Uterine Involution

12 hours post-partum

     The Bovine uterus may hold up to 70 kilograms at term, half of which is fetal fluids, half  is fetus and fetal membranes.  The uterus dramatically decreases in size the first few days post partum.  The early post partum uterus has a corrugated character due to the linear rugae as shown.  The uterus wall normally is thick and has tone.

5 days post-partum

The caruncles are quite prominent on the endometrial surface of the uterus.

9 days post-partum

     At 9 days post-partum there is asymmetry in the uterine horns and as time progresses the horns become closer in size.  A uterus with metritis will feel thin walled and have poor tone.  Up until approximately 15 days the diameter of the cervix is smaller than that of the uterine body. 

     Reddish-brown lochia, or uterine fluid, is normal for the first 8 or 9 days,  After 10 to 12 days post-partum the caruncles begin to slough and the lochia may contain more blood and even pieces of white sloughed caruncle.  As the caruncles become necrotic the uterine discharge may become dark brown or bright red. 

30 days post-partum

     The horns are symmetrical and the uterus has decreased is weight from approximately 10 kilograms at birth to 1 kg. The diameter of the uterine body is now smaller than the cervix.

     The caruncles are much smaller and by 40-45 days the epithelium of the caruncles has grown over the caruncular site from the intercaruncular surface.

Bovine Uterus after Metritis Therapy

     A bovine ovary is present and the uterine horn has been cut open to expose the endometrium.  What is missing from this picture? 
     There are no caruncles.  This uterus was lavaged with Lugol's iodine solution.  This solution can be quite irritating to the endometrium particularly if endometritis or metritis is present.  This cow sloughed her uterine lining and caruncles.  The endometrial epithelium has healed but no caruncles remain.  This cow would have difficulty developing a normal placenta. 

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