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  • 1
    Electronic Resource
    Electronic Resource
    The coagulation system in placental insufficiency: a study in the fetal circulation (1993)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 100 (1993), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objective To examine the hypothesis that Doppler-defined umbilical placental insufficiency is associated with intravascular coagulation in the fetal circulation.Design A prospective, descriptive, single centre study.Setting The University of Sydney, Department of Obstetrics at Westmead Hospital.Subjects Ninety-one infants were classified on the basis of the systolic: diastolic (SD) ratio of the umbilical artery flow velocity waveforms into severe (SD 〉 99.9th centile), moderate (SD 〉95th centile) or control groups.Intervention Blood was collected from the umbilical vein at delivery.Main outcome measures The coagulation variables measured were the plasma concentrations of thrombin-antithrombin, fibrinopeptide A and fibrinogen, the antithrombin III activity, the prothrombin time and the activated partial thromboplastin time.Results There were no differences in activated partial thromboplastin time, antithrombin III activity, fibrinopeptide A or thrombin-antithrombin complex concentrations between fetuses with placental insufficiency and those with no placental disease. Fetuses with severe and moderate placental insufficiency had a statistically significant prolongation of their mean prothrombin time compared to controls (23.7 ± 0.8, 23.6 ± 1.6, and 19.9 ± 0.6 s, respectively). Infants in the severe group had a lower plasma fibrinogen concentration than control fetuses (1.66 ± 0.09 and 1.94 ± 0.09 g/l, respectively). The activated partial thromboplastin time and antithrombin III activity were both highly dependent on gestational age.Conclusions These results do not support the hypothesis that Doppler-defined umbilical placental insufficiency is associated with activation of coagulation in the fetal circulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1993.tb15173.x
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  • 2
    Electronic Resource
    Electronic Resource
    Angiotensin sensitivity predicts aspirin benefit in placental insufficiency (1993)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 100 (1993), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objective To determine whether the beneficial effects of aspirin in the treatment of Doppler umbilical placental insufficiency correlate with the maternal pressor response to angiotensin infusion.Design An open trial.Setting A tertiary referral obstetric service.Patients Women identified at between 25 and 36 weeks of pregnancy with an elevated umbilical artery Doppler systolic/diastolic (S/D) ratio and a positive pressor response to angiotensin infusion.Intervention Low dose aspirin (100mg/day) treatment of mothers.Main outcome measure Fetal and placental size at delivery in relation to subsequent maternal angiotensin responsiveness.Results Women who converted from a positive angiotensin pressor response to angiotensin refractoriness after aspirin administration had larger infants and placentas compared with those whose response remained positive.Conclusion Angiotensin sensitivity predicts women with umbilical Doppler detected placental insufficiency responding to aspirin therapy. Loss of the normal refractory response in pregnancy may be a consequence of vascular pathology in the placenta.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1993.tb12949.x
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  • 3
    Electronic Resource
    Electronic Resource
    Fetal volume blood flow and umbilical artery flow velocity waveform analysis: a comparison (1986)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 93 (1986), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. The estimation of fetal umbilical vein and aortic volume blood flow was compared with umbilical artery flow velocity-time waveform analysis in 42 pregnancies. The volume blood flow measurements were made with a combined linear array B-mode and pulsed Doppler ultrasound system. The umbilical artery flow velocity-time waveform analysis was made with either pulsed or continuous wave 2 MHzDoppler ultrasound and the systolic/diastolic (A/B) ratio was used as an index of flow resistance. There was no difference when continuous wave was compared to pulsed Doppler ultrasound as a method of recording flow velocity waveforms. Analysis of the umbilical artery flow velocity-time waveform was more sensitive (100%-50%) than the measurement of umbilical vein volume blood flow (ml/kg/min) in the detection of the small-for-gestational age (SGA) fetus. The predictive value of a positive test was higher (71%-45%) while specificity was similar (88%-81%). Descending aortic volume flow was reduced in only one SGA fetus. The increase in umbilical placental downstream resistance (high systolic/ diastolic ratio) was associated with a reduction in the percentage of fetal aortic blood flow directed to the umbilical placental circulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1986.tb08654.x
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  • 4
    Electronic Resource
    Electronic Resource
    Umbilical cord whole blood viscosity and the umbilical artery flow velocity time waveforms: a correlation (1986)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 93 (1986), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. The possibility was examined of an association between umbilical cord whole blood viscosity and umbilical artery flow velocity time waveforms obtained with continuous wave Doppler ultrasound. The cord blood viscosity was measured at both high (100 s-l) and low (0·1 s-I) shear rates with a concentric cylinder viscometer. Plasma viscosity and fibrinogen were also measured. An abnormal pattern in the umbilical artery flow velocity waveform (high A/B ratio) indicative of high resistance was associated with an increase in whole blood viscosity at high shear (which may reflect a change in red cell rigidity). Viscosity at low shear (reflecting red cell aggregation and rouleaux formation) did not differ. There was a significant association between the small-for-gestational age fetus and abnormal umbilical artery waveform study (P 〈0·002) but not abnormal whole blood viscosity at high (P=0·09) or low (P=0·08) shear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1986.tb08655.x
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  • 5
    Electronic Resource
    Electronic Resource
