sentence: A 1978 postoperative PCI study conducted by Branden et al. showed that puncture and operative technique-related bleeding accounted for 42.1 % and nonpuncture site bleeding accounted for 57.9 % ( including gastrointestinal bleeding ( 16.6 % ) , retroperitoneal hemorrhage ( 13.3 % ) , urogenital tract bleeding ( 5.0 % ) and other bleeding ( 23.0 % ) ) .