Diagnosing and Monitoring Growth Restriction
Doppler assessment of flow patterns through the inferior vena cava, umbilical vein, and the ductus venosus have all been suggested as supplementary tests—experimentation is underway particularly in Europe—but it is flow through the ductus venosus that may warrant the most attention at this point in time in institutions that have appropriately trained personnel. When flow during atrial contraction is absent or reversed in the ductus venosus, urgent intervention is usually necessary.
Our decisions to deliver, of course, should always be highly individualized, taking into account gestational age, the progression of change, institutional resources and expertise, and other issues. In general, though, once we're at or beyond 34 weeks of gestation, there is no benefit to prolonging the pregnancy if we have any ominous findings.
The absence of end-diastolic flow on the umbilical arterial Doppler, for instance, should prompt delivery once we've reached 34 weeks, whereas before 34 weeks we could instead intensify surveillance and watch for additional ominous findings. (Many, however, would use a cut-off of 32 completed weeks based on outcomes in the intensive care nursery of their institution).
We also should not allow pregnancies involving growth restriction to become postdated. There are no clear-cut guidelines addressing the question of whether we should induce babies who have come to term, but if the baby is in jeopardy—if there are multiple signs of compromise or distress—the baby will have a limited ability to tolerate labor, and a cesarean section is best.
Our most difficult decisions come with gestations of less than 28 weeks. Unfortunately, a recent randomized controlled trial of delivering early vs. delaying delivery (the Growth Restriction Invention Trial) brought us no clear answers.
This means that we have to continue utilizing our clinical judgment about the respective risks of a hostile intrauterine environment and the risk of pulmonary immaturity, and have a compassionate, nonpatronizing discussion with the parents. In general, if multiple parameters are abnormal, too much waiting will deprive the fetus of any chance of survival.
Umbilical arterial Doppler is an effective tool for monitoring fetal growth restriction. The image on the left shows normal end-diastolic flow in the umbilical artery; the image on the right shows absent end-diastolic flow. Photos courtesy Dr. Dev Maulik
ELSEVIER GLOBAL MEDICAL NEWS
Fetal Growth Assessment
On the other hand, in some pregnancies we encounter excessive fetal growth or restrictive fetal growth. Both of these conditions require careful attention, careful assessment and, sometimes, careful intervention.
Fetal growth restriction may occur under certain clinical conditions. Some of these conditions may be nutritional, some may be related to medical conditions such as diabetes or hypertension, and some may be due to a congenital cause or even an environmental cause such as smoking. Regardless of the actual etiology, if indeed fetal growth restriction is suspected or detected, it requires intense fetal surveillance because of the potential complications that can occur either in the short term or the long term. Some of these complications can result in significant comorbidities or even mortality.
It is for this reason that this month's Master Class will provide an in-depth look at fetal growth restriction and some of the diagnostic and management approaches that may be employed. I am pleased to welcome as our guest professor Dev Maulik, M.D., Ph.D., who is currently chair of obstetrics and gynecology at Winthrop University Hospital in Mineola, N.Y., and professor of obstetrics and gynecology at the State University of New York at Stony Brook.
Dr. Maulik has written extensively about low birth weight and prematurity, predicting adverse perinatal outcome, and detecting and managing fetal growth restriction. He has recently accepted a new appointment as professor and chair of obstetrics and gynecology at the University of Missouri-Kansas City.
