Critical analysis of the validity of electronic fetal monitoring.
The validity of the diagnosis fetal distress based on electronic fetal monitoring (EFM) is low. It can be argued that the prediction of fetal distress may be influenced by the obstetric intervention, and a number of false-positive (FP) decisions are in fact cases of successful prevention of acidosis. The false-negative decisions (FN) may include cases in which an operative delivery was not performed, although the impaired fetal condition was correctly recognized. To estimated the magnitude of these effects, deliveries after 28 weeks of gestation, in which EFM was applied, were studied. The medical staff involved in these deliveries was asked to estimate the umbilical artery pH immediately before birth. After birth the pH was measured. Cases were classified as operative delivery for fetal distress or other. Fetal distress was supposes to be confirmed if the umbilical artery pH was less than or equal to 7.14. Pre-birth estimates of the pH were obtained in 393 cases. Of the 20 FP cases, 70% were real FP after considering the prebirth estimate; of the 35 FN cases, 89% were real FN. After correction for mistaken false results the sensitivity increased from 20.5% to 29.5% and the predictive value from 31.0% to 51.7%. Although validity and predictive values improve after correcting for the mistaken false results, their values are still unsatisfactorily low.
Jongsma
H W
HW
Department of Obstetrics and Gynaecology, Academic Hospital Nijmegen, The Netherlands.
Nijhuis
J G
JG
D001034:Apgar Score; D004582:Electronics, Medical; D005188:False Negative Reactions; D005189:False Positive Reactions; D005316:Fetal Distress / Q000175:diagnosis*; D005323:Fetal Monitoring / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007231:Infant, Newborn; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014469:Umbilical Arteries / Q000502:physiology