172 DISEASES OF DOMESTICATED BIRDS 
DISEASES OF THE PERITONEAL CAVITY 
ABDOMINAL YOLK CONCRETIONS 
The presence of masses of yolk material lying free in the peri- 
toneal cavity of hens is frequently observed on post-mortem ex- 
amination. The cause of this condition is not always apparent. 
Injuries to the membrane of the fallopian tube, or tumor forma- 
tions in the oviduct which interfere with the entrance of the yolk 
or its passage through the oviduct are usually responsible. Yolks 
or partly formed eggs may be returned through the oviduct and 
aborted into the peritoneal cavity by reverse peristalsis induced by 
inflammatory changes in the wall of the oviduct. At times the 
contents of only one yolk or ovum may be present while in other 
cases the concentric layers of yolk substance indicate that the process 
has been going on for a considerable period of time. In the latter 
instance the mass may be as large as a tennis or base ball and of 
firm consistency. The layers are easily separated when newly 
formed or before organization or decomposition changes have pro- 
gressed. Some accumulations reveal a center of albumin, or par- 
tially formed shell membrane, while others exhibit a yolk formation 
throughout. Occasionally a normal yolk is found surrounded by 
a small amount of albumin and inclosed in a soft or partially cal- 
cified membrane. In this case there is evidence that the ovum 
has passed into the oviduct and owing to an abnormal state of this 
organ, reverse peristalsis has caused its return through the fallo- 
pian membrane into the abdominal cavity. Quite frequently as 
many as five to seven perfectly formed yolks in a good state of 
preservation are found between the intestinal convolutions. These 
apparently represent a recent discharge from the ovary in contrast 
to the solidified yolk substance constituting the typical yolk con- 
cretion. 
Symptoms. The presence of yolk deposits is not disclosed by 
external appearances where putrefactive changes are absent. The 
tendency is for the material to become partially absorbed. The un- 
absorbed portion is formed into a rounded body which increases in 
size according to the number of ova aborted into the cavity. In the 
event that organisms find their way into the peritoneal cavity, pre- 
sumably by way of the oviduct, a favorable culture medium is at 
hand and decomposition changes may be inaugurated which lead to a 
septic condition and result in peritonitis, or septicemia. 
