The application of multiple-parameter scoring to antepartum fetal heart rate testing

Three hundred twenty-nine high-risk obstetric patients, undergoing 1,198 nonstressed tests (NSTs) and 101 subsequent contraction-stress tests (CSTs), were delivered during a 13-month study period. Each test was concurrently evaluated by conventional assessment criteria and by a 12-point multiple-parameter scoring system. The last test performed within one week of delivery was correlated with perinatal outcome, and the predictive accuracy of scoring was compared with conventional grading. Three NST groups were identified: group I (score: 9 to 12) had little perinatal compromise and overlapped extensively with the normally reactive group; group III (score: 0 to 4) were nearly all compromised, nonreactive by standard criteria and consistently followed by abnormal CSTs. Group II (score: 5 to 8) had an intermediate rate of compromise (33%) and was further categorized by subsequent CST outcome into normal, compromised or persistently equivocal subgroups. Scoring improved the sensitivity of CSTs, as well, when abnormal (positive or persistently equivocal). CSTs scoring below 5 were associated with a fetal compromise rate of 86%, approximately twice that of the group scoring in the 5-to-8 range. It was concluded that multiple-parameter scoring was of little benefit in improving test accuracy when the NST was normally reactive; however, scoring clearly delineated the most compromised fetal group from those requiring further evaluation when the NST was nonreactive. By combined NST-CST scoring alone, 90% of fetuses could be assigned to high- or low-risk prognostic groups with confidence; the remainder would require additional fetal data to complete their assessment.