoma may occur.⁸ Diagnosis can be established through percutaneous transhepatic cholangiography, upper gastrointestinal endoscopy, ERCP, MRCP, and barium meal.⁶ In two studies of 18 and eight patients with ectopic biliary insertions, computerized tomography revealed no specific findings.^4,5 Treatment of ectopic biliary drainage is guided by the biliary symptomatology and any associated peptic ulcer complications.¹² Cholangitis must be treated promptly, with efforts made to prevent recurrent episodes.¹² Surgery is often considered the last resort after failed endoscopic therapy or recurrent complications. Surgical options include choledochoenterostomy, choledochotomy, hepaticojejunostomy, and, in rare cases, pancreatoduodenectomy.

In conclusion, if the ampulla is not visible in its usual anatomical location, the possibility of ectopic ampulla should be considered, and the endoscopist should carefully examine the stomach and duodenum. A standard forward-viewing gastroscope may be employed for improved visualization of the stomach. Large sphincterotomy should be avoided due to the high risk of perforation. To remove large bile duct stones, ampullary balloon dilation is advised. The presence of peptic ulcer disease or gastric outlet obstruction resulting from a peptic ulcer, accompanied by cholangitis or cholestasis, should raise the suspicion of ectopic papilla.

None.

The data that support the findings of this study are available from the corresponding author upon reasonable request.

No potential conflict of interest relevant to this article was reported.