In-vitro Contracture Test (IVCT) is the only widely accepted diagnostic test for MH. It is nearly 100% sensitive. This is done to minimize false negatives. Although MH is rare, it is a potentially fatal syndrome if not recognized and treated early. Therefore, a false negative muscle biopsy in a true MH susceptible patient has catastrophic consequences that can result to high morbidity and mortality. IVCT is 85% specific. Therefore, there are false positives. The test may be positive occasionally with other myopathies or muscle disorders that have no direct relationship with MH. (to read more on improvement of the predictive value of this test refer to the article by Loke, JC in Anesthesiology (19).