Extracranial/intracranial bypass to reduce the risk of stroke, was first introduced in 1967 and widely adopted by the mid-1970s. In 1987, findings of a random trial of 1,377 patients found no discernible difference in the incidence of strokes between patients who had received operations and those given aspirin. Carotoid endarterectomy, the surgical removal of the diseased inner layer of the artery in patients with varying degrees of stenosis (narrowing of the arteries), is also a procedure designed to prevent strokes. A European study found that in severe forms of stenosis, each ten operations might prevent two strokes and cause one.
The development in 1988 of laparoscopes, surgical devices which can be used to conduct operations without cutting open the body, has started a fashion in laparoscopy. Because the surgery is "blind" (aided by small internal cameras), in the hands of the inexperienced, vital arteries or organs can be damaged. Without thorough checking, bits of gallstone can be left behind and block the bile duct. Another concern is that removal of the gall bladder (cholecystectomy) is now so simple that the mere finding of gallstones may prompt a surgeon to take out the gall bladder, even though gallstones do not always cause problems.