OVERVIEW
Sphincter of Oddi dysfunction (SOD) is a persistent narrowing or abnormally high tension of the bile duct or pancreatic duct sphincter, causing a benign, nonstrumental, obstructive dysfunction of the sphincter, leading to pancreatic and biliary pain, cholestasis, or pancreatitis. The underlying lesions include inflammation, fibrosis, smooth muscle hypertrophy, or endothelial ectasia in the papillary region, mostly due to its structural changes or simple smooth muscle dysfunction. It is more common in women than in men. This disease has a great impact on the patient’s quality of life, and in severe cases, it can lead to the patient’s activities, disability, etc. This disease is difficult to diagnose, so it is more important to pay attention to the study of this disease.
Causes
1.Injury
Gallstones, surgery and endoscopic operation can damage the sphincter of Oddi, causing inflammatory reaction and muscle fibrosis.
2. Infection
Infected bile can cause duodenal papillitis. Infection with cytomegalovirus or nematode-like bacteria may also cause the disease.
3. Inflammation and tumors
Inflammation and tumors, such as those of the pancreas or duodenum, may also cause sphincter of Oddi dysfunction.
Symptoms
The disease can occur at any age and is more common in middle-aged women. Since the sphincter of Oddi is located at the confluence of the common bile duct, main pancreatic duct and duodenum, sphincter of Oddi dysfunction can manifest as either biliary or pancreatic type, with the biliary type being the most common.
1. Biliary tract type
The main manifestation of biliary pain is pain in the epigastrium or right epigastric pain, which may radiate to the back or right intra-scapular region, accompanied by nausea and vomiting, lasting more than 20 minutes. The pain may come on after a meal or wake up with pain at night. The pain may be paroxysmal or persistent with paroxysmal increases. On examination, there may be mild pressure pain in the epigastrium or right upper abdomen. The onset of pain is often accompanied by temporary elevation of serum aminotransferases, direct bilirubin and alkaline phosphatase.
2. Pancreatic type
Pancreatic type is less common. Patients sometimes present with recurrent episodes of pancreatitis or pancreatogenic pain with elevated amylase or lipase. The pain may be partially relieved by bending the patient’s torso forward.
Examination
1. Laboratory tests
Serum aminotransferases, direct bilirubin and alkaline phosphatase may be temporarily elevated during painful episodes of the disease.
2. Fasting ultrasound
Under normal circumstances, fasting ultrasound shows that the diameter of the common bile duct is ≤6 mm, and dilatation of the common bile duct indicates that the sphincter of Oddi has increased resistance and bile outflow is impeded. However, in some cholecystectomized patients, the symptoms disappear after surgery, and the common bile duct appears to have compensatory dilatation. it is difficult to recognize a normal-sized pancreatic duct on ultrasound. If the lumen of the main pancreatic duct is clearly seen on ultrasound, it means that the resistance of sphincter of Oddi is increased and the flow of pancreatic juice is obstructed.
3. Bile duct scintigraphy
It is capable of evaluating the flow of bile through the bile ducts after cholecystectomy.
4. Endoscopic retrograde cholangiopancreatography
It can directly visualize the duodenal papilla and can exclude clinical symptoms due to obstruction of the pancreatic and biliary system by stones and tumors.
5. Endoscopic Sphincter of Oddi Yang Pressure Measurement
Manometry can directly measure the pressure of the biliary and pancreatic ductal segments of the sphincter, which is currently the most direct and effective means of examination. However, the pressure recording time is relatively short, and it is susceptible to factors such as preoperative medication, the presence of endoscopy in the duodenum, and intraoperative gas injection.
Diagnosis
Diagnostic criteria for sphincter of Oddi dysfunction:
1. moderate or severe biliary or pancreatic pain in the epigastrium or right upper abdomen lasting 20 minutes or more with recurrent episodes for at least 3 months, or recurrent episodes of acute pancreatitis.
