Ultrasound-assisted pregnancy model in rats

Bubnov R.V.1,2, Dragulian M.V.3, Buchek P.V.3, Gulko T.P.3

1 Clinical Hospital "Pheophania", Kyiv, Ukraine

2 Zabolotny Institute of Microbiology and Virology, NAS of Ukraine, Kyiv, Ukraine

3 Institute of Molecular Biology and Genetics, NAS of Ukraine, Kyiv, Ukraine


Ultrasound diagnosis (US) is a relevant and widespread method for imaging female genitalia and diagnosis pregnancy, is a convenient and safe for a fetus. However the ultrasound of uterus in small laboratory animals like rats for experiment was not enough studied and implemented. Diagnosis of early pregnancy and fetal development in laboratory rats of Wistar line should become an important diagnostic technique for enormously extend the possibilities of experiment.

The aim was to develop pregnancy model in laboratory rats for experimental research.

Materials and methods.

The uterus of rats of Wistar line (aged 2-3 months) underwent US examination at the 3rd, 6th, 12th, 16th and 20th days of pregnancy in a real-time mode using 8-12 MHz probes of general use US equipment. Number of fetuses, position, cranio-coccygeal length (CRL), position and thickness of placenta, embryo’s heart rate, etc. were registered.


All the pregnant rats gave the birth on the 21-22 day after fertilization. The amount of infant rats was 8-10. 10 % of pregnant animals on the 3rd day were pseudo negative on US. At the period of 3-20 days the embryo vesicles filled with fluid at early stages were diagnosed as a round or oval structures in uterine horn lumens. Abdominal and spinal borders of uterine were visible as a parallel thin hyperechogenic lines. The nomogram demonstrating CRL development during pregnancy in rats from day 3 to 20 of pregnancy is presented on Figure 1. The embryo heart beat is possible to determine on the 3rd day. The placenta is visible on the 12th day as an ellipsoid isoechoic structure. The ossification of the braincase is seen on the 16th day. The amniotic fluid is poorly visualized at later stages.


Ultrasound diagnosis of small pelvis of pregnant rats allows to reveal embryo vesicles as an evidence of pregnancy at the earliest stages. The developed CRL-pregnancy term nomogram and phetometry allow to determine a presumably term of pregnancy, and to predict the pregnancy development, and conduct term-related US-guided experimental interventions and develop personalized hybrid treatment technologies in humans.


Figure 1. The nomogram demonstrating CRL development during pregnancy in rats