ASCITES 241 



may be effected by keeping the patient in the semi-sitting 

 posture or by raising the head of the bed. 



When the transudation from the abdominal veins is exces- 

 sive, the stomata are unable to carry away all the fluid, and the 

 condition of ascites is brought about. It may result from any 

 pathological state which retards the outflow of blood from the 

 portal vein or from the inferior vena cava. Thus it may be 

 due to cardiac lesions (p. 316), cirrhosis of the liver (p. 274), 

 or abdominal tumours. 



When fluid is present in the peritoneal cavity, it obeys the 

 law of gravitation, unless it is limited by adhesions. If the 

 examination is conducted with the patient in the dorsal 

 decubitus, it will be found that the lateral regions of the 

 abdomen are dull to percussion, whereas the areas near the 

 median plane are tympanitic. If, however, the patient turns 

 over on to his right side, it will be found that the left lateral 

 region has become tympanitic, whereas the dulness is confined 

 to the right half of the body. This alteration is partly due to 

 gravitation and partly to the fact that the hollow viscera float 

 on the upper surface of the ascitic fluid. 



Paracentesis Abdominis. This operation may be carried 

 out by means of Southey's tubes or by means of a simple 

 trochar and cannula. It is of great importance to ascertain 

 that the patient's bladder is empty (p. 367) before paracentesis 

 abdominis is performed. The patient is placed in a sitting or 

 semi-sitting posture, because, in that position, the fluid to be 

 drawn off is brought into contact with the lower part of the 

 anterior abdominal wall and the intestines, which float on its 

 upper surface, are removed from risk of injury. The upper limit 

 of the fluid is determined by percussion and the trochar is 

 inserted, after due attention to asepsis, through the linea alba 

 into the dull area. The fluid should be allowed to drain away 

 slowly and the alteration of the intra-abdominal pressure, 

 caused by its removal, may be compensated for by the gradual 

 tightening of an adjustable abdominal bandage. 



NERVE-SUPPLY OF THE PERITONEUM. For many years 

 16 



