CHAPTER XXXIII 

 CYTODIAGNOSIS AND SPINAL FLUID EXAMINATIONS 



THIS method of diagnosis is chiefly employed in the examination of 

 cellular sediments of pleural, ascitic, and cerebrospinal fluid. 



The fluids which pathologically collect in the serous cavities are 

 divided into two classes, i. the transudates, which form as the result 

 of some circulatory inadequacy and 2. the exudates, which result from 

 inflammatory processes. 



Transudates have little or no fibrin and very few cellular elements and do not 

 contain nucleo-albumin. Exudates contain nucleo-albumin and usually have a 

 specific gravity above 1018, while that of the transudates is lower than 1018. 



There are two simple methods for differentiating transudates and exudates. 

 Moritz adds 2 drops of a 5% solution of acetic acid to the fluid to be tested. A 

 heavy, cloud-like precipitate shows the fluid to be of inflammatory origin (an 

 exudate). A transudate may produce a slight opalescence. Rivalta's test consists 

 in dropping a drop of the fluid to be tested into a cylinder containing 2 drops of 

 glacial acetic acid in 100 c.c. distilled water. A nebulous cloud as the drop of fluid 

 sinks shows an exudate. 



For pleural fluids we should receive the material in centrifuge tubes about one- 

 fourth filled with 2% sodium citrate salt solution. This prevents clotting. Having 

 thrown down the sediment, the supernatant fluid is poured off, and in its place a i% 

 aqueous solution of formalin is added. After mixing and allowing to stand for about 

 five minutes, centrifugalization is again repeated and, pouring off the supernatant 

 formalin solution, we make smears from the sediment. This is either stained by a 

 Romano wsky method or, after fixing with heat (burning alcohol), the smear is 

 stained with haematoxylin and eosin. 



With ascitic fluid it is usually sufficient to centrifuge the fluid, then decant off the 

 supernatant fluid and drain by means of a piece of filter-paper held at the mouth 

 of the upturned tube. The sediment adheres to the bottom of the tube and is 

 best emulsified with the small amount of fluid remaining by means of a bulb pipette. 

 The material is sucked up, smeared out on a slide with a second slide as for blood 

 and stained preferably with Giemsa after fixation. H. E. staining brings out 

 mitotic figures best. If the fluid has coagulated it is best to take a little of the 

 coagulum and stain it with neutral red as for vital staining. It is difficult to disso- 

 ciate the cells from the clot. I now make it a rule to collect a portion of the pleural 

 or ascitic fluid in citrated salt solution in order to prevent coagulation. The mate- 

 rial is then centrifuged and after removal of supernatant fluid with a bulb pipette 

 the cell sediment is drawn up and smeared out on a slide for cell or bacterial staining. 



423 



