Sphincter of Oddi dysfunction (biliary sphincter disorder): symptoms and treatment

Bile, made by the liver and stored in the gallbladder, helps digest fats. Guts UK explains that it travels along the common bile duct, which meets the main pancreatic duct, carrying pancreatic enzymes, at a small shared opening, the ampulla of Vater, where it enters the first part of the small intestine, the duodenum. A small ring of muscle, the sphincter of Oddi, controls the flow by relaxing and contracting at the right time.

If the sphincter does not relax properly, the duct can stay tightly closed or go into spasm. The juices back up and the pressure inside the ducts rises, which can produce attacks of severe abdominal pain and nausea. This is the basis of what used to be called sphincter of Oddi dysfunction (SOD).

Guts UK says that previous Type I, II and III groups have been replaced by a new classification: biliary sphincter stenosis or obstruction, where blood tests and scans show abnormalities; functional biliary sphincter disorder, where some abnormalities are seen but may not warrant invasive treatment; and functional biliary sphincter pain, where tests are normal.

Guts UK says the most common symptom is abdominal pain in the upper right abdomen after eating, with a particular link to fatty foods. It occurs just under the right side of the rib cage, lasts at least 30 minutes, is not improved by bowel movements or changes in posture and can be severe enough to affect daily activities. It may spread round to the back and wake people at night, but it is rarely a daily or constant pain. Other symptoms include nausea, vomiting, weight loss and diarrhoea.

Because pain like this has several explanations, the NHS emphasises caution. The NHS says to ask for an urgent GP appointment or call NHS 111 if you have tummy pain lasting longer than 30 minutes, and to call 999 or go to A&E if you have sudden, severe tummy pain, pain spreading to your back with vomiting, a very high temperature or feeling hot, cold or shivery, or yellow skin or whites of the eyes. These can signal gallstone complications or pancreatitis, which need prompt treatment.

• Upper right tummy pain after meals, especially fatty ones.

• Pain lasting 30 minutes or longer, sometimes waking you at night.

• Nausea, vomiting, weight loss or diarrhoea.

• Pain that returns after gallbladder surgery.

Guts UK says one of the commonest causes of stenosis or obstruction is a gallstone becoming trapped in the common bile duct after being ejected from the gallbladder, which can lead to scarring of the sphincter and duct. Other causes include gallbladder disease and gallbladder surgery, ERCP procedures, pancreatitis and cholangitis.

The causes of the functional types are not always clear. One theory offered by Guts UK for why people who have had gallbladder surgery are more commonly affected is that nerves are damaged during surgery, affecting how the sphincter functions. It also describes how subtle changes in communication between the brain and gut, such as central sensitisation, can amplify pain, and stresses that pain without abnormal scans is no less real.

The NHS describes gallstones as common, and notes that most people with gallstones do not get symptoms; those who do may need surgery to remove the gallbladder. Guts UK estimates that up to 5 to 10 per cent of people who have the operation go on to have long-term symptoms.

Guts UK lists the tests used: blood tests for liver enzymes (AST, ALT, ALP) and pancreatic enzymes (lipase, amylase), and imaging such as abdominal ultrasound, CT, endoscopic ultrasound and MRI, including MRCP, which images the bile and pancreatic ducts. A HIDA scan can follow the flow of bile from the liver to the small intestine.

For biliary sphincter stenosis, blood tests show raised liver or pancreatic enzymes during or soon after a painful attack, and scans show a widened bile or pancreatic duct. For the functional types, diagnosis may follow either raised enzymes or a dilated duct, or, for functional sphincter pain, normal tests after other serious conditions have been ruled out. Guts UK says that if pain continues after gallbladder surgery the possibility of a biliary sphincter disorder should be investigated.

Guts UK stresses that treatment depends on the type. People with stenosis or obstruction may be offered ERCP with sphincterotomy, in which a small cut is made in the sphincter, or balloon dilation or a stent. It notes that cutting the sphincter can cause inflammation of the pancreas (post-ERCP pancreatitis), so a stent may be placed to keep the duct open while inflammation settles.

Guts UK recognises that ongoing symptoms with no clear cause can cause major upset and feelings of hopelessness, and encourages people to tell their doctor so support can be organised. It says that if symptoms of the functional types are well controlled, regular follow-up is not necessarily needed, but that symptoms often come and go, in which case regular review is useful.

Keeping a food and symptom diary helps you and your clinician see patterns. Do not stop prescribed medicines without advice. It is also worth asking whether a referral to a specialist unit is appropriate if an ERCP is being considered, as Guts UK suggests.

On the NHS, a GP usually arranges initial blood tests and scans, with referral to gastroenterology or hepatobiliary services for more specialised tests and ERCP. Because the procedures carry a risk of pancreatitis and the evidence for benefit differs by type, decisions are made individually and are often discussed by a specialist team.

Private gastroenterology is available for those who want faster access to scans or ERCP, or a second opinion. Whichever route you take, ask which classification you fall into, what benefit is expected from any procedure, what the risks are and what the alternatives are.