Placental Mosaicism
The presence of chromosomally abnormal cells only in placental tissue while fetal cells remain normal.
Full Definition
Placental mosaicism, also known as confined placental mosaicism (CPM), is a condition where chromosomal abnormalities are present in placental cells but absent from fetal cells. This phenomenon occurs in approximately 1-2% of pregnancies and can lead to discrepant results between chorionic villus sampling and amniocentesis. CPM can result in false positive screening results and may be associated with intrauterine growth restriction due to placental insufficiency. The condition arises from mitotic errors during early placental development and highlights the importance of understanding the limitations of different prenatal diagnostic procedures.
Usage
Usage note: Often abbreviated as CPM in clinical documentation.
In Context
- "Placental mosaicism was suspected when CVS showed trisomy 16 but amniocentesis was normal." — Genetic counseling documentation
- "The discrepant results were explained by confined placental mosaicism affecting only the chorionic villi." — Prenatal diagnosis report