research day - University of Toronto Department of Obstetrics and ...

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ABSTRACT #P-L5
SPECTRUM OF VASCULAR LESIONS ASSOCIATED WITH FETAL VASCULAR
OBSTRUCTION
Aseel Hamoudi [R], Sarah Keating, John Kingdom, Geoffrey Machin.
Department of Perinatal Pathology, Mount Sinai Hospital, University of Toronto.
Objective: Placental changes of chronic fetal vascular obstruction (FVO) are relatively common
occurring in approximately 5-10% of placental specimens. Histologically, they are characterized
by thrombi in umbilical, chorionic plate and stem villous vessels and secondary regressive changes
in villi in proximity to the thrombi. The currently favored pathologic term is fetal thrombotic
vasculopathy. It requires vascular thrombosis (FTV) and at least one cluster of avascular terminal
villi. Placental FVO represents an important, possibly under recognized cause or marker of sudden
intrauterine death, intrauterine growth restriction (IUGR), neonatal thrombosis, fetal and maternal
coagulopathy, neonatal cerebral infarcts and encephalopathy. The purpose of our study is to assess
the full spectrum of vascular lesions in placentas with evidence of FVO and to identify which of
these histologic findings are associated with predictors of poor neonatal outcome.
Methods: We retrospectively gathered 101 placentas for the years 2006 and 2007 from the
pathology archives at Mount Sinai hospital in which a diagnosis of fetal vascular obstructive
lesions was made. Twin placentas and placentas showing moderate or severe villitis were excluded
from analysis. Each placenta was assessed for the presence and location of vessels showing
thrombi, fibrin cushions, endothelial cushions, dilatation, fibromuscular luminal stenosis or
obstruction. In addition, the presence of avascular villi, villous stromal vascular karyorrhexis, distal
villous hypoplasia (DVH), accelerated villous maturation (AVM), infarcts and other significant
pathology were recorded.
The following clinical data were gathered on chart review: general characteristics, antepartum and
intrapartum findings, placental function tests and neonatal outcome.
Results: Our preliminary results show that mothers whose placentas demonstrate FVO were young
with a median age of 32 years, 12 of them had a previous history of 2 or more miscarriages and 7
had a history of hypothyroidism. Although biochemical markers for placental function were
normal, in 17 cases there was abnormal placental morphology seen on third trimester ultrasound.
FVO was associated with the following antenatal complications: IUGR, oligohydramnios without
membrane rupture, and vaginal bleeding during pregnancy. Median gestational age at delivery was
34.5 weeks, however, 50 patients delivered before 37 weeks and 25 of them were extremely
premature. During the course of labour 29 women had abnormal fetal cardiotocography and, of
those, 25 had variable decelerations.
Addition of controls and subdivision of the severity of placental pathology is underway and will be
associated with clinical findings.