Radiology residents working 12-hour overnight call shifts made significantly more errors during the final two hours of consecutive overnight shifts, according to a study published in the March issue of Academic Radiology.

As the drumbeat for resident work-hour limits has amplified and shorter shifts have been implemented, few studies have examined the impact of resident fatigue in radiology.

Alexander T. Ruutiainen, MD, of the department of radiology at University of Pennsylvania Hospital in Philadelphia, and colleagues designed a study to determine if the rate of major discrepancies between resident preliminary reports and faculty final reports increases during the final hours of consecutive 12-hour overnight call shifts.

The researchers reviewed 8,062 preliminary radiology reports interpreted by 10 residents between January 2010 and June 2010, and found 79 major discrepancies.

Although there were no significant differences in the rate of discrepancies during the first 10 hours of the overnight shift (either 7 p.m. or 7:30 p.m. to 7 a.m. or 7:30 a.m.), the error rate swelled during the final two hours. A total of 29 percent of errors occurred in the final two hours of the shift, Ruutiainen et al reported. The researchers also observed that x-ray imaging was less likely to have a major discrepancy than cross-sectional exams.

Possible causes for the significant drop in accuracy include acute sleep deprivation, chronic partial sleep loss and circadian desynchronization, according to Ruutiainen and colleagues.

Patient outcomes, however, are rarely affected. “One of the reasons why resident major discrepancies infrequently result in adverse patient outcomes is that most decisions are made based on multiple clinical factors, with imaging frequently playing an important role but rarely acting as the sole guiding factor in patient management,” they wrote.

The researchers suggested the optimal shift length for consecutive nights of overnight call is 10 hours, drastically less than the maximum overnight call shift length of 24 hours for non-postgraduate year-one residents.

For more about radiologists and fatigue, please read "Imaging Displays: How to Zap the Nap," in Health Imaging.