The calculator in question is the Clinical Diagnostic Criteria of IgG4-Related Sclerosing Cholangitis. This diagnostic tool is used specifically for patients suspected of having IgG4-Related Sclerosing Cholangitis, a chronic fibroinflammatory disease that can lead to biliary strictures mimicking cholangiocarcinoma or primary sclerosing cholangitis.

The clinical utility of this calculator is to aid in the diagnosis of IgG4-Related Sclerosing Cholangitis, which can be challenging due to its similar presentation to other biliary diseases. The criteria include clinical, laboratory, imaging, and histopathological features, and a diagnosis can be made based on a combination of these.

Exclusion criteria for its use would be patients who do not present with symptoms of biliary disease or those who have confirmed diagnoses of other conditions that could cause similar symptoms, such as cholangiocarcinoma or primary sclerosing cholangitis. It's also important to note that this calculator should be used in conjunction with other diagnostic tools and clinical judgment, as it is not definitive on its own.

Clinical diagnostic criteria of IgG4-related sclerosing cholangitis

# Criteria
 A. Diffuse or segmental narrowing of the intrahepatic and/or extrahepatic bile duct associated with thickening of bile duct wall on biliary tract imaging
B. Elevated serum IgG4 levels (>= 135 mg/dL)
C. Coexistence of autoimmune pancreatitis, IgG4-related dacryoadenitis/sialadenitis, or IgG4-related retroperitoneal fibrosis
D. Marked lymphocytic and plasma cell infiltration and fibrosis
E. Infiltration of IgG4-positive plasma cells (> 10 IgG4-positive plasma cells/hpf)
F. Storiform fibrosis
G. Obliterative phlebitis
H. Effectiveness of corticosteroid therapy

# Conditions
- A and C
- A and B and D and E
- D and E and F
- D and E and G
- A and B and H
- A and B
- true