Application of rejection criteria for stool ovum and parasite examinations.

We retrospectively determined the yield of 2,015 stool ovum and parasite (O&P) examinations performed over an 11-month period. Two aspects were evaluated: the yield of positive results from multiple specimens per patient versus the result of a single examination, and the yield of positive results from stools submitted after 3 days of hospitalization. There were 131 (6.7%) positive O&P examinations from 75 patients: for 35 patients the single examination was positive; for 18, two of two examinations were positive; and for 15, three of three examinations were positive. The remaining seven patients had at least one negative examination in a series, but pathogenic intestinal parasites were detected in only three of these patients. Seventeen patients with positive O&P examinations were inpatients: seven of nine patients examined for O&P within 3 days of admission had stool specimens that contained recognized pathogens, in contrast to only two of eight patients examined after 3 days of hospitalization. After reviewing the data and informing hospital clinics, wards, and physicians, we instituted the following policy for screening stool specimens submitted for O&P examination. Only one O&P examination was performed for each outpatient visit and for inpatients hospitalized for 3 days or less, and examinations were not performed on stools submitted after 3 days of hospitalization unless the clinician arranged for the examination on the basis of clinical need. Over the 6-month follow-up period, 29.9% of O&P requests were rejected, 22% for patients in hospital for longer than 3 days and 7.9% for multiple O&P requests. Of 265 initially rejected specimens, 22 (8.3%) were examined after the referring physician contacted the laboratory. None of these specimens was positive. We conclude that eliminating O&P examinations of patients hospitalized for more than 3 days and initially performing only one examination per patient significantly reduces the number of examinations performed and reduces laboratory charges without adversely affecting patient care.

Duke Scholars

Author Lyman Barth Reller Pathology