Sphincter dysfunction is usually only considered in patients with severe attacks of pain persisting or recurring after gall bladder surgery (cholecystectomy), and in whom standard tests show no evidence for structural causes, such as a small tumor, or perhaps a stone. Initial investigations: Blood is drawn to check on liver and pancreas tests (particularly alkaline phosphatase, transaminases and amylase/lipase). Standard ultrasound and CT scans are used to look for structural causes, but are not completely accurate. When these are unrevealing, most experts recommend other imaging procedures, such as Magnetic Resonance Cholangiopancreatography (MRCP) and Endoscopic Ultrasound (EUS). One of these should be used before considering more invasive and risky procedures like ERCP. Another test (HIDA scanning) is sometimes used to detect poor emptying of the bile duct due to sphincter activity, and BOTOX injection into the sphincter has been explored as a test for over-activity. The suspicion that the sphincter may be overactive and causing pain is greater if the scans and/or blood tests show some evidence of obstruction to the bile duct. Indeed, SOD is divided into two types. Type I consists of patients with troublesome biliary-type pain, a bile duct greater than 9mm in diameter, and elevated liver tests. Type II patients have a dilated duct or liver test abnormalities, but not both. There used to be a Type III —patients with pain but none of those findings— but a recent study (EPISOD) showed that such patients do not respond to cutting the sphincter. Type I and II patients are usually advised to undergo ERCP, with or without measurement of the sphincter pressures, by Sphincter of Oddi Manometry (SOM), and are often treated by cutting the sphincter (sphincterotomy). The prior type III patients (with pain only) should not be offered ERCP, except perhaps in a research study with fully informed consent. For ERCP (and while the patient is under sedation or anesthesia), a doctor passes a special flexible endoscope down the throat and into the duodenum. The purpose of this procedure is to examine the drainage hole of the bile duct at the papilla of Vater. Locating the Sphincter of Oddi is often difficult, as it may be tightly closed, and sits in the folds of the duodenum. Once it is located, dye may be injected into the bile duct and pancreatic duct to double-check for stones and other forms of obstruction. The possibility of sphincter spasm (dysfunction) is tested during the ERCP by measuring the squeeze pressure in the sphincter, with manometry (SOM). SOM is performed only in special referral hospitals. Like all types of ERCP examination, there are risks, particularly the chance of suffering an attack of pancreatitis. For this reason, ERCP in this context is usually done only after other simpler tests have been exhausted.
Posted on: Wed, 22 Oct 2014 18:14:37 +0000
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