Objective: To determine the microvessel density (MVD) at the implantation site of normal placenta (NP) and molar pregnancies and to correlate MVD with clinical data and underlying angiogenic factors.
Study design: Immunolocalization of CD31, vascular endothelial growth factor and angiopoietin 1 and 2 were performed on NPs, nonpersistent partial moles, persistent partial moles (PPM), nonpersistent complete moles and persistent complete moles (PCM).
Results: Significant differences were identified in the MVD between NP and complete mole (CM), and PM and CM (p < 0.001 and p < 0.035, respectively). MVD in PPM and PCM was significantly higher (p = 0.036 and p < 0.001, respectively) when compared to NP. MVD > 100 per high-power field was associated with an increased risk of persistence (p < 0.04). MVD showed a strong correlation with immediate postevacuation hCG levels (p < 0.03). Angiopoietin 2 staining was more heterogeneous, with lower overall expression in molar pregnancies as compared to more homogeneous expression in NP (p < 0.05).
Conclusion: MVD is highly correlated with hCG levels, suggesting that hCG may act as an angiogenic factor during implantation of molar pregnancy. MVD at the implantation site may be associated with excessive trophoblastic proliferation or reflect high hCG levels, which places patients at increased risk of persistent neoplasia.