Tests and Limitations of Commonly performed diagnostic tests
Ultrasonography — It's accuracy is dependent on the size and location of the ovarian remnant or cryptorchid testis and on the sonographer's skill level.
Vaginal Cytology — May be useful only if the animal presents during late proestrus or estrus.
LH — A single high LH test will not confirm spay status. False positives can occur around the time of ovulation and retesting is recommended, which can be expensive.
Stimulation Testing — Dynamic testing is costly and requires multiple blood tests.