Evaluation and analysis of influencing factors of placental mesenchymal dysplasia diagnosed using prenatal ultrasonography and pregnancy outcomes: case series.

Background: Placental mesenchymal dysplasia (PMD) is a rare placental vascular malformation of unknown etiology. PMD may coexist with a healthy fetus, and its ultrasound appearance is similar to that of a hydatidiform mole, especially the partial type. Prenatal ultrasonography is vital for accurate diagnosis of these conditions. This study aimed to summarize the characteristics of prenatal ultrasonographic images across different gestational weeks (W) for PMD and evaluate and analyze factors that influence pregnancy outcomes related to PMD. The goal is to improve the diagnosis of PMD, effectively assess fetal prognosis, and provide a reference for prenatal consultations and clinical management.

Case Description: Of the 15 included patients, 4, 8, and 3 had PMD in early pregnancy (<13 W), mid-pregnancy (approximately 14-27 W), and late pregnancy (>28 W), respectively. Among the 15 patients, 5 successfully underwent delivery, thereby resulting in fetal survival; 3 experienced intrauterine death, 1 had a miscarriage, and 6 pregnancies were terminated. During early pregnancy, ultrasonographic manifestations of PMD included microscopic anechoic cystic areas in the placental parenchyma. In the second trimester, the placenta exhibited diffuse enlargement and thickening, with the placental parenchyma showing cellular anechoic cystic areas clearly separated from the surrounding normal placental tissue. As the pregnancy progressed, the cystic areas gradually reduced in the third trimester. Additionally, localized umbilical blood vessels showed tumorous lesions, sometimes accompanied by intravascular thrombosis. Some cases exhibited tortuosity and dilation in the umbilical vein.

Conclusions: PMD exhibited varying ultrasonographic characteristics across different gestational stages and demonstrated regular disease evolution corresponding to gestational W. This condition is associated with adverse pregnancy outcomes, with the location, extent, and severity of lesions being crucial factors affecting fetal development in utero.