Sclerosing Cholangitis

Introduction and Scientific Basis

The role of ERCP in the diagnosis of PSC has become more controversial with the availability of high-quality MRCP ( Box 48.1 ). The latter has the benefit of being noninvasive, but is operator dependent and machine dependent and does not allow therapeutic intervention or cytologic sampling. Furthermore, subtle intrahepatic strictures as the only manifestation of PSC can be missed by MRCP. ERCP is still considered the gold standard and allows sampling and intervention, although it is also dependent on the machine (i.e., the quality of the radiographic equipment) and the operator. In addition, ERCP provides endoscopic staging of portal hypertension through assessment of varices and portal hypertensive gastropathy.

Several studies have compared ERCP and MRCP in patients with clinical or biochemical evidence of cholestasis. MRCP has a comparable diagnostic accuracy of over 90% and a specificity of 99%. However, many patients also require therapeutic intervention.

Description of Technique

The technique for ERCP in PSC does not differ from the standard approach to biliary cannulation and is described elsewhere (see Chapter 14 ). In certain cases, particularly in the setting of prior biliary sphincterotomy and also in the presence of an intact gallbladder, an occlusion cholangiogram is required to fill the intrahepatic ducts, using a stone-extraction balloon to prevent drainage of contrast from the biliary tree or filling of the gallbladder (after passing the balloon above the takeoff of the cystic duct). However, care should be taken to avoid filling of segments of the intrahepatic ducts that subsequently cannot be drained, which increases the risk of infection (cholangitis). The American Society for Gastrointestinal Endoscopy recommends prophylactic antibiotics in cases in which there exists the possibility of opacifying but not draining an obstructed bile duct. This scenario exists for all PSC patients, and we administer antibiotics to all patients immediately before and continue for several days after ERCP.

Indications/Contraindications

Any patient with a clinical picture consistent with cholestasis is a candidate for imaging of the biliary tree. This is especially true for patients with underlying inflammatory bowel disease. The use of ERCP or MRCP will be affected by several factors, as described in preceding sections. If therapy is potentially indicated, then ERCP has the advantage of treating a stricture without the need for an additional test, although MRCP may help in planning a therapeutic intervention.

Secondary causes of biliary sclerosis need to be excluded before a diagnosis of PSC can be confidently made. Biliary surgery, calculi and neoplasms, hepatic artery injury, hepatic arterial chemotherapy, and AIDS can lead to strictures in the biliary tree. Fig. 48.3 illustrates the cholangiogram of a patient several months after intra-arterial chemotherapy with floxuridine (FUDR) with resultant toxic cholangiopathy.

Several processes can mimic PSC on a cholangiogram. IgG4-mediated autoimmune cholangiopathy, hepatic malignancies, polycystic liver disease, infiltrative liver disease, and inflammatory pseudotumors need to be considered. Abdominal computed tomography scan or ultrasonography can differentiate many of these disease entities from PSC.

Complications

The adverse events (AEs) of ERCP in the setting of PSC are typical of those for any other indication and are described in Chapter 8 . There appears to be an increased risk of cholangitis despite the use of prophylactic antibiotics. A recent study examined 294 patients with PSC and 657 ERCPs in a single center over 14 years and noted an overall AE rate of 4.3%, with a 2.4% rate of cholangitis. Performing a biliary sphincterotomy had a fivefold increased risk of adverse events. Comparing 168 patients with PSC and 981 non-PSC patients undergoing ERCP over a 1-year period, Bangarulingam et al. noted no difference in the overall AE rate but a 4% incidence of cholangitis in PSC patients (compared with 0.2% in the non-PSC group), which correlated with the length of the procedure. In comparison to patients with biliary strictures from other diseases, ERCP in PSC patients appears to carry the same overall AE rate in elective cases (13%), but this can increase in cases with an acute indication (29%). In a large Swedish registry study the risk of post-ERCP pancreatitis was doubled in PSC patients compared with non-PSC patients undergoing ERCP.

Relative Cost

Studies examining the relative cost of MRCP versus ERCP in the diagnosis of PSC have been conflicting and are affected by the prevalence of disease and the quality of imaging. One study suggested that the average cost per correct diagnosis by MRCP or ERCP as the initial testing strategy in 73 patients with clinically suspected biliary disease was $724 and $793, respectively. MRCP had a sensitivity of 82% and a specificity of 98%. MRCP thus resulted in cost savings when used as the initial test strategy for diagnosing PSC, particularly as there are essentially no procedure-related adverse events. However, this was in a cohort of patients with a 32% prevalence of PSC and with a very high specificity of MRCP. With a lower MRCP specificity (<85%) and a higher prevalence of PSC (>45%), ERCP becomes more cost-effective, suggesting that ERCP should be used when the suspicion of PSC is high, when local MRCP is suboptimal, and when MRCP is nondiagnostic. The same study illustrated the high cost of dealing with ERCP-related AEs in PSC patients. The average cost of managing post–ERCP-related AEs was $2902, with a range of $1915 to $5032.

A cost-effectiveness analysis suggested that in patients with suspected PSC, an initial negative MRCP followed by ERCP is the most cost-effective method in the workup of these patients.