Confined Placental Mosaicism (CPM):
Confined placental mosaicism (CPM) is a condition characterized by the discrepancy between the chromosomal/genetic makeup of the fetus and placenta. Genetic and chromosomal makeup of the placenta and fetus are almost always the same because they both develop from the same zygote (egg). However, in about 1 in 50-100 pregnancies, CPM occurs due to problems during cell division in the placenta. There are no specific signs and/or symptoms associated with CPM.
Typically, CPM is diagnosed by the CVS procedure. The condition can occur in all pregnancies regardless of age, race, ethnicity, or geographical predilection. Although there is a slightly increased risk for pregnancy loss and potential problems with the normal growth and development of the fetus, in the majority of cases of CPM, no fetal and maternal complications occur. Typically, there is no specific treatment for CPM. Women diagnosed with CPM require more frequent antenatal visits to their physician to ensure the pregnancy is progressing in a normal manner.
Since the source of cells obtained using the CVS procedure is derived from the placenta and not the fetus itself, the presence of CPM can cause the CVS procedure to yield cytogenetically ambiguous results. In these instances, a follow-up amniocentesis might be required to clarify results.