Introduction

The fetal kidneys are routinely imaged in the second and third trimester, but they are not usually measured unless an abnormality is suspected. Nomograms are available not only for kidney length ( Table 9.1 ) but also for anterior-posterior diameter ( Table 9.2 ) and transverse diameter ( Table 9.3 ). An abnormality of kidney size can occur as a normal variant, as a physiologic adaptation (i.e., compensatory hypertrophy), as a manifestation of a renal anomaly or tumor, or as a component of a genetic syndrome. If an abnormality of kidney size is suspected, further evaluation may reveal information about underlying pathology and assist with counseling about prognosis.

TABLE 9.1
NOMOGRAM FOR KIDNEY LENGTH IN MILLIMETERS ACCORDING TO GESTATIONAL AGE
Data from Chitty LS, Altman DG: Charts of fetal size: kidney and renal pelvis measurements, Prenat Diagn 23:891–897, 2003.
Weeks' Gestation 3rd 10th 50th 90th 97th
14 7.5 8.0 9.3 10.8 11.6
15 8.8 9.5 11.0 12.8 13.7
16 10.2 11.0 12.7 14.8 15.8
17 11.6 12.5 14.5 16.8 18.1
18 13.1 14.1 16.3 18.9 20.3
19 14.6 15.6 18.2 21.1 22.6
20 16.1 17.2 20.0 23.2 24.9
21 17.5 18.8 21.8 25.4 27.2
22 19.0 20.4 23.6 27.4 29.4
23 20.4 21.9 25.4 29.5 31.6
24 21.8 23.4 27.1 31.5 33.8
25 23.1 24.8 28.8 33.4 35.8
26 24.4 26.2 30.4 35.3 37.8
27 25.6 27.5 31.9 37.1 39.7
28 26.8 28.7 33.4 38.7 41.5
29 27.9 29.9 34.7 40.3 43.2
30 28.9 31.0 36.0 41.8 44.8
31 29.9 32.1 37.2 43.2 46.3
32 30.8 33.0 38.3 44.5 47.7
33 31.6 33.9 39.4 45.7 49.0
34 32.4 34.7 40.3 46.8 50.2
35 33.1 35.4 41.1 47.8 51.2
36 33.7 36.1 41.9 48.7 52.2
37 34.2 36.7 42.6 49.4 53.0
38 34.7 37.2 43.2 50.1 53.8
39 35.1 37.6 43.7 50.7 54.4
40 35.4 38.0 44.1 51.2 54.9
41 35.7 38.3 44.5 51.6 55.4
42 36.0 38.6 44.8 52.0 55.7

TABLE 9.2
NOMOGRAM FOR KIDNEY ANTERIOR-POSTERIOR DIAMETER IN MILLIMETERS ACCORDING TO GESTATIONAL AGE
Data from Chitty LS, Altman DG: Charts of fetal size: kidney and renal pelvis measurements, Prenat Diagn 23:891–897, 2003.
Weeks' Gestation 3rd 10th 50th 90th 97th
14 4.6 5.2 6.5 8.3 9.2
15 5.4 6.0 7.6 9.6 10.7
16 6.2 6.9 8.6 10.9 12.1
17 7.0 7.8 9.7 12.2 13.6
18 7.8 8.7 10.8 13.6 15.1
19 8.6 9.5 11.9 14.9 16.6
20 9.4 10.4 13.0 16.3 18.0
21 10.2 11.3 14.1 17.5 19.4
22 11.0 12.2 15.1 18.8 20.8
23 11.8 13.0 16.1 20.0 22.1
24 12.5 13.8 17.1 21.1 23.3
25 13.2 14.6 18.0 22.2 24.5
26 13.9 15.4 18.9 23.2 25.6
27 14.6 16.1 19.7 24.2 26.6
28 15.2 16.7 20.5 25.1 27.6
29 15.8 17.4 21.2 25.9 28.4
30 16.4 18.0 21.9 26.7 29.2
31 16.9 18.5 22.5 27.3 29.9
32 17.4 19.0 23.1 27.9 30.6
33 17.8 19.5 23.6 28.5 31.2
34 18.2 19.9 24.0 29.0 31.6
35 18.6 20.3 24.4 29.4 32.1
36 18.9 20.6 24.8 29.7 32.4
37 19.2 20.9 25.1 30.0 32.7
38 19.5 21.2 25.3 30.3 32.9
39 19.7 21.4 25.5 30.5 33.1
40 19.9 21.6 25.7 30.6 33.2
41 20.1 21.8 25.8 30.7 33.2
42 20.2 21.9 25.9 30.7 33.2

TABLE 9.3
NOMOGRAM FOR KIDNEY TRANSVERSE DIAMETER IN MILLIMETERS ACCORDING TO GESTATIONAL AGE
Data from Chitty LS, Altman DG: Charts of fetal size: kidney and renal pelvis measurements, Prenat Diagn 23:891–897, 2003.
Weeks' Gestation 3rd 10th 50th 90th 97th
14 4.4 5.0 6.3 8.0 8.9
15 5.1 5.7 7.3 9.2 10.2
16 5.9 6.5 8.3 10.4 11.6
17 6.6 7.4 9.3 11.7 13.0
18 7.4 8.2 10.3 12.9 14.4
19 8.1 9.0 11.3 14.2 15.7
20 8.9 9.9 12.3 15.4 17.1
21 9.7 10.7 13.3 16.6 18.4
22 10.4 11.5 14.3 17.8 19.7
23 11.2 12.3 15.3 18.9 20.9
24 11.9 13.1 16.2 20.1 22.1
25 12.6 13.9 17.1 21.1 23.3
26 13.3 14.7 18.0 22.1 24.4
27 14.0 15.4 18.9 23.1 25.4
28 14.6 16.1 19.7 24.0 26.4
29 15.2 16.7 20.4 24.9 27.3
30 15.8 17.4 21.1 25.7 28.2
31 16.4 18.0 21.8 26.5 29.0
32 17.0 18.5 22.4 27.2 29.7
33 17.5 19.1 23.0 27.8 30.4
34 17.9 19.6 23.6 28.4 31.0
35 18.4 20.1 24.1 29.0 31.6
36 18.8 20.5 24.6 29.4 32.1
37 19.2 20.9 25.0 29.9 32.5
38 19.6 21.3 25.4 30.3 32.9
39 19.9 21.6 25.7 30.6 33.2
40 20.3 21.9 26.0 30.9 33.5
41 20.5 22.2 26.3 31.1 33.7
42 20.8 22.5 26.5 31.3 33.9

Normal Anatomy

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