Antepartum non stress cardiotocography and quantified short term variability of foetal heart rate in high-risk pregnancies.
The clinical significance of non-stress cardiotocography (CTG) and antepartum quantified short-term variability (differential index = DI) of foetal heart rate (FHR) were assessed for prediction of foetal outcome in 461 high-risk pregnancies. The analysis of FHR variability were made by a microprocessor based on-line method which utilizes abdominal foetal electrocardiogram (aFECG) as a triggering signal. In 24 pregnancies no acceptable aFECG was obtained. CTG was classified as pathological in 167 pregnancies (36%), and DI was abnormal in 74 pregnancies (15%) in the last test before delivery. Foetal distress developed in 97 pregnancies. There were no antepartum foetal deaths, but six newborn infants died (perinatal mortality 1.3%). CTG was more sensitive but less predictive, and less specific than DI. Risk of foetal distress after a pathological CTG was 8.9 times that after a normal CTG (relative risk, p less than 0.001), and after a pathological DI 8.0 times that after a normal DI (p less than 0.001). Both tests were pathological in 64, and both normal in 265 cases. The risk of foetal distress after combined pathological tests was 20.3 times that after normal combined tests (p less than 0.001). These results suggest that prediction of foetal outcome may be improved by combining CTG and DI. Since the false abnormal rate of CTG was high, further evaluation is required. DI picked out 74 of 86 cases with false abnormal CTGs. These results suggest that DI could be used for further testing of abnormal CTGs.
D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005316:Fetal Distress / Q000175:diagnosis*; D005318:Fetal Heart / Q000503:physiopathology; D005323:Fetal Monitoring / Q000379:methods*; D006339:Heart Rate; D006801:Humans; D011247:Pregnancy; D011248:Pregnancy Complications; D011296:Prenatal Diagnosis / Q000379:methods; D012306:Risk