Almost all gall bladder removals (cholecystectomy) are done through a laparoscope nowadays - the complication rate is 2%.
Less than 5% are converted to open procedures. Scarring
from previous surgery or infection, xs bleeding or difficult anatomy are the usual causes. Check out this site for details: http://www.Surgery.Usc.Edu/divisions/tumor/pancreasdiseases/web%20pages/biliary%20system/laparosc.