Related Experiment Video
Updated: Feb 26, 2026
Ultrasonography in Experimental Reproductive Investigations on Rats
Published on: December 2, 2017
Ultrasound-Guided Intrauterine Labeling of Rat Fetuses
Hatice Gulcin Gumus1, Miriam Illa, Laura Pla
1Fetal i+D Fetal Medicine Research Center, BCNatal - Barcelona Center for Maternal-Fetal and Neonatal Medicine (Hospital Clínic and Hospital Sant Joan de Deu), IDIBAPS, University of Barcelona, Barcelona, Spain.
Aim:
To compare intra-amniotic versus fetal subcutaneous injections for selective fetal labeling in multifetal rat pregnancies.
Methods:
A total of 14 pregnant rats were randomized to receive intra-amniotic injections of dyes (including Fluorescein, Indigo Carmine, or Evans Blue) or fetal subcutaneous injections (of commercial tattoo ink) both guided by ultrasound at 15-17 days of gestation. Survival, injection, and labeling success rates of both techniques were compared.
Results:
Survival rates (84.4% for intra-amniotic injections vs. 90.9% for fetal subcutaneous injections) and injection success rates (94% for intra-amniotic injections vs. 100% for fetal subcutaneous injections) were similar among both groups. None of the neonates from the intra-amniotic injections group were labeled at birth, while 93% of the neonates from fetal subcutaneous injections group were tagged, showing a visible spot in the skin at birth.
Conclusion:
Our results suggest that ultrasound-guided fetal subcutaneous injections might be an adequate strategy for selectively labeling fetuses in multifetal pregnant animals.
