Prevalence of abnormal umbilical arterial flow on Doppler ultrasound in low-risk and unselected pregnant women: a systematic review

Table 2 Characteristics of women and Doppler assessments in included studies

Study population	N (studies)	%
Maternal risk
Low-risk women only	36	85.7
Unselected women	6	14.3
Doppler assessments
Doppler ultrasound of umbilical artery only reported	15	35.7
Doppler ultrasound of umbilical artery plus other Doppler investigations reported^a	27	64.2
Type of Doppler
Colour Doppler	12	28.6
Continuous-wave Doppler	6	14.3
Pulsed-wave Doppler	6	14.3
Pulsed-wave Doppler; colour Doppler	9	21.4
Pulsed-wave and continuous-wave Doppler	1	2.1
Doppler (not otherwise specified)	8	19.0

^aFetal cerebral circulation, fetal aorta, fetal renal arteries, umbilical vein, ventricular outlets, femoral vessels, uterine/placental vessels

ISSN: 1742-4755