Doppler ultrasound in obstetric practice: 2.

Doppler ultrasound has been widely introduced into clinical obstetric practice with minimal proven benefits, except in high-risk and twin pregnancies, and as a potential screening tool for pre-eclampsia. This article considers the practical aspects of the technique.

Doppler ultrasound in obstetric practice: 1.

The Doppler effect has been recognized for around 150 years. The practical application of the phenomenon to the study of fetomaternal haemodynamics has been applied for almost 20 years. This article considers the theory of the effect in relation to obstetric practice.

Evaluation of biophysical fetal assessment in high-risk pregnancy to assess ultrasound parameters suitable for screening in the low-risk population.

During a 1-year period, 662 pregnant women at 24-43 weeks' gestation were referred to the Department of Obstetrics and Gynaecology, at the Queens University Belfast, for fetal assessment because they were clinically suspected to be at high risk of perinatal complications. The results of our investigations were made available to the referring obstetricians who undertook the further management of the pregnancies. Subsequently six pregnancies resulted in perinatal deaths and 97 (14.7%) in the delivery of small-for-gestational-age infants. We restrospectively analyzed the data from ultrasonographic evaluation of the fetus and subjective and objective assessments of the amniotic fluid volume to determine their value in the prediction of adverse perinatal outcome. A fetal abdominal circumference < 10th centile for gestation or a subjectively reduced amniotic fluid volume identified 87 (90%) of small-for-gestational-age infants and five of the six perinatal deaths. When comparing the abdominal circumference and subjective liquor volume, both were sensitive in predicting delivery of a small-for-gestational-age fetus (sensitivity 86% vs. 53%, respectively) and perinatal death (sensitivity 50% vs. 83%, respectively). We suggest that, since assessments of these two factors are complementary in evaluating a high-risk pregnancy and can be measured in under 5 min, they now warrant consideration for screening in a prospective randomized trial in an unselected low-risk population.

Association of Chlamydia trachomatis with tubal infertility.

A study was undertaken to determine whether the positive correlation between Chlamydia trachomatis antibodies and tubal infertility, noted by workers in other countries, also applied to infertile women in Northern Ireland. Ninety-one infertile women and 106 fertile controls were tested for current cervical infection with C. trachomatis and for evidence of past chlamydial infection. The incidence of C. trachomatis infection of the cervix was 5.8% in the infertile group and 2.8% in the control group. The prevalence of C. trachomatis antibody was 22% in the infertile group and 18.9% in the control group. Previous termination of pregnancy, history of sexually transmitted disease and number of sexual partners were identified as risk factors for seropositivity and tubal disease. We concluded that it would be of value to screen women attending the infertility clinic for C. trachomatis infection of the cervix, and that testing these patients for chlamydia antibodies may also be useful in planning further investigation.

Antenatal screening for intrauterine growth retardation with umbilical artery Doppler ultrasonography.

To assess the usefulness of continuous wave Doppler ultrasonography as an antenatal screening tool for the detection of intrauterine growth retardation and fetal compromise 2097 singleton pregnancies were studied. Umbilical artery velocity waveforms were obtained at 28, 34, and 38 weeks of gestation, from which the pulsatility index, A/B ratio, and resistance parameter were calculated. No abnormal features or indices of neonatal outcome were adequately predicted. The most sensitive index for being delivered of a growth retarded infant (less than 5th centile birth weight for gestation) was an A/B ratio at 34 weeks (sensitivity 40%, specificity 84%). Other measures that show poor neonatal nutritional state (ponderal index, skinfold thickness, and ratio of mid-arm circumference to head circumference) were even less well predicted. Acute and chronic hypoxia as determined by Apgar score, pH in blood from the cord artery, and packed cell volume correlated poorly with umbilical artery waveform indices, and there was no obvious difference between the indices of those who subsequently required operative or instrumental delivery for fetal distress and those requiring no intervention. There were three unexplained stillbirths in the series, in each of which the fetus had shown waveform patterns that suggested increased peripheral resistance, though the technique did not appear to be useful for predicting the time of subsequent death. Screening for small for dates babies in a three stage programme was of no value regardless of the threshold or index chosen. Obstetricians should resist the temptation to introduce screening with Doppler ultrasonography until its proper role has been determined.