Peak systolic over protodiastolic ratio as an objective substitute for the uterine artery notch.
OBJECTIVE
To measure the inter-rater agreement for the identification of a uterine artery notch, as well as the association between an observed notch and the peak systolic over protodiastolic (A/C) ratio.


METHODS
Cohort study.


METHODS
Tertiary care university hospital.


METHODS
Six hundred and sixty-five nulliparous women in whom 1022 examinations of uterine artery velocity waveforms were performed by pulsed Doppler at 18 and at 26 weeks of gestation. Agreement between two independent raters was analysed using Cohen's kappa statistics. A/C ratios of flow velocity waveforms with or without a notch were compared. The agreement between A/C values and the presence of a notch was estimated by measuring the surface under the receiver operating characteristic (ROC) curve.


RESULTS
Inter-rater agreement for the identification of a notch was 0.74 (95% CI 0.64-0.83) at 18 weeks and 0.72 (95% CI 0.64-0.80) at 26 weeks. A/C ratios were higher when a notch was present (P < 0.0001). The area under the ROC curve was 0.86 (95% CI 0.81-0.91) for the placental uterine artery and 0.93 (95% CI 0.90-0.96) for the nonplacental artery. An A/C value > or = 2.5 in any uterine artery had a sensitivity of 88% and a specificity of 86% to detect a notch.


CONCLUSIONS
Although there is no definitive definition of the notch, its detection is reproducible within a center. However, published prevalences between centers in unselected populations vary. The measure of the A/C ratio can serve as an objective substitute.
Irion
O
O
Department of Obstetrics and Gynaecology, Faculty of Medicine, Université Laval, Québec, Canada.
Massé
J
J
Forest
J C
JC
Moutquin
J M
JM
D000328:Adult; D019540:Area Under Curve; D001158:Arteries / Q000502:physiology; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000502:physiology*; D015331:Cohort Studies; D003971:Diastole; D005260:Female; D006801:Humans; D011247:Pregnancy / Q000502:physiology*; D011256:Pregnancy Outcome; D015203:Reproducibility of Results; D013599:Systole; D018617:Ultrasonography, Doppler, Pulsed; D014599:Uterus / Q000098:blood supply*; D014655:Vascular Resistance