A critical analysis of the routine testing of newborn stools for occult blood and reducing substances

Stool tests for occult blood or reducing substances were introduced in the neonatal intensive care unit (NICU) as potential aids in the early recognition of necrotizing enterocolitis (NEC) in high-risk neonates, and have been recommended by some as routine nursing procedures. Neither the performance characteristics of these tests with respect to NEC, nor their indirect impact, were evaluated formally before widespread adoption into clinical care. The published evidence suggests that these tests are not useful as diagnostic or screening tools. There is no evidence that routine stool screening for occult blood or reducing substances predicts NEC or decreases the rate or severity of this disease. The direct costs of the tests are significant. A greater concern is their potential unintended consequences, which include the cost of secondary tests, restricted nutritional intake, and the accumulation of distracting, useless data. The logistics of maintaining quality control, the demands on nursing time, and the cost of testing are increasingly important considerations. This installment of Focus on the Physical diverges from a step-by-step systematic physical assessment by addressing the utility of testing neonatal stools for occult blood and reducing substances as aids in the early diagnosis or prevention of NEC. Using the information from these tests requires a framework for understanding their rationale, the test performance characteristics in the NICU setting, and the potential benefits, costs, and risks of their routine use.