P06.08: Monitoring of sacrococcygeal teratoma: clinical evaluation of a computerised model

Abstract

Clinical validation of a computer model assessing the excess cardiac output in fetuses with sacrococcygeal teratoma (SCT). A computational risk prediction model for SCT was developed. The model accounted for viscosity, sheer stress and the relationship between vessel diameter and flow. Drainage from the SCT (DvSCT) was represented by the differences between superior and inferior caval venous diameters. The additional cardiac output required to perfuse the SCT was represented by the diameter of the umbilical vein (UV) divided by DvSCT and plotted against the gestational age (GA) risk-line modified from the model. Serial fetal monitoring using ultrasound and Doppler methodology measured the ratio of SCT to estimated fetal weight (EFW) and derived indices of combined cardiac output corrected for EFW (iCCO). These were compared with the high or low estimated risk from the model. Standard practice at our Centre was to deliver fetuses with uncomplicated SCT at 36 weeks gestation. Delivery at < 32 weeks was therefore used as a surrogate for fetal compromise. Twelve fetuses with SCT were included and monitored serially; outcome was known in 9 fetuses: 6 were delivered prematurely (3 ≤ 32 weeks) and 3 at term. Mean GA at delivery was 33.2 ± 3.6 weeks. One neonate born at 29 weeks demised. UV/DvSCT measurements could be obtained in all fetuses. UV/DvSCT risk at first visit (23.6 ± 2.2 weeks) correlated significantly with GA at delivery (r=0.756; p=0.030). UV/DvSCT ratio correlated with GA delivery < 32 weeks (r=0.393, p=0.011) and the presence/absence of hydrops (r=0.409, p=0.07). No significant correlation was found between iCCO and UV/DvSCT or iCCO and GA at delivery. Measurement of UV/DvSCT is simple and reliable. Unlike iCCO, the UV/DvSCT risk at mid-gestation correlates with GA at delivery. It is a useful adjunct to SCT/EFW ratio as it reflects excess fetal cardiac output required to perfuse the SCT and thus is a useful physiological monitor of fetuses with SCT.