The effects of different sampling techniques on smear quality and the diagnosis of cytological abnormalities in cervical screening.

A major cause of false-negative cervical smear is sampling error. We examined the results obtained with three different instruments in 126,608 smears from general practitioners. The spatula/brush combination yielded the highest proportion of smears showing cytological abnormalities, and the Cervex brush the lowest. Although not a randomized study, this paper highlights the shortcomings of the Cervex brush. We postulate a mechanical deficiency. Diagnostic accuracy rather than a high proportion of good quality smears should dictate the choice of instrument.