Hydatidiform Mole Workup

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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Laboratory Studies

The following laboratory studies may be used to evaluate patients with suspected hydatidiform mole:

  • Quantitative beta-hCG levels: hCG levels greater than 100,000 mIU/mL indicate exuberant trophoblastic growth and raise suspicion for a molar pregnancy. However, a molar pregnancy may have a normal hCG level.
  • Complete blood cell count with platelets: Anemia could be present and coagulopathy could occur.
  • Clotting function studies: Test clotting function to exclude the development of a coagulopathy or to treat one if discovered.
  • Liver function tests
  • Blood urea nitrogen (BUN) and serum creatinine levels
  • Blood type and Rh factor
  • Thyroxine level: Although women with molar pregnancies are usually clinically euthyroid, biochemical hyperthyroidism has been reported in 6% of patients with hydatidiform mole diagnosed at 5-9 weeks of gestation and in 28% when the diagnosis is made after 10 weeks' gestation. Patient may present with signs and symptoms of hyperthyroidism. Clinical hyperthyroidism occurs in less than 3% of cases.
  • Serum inhibin A and activin A levels: Serum inhibin A and activin A have been shown to be 7- to 10-fold higher in molar pregnancies than normal pregnancies at the same gestational age. The fall in inhibin A and activin A after evacuation may prove helpful. [38] However, of the readily available markers, serum hCG levels is the standard of care.

Imaging Studies

Ultrasonography is the criterion standard for identifying both complete and partial molar pregnancies. The classic image, using older ultrasonographic technology, is of a snowstorm pattern representing the hydropic chorionic villi. High-resolution ultrasonography shows a complex intrauterine mass containing many small cysts.

Once a molar pregnancy is diagnosed, a baseline chest radiograph should be taken. The lungs are a primary site of metastasis for malignant trophoblastic tumors (see the Medscape Drugs & Disease article Gestational Trophoblastic Neoplasia).


Histologic Findings

Complete mole

Complete hydatidiform moles have edematous placental villi, hyperplasia of the trophoblasts, and lack or scarcity of fetal blood vessels. Their chromosomal complement is 46,XX in most cases or 46,XY in approximately 10-15% of cases. Additionally, complete moles show overexpression of several growth factors, including c-myc, epidermal growth factor, and c-erb B-2, compared with normal placenta. [39]

Partial mole

In the incomplete or partial hydatidiform mole fetal tissue is often present, as well as amnion and fetal vessels with fetal red blood cells within the mesenchyme of the villi. Like in complete hydatidiform moles, hydropic (edematous) villi and trophoblastic proliferation are present. In addition, due to tangential sectioning, scalloping of the villi results in apparent trophoblastic inclusions within the mesenchyme of the villi. Paternally imprinted gene products (eg, p57, PHLDA2) are normally expressed only by maternal chromosomes. In the absence of maternal chromosomes, as is the case in complete moles, the nuclei of the villous stroma and the cytotrophoblasts do not stain for p57 or PHLDA2 (Pleckstrin homology-like domain, family A, member 2). In contrast, these cells are positive for p57 and PHLDA2 in partial moles (which are triploid) and missed abortion with hydropic degeneration (which are diploid). [40, 41, 42]