Clinical Significance of the Large Fetal Vessel Lesions in Placental Fetal Vascular Malperfusion

Fetal vascular malperfusion (FVM) is an important pattern of placental injury. Although the significance of distal villous FVM (clusters of sclerotic and/or mineralized chorionic villi) is well documented, the clinical significance of proximal (large vessel) lesions of FVM is less clear, which is the aim of this retrospective analysis. To evaluate the clinical significance and placental associations of single and coexisting categories of lesions of large vessel FVM, 24 clinical and 44 placental phenotypes of 804 consecutive placentas with at least 1 lesion of proximal vessel FVM from the second half of pregnancy, divided according to the type or category of the individual FVM lesion (fetal vascular ectasia, fetal vascular thrombi, intramural fibrin deposition, and stem vessel obliteration): 689, 341, 286, and 267 placentas, respectively (first analysis) and single or coexisting large fetal vessel lesions (1, 2, 3, and 4 coexisting categories of lesions: 276, 321, 162, and 45 placentas, respectively) were statistically compared (analysis of variance, χ², univariate analysis). Because of multiple comparisons, Bonferroni-corrected P < .001 was used as a threshold of statistical significance. In this population of high-risk pregnancies dominated by fetal congenital anomalies, single individual or 1 to 2 coexisting categories of lesions of the large vessel FVM, including fetal vascular thrombi, did not consistently correlate with clinical or placental variables and were not prognostically useful, but the coexistence of 3 or 4 lesions was associated with the most advanced gestational age, fetal congenital anomalies, distal villous FVM, particularly high-grade, chorangioma or chorangiomatosis, hypercoiled umbilical cord, perivascular stem edema, and marginate or vallate placenta. Therefore, the finding of multiple lesions of the large vessel FVM not only merits a diligent search for the distal villous lesions including the CD34 immunostaining, but also justifies putting the large vessel (global) FVM on the final placental diagnosis line, which in the case of up to only 2 lesions may not be justified.