Limitations of conventional pap smear

•Inadequate samples constitute about 8% of the specimens received.

•False-negative results as high as 20-30% have been reported, which occurred due to clumping of cells when the cells are not uniformly spread on the glass slide.

•Sometimes, other contents of the cervical specimen such as blood, mucus, bacteria and yeasts contaminate the sample and prevent the detection of abnormal cells.

•If exposed to air for too long before being fixed on the slide, cervical cells can become distorted.

•Human error is probably the primary threat to accurate interpretation. An average Pap smear slide contains 50,000-300,000 cells that must be examined and if the sample contains only a few abnormal cells within a crowded background of healthy cells, the abnormal cells may be missed.

•Due to limited capacity, long back-logs for reporting cervical cytology were often seen. An automated system was needed to improve screening productivity and reduce manual workload.