PART III 



CYTO-DIAGNOSIS 



Cyto-diagnosis is the diagnosis of the cause of exudates by the 

 recognition of the cells which they contain. It may be regarded 

 as a branch of hsematology, though the cells which are 

 encountered are not wholly those of the blood. Its results are 

 less certain than those obtained by the recognition of the organism 

 (if any) present in the exudate, but are often easier to obtain ; 

 they are more certain than those obtained by an examination of 

 the blood, as easy to obtain, and in most cases very much easier 

 to interpret. As the methods are very simple and require no 

 special apparatus (though a centrifuge is a very great help), they 

 are within the reach of all practitioners, and a cytological examina- 

 tion should always be made when fluid is withdrawn from the 

 chest, abdomen, etc., whether for diagnosis or treatment. 



Method of collecting the Cells. — No description will be 

 given of the methods of obtaining the exudate, as those which 

 are not in general use have been dealt with already. 



If the fluid does not clot spontaneously, it is only necessary to 

 centrifugalize a portion (as much as the tube will hold — about 

 10 c.c.) for five minutes or so, and then to invert the tube and pour 

 off as much of the supernatant fluid as will come away. The sedi- 

 ment will be left, and a drop or two of fluid will run back down 

 the sides of the tube. These must be thoroughly mixed in with 

 the deposit so as to form a uniform emulsion. 



In the absence of a /fcentrifugal machine, allow the fluid to 

 stand for twelve hours or so to settle, adding a crystal of thymol 

 to prevent decomposition. Then remove some of the deposit 

 with a pipette ; you cannot invert the tube in this case, as the 

 sediment is not so compact, and will pour out. 



When the fluid has coagulated, put it in a strong bottle with 



253 



