Copyright 2010
Definition
Hydatidiform mole or Molar Pregnancy is a disease of abnormal growth of placental tissue. Most follow a benign course, but a small number of molar pregnancies have the potential for malignancy.
Hydatidiform mole is caused by an aberrant fertilization event.
The result is uncontrolled growth of placental structures called chorionic villi within the uterus.
The structural change is characterized by a mass of vesicles filling and distending the uterus.
The functional change is characterized by the growth of placental tissues from an egg and one or two sperm that have undergone abnormal fertilization without the development of fetal tissues. In a partial mole, a non-viable fetus with multiple anomalies may develop with the placental mass.
The clinical presentation is of abnormal uterine bleeding in the first trimester of pregnancy and a uterus that is larger than expected for a fetus’s gestational age. Imaging is useful in the evaluation of suspected hydatidiform mole with ultrasound. Ultrasound characteristically shows a heterogeneous mass with multiple hypoechoic spaces, described as a “snowstorm” pattern.
Diagnosis is suspected with a combination of clinical presentation and atypical elevation of bhCG, a hormone elevated in pregnancy and a tumor marker for hydatidiform mole.
Treatment for a hydatidiform mole consists of removal of the mass by suction curettage. After removal of a molar pregnancy, levels of bhCG should be monitored for recurrence. In rare cases where an invasive mole develops, a high rate of cure can be achieved with chemotherapy. After removal, subsequent pregnancy and delivery are often possible.