Umbilical artery blood velocimetry: a prospective longitudinal study in search of the intrauterine growth-retarded fetus

Amino acids, glucose and lactate concentrations in umbilical cord blood in relation to umbilical artery flow patterns

OBJECTIVE

To study possible relationships between abnormal placental perfusion, hypoxemia and impaired fetal nutrient supply.

STUDY DESIGN

Umbilical artery flow velocity waveforms were assessed in high risk pregnancies and compared with controls. Three groups were studied. In group I (n = 13) the pulsatility index (PI) was within normal limits, in group II (n = 9) PI was > 2 S.D. in the presence of positive end diastolic velocities and in group III (n = 13) end diastolic velocities were absent. pH and PO2 levels and concentrations of amino acids, glucose and lactate were measured in umbilical blood obtained at cesarean section (n = 35).

RESULTS

An inverse correlation was found between concentrations of essential amino acids concentrations and the pulsatility index in the umbilical artery (P = 0.03). No correlation with hypoxemia was found (P = 0.32). The glycine/valine ratio was significantly increased in the groups with abnormal Doppler velocity indices (P = 0.02). Glucose concentrations were significantly reduced in the case of absent end diastolic velocities (P = 0.001). No significant differences were found between the three groups concerning lactate concentrations and acid-base balance parameters.

CONCLUSIONS

These findings, especially the increased glycine/valine ratio, which is characteristic for kwashiorkor, indicate that abnormal placental perfusion is associated with impaired fetal nutrient supply, in the presence of a normal fetal oxygenation.

Management of patients with poor symphysis pubis-fundus growth by Doppler flow velocimetry of the umbilical artery--an effective method to detect the fetus at risk

This study evaluated Doppler flow velocimetry of the umbilical artery in patients with suspected intrauterine growth retardation as detected by poor symphysis-fundus growth (SFG). The sensitivity of Doppler in detecting light for gestational age babies and intrauterine growth retardation was poor. Antenatal complications, neonatal morbidity and perinatal mortality occurred significantly more frequently in patients with abnormal flow. Doppler flow velocimetry is an excellent test to identify babies at high risk for perinatal morbidity and mortality, when poor SFG is present.

Validity of umbilical artery blood velocimetry in the prediction of intrauterine growth retardation and fetal compromise

In a prospective longitudinal investigation, the validity of umbilical artery velocimetry in the detection of IUGR and fetal compromise was calculated in a group of 105 patients. With the help of pulsed Doppler ultrasound, measurements were performed from a menstrual age of 15 weeks onwards till term. The pulsatility index was calculated. The sensitivity, specificity, likelihood ratio and post test probability were determined with regard to the ability to predict IUGR and fetal compromise. The sensitivity in the detection of IUGR was 44.4%, the post test probability was 32.4%. For the prediction of fetal distress a sensitivity of 77.8% and a post test probability of 40.1% was calculated. In a selected group of high-risk patients (IUGR or PIH) the post-test probability was 77.6%. It seems clear that umbilical artery velocimetry is not useful as a screening tool for IUGR, but it has some potential to predict fetal distress.

The blood flow velocity waveform index in the fetal thoracic aorta and its ability to detect fetal compromise in the small for gestational age fetus

In a prospective longitudinal study of 96 patients, mean values of blood velocity waveform indices of the fetal thoracic aorta are established with a combined linear array real-time and pulsed Doppler transducer. The course of the various blood velocity waveforms is elucidated. The most striking finding is the restricted variability of the pulsatility index (PI), resistance index (RI), A/B ratio, acceleration time (AcT) and acceleration time percentage (AcTP) during the last trimester of pregnancy. In 17 proven and evaluable SGA infants the various blood velocity waveform indices were compared with the established mean values. Fourteen of these 17 (82%) infants were proven to be intrauterine growth-retarded (IUGR). Only 3 of these 14 (21%) showed a significant increase in PI values.