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Table 5 Gestational age-defined reference ranges for MCA PI/UA PI ratio

From: Ultrasound angiology reference standards of fetal cerebroplacental flow in normal Egyptian gestation: statistical analysis of one thousand observations

GA (weeks)

Centiles of MCA/UA PI

1st

2.5th

5th

10th

90th

95th

97.5th

99th

13.0

0.40

0.45

0.49

0.55

1.10

1.20

1.30

1.41

13.5

0.42

0.47

0.52

0.58

1.14

1.24

1.34

1.46

14.0

0.44

0.50

0.54

0.60

1.18

1.29

1.39

1.51

14.5

0.47

0.52

0.57

0.63

1.22

1.33

1.44

1.56

15.0

0.49

0.54

0.59

0.65

1.26

1.38

1.48

1.61

15.5

0.51

0.56

0.62

0.68

1.31

1.42

1.53

1.66

16.0

0.53

0.59

0.64

0.71

1.35

1.47

1.58

1.71

16.5

0.55

0.61

0.66

0.73

1.39

1.51

1.62

1.76

17.0

0.57

0.63

0.68

0.75

1.43

1.55

1.67

1.81

17.5

0.58

0.65

0.71

0.78

1.47

1.60

1.71

1.86

18.0

0.60

0.67

0.73

0.80

1.51

1.64

1.76

1.91

18.5

0.62

0.69

0.75

0.82

1.55

1.68

1.80

1.96

19.0

0.64

0.70

0.77

0.84

1.59

1.72

1.85

2.01

19.5

0.65

0.72

0.78

0.86

1.62

1.76

1.89

2.05

20.0

0.67

0.74

0.80

0.88

1.66

1.80

1.94

2.10

20.5

0.68

0.75

0.82

0.90

1.70

1.84

1.98

2.15

21.0

0.69

0.77

0.83

0.92

1.73

1.88

2.02

2.19

21.5

0.70

0.78

0.85

0.94

1.77

1.92

2.06

2.24

22.0

0.71

0.79

0.86

0.95

1.80

1.96

2.11

2.29

22.5

0.72

0.80

0.87

0.96

1.84

2.00

2.15

2.33

23.0

0.73

0.81

0.89

0.98

1.87

2.03

2.19

2.38

23.5

0.74

0.82

0.90

0.99

1.90

2.07

2.23

2.42

24.0

0.74

0.83

0.90

1.00

1.93

2.11

2.27

2.47

24.5

0.75

0.83

0.91

1.01

1.96

2.14

2.31

2.51

25.0

0.75

0.84

0.92

1.02

1.99

2.18

2.34

2.55

25.5

0.76

0.84

0.93

1.03

2.02

2.21

2.38

2.60

26.0

0.76

0.85

0.93

1.03

2.05

2.24

2.42

2.64

26.5

0.76

0.85

0.93

1.04

2.08

2.28

2.46

2.69

27.0

0.76

0.85

0.94

1.04

2.11

2.31

2.50

2.73

27.5

0.76

0.85

0.94

1.05

2.13

2.34

2.53

2.77

28.0

0.76

0.85

0.94

1.05

2.16

2.37

2.57

2.82

28.5

0.75

0.85

0.94

1.05

2.18

2.40

2.61

2.86

29.0

0.75

0.85

0.94

1.05

2.21

2.43

2.64

2.90

29.5

0.74

0.84

0.93

1.05

2.23

2.46

2.68

2.94

30.0

0.74

0.84

0.93

1.05

2.26

2.49

2.71

2.99

30.5

0.73

0.83

0.93

1.05

2.28

2.52

2.75

3.03

31.0

0.72

0.82

0.92

1.04

2.30

2.55

2.79

3.08

31.5

0.72

0.82

0.92

1.04

2.33

2.58

2.82

3.12

32.0

0.71

0.81

0.91

1.03

2.35

2.61

2.86

3.16

32.5

0.70

0.80

0.90

1.03

2.37

2.64

2.89

3.21

33.0

0.69

0.79

0.89

1.02

2.39

2.67

2.93

3.26

33.5

0.68

0.78

0.88

1.01

2.41

2.70

2.97

3.30

34.0

0.67

0.77

0.87

1.01

2.44

2.73

3.00

3.35

34.5

0.65

0.76

0.86

1.00

2.46

2.76

3.04

3.40

35.0

0.64

0.75

0.85

0.99

2.48

2.79

3.08

3.44

35.5

0.63

0.74

0.84

0.98

2.50

2.82

3.12

3.49

36.0

0.62

0.73

0.83

0.97

2.52

2.85

3.15

3.54

36.5

0.60

0.71

0.82

0.96

2.54

2.88

3.19

3.60

37.0

0.59

0.70

0.81

0.95

2.56

2.91

3.23

3.65

37.5

0.58

0.69

0.79

0.94

2.59

2.94

3.27

3.70

38.0

0.56

0.67

0.78

0.92

2.61

2.97

3.32

3.76

38.5

0.55

0.66

0.77

0.91

2.63

3.00

3.36

3.81

39.0

0.53

0.65

0.76

0.90

2.65

3.04

3.40

3.87

39.5

0.52

0.63

0.74

0.89

2.68

3.07

3.45

3.93

40.0

0.51

0.62

0.73

0.87

2.70

3.10

3.49

4.00

  1. Reference ranges for MCA PI/UA PI based on 1284 observations show progressive course which ranges from 0.40 to 2.64 with average 1.24 at 2nd trimester, and ranges from 0.76 to 4.00 with average 1.71 at 3rd trimester