molar pregnancy
Meaning of molar pregnancy: A molar pregnancy occurs when abnormal fertilization causes placental tissue to overgrow into fluid filled cysts instead of a viable embryo.
Definition of molar pregnancy
A molar pregnancy, also called a hydatidiform mole, results from an abnormality at fertilization that causes the tissue destined to become the placenta, called trophoblastic tissue, to grow abnormally into a mass of small fluid filled cysts rather than developing normally alongside an embryo. A complete mole contains no fetal tissue, while a partial mole may contain some abnormal fetal tissue that cannot survive.
Most molar pregnancies are noncancerous and are removed from the uterus once diagnosed, but they belong to a broader group of conditions called gestational trophoblastic disease, which also includes an invasive mole, in which abnormal tissue grows into the uterine wall, and choriocarcinoma, a rare cancer that can develop from residual trophoblastic tissue.
Because a molar pregnancy cannot develop into a viable pregnancy, and because a small proportion of cases are followed by continued abnormal tissue growth, monitoring after removal typically continues until levels of a pregnancy related hormone return to their expected baseline.
Also known as
Used in a sentence
Ultrasound findings during the first trimester raised concern for a molar pregnancy, which was later confirmed after the tissue was removed and examined.
Good to know
A molar pregnancy cannot progress into a viable pregnancy even when some fetal tissue is present, and its removal is generally followed by monitoring to detect the small chance of persistent abnormal tissue growth afterward.
Word origin
Where “molar pregnancy” comes from
Formed from Latin mola, meaning millstone, an old description of the mass of grape-like cysts, and hydatidiform, from Greek hydatis, meaning a drop of water, combined with Latin forma, meaning shape.