In an observational study of surgical performance, which brought human factors experts into Brigham and Women's Hospital operating rooms to examine 10 complex cases, counting protocols for tracking instruments and sponges in particular played a surprisingly negative role on team performance. After the incision was made, nurses devoted an average of 35 minutes to the counting protocols. This represented 14.5% of the operative time. During this time, the investigators were able to document substantial negative effects on surgical work while the nurses were involved in the counting protocol. Furthermore, a counting discrepancy was observed to occur in two-thirds of the cases with a total of 17 discrepancies in 9 cases. As a result, in several patients, progress of a still-incomplete operation had to be substantially delayed or suspended while the nurses attempted to reconcile inconsistencies.