Characterization of image and labor requirements for positive pregnancy diagnosis in swine using two methods of real-time ultrasound

In Experiment 1, in order to compare and characterize labor and image requirements for early pregnancy diagnosis by transrectal and transabdominal real-time ultrasound (RTU), 100 sows were examined at 16 to 24 days of gestation using both methods. On day 20, over 71% of sows were diagnosed using transrectal RTU compared to 2% with transabdominal RTU. By day 22, 98% were diagnosed using transrectal RTU compared to 53% for transabdominal RTU, and by day 24, there was little difference between methods. Accuracy was greater for transrectal RTU prior to day 22, but also required more time for diagnosis. In Experiment 2, 183 sows were examined using transrectal RTU at gestation days 15 to 21 (uterine fluid diameter measured), and by transabdominal RTU between days 22 and 72 (fluid diameter and time to make a diagnosis measured). Fluid diameter increased to day 30, decreased to day 39, and increased thereafter. Diagnosis required more time prior to day 24. These results indicate that pregnancy can be diagnosed accurately in most sows by day 22 using transrectal RTU and by day 24 using transabdominal RTU. The largest fluid vesicles and least amount of time required for diagnosis occurred on day 30.