RESUMO
OBJECTIVES: We hypothesized that, as with other areas of the peripheral circulation, fetal splenic artery blood flow undergoes changes in small-for-gestational age (SGA) fetuses due to a redistribution of cardiac output, and that the Doppler peak systolic velocity (PSV) reflects such changes and thus may be used to predict fetuses being SGA. METHODS: Splenic artery Doppler PSV, end-diastolic velocity (EDV), resistance index (RI) and umbilical artery RI were measured prospectively in fetuses at risk for being SGA at birth. Normal reference data were generated from appropriately grown fetuses delivering at > or = 37 weeks without complications, and SGA was defined as birth weight < 10th percentile. The Doppler indices were expressed as multiples of the normal median (MoM) for gestational age. Using receiver operating characteristic curves, optimal Doppler thresholds for the detection of SGA cases were determined and the areas under the curves calculated. The analysis was limited to singleton pregnancies delivered within 2 weeks of the last Doppler examination. RESULTS: There were 88 study patients of which 60 had SGA babies. The mean gestational age at Doppler examination was 31.4 weeks with a mean interval of 5.6 days from Doppler to delivery. The splenic artery PSV was lower in SGA, compared to normal cases: mean PSV (MoM), 0.93 vs. 1.09, respectively (P = 0.0001). The sensitivity, specificity and area under the curve were 70.0%, 72% and 0.734, respectively (P < 0.003), for the PSV in the prediction of delivery of a SGA fetus. For the splenic artery RI, values were 70%, 46% and 0.539, respectively (not significantly different), and for umbilical artery RI these were 70%, 61% and 0.689, respectively (P < 0.01). Splenic artery EDV was significantly reduced in SGA vs. normally grown fetuses (0.924 MoM vs. 1.145 MoM, P = 0.007). CONCLUSIONS: Fetal splenic artery PSV decreases in SGA infants, and is a strong predictor of the delivery of a SGA infant. It appears to be superior to the standard Doppler index, the RI, in predicting this outcome.
