Intrauterine Deaths in High-Risk Pregnancies with Normal and Borderline Umbilical Artery Doppler Flow Velocity Waveforms

Objective. To investigate the use of a personal computer (PC)-based; continuous-wave Doppler device by a trained midwife at the fetal evaluation clinic at a tertiary hospital to assess flow velocity waveforms (FVWs) of the umbilical artery flow in referred women. Methods. Pregnant women referred for suspected poor fetal growth were evaluated from June 2002 through December 2004. The Umbiflow device (still prototype; developed by CSIR/MRC/Stellenbosch University); consisting of a Pentium 3 PC with an ultrasound transducer plugged into the USB port; was used to analyse the FVW of the umbilical artery. Pregnancies in which the resistance index (RI) was 75th percentile (P75) were not further evaluated for fetal well-being unless the clinical condition of the mother had changed. Pregnancies with an RI P75 were followed up according to a specific protocol. Primary endpoints were intrauterine death and intrauterine growth restriction. Results. Doppler FVWs were assessed in 955 pregnancies. The RI was P75 in 529 participants (55.4); between the P75 and P95 percentile in 350 (36.6) and P95 in 53 (5.5). In 23 cases (2.4) end-diastolic flow was absent or reversed (AREDF). Intrauterine death within 1 week of the test occurred in 1; 4; 0 and 2 women respectively in these four groups; and 16.7; 34.5; 54.9and 65.5respectively gave birth to infants that were small for gestational age. Conclusions. Intrauterine death; within 1 week of the test; was extremely rare when the RI was P75 (0.2). Relatively more deaths within a week of the Doppler examination occurred in the P75 - P95 group. This group should be regarded as being at high risk and needs careful antenatal surveillance

Comparison between a newly developed PC-based Doppler umbilical artery waveform analyser and a commercial unit.

OBJECTIVES: To determine the accuracy of the resistance index (RI) of flow velocity waveforms of the umbilical artery measured using a newly developed PC-based continuous wave Doppler device (Umbiflow) with regard to systematic and random variations when compared with a commercial standard (Vasoflow). DESIGN: A cohort study. SETTING: The fetal evaluation clinic (FEC) at Tygerberg Hospital. SUBJECTS: Patients referred to the FEC at Tygerberg Hospital with suspected chronic placental insufficiency. OUTCOME MEASURES: The correlation coefficients indicating the strength of the relationship between the two devices and their agreement using the method of Bland and Altman. RESULTS: A total of 248 patients were studied. The mean RIs of the first Doppler assessment were 0.69 (standard deviation (SD) 0.11) and 0.67 (SD 0.11) using the Vasoflow and Umbiflow respectively. The Pearson's correlation coefficient comparing the RI of the first test was 0.85. The degree of agreement between the two methods was excellent, the mean differences being very small (< 0.024) with tight confidence intervals. One hundred and ninety-four patients (78.2%) of patients remained in the same percentile category with both the Vasoflow and Umbiflow. CONCLUSIONS: The accuracy of the Umbiflow has been proved. A non-significant trend towards slightly lower values needs to be considered. This could be addressed by changing the percentile cut-off to slightly lower values.

A community-based obstetric ultrasound service.

OBJECTIVES: To investigate the impact of an ultrasound dating service on obstetric services. METHODS: A prospective trial with 3009 unselected women presenting for antenatal care at two Midwife Obstetric Units in a socioeconomically deprived urban area, South Africa. In the study unit, student ultrasonographers provided a basic ultrasound service. In the control unit, obstetric ultrasound was only available for specific indications. The main outcome measures were number of antenatal visits and referrals for fetal surveillance. RESULTS: The two cohorts were comparable except for the number of primigravidas but stratified analysis according to parity did not affect the results. Ultrasonography did not alter pregnancy outcome but reduced the number of perceived preterm labors/ruptured membranes (12.0 vs. 16.7%, P<0.003), post-term deliveries (8.1 vs. 10.8%, P<0.04) and referrals for fetal surveillance [15.9 vs. 29.6%, P<0.000, RR 0.79 (0.71-0.88)]. CONCLUSIONS: This community-based basic ultrasound service significantly reduced referrals to a regional center for fetal surveillance and delivery.