Sphincter of Oddi Disorder

Sphincter of Oddi disorder is a functional or structural abnormality (dysfunction or stenosis) of the muscular sphincter controlling flow of bile and pancreatic juice into the duodenum.

• Biliary type presents with biliary-type pain; pancreatic type with recurrent pancreatitis-like pain.
• It is most common in women aged 30 to 50 years, often after cholecystectomy (the postcholecystectomy pain syndrome).
• Risk factors: previous cholecystectomy, chronic pancreatitis, pancreas divisum, ampullary stenosis, opioid use, HIV, and microlithiasis.

Episodic severe epigastric or right upper quadrant pain lasting 30 minutes or longer, building to a plateau, radiating to the back or shoulder, sometimes with nausea and vomiting, not relieved by bowel movement, antacids or posture.

• Transient rises in liver enzymes (above twice the upper limit of normal on two occasions) and dilated common bile duct (above 8 mm) during pain define the strongest biliary subgroup.
• Differential diagnosis: retained or recurrent common bile duct stones, biliary sludge, chronic pancreatitis, peptic ulcer disease, functional dyspepsia, irritable bowel syndrome, gastroparesis, mesenteric ischaemia, ampullary tumour, opioid-induced biliary spasm, cholecystitis.
• Complications: recurrent acute pancreatitis, chronic pancreatitis, ascending cholangitis, chronic opioid dependence, psychosocial disability and repeated hospital admissions.

Diagnosis is by exclusion.

• Liver profile and lipase during an attack; fasting and between attacks.
• Ultrasound, MRCP (with secretin enhancement where available) and endoscopic ultrasound exclude stones, strictures, masses and pancreatic disease; upper endoscopy excludes peptic disease.
• Sphincter of Oddi manometry (basal pressure above 40 mmHg) is the reference but carries a pancreatitis risk of 10 to 20 percent and is used only in expert centres.
• Hepatobiliary scintigraphy with cholecystokinin is of limited accuracy.
• Psychological assessment, opioid history.

Supportive: reassurance, small low fat meals, avoid opioids, treat anxiety and depression, regular follow-up.

Pharmacological

• Smooth muscle relaxants: nifedipine 10 to 20 mg orally (or sublingually) three times daily, hyoscine butylbromide 10 to 20 mg three times daily, isosorbide dinitrate 5 mg sublingually during attacks, peppermint oil capsules.
• Neuromodulators for chronic pain: amitriptyline 10 to 25 mg at night increasing to 50 mg, gabapentin 300 mg daily increasing to 900 to 1800 mg daily in divided doses.
• Analgesia for severe pain: paracetamol 1 g every 6 hours; opioids are avoided because they raise sphincter pressure.

Procedures

• Endoscopic sphincterotomy (biliary) for patients with objective abnormality (abnormal enzymes and dilated duct); with a pancreatic stent and rectal indomethacin 100 mg before or after the procedure to lower post-procedure pancreatitis.
• Sphincterotomy offers no benefit when pain is the only abnormality; avoid.
• Botulinum toxin injection (100 units into the sphincter) in selected cases.
• Surgical transduodenal sphincteroplasty for failed endoscopic therapy or papillary stenosis.

Special groups: women with prior cholecystectomy (most affected), patients with chronic opioid use (detoxification), pancreatic-type disease (pancreatic duct sphincterotomy in specialist centres).

Red flags: fever with jaundice, rising lipase above three times the upper limit of normal, weight loss, new dilated ducts, mass lesion.

Follow-up: pain diary and review every 3 months; stop ineffective drugs after 6 to 8 weeks; refer for pain management and psychology if persistent.