Tc-99m HIDA cholescintigraphy: the distended photon-deficient gallbladder.

Four patients with distended, photon-deficient gallbladders are presented. Markedly delayed apearance of Tc-99m HIDA in a distended gallbladder may represent chronic cholecystitis, partial obstruction of the common bile duct, or physiologic gallbladder distention. Obtaining delayed images is important in this group of patients to avoid premature diagnosis of cystic-duct obstruction. If the distended gallbladder fails to visualize within 24 hr, hydrops with cystic-duct obstruction is suggested.