This document discusses acute cholecystitis, including its pathogenesis, clinical manifestations, and diagnosis. It notes that acute cholecystitis is usually caused by gallstone-induced cystic duct obstruction and gallbladder wall irritation. Clinical features include right upper quadrant pain, fever, and leukocytosis. Diagnosis involves imaging like ultrasound showing gallbladder wall thickening or a positive "sonographic Murphy's sign." Cholescintigraphy can also confirm diagnosis by showing gallbladder non-filling.