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Uterine or Endometrial Biopsy



Uterine biopsy is a common diagnostic test performed on mares to assess uterine health and the ability of a mare to carry a foal to term. It is performed in the standing, often unsedated, mare and is considered minimally invasive.

This procedure involves sterile technique and long-handled cutting forceps called a uterine biopsy instrument. The vet passes the instrument through the cervix into the uterus. One or more pieces of the uterine tissue (endometrium), are sampled and placed in formalin. This tissue is sent to a reproductive laboratory where it is examined under the microscope for abnormalities and scored based on a set of characteristics. This biopsy can be repeated after treatment to assess improvement.


Relatively safe and simple procedure. Although the results of this test should be evaluated in conjunction with other diagnostics, a complete history, and physical exam, it is fairly reliable in predicting a mare's ability to maintain a pregnancy to term.


Time delay due to offsite evaluation. Since only a tiny piece (or pieces) of the uterus is sampled, regional differences in the uterine lining may be missed. Uterine infections can be missed.

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  • Does this diagnostic provide additional information that may change our approach to treating the mare?
  • Do the results change my mare's prognosis and potential value as a broodmare?
  • Author: Doug Thal DVM Dipl. ABVP


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