Ante-Partum Cardiotocography and DopplerFlowmetry in the Diagnosis of Foetal Hypoxia

Ante-Partum Cardiotocography and DopplerFlowmetry in the Diagnosis of Foetal Hypoxia

Objective:
To evaluate by analysis of the most serious obstetric cases during a five-year period thecontribution of ante-partum CTG and Doppler flowmetry in the diagnosis of foetal risk and toassess the part of risk factors of hypoxia during pregnancy.Design: Retrospective epidemiological analysis.Setting: Gynaecological and Obstetric Clinic Medical Faculty Palacký University and FacultyHospital Olomouc.Method: In a retrospective analysis based on 6494 deliveries during a five-year period (1996–2000)the authors evaluate a selected sample of 1087 most serious conditions with the diagnosis ofimminent foetal hypoxia. In the evaluated group 90.3% of the women had a cardiotocographicexamination, 50.8% Doppler flowmetry with assessment of umbilical RI and PI indexes. The diagnosisof neonatal hypoxia was based on evaluation according to Apgar score < 7 and pH ofarterial blood < 7.20. The authors compare both diagnostic methods with a common gold standardas regards their ability to predict hypoxia. In the logistic regression model they evaluaterisk factors of pregnancy in relation to foetal hypoxia.Results: Clinical manifestations of hypoxia were recorded in 114 neonates (10.5%). Perinatal deathsoccurred in 46 infants, 16 were stillborn. Pathological ante-partum CCTG findings are associatedwith more active approaches (earlier termination of pregnancy, SC, preinduction by prostaglandins).Pathological ante-partum CTG and flowmetry was paradoxically more frequently associatedwith a better condition of the neonate. Pathological findings of ante-partum CTG weresignificantly less frequent in neonates with hypoxia than those without it (27%) vs. (40.9%), (relativerisk 0.56 [95% CL 0.36–0.88], P=0.01) while pathological findings of umbilical flowmetry wereinsignificantly more frequent (34.9%) vs. (33%), (relative risk 1.08 [95% Cl 0.59–1.97], P=0.9). Bothexaminations were made in 547 (50.3%) women of the whole group, in 43 (7.9%) hypoxia of thefoetus developed. Sensitivity: CTG 32.6%, Doppler 34.9%, Specificity: CTG 51.4%, Doppler 67.3%.Falsely positive CTG 48.6%, Doppler 32.7%.Analysis of risk factors of pregnancy in relation to foetal hypoxia defines by retrospective eliminationas significant risks haemorrhage during pregnancy (n=76, OR 2.35 [95% Cl 1.31–4.23],P=0.01) and premature delivery (n=258, OR 2.02 [95% Cl 1.34–3.05], P=0.0004).Conclusion: The value of ante-partum CTG and Doppler flowmetry in the prognosis of neonatalhypoxia is low. The lower rate of pathological findings in affected neonates is probably associatedwith the fact that part of the hypoxias develop during delivery and cannot be predicted beforedelivery. The high number of falsely positive findings may by due by the adaptational abilitiesand reserves of the infant, by a more active approach when there are signs of danger and incorrectinterpretation of findings. Premature delivery and haemorrhage are significant risks ofneonatal hypoxia.

Klíčová slova:
ante-partum cardiotocography, umbilical Doppler flowmetry, neonatal hypoxia, riskfactors