M*A*S*H (1972)

S1E21 Sticky Wicket

Hawkeye and Frank get into a heated debate about Frank's skills as a surgeon. After Hawkeye undertakes a challenging surgery, the patient surprisingly fails to survive, leading Hawkeye to question his own competence. Feeling overwhelmed, he decides to leave The Swamp. Later, he re-examines the patient and finds a small nick in the colon that even Frank concedes could easily have been overlooked.