Consider underlying pathology; Fetal surveillance: match the test to the risk.(Obstetrics)

NEW YORK -- Fetal surveillance in high-risk pregnancies should be based on the specific underlying pathophysiologic threat, Dr. Anthony M. Vintzileos said at an obstetrics symposium sponsored by Columbia University and New York Presbyterian Hospital.

"There is no one test that predicts everything, so we must look at the fetus as any doctor looks at a patient: We try to identify the pathophysiologic process that puts them at risk, then figure out what type of testing they deserve," said Dr. Vintzileos, professor and acting chair of the department of obstetrics, gynecology, and reproductive sciences at Robert Wood Johnson Medical School, New Brunswick, N.J.

Each of the seven pathophysiologic processes leading to fetal asphyxia or death should be considered separately, and the available evidence used to decide on the best test, as follows:

* Decreased uteroplacental blood flow. Pregnancies at risk include those complicated by maternal chronic hypertension, pregnancy-induced hypertension (PIH)-preeclampsia, collagen/renal/vascular disease, and idiopathic fetal growth restriction.

Here, the best (level I) evidence backs Doppler assessment, while other tests for decreased uteroplacental blood flow that are supported by level I or level II evidence include estimated fetal weight by ultrasound, amniotic fluid assessments, nonstress tests (NSTs), and fetal biophysical profiles (FBPs). Doppler appears to be the most useful in gestations with fetal growth restriction less than 34 weeks, Dr. Vintzileos said.

Doppler velocimetry of the uterine artery gives clinical information about maternal blood flow to the uterus, Doppler of the umbilical artery shows the degree of placental resistance, and middle cerebral artery Doppler can demonstrate fetal compensation or adaptation.

Venous circulation evaluation via Doppler is used to test for fetal cardiac dysfunction, which is usually seen in the final stages of fetal compromise, he noted.