Distal villous lesions are clinically more relevant than proximal large muscular vessel lesions of placental fetal vascular malperfusion.

BACKGROUND: Fetal vascular malperfusion (FVM) can be diagnosed on placental examination based on histology of distal placental villi and large muscular placental vessels. While histology of both those placental compartments can be low grade or high grade, it is not known if these are clinically equivalent. This retrospective study aimed to compare the impact of placental distal villous and large vessel FVM lesions on clinical and placental phenotypes.
METHODS: Clinical and placental phenotypes of 479 consecutive ≥20 weeks of gestation at delivery cases of placental FVM were analyzed among 3 groups: Group 1: 86 cases with distal FVM (clusters of sclerotic distal villi and/or those with stromal vascular karyorrhexis and/or mineralization, and/or endothelial fragmentation by CD34 immunostain) without large vessel lesions; Group 2: 186 cases with large vessel lesions (fetal vascular ectasia, vascular thrombi, stem vessel obliteration, intramural fibrin deposition) without distal villous lesions; and Group 3: 207 cases showing both distal villous lesions and large fetal vessel lesions.
RESULTS: Statistically significant differences (Bonferroni correction) were observed in: average gestational age at delivery 31, 35, 34 weeks, fetal growth restriction 24, 9, 25%, average placental weight 318, 413, 366 g, postuterine pattern of chronic hypoxic placental injury 12, 2, 6%, luminal vascular abnormalities in stem vessels 16, 3, 11%, and high grade FVM 33, 16, 39%, among Groups 1-3, respectively.
CONCLUSION: Because of longer time needed for its development, distal FVM portends poorer prognosis for the fetus than large vessel FVM.