Induction of antenatal periventricular leukomalacia by hemorrhagic hypotension in the chronically instrumented fetal sheep

OBJECTIVES: Our purpose was to determine whether systemic hypotension induc ed by rapid withdrawal of fetal blood would induce periventricular leukomal acia in the brain of premature fetal sheep. STUDY DESIGN: At 113 days' gestation, systemic hypotension (mean blood pres sure <30 mm Hg) was induced by withdrawing approximately 35% of the fetopla cental blood volume in the hemorrhage group (n = 6), whereas in the control group (n = 4) isovolemic exchange transfusion was carried out. Six days af ter the insult, fetal brains were removed and processed for histologic anal ysis. RESULTS: Five of the 6 fetuses in the hemorrhage group exhibited periventri cular white-matter lesions, consisting of nodular coagulation necrosis or d iffuse axonal swellings or both. No abnormal findings other than these lesi ons were detected in the fetal brains in either experimental group. CONCLUSION: Hemorrhagic hypotension antenatally induced brain lesions simil ar to those of periventricular leukomalacia, suggesting that it is an essen tial element in the pathogenesis of periventricular leukomalacia in prematu re fetuses.