Use of Real-Time Ultrasonography as an Alternative Method for Early Detection, Confirmation and Evaluation of Rat Pregnancy

Researchers sometimes face difficulties in the diagnosis of pregnancy and assessment of embryonic development. Ultrasonography (US) is a non-invasive imaging method with minimal side effects on the subjects or operators. It provides real-time evaluation of the physiology of rapidly moving structures (i.e., heart) and facilitates evaluation of fetal tissue development. US discerns tissues based on composition, making it the imaging method of choice for abdominal examination. In this study we used real-time US as an alternative method for early diagnosis of pregnancy in rats. Sixty-four Wistar rats aged 16-20 wk were examined, and day 8 was the earliest point at which pregnancy could be detected. We constructed a detailed timeline of embryonic features detectable by US on days 8 to 19. We trust this index will be a valuable tool. More refined work toward a more detailed “atlas” will help to reduce animal sacrifice during embryonic development studies.