Investing Time In Microscopy: an Opportunity to Optimize Smear-Based Case Detection of Tuberculosis |
OBJECTIVE: To measurethe time spent during routine sputum smear microscopy and assess whetherre-examining slides for 10 min translates into higher case detection ofsmear-positive cases. DESIGN: A prospectiveobservational study over a12-month period with three components: 1) timing ofroutine sputum smear examination; 2) blinded re-examination of all slides for10 min and results compared with initial readings; and 3) blindedre-examination, by the original microscopists, of a portion of false-negativeslide smixed with true negatives for 10min. RESULTS: A total 612sputum specimens for screening. The routine examination time The median routineexamination time was 5 min. A 10 min examination significantly increased thenumber of positive smears from 94 to 131. On review by the original readers,more than half of the false-negative slides were reported as positive after 10min. CONCLUSION: Sputumsmear microscopy has low sensitivity if performed too quickly, and 10 minre-examination significantly increases case detection. Ensuring that smears areexamined for the recommended duration may be a simple and low-cost way toimprove case detection.