<prompt> Causes of Acalculous cholecystitis are the following exceptBile duct strictureSchistosomiasisProlonged TNPMajor operations  <response>: Ans. b SchistosomiasisRef: Sabiston Page 1508, 20th editionRisk factors of Acalculous cholecystitis: Old age Critical illness Burns Prolonged TPN Major operations Diabetes Immunosuppression 