Webster's New World Medical Dictionary

chorea, Huntington’s
See 
Huntington’s dis-
ease.
chorea, Sydenham’s
See 
Sydenham’s chorea.
chorioamnionitis
Inflammation of the chorion
and the amnion, the membranes that surround the
fetus. Chorioamnionitis usually is associated with a
bacterial infection. This may be due to bacteria
ascending from the mother’s genital tract into the
uterus to infect the membranes and the amniotic
fluid. Chorioamnionitis is dangerous to the mother
and child.
chorioangioma, placental
A benign tumor of a
blood vessel in the placenta. Large chorioangiomas
can cause complications, including excess amniotic
fluid (polyhydramnios), maternal and fetal clotting
problems (coagulopathies), premature delivery,
toxemia, fetal heart failure, and hydrops (excess
fluid) affecting the fetus. Chorioangiomas probably
act as shunts between arteries and veins (arteriove-
nous shunts), leading to progressive heart failure of
the fetus.
choriocarcinoma
A highly malignant tumor that
arises from trophoblastic cells within the uterus.
Choriocarcinoma may follow any type of pregnancy
but is especially likely to occur with a hydatidiform
mole. The prognosis for women with metastatic
choriocarcinoma has improved with the advent of
multidrug chemotherapy. See also 
hydatidiform
mole.
chorion
The outermost of the two fetal mem-
branes (the amnion is the innermost) that surround
the embryo. The chorion develops villi (vascular
finger-like projections) and develops into the pla-
centa.
chorionic gonadotropin, human
See 
human
chorionic gonadotropin.
chorionic villus sampling
A procedure for
first-trimester prenatal diagnosis. Abbreviated CVS.
CVS may be done between the eighth and tenth
weeks of pregnancy. The aim is to diagnose severe
abnormalities that are present in the fetus. Tissue is
withdrawn from the villi of the chorion, a part of the
placenta, and then prepared for diagnostic analysis.
choroiditis
An inflammation of the layer of the
eye behind the retina, either in its entirety (multifo-
cal choroiditis) or in patches (focal choroiditis).
The only symptom is usually blurred vision.
Choroiditis is treated with medications that reduce
inflammation. See also 
uveitis.