ultrasonography

https://doi.org/10.1351/goldbook.11336

Imaging technique that creates a picture of internal body structures from differentially reflected ultrasound waves.

Note: By using this technique, the human embryo can be observed in utero as early as \(\pu{5 1\!{/}\! 2 weeks}\) of gestation: fetal monitoring by this technique (obstetric ultrasound) is standard.
Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 816 (https://doi.org/10.1515/pac-2015-1202)