Rjiptiire of the Uterus and Vagina 815 



extremity becoming so misdirected that, during the expulsive 

 efforts of the mother, it may be forced through the uterine wall 

 and bring about a perforating wound of the peritoneal cavity. 



In the anterior presentation, with the two posterior limbs ex- 

 tended beneath the body of the fetus and lodged just in front of 

 the pubic brim upon the uterine floor, the forcing of the fetus 

 into the passage brings about a great concentration of pressure 

 upon the uterine floor by the feet. The croup and thighs are 

 rigidly and firmly pressed against the sacrum and lumbar verte- 

 brae, while the extended limbs are forced, under enormous pres- 

 sure, downward and forward against the floor of the uterus. 

 Such pressure is constantly liable to cause the toes of the fetus 

 to force their way through the uterine floor. 



When the fetus presents anteriorly in thedorso-sacral position, 

 with a foot crossed over the head, or a foot misdirected upward 

 from other causes, the misplaced extremity tends constantly to 

 push upward and force its way through the roof of the vagina. 

 So with other misdirections of the anterior or posterior ex- 

 tremities. 



In the bicornual development of the fetus, as already described 

 on page 716, extensive and fatal rupture of the uterus is very 

 liable to occur when traction is applied in order to bring about 

 delivery. 



In torsion of the uterus, as already related on page 704, trans- 

 verse rupture is a common result of the displacement, and follows 

 regularly when the torsion has acquired an extreme degree. 



A further and not rare cau.se of uterine rupture is the attempt 

 of the veterinarian to force a fetus through a constricted passage, 

 or a fetus which is too large or presents improperh^ through a 

 normal passage. In discussing the question of atresia or indu- 

 ration of the cervex uteri, we related an experience in which, in 

 a heifer, we attempted to force the fetus, normal in size and posi- 

 tion, through a very narrow cervical canal, with the result that 

 we ruptured the cervix for its entire length. 



Another, and highly important, way by which rupture of the 

 uterus may be caused during traction consists in tearing and 

 rupturing the walls of the organ by forcing it against some pro- 

 jecting portion of the pelvis, as already described on page 676. 

 We meet occasionally in the mare and cow with projections or 

 eminences upon the pelvic inlet, which assume such a form that, if 



