(4) Slide-checking
The medical technologist or microscopist of QC center or higher level laboratory (second reader) should assess smear preparation and staining prior to rechecking under microscope. The smears prepared too thin, too thick, too small too large or sloughed off should be evaluated as "poor smear preparation" and understained, overstained with counter stain or not well destained should be evaluated as "poor staining". The slides should be read as they arrived, independently without knowing the results of the first reading. If the slides are unreabable due to poor staining or dirt, then they can be restained prior to reading. The results are then recorded in the Form 2 accompanying the slides and hand it over to the TB coordinator.
The TB coordinator reviews the independent reading results of PMC microscopist (1st reader) and QC center microscopist (2nd reader). If there are any discrepancies, the TB coordinator ask another microscopist (3rd reader) in QC center to read again independently without knowing the results of the previous readings. Final results will be based on the third reading.
(5) Analysis and feed-back of slide-checking results
The TB coordinator should feed-back the results soon after completion of analysis of the slide rechecking results. Analysis should be made on (1) false positive rate, (2) false negative rate, (3) false positive diagnosis rate, (4) false negative diagnosis rate, (5) over-all agreement, (6) poorly prepared smears, and (7) poorly stained smears. If there are false negative cases (smear positive cases missed by the first reader), the corrective action should be taken immediately by commencement of treatment in case of diagnosis or by an appropriate case-management action in case of monitoring the patient's response to treatment. The action for false positive cases (cases diagnosed as smear positive by the first reader but negative by the second reader) must be taken with extreme care only by the doctor taking account of clinical symptoms and or radiographic findings because there is possibility to miss by the second and third readers if the selected slides had a very few bacilli and kept poorly.
The TB coordinator complete Form 3 and disseminate it to not only all the participating microscopy centers but also to the Regional and Central TB Control Offices.
