Sphincter of Oddi dysfunction

Sphincter of Oddi Dysfunction

Diagram of the hepato-biliary system, including the Sphincter of Oddi.

Sphincter of Oddi Dysfunction (SOD) is a condition affecting the sphincter of Oddi, a muscular valve that controls the flow of digestive juices, such as bile and pancreatic juice, through the ampulla of Vater into the duodenum. This dysfunction can lead to abdominal pain, jaundice, and pancreatitis.

Anatomy and Physiology

The sphincter of Oddi is located at the junction where the common bile duct and the pancreatic duct meet before emptying into the duodenum. It plays a crucial role in regulating the flow of bile and pancreatic juices, preventing the backflow of intestinal contents, and coordinating the release of these digestive fluids during digestion.

Types of Sphincter of Oddi Dysfunction

SOD is classified into three types based on the clinical presentation and the results of diagnostic tests:

Type I

Type I SOD is characterized by biliary-type pain, elevated liver enzymes, and dilated bile ducts. It is the most severe form and often requires intervention.

Type II

Type II SOD presents with biliary-type pain and either elevated liver enzymes or dilated bile ducts, but not both.

Type III

Type III SOD involves biliary-type pain without any objective findings of elevated liver enzymes or dilated bile ducts. It is the most challenging to diagnose and treat.

Symptoms

Patients with SOD may experience:

• Recurrent episodes of severe abdominal pain, often in the upper right quadrant or epigastric region.
• Nausea and vomiting.
• Jaundice, due to bile duct obstruction.
• Pancreatitis, if the pancreatic duct is involved.

Diagnosis

The diagnosis of SOD can be challenging and often involves:

• Endoscopic retrograde cholangiopancreatography (ERCP) with sphincter of Oddi manometry to measure the pressure within the sphincter.
• Magnetic resonance cholangiopancreatography (MRCP) as a non-invasive imaging alternative.
• Blood tests to check liver function and pancreatic enzymes.

Treatment

Treatment options for SOD include:

• Medications such as calcium channel blockers or nitrates to relax the sphincter.
• Endoscopic sphincterotomy, a procedure to cut the sphincter and relieve obstruction.
• Botulinum toxin injections to temporarily relax the sphincter.
• Surgical options in severe cases.

Prognosis

The prognosis for patients with SOD varies depending on the type and severity of the condition. Type I SOD often responds well to endoscopic treatment, while Type III SOD may require a more conservative approach due to the lack of objective findings.

Related Pages

• Biliary dyskinesia
• Pancreatitis
• Cholecystitis
• Gallstones