Nothing is an offense which is done by accident or misfortune and without any criminal intention or knowledge in the doing of a lawful act in a lawful manner by lawful means and with proper care and caution. 

Accident here refers to something that occurs without the prior knowledge or intention of causing the evil effect. For instance, postpartum hemorrhage (PPH) is a complication of cesarean section delivery. Sometimes, PPH may not respond to usual treatment and may lead to death. So, in such instances where death is unintended, one cannot hold the doctor liable if he took all precautions and treated the complications in time.