Hydatidiform Mole Clinical Presentation

Updated: Apr 08, 2021
  • Author: Lisa E Moore, MD, MS, FACOG, RDMS; Chief Editor: Leslie M Randall, MD, MAS, FACS  more...
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Complete mole

The typical clinical presentation of complete molar pregnancies has changed with the advent of high-resolution ultrasonography. Most moles are now diagnosed in the first trimester before the onset of the classic signs and symptoms. [30, 31, 32]

Vaginal bleeding

The most common classic symptom of a complete mole is vaginal bleeding. Molar tissue separates from the decidua, causing bleeding. The uterus may become distended by large amounts of blood, and dark fluid may leak into the vagina. This symptom occurs in 50% of cases.


Patients may also report severe nausea and vomiting. This is due to extremely high levels of human chorionic gonadotropin (hCG). This is reported to occur in 4% of patients diagnosed at 5-9 weeks of gestation, and in 23% when the diagnosis is made after 10 weeks' gestation.


Signs and symptoms of hyperthyroidism can be present due to stimulation of the thyroid gland by the high levels of circulating hCG or by a thyroid stimulating substance (ie, thyrotropin) produced by the trophoblasts. [33]  Clinical hyperthyroidism has been reported in 3.7% of women with a hydatidiform mole diagnosed after the 10th week of gestation.

Partial mole

Patients with partial mole do not have the same clinical features as those with complete mole. These patients usually present with signs and symptoms consistent with an incomplete or missed abortion, including vaginal bleeding and absence of fetal heart tones.

In a retrospective study (1994-2013) at a Brazilian trophoblastic disease center, investigators evaluated the clinical presentations and incidence of postmolar gestational trophoblastic neoplasia (GTN) among 355 women with complete mole (n =186) or partial mole (n = 169), with the following findings [34] :

  • Risk of vaginal bleeding, biochemical hyperthyroidism, anemia, uterine size larger than dates, and hyperemesis: Reduced risk in women with partial mole
  • Preevacuation serum hCG levels: Lower in women with partial mole
  • Median gestational age at evacuation: complete mole, 9 weeks; partial mole, 12 weeks
  • Development of GTN:  women with complete mole, 17.7%; women with partial mole, 4.1%

Those with complete mole were diagnosed more commonly before evacuation than women with partial mole because they presented more often with signs/symptoms of molar disease. [34]


Physical Examination

Complete mole

Note the following:

  • Size inconsistent with gestational age: A uterine enlargement greater than expected for gestational age is a classic sign of a complete mole. Unexpected enlargement is caused by excessive trophoblastic growth and retained blood. However, patients also present with size appropriate or smaller than expected for the gestational age.

  • Preeclampsia: Pelvic ultrasonography has resulted in the early diagnosis of most cases of hydatidiform mole and preeclampsia is seen in less than 2% of cases. [31]

  • Theca lutein cysts: These are ovarian cysts greater than 6 cm in diameter and accompanying ovarian enlargement. These cysts are not usually palpated on bimanual examination but are identified by ultrasonography. Patients may report pressure or pelvic pain. Because of the increased ovarian size, torsion is a risk. These cysts develop in response to high levels of beta-hCG. They are reported in 11% of cases diagnosed at  longer than10-weeks' gestational age. The cysts spontaneously regress after the mole is evacuated, but it may take up to 12 weeks for complete regression.

    Theca lutein cysts. Theca lutein cysts.
    Complete mole. Complete mole.
    Complete mole with an area of clot near cervix con Complete mole with an area of clot near cervix consistent with bleeding.

Partial mole

Uterine enlargement and preeclampsia is reported in only 5% of patients. [35]  Theca lutein cysts, hyperemesis, and hyperthyroidism are extremely rare.


Twinning with a complete mole and a fetus with a normal placenta has been reported (see image below). Cases of healthy infants in these circumstances have been reported. [12, 36]

Women with coexistent molar and normal gestations are at higher risk for developing persistent disease and metastasis. [20]  Termination of pregnancy is a recommended option.

The pregnancy may be continued as long as the maternal status is stable, without hemorrhage, thyrotoxicosis, or severe hypertension. The patient should be informed of the risk of severe maternal morbidity from these complications. [37]

Prenatal genetic diagnosis by chorionic villus sampling or amniocentesis is recommended to evaluate the karyotype of the fetus.

Twin gestation. Complete mole and normal twin. Twin gestation. Complete mole and normal twin.