The Gem Brochos 54b says
ארבעה צריכין להודות:יורדי הים, הולכי מדברות ומי שהיה חולה ונתרפא ומי שהיה חבוש בבית האסורים
Four types of people have to give thanks … sick people who were healed
Medical practice includes prophylactic procedures. Surgery, for example, can be instituted to remove a potential threat to the patient's health even though the patient exhibits no symptoms now.
Is there discussion in the poskim whether a prophylactic procedure on a patient without symptoms is sufficient cause to necessitate “bensching gomel” = Blessing of Thanksgiving ?