2. temporary elevation of serum transaminases, direct bilirubin and alkaline phosphatase. Dilatation of the bile duct or pancreatic duct.
3. other organic pathology excluded by imaging and endoscopic retrograde cholangiopancreatography.
Currently, SOD is classified into 3 types, Type I SOD:i.e., papillary stenosis type, which is associated with the formation of papillary sphincter fiber stenosis.Clinical features include pain, bile duct dilatation, and painful episodes accompanied by hepatic abnormalities, such as elevated transaminases, transketolase, alkaline phosphatase, etc.ERCP showed dilatation of the common bile duct, smooth stenosis at the lower end of the duct in the shape of a bird’s beak, and delayed emptying of the contrast medium. According to Milwaukee’s diagnostic criteria, the diagnosis can be made if the following criteria are met: ① typical biliary colic; ② AST should be 2 times higher than normal at the onset of more than 2 episodes; ③ diameter of bile duct dilatation is more than 1.2cm; systolic blood pressure of sphincter of Oddi is more than 40mmHg; although it is believed that the most effective diagnostic method is endoscopic sphincter of Oddi manometry, the equipment and technical requirements are very high, and the examination is not widely carried out in clinic at the moment. Although the most effective diagnostic method is endoscopic Oddi sphincter manometry, its equipment and technical requirements are very high and it is not widely carried out in clinic, and the test can easily lead to pancreatitis, so type I SOD can be directly performed papillary sphincterotomy without manometry, and the efficiency can reach more than 90%. type II clinical symptoms, liver enzymology and bile duct changes are not as typical as type I, and some people think that it is the middle stage of SOD, between type I/III, and it belongs to the dysfunction or early fibrosis, and it is better to perform the measurement of the pressure of sphincter before sphincterotomy. Sphincter pressure measurement, typical episodes of biliary colic with increased enzymology can be empirically papillotomy. type III SOD, i.e., dysfunctional type, is mainly caused by spasm, incoordinated movement or dysfunction of the papillary sphincter, usually only clinical symptoms, but no hepatic enzymological changes and bile duct dilatation, but this type is rare in the clinic. type III SOD, if biliary pressure measurement is normal, only 10% of the patients with normal pressure measurement will have an effective papillotomy. If papillotomy is normal, only 10% of patients will be effective after papillotomy; when papillotomy is abnormal, 60% of patients will be effective for papillotomy treatment, so patients with this type should be examined for bile duct pressure before treatment.
Treatment
The principle of treatment for sphincter of Oddi dysfunction is to reduce the resistance of sphincter of Oddi to the discharge of bile and pancreatic fluid, with the aim of relieving epigastric pain.
1. General treatment
Pay attention to rest, avoid emotional fluctuations, pay attention to the regularity of life, and suggest a low-fat diet to reduce the stimulation of pancreas and bile.
2.Medication
For patients with type II moderate pain and type III sphincter of Oddi dysfunction, medication should usually be preferred before attempting aggressive endoscopic or surgical treatment. Patients with sphincter of Oddi dysfunction in type I and type II severe pain respond poorly to pharmacologic therapy; therefore, pharmacologic therapy is an optional option. Nitroglycerin reduces basal Sphincter of Oddi pressure in healthy volunteers and in patients with biliary dyskinesia, and calcium channel blockers reduce Sphincter of Oddi pressure and decrease the amplitude, duration, and frequency of temporal contractions.
3. Sphincterotomy
There are two approaches to sphincterotomy: endoscopic or transduodenal surgery. Endoscopic sphincterotomy is the most common treatment for patients with biliary sphincter dysfunction. It is easily accepted by patients and has a lower complication rate than open surgery. Currently, open surgery is mainly used in patients with restenosis after endoscopic treatment and in those who do not have access to endoscopy or treatment, or in whom endoscopic treatment is unsuccessful. It is a commonly used and effective treatment method.