Feline uterine rupture and mummification
Keywords: feline, uterus, rupture, mummy
During routine ovario-hysterectomy of a shelter cat, the usual structure of the ovaries and uterine horns could not be defined. The right uterine horn had undergone torsion of 360 degrees. However, on examination, the torsion had been relieved so the direction of torsion was not obvious. Nevertheless, the extent of torsion was deduced from the finding that the horn was found to be lying in approximately its normal position and orientation despite that torsion. Importantly, the left uterine horn was still attached to the left ovary but the cranial half appeared to have been torn from its caudal portion. Also, the uterus was no longer attached to the cervix, presumably torn away as well.
The left kidney was absent.
A partially mummified fetus lay in the left caudal quadrant of the abdomen and there were numerous adhesions between the omentum and both uterine horns. A dorsal view of the specimen is shown below; laid out in its approximate in-situ location. A keyed image is shown below this one. Two masses of unknown origin were also found in the abdomen. These are shown at upper left and right in the image.
Dissection of the specimen revealed the following:
Histology of structures A & B was unrewarding; they consisted of masses of homogeneous to broken eosinophilic hyaline-like material, interspersed with cell debris. In some areas there were thin, lamella like structures that may have been membranes at one time. In summary, these were probably necrotic remains of placental fragments.
The orange ring shows the area of probable tearing in the left horn. The red ring indicates the area where the uterus would have been attached to the cervix and vagina. The fetuses have been numbered.
There were five fetuses in the uterus when it had been severely damaged by an unknown accident. Remarkably, there were no overt suggestions of serious trauma to the cat and it was bright, alert and apparently normal on presentation. Yet, during this accident, possibly a car strike, most of the uterus appears to have been torn from both the cervix and the left uterine horn. At that time, it probably underwent torsion, resulting in vascular embarrassment and fetal death. In one case, the uterus obviously ruptured, releasing a fetus into the abdomen.
Extra-uterine pregnancies are not rare in cats Most are thought to result from trauma during pregnancy. Despite its intimate (hemo-chorial) placentation, cats are highly unlikely to have true extra-uterine pregnancies such as those that occur in humans. In humans, placentation is aggressive and nidation on the peritoneal surface is possible.
The left kidney was congenitally absent, a relatively common finding in cats.
For a brief review of extra-uterine pregnancy see this LORI entry.
The author wishes to thank Dr K Ling, AVC community practice & Ms G. Marsh, AVC 2104 for bringing this case to his attention.