    Doppler ultrasound waveform indices: A/B ratio, pulsatility index and Pourcelot ratio (1988)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 95 (1988), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. Three different indices, the A/B ratio, the pulsatility index (PI) and the Pourcelot ratio (PR), are in common use for quantitative analysis of umbilical artery Doppler ultrasound waveforms. A detailed examination of the similarities and differences between these indices, together with the expected errors for each, was undertaken to enable informed comparisons and choices to be made. The indices were calculated from 133 last trimester recordings using an objective and very reliable computer analysis technique. The PI is more difficult to calculate than the other two quantities and the extra computation does not provide any extra information. The A/B ratio appears the simplest index to use but the values are not normally distributed. With the PR a normal distribution of values can be assumed. A theoretical consideration of errors showed that none of the indices is intrinsically less error prone for last trimester waveforms overall. The errors in the A/B ratio increase as the value of the index increase, whereas the converse holds for the PI and PR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1988.tb09487.x
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  • 6
    Electronic Resource
    Electronic Resource
    Umbilical artery velocity waveforms: normal reference values for A/B ratio and Pourcelot ratio (1988)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 95 (1988), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. Normal reference values for the umbilical artery Pourcelot ratio and A/B ratio are reported. Thirty-five normal patients were studied serially from 20 weeks to term. The A/B ratio centilcs were corrected for non-normality of the underlying distribution by transforming from the Pourcelot ratio values. The correction needed was small during the last trimester, but larger for second trimester data. Of the 35 patients 24 were nulliparous and there was a slight tendency for the waveform indices to be higher in the nulliparae, but the numbers in this study were too small to be conclusive about the effect of parity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1988.tb09488.x
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  • 7
    Electronic Resource
    Electronic Resource
    Fetal volume blood flow and umbilical artery flow velocity waveform analysis: a comparison (1986)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 93 (1986), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. The estimation of fetal umbilical vein and aortic volume blood flow was compared with umbilical artery flow velocity-time waveform analysis in 42 pregnancies. The volume blood flow measurements were made with a combined linear array B-mode and pulsed Doppler ultrasound system. The umbilical artery flow velocity-time waveform analysis was made with either pulsed or continuous wave 2 MHzDoppler ultrasound and the systolic/diastolic (A/B) ratio was used as an index of flow resistance. There was no difference when continuous wave was compared to pulsed Doppler ultrasound as a method of recording flow velocity waveforms. Analysis of the umbilical artery flow velocity-time waveform was more sensitive (100%-50%) than the measurement of umbilical vein volume blood flow (ml/kg/min) in the detection of the small-for-gestational age (SGA) fetus. The predictive value of a positive test was higher (71%-45%) while specificity was similar (88%-81%). Descending aortic volume flow was reduced in only one SGA fetus. The increase in umbilical placental downstream resistance (high systolic/ diastolic ratio) was associated with a reduction in the percentage of fetal aortic blood flow directed to the umbilical placental circulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1986.tb07930.x
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Umbilical cord whole blood viscosity and the umbilical artery flow velocity time waveforms: a correlation (1986)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 93 (1986), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. The possibility was examined of an association between umbilical cord whole blood viscosity and umbilical artery flow velocity time waveforms obtained with continuous wave Doppler ultrasound. The cord blood viscosity was measured at both high (100 s−l) and low (0·1 s−I) shear rates with a concentric cylinder viscometer. Plasma viscosity and fibrinogen were also measured. An abnormal pattern in the umbilical artery flow velocity waveform (high A/B ratio) indicative of high resistance was associated with an increase in whole blood viscosity at high shear (which may reflect a change in red cell rigidity). Viscosity at low shear (reflecting red cell aggregation and rouleaux formation) did not differ. There was a significant association between the small-for-gestational age fetus and abnormal umbilical artery waveform study (P 〈0·002) but not abnormal whole blood viscosity at high (P=0·09) or low (P=0·08) shear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1986.tb07931.x
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  • 9
    Electronic Resource
    Electronic Resource
    Administration of low-dose aspirin to mothers with small for gestational age fetuses and abnormal umbilical Doppler studies to increase birthweight: a randomised double-blind controlled trial (2000)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 107 (2000), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.2000.tb13319.x
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  • 10
    Electronic Resource
    Electronic Resource
    Is an atherogenic lipoprotein profile in the fetus a prerequisite for placental vascular disease? (2000)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 107 (2000), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objective To measure the blood apolipoprotein A-1 and apolipoprotein B in the fetal circulation in normal pregnancy and in pregnancy with evidence of vascular disease in the fetal umbilical placental circulation defined in the antenatal period by Doppler ultrasound study.Design An observational study to compare fetal plasma apolipoprotein levels in normal and complicated pregnancy.Setting A university hospital tertiary referral obstetric unit.Samples Umbilical vein blood was collected at delivery from 22 normal fetuses delivered by elective caesarean section for non fetal reasons and 30 fetuses with evidence of umbilical placental vascular disease identified antenatally by Doppler ultrasound study.Methods Plasma apolipoprotein A-1 and B were determined using an enzyme-linked immunosorbent assay (ELISA) methods.Main outcome measures Fetal plasma levels of apolipoprotein A-1 and B were measured.Results There was a significantly lower level of fetal plasma apolipoprotein A-1 in placental insufficiency [placental insufficiency vs normal pregnancy, median 0.30 g/L (interquartile range 0.24, 0.39 g/L) vs 0.35 g/L (0.31, 0.42 g/L), P= 0.045]. In contrast, the levels of fetal plasma apolipoprotein B in placental insufficiency [0.20 g/L (0.17, 0.26 g/L)] were significantly increased compared with normal pregnancy [0.16 g/L (0.14, 0.20 g/L), P= 0.03]. The ratio of fetal plasma apolipoprotein B to A-1 was also substantially higher in placental insufficiency [0.68 (0.55, 0.83)] than in normal pregnancy [0.45 (0.36, 0.60), P= 0.0003].Conclusions Our study has demonstrated that levels of fetal plasma apolipoprotein A-1, apolipoprotein B and the ratio of apolipoprotein B to A-1 were altered in the fetuses who are victims of umbilical placental insufficiency in the same direction as in adults associated with a high risk of atherogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.2000.tb13270.x
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