Blood flow to the scarred gravid uterus at 22–24 weeks of gestation

Authors

  • K Flo,

    Corresponding author
    1. Women's Health and Perinatology Research Group, Department of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
    2. Department of Obstetrics and Gynaecology, University Hospital of North Norway, Tromsø, Norway
    • Correspondence: Dr K Flo, Department of Obstetrics and Gynaecology, University Hospital of North Norway, Sykehusveien 38, PO Box 24, N–9038 Tromsø, Norway. Email kari.flo@uit.no

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  • C Widnes,

    1. Women's Health and Perinatology Research Group, Department of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
    2. Department of Obstetrics and Gynaecology, University Hospital of North Norway, Tromsø, Norway
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  • Å Vårtun,

    1. Women's Health and Perinatology Research Group, Department of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
    2. Department of Obstetrics and Gynaecology, University Hospital of North Norway, Tromsø, Norway
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  • G Acharya

    1. Women's Health and Perinatology Research Group, Department of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
    2. Department of Obstetrics and Gynaecology, University Hospital of North Norway, Tromsø, Norway
    3. Department of Clinical Sciences, Intervention and Technology, Karolinska Institute, Stockholm, Sweden
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Abstract

Objective

To compare uterine artery volume blood flow (Quta), vascular resistance (Ruta), pulsatility index (Uta PI), and the fraction of maternal cardiac output (CO) distributed to the uteroplacental circulation in pregnant women with and without a previous caesarean section.

Design

Cross-sectional observational study.

Setting

University hospital in Norway.

Population

Thirty-two pregnant women with previous caesarean section and 32 matched controls.

Methods

Ultrasonography was used to measure uterine artery diameter and blood flow velocity between 22+0 and 23+6 weeks of gestation. Impedance cardiography was used to assess maternal haemodynamics.

Main outcome measures

Quta, Ruta, Uta PI, and the fraction of maternal CO distributed to the uteroplacental circulation.

Results

The mean Quta was 356.26 ± 213.72 ml/minute in cases and 456.41 ± 209.70 ml/minute in controls (P = 0.038). Ruta was significantly (P = 0.026) higher among cases compared with controls (0.32 ± 0.20 versus 0.22 ± 0.14 mmHg/ml/minute), but the Uta PI did not differ between the groups (0.93 ± 0.23 versus 0.92 ± 0.47; P = 0.929). The fraction of maternal CO distributed to the uteroplacental circulation was 5.75 ± 3.68% in cases and 8.45 ± 5.02% in controls (P = 0.014).

Conclusions

Uterine artery volume blood flow and the fraction of maternal cardiac output distributed to the uteroplacental circulation are lower, and uterine vascular resistance (but not Uta PI) is higher, in women with previous caesarean section compared with the control group.

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