Rehydration of air-dried smears with normal saline. Application in fine-needle aspiration cytologic examination.

In fine-needle aspiration cytologic examination, nuclear features are often better assessed in hematoxylin and eosin (H and E) or Papanicolaou- (Pap) stained than Romanowsky-stained smears. However, both H and E and Pap stains require the use of immediately wet-fixed smears for cytomorphologic preservation. Some degree of air drying is usually inevitable. Placing air-dried smears in normal saline for 30 seconds before fixation in 95% alcohol is found to be a simple means of rehydrating the cells. The quality of the rehydrated smears is superior or identical to that of the immediately wet-fixed smears, provided that the period of drying does not exceed 30 minutes.