Agenesis means that an organ or body part never formed during embryonic development. In sonography, this finding can be detected both prenatally and in postnatal or adult imaging. Common examples include renal agenesis, where one or both kidneys fail to develop, and agenesis of the corpus callosum, a brain structure that can be evaluated with neonatal cranial ultrasound. When one kidney is absent, the remaining kidney typically undergoes compensatory hypertrophy, growing larger to handle the workload of two kidneys, which is a finding sonographers should recognize and document.
Sonography Term