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Biomedical subjects

K P Hanretty

Publications and source records attributed to K P Hanretty.

17 recordsLinked to original sources
PubMed1996

Is the incidence of ovarian ectopic pregnancy increasing?

Although tubal pregnancy is increasing, ovarian ectopic pregnancy has remained a rare event. However, North American reports suggest an increasing incidence relative to both tubal and term pregnancies. We report an unexpected increase in our practice with five primary ovarian pregnancies over the past year. Current understanding of the aetiological factors, pathogenesis and implications for management are outlined.

Adult↗
PubMed1994

Screening for the compromised fetus: a randomized trial of umbilical artery velocimetry in unselected pregnancies.

OBJECTIVE: Meta-analysis of randomized trials of Doppler ultrasonography in high-risk pregnancies has showed reduced mortality rates among normally formed fetuses. This trial addressed the impact on outcome of umbilical artery velocimetry in a nonselected population (i.e., as a screening test in low-risk and high-risk pregnancies). STUDY DESIGN: A randomized, controlled trial with Doppler ultrasonographic investigation was performed at two gestational age windows: 26 to 30 weeks and 34 to 36 weeks. The 2986 women were randomly allocated to revealed or concealed groups in which the Doppler results were either made available or not made available to clinicians; 1056 women were studied at only the first window, 544 at only the second, and 1386 at both. RESULTS: There were no significant differences between groups in antenatal admissions to hospital, preterm deliveries, rates of cesarean section, admission to the neonatal unit, and need for assisted ventilation. There was, however, a trend toward fewer stillbirths in the "revealed" group (three vs eight, odds ratio 0.34, confidence interval 0.10 to 1.07). CONCLUSIONS: The incidence of stillbirths was reduced by more than half in the Doppler-revealed group, but the confidence intervals were wide and these findings could be compatible with chance.

Adult↗
PubMed1993

Fetal catecholamine responses to vibroacoustic stimulation.

OBJECTIVE: The aim of this study was to determine whether fetal vibroacoustic stimulation caused a surge of catecholamines from the fetal sympathoadrenal system. STUDY DESIGN: A randomized, prospective, controlled trial was performed at The Queen Mother's Hospital, Glasgow. Circulating catecholamine levels in cord blood from a group of fetuses who received vibroacoustic stimulation 1 to 2 minutes before delivery by elective cesarean section (n = 25) were compared with those from a group of controls (n = 23) (Mann-Whitney U test). Fetal heart rate response to vibroacoustic stimulation was recorded in 10 additional pregnancies under identical experimental conditions. RESULTS: No differences were found in norepinephrine or epinephrine levels between the vibroacoustic stimulation group and the control group. A positive fetal heart rate response was observed in seven of 10 fetuses tested. Fetal norepinephrine levels were also found to be influenced by maternal blood pressure and administration of ephedrine. CONCLUSIONS: Under these conditions vibroacoustic stimulation does evoke the characteristic fetal heart rate response, but it does not induce a surge of catecholamines from the fetal sympathoadrenal system. Therefore it is unlikely that the immediate fetal heart rate response to vibroacoustic stimulation is induced by a surge in systemic catecholamines.

Acoustic Stimulation↗
PubMed1990

The use of Doppler ultrasound in the study of fetal cardiovascular physiology.

Doppler velocimetry of the uteroplacental and umbilical arteries provides an opportunity for the safe, reproducible and repeatable study of these circulations and already has led to an increased knowledge of the pathophysiology of pregnancy induced hypertension and intra-uterine growth retardation. This technique, which has only recently been introduced widely into obstetrics, also permits the study of the cardiovascular effects on the fetus of maternally administered drugs. The use of Doppler for these purposes is illustrated with particular reference to intra-uterine growth retardation and the use of the antihypertensive drugs, atenolol and nifedipine.

Animals↗
PubMed1989

Pregnancy screening by Doppler uteroplacental and umbilical artery waveforms.

Doppler waveforms from the uteroplacental and umbilical arteries were studied in 543 unselected women attending an antenatal clinic. Overall, 357 women were studied at 26-30 weeks and 395 at 34-36 weeks; 209 were studied at both gestation periods. Results were not made available to clinicians. There was no difference in outcome of pregnancies between those with normal and abnormal uteroplacental waveforms, but birthweights were significantly lower in those with an abnormal umbilical artery waveform at either gestation. There were no other statistically significant differences between groups. Although the power of the study to detect differences in outcome in this sample size is limited, our findings do not support the introduction of this new technique into clinical practice before sufficiently large randomized controlled trials have shown some benefit.

Adult↗
PubMed1989

The effect of intravascular transfusion for rhesus haemolytic disease on umbilical artery Doppler flow velocity waveforms.

To test the hypothesis that an increase in fetal blood viscosity is associated with an increase in resistance to flow, the effect on Doppler flow velocity waveforms of percutaneous umbilical blood sampling and intravascular transfusion was studied in 20 patients undergoing a total of 35 procedures. All but four of the 22 transfusions were associated with a decrease in resistance to flow, as shown by a reduction in the umbilical artery systolic/diastolic ratio, and this also occurred on 10 of the 13 occasions when blood sampling only was performed. These findings suggest that acute changes in blood viscosity following intravascular transfusion are not associated with an increase in resistance to flow as assessed by Doppler velocimetry. Umbilical blood sampling per se may be associated with a humorally mediated reduction in placental vascular resistance to flow.

Blood Transfusion, Intrauterine↗
PubMed1989

Potential use of Doppler ultrasound in developmental pharmacology.

The non-invasive study of the human fetal circulation is now possible using Doppler ultrasound techniques. Until recently, these methods have been used to study fetal physiology but are increasingly being used to assess the effect of maternally administered drugs on fetal cardiovascular dynamics. Drugs studied include established and experimental antihypertensive treatments, tocolytics and regional anaesthetics. This new application of Doppler ultrasound will increase our knowledge of drug effects in pregnancy and provides a new method of assessing novel treatments.

Female↗
PubMed1988

Doppler uteroplacental waveforms in pregnancy-induced hypertension: a re-appraisal.

Uteroplacental waveforms in 32 untreated patients with pregnancy-induced hypertension (PIH) were compared with those in 32 carefully matched women with normal pregnancies (alpha = 0.05; beta = 0.80 for 30% difference between groups). Although some of the PIH patients showed high-resistance waveforms, both high and low resistance patterns were obtained from all controls and all but 1 PIH patient, and there was no overall difference in pulsatility index between groups (p greater than 0.1). Further careful prospective evaluation is necessary to determine the diagnostic value of doppler uteroplacental velocimetry in clinical practice.

Adult↗
PubMed1988

Ultrasonographic estimation of fetal weight during labour. Evaluation and comparison of two formulae.

Estimation of fetal weight is a major component of obstetric practice and is important in determining management of the high-risk patient in particular. Many patients at high risk for perinatal morbidity and mortality present for the first time in established labour. As clinical methods in these circumstances are of limited accuracy, ultrasonography is increasingly being used for this purpose. The commonly used formulae relating ultrasound measurements to fetal weight were derived from a different population from our at-risk population, and we therefore measured abdominal circumference and biparietal diameter in 51 patients to assess the accuracy of two such formulae. While one of the formulae was superior to the other, the overall accuracy of both was disappointing and we feel that ultrasonographic estimation of fetal weight in labour is of limited value.

Birth Weight↗