Feldman and Smith published data on male penile length and width for fetuses and newborn infants. This data can be used to evaluate the significance of ambiguous or small genitals in the genetic male. The authors were from the University of Washington in Seattle.
Measurement:
(1) Length: distance from the pubic ramus to the tip of the glans penis
(2) Traction applied for fetuses 27 weeks or older (see below).
(3) Diameter: determined using a hole gauge
Male Fetus from 10-24 Weeks
The measurements were taken on formalin-fixed male fetuses without traction. Since formalin fixation can result in mild shrinkage, the measurements are best considered estimates.
The rate of growth for the early fetal penis is 0.72 mm per week.
|
|
Diameter in mm |
||
|---|---|---|---|
|
week |
+2.0 SD |
Mean |
- 2.0 SD |
|
10 |
1.74 |
1.31 |
0.58 |
|
12 |
2.32 |
1.88 |
1.23 |
|
14 |
3.04 |
2.53 |
1.88 |
|
16 |
3.62 |
3.11 |
2.46 |
|
18 |
4.27 |
3.76 |
3.04 |
|
20 |
4.92 |
4.34 |
3.69 |
|
22 |
5.57 |
4.99 |
4.34 |
Figure 2, page 396
line for +2 SD in mm =
= (0.32 * (week)) – 1.48
line for mean in mm =
= (0.3069643 * (week)) – 1.78
line for -2 SD in mm =
= (0.31 * (week)) – 2.5
|
|
Length in mm |
||
|---|---|---|---|
|
week |
+2.0 SD |
Mean |
- 2.0 SD |
|
12 |
7.28 |
4.34 |
1.25 |
|
14 |
8.82 |
5.81 |
2.65 |
|
16 |
10.29 |
7.28 |
4.12 |
|
18 |
11.76 |
8.75 |
5.59 |
|
20 |
13.23 |
10.22 |
7.06 |
|
22 |
14.70 |
11.69 |
8.53 |
|
24 |
16.17 |
13.16 |
10.00 |
Figure 1, page 396
line for +2 SD in mm =
= (0.73875 * (week)) – 1.5475
line for mean in mm =
= (0.735 * (week)) – 4.48
line for -2 SD in mm =
= (0.73125 * (week)) – 7.5625
Male Fetus and Neonate from 27-40 Weeks
The penile length measurement was taken with traction applied along the length of the phallus to the point of increased resistance. This is a consistent measure that correlates with the length of the erect penis.
|
|
Diameter in mm |
||
|---|---|---|---|
|
week |
+2.0 SD |
Mean |
- 2.0 SD |
|
27 |
9.55 |
7.71 |
6.00 |
|
28 |
9.84 |
8.13 |
6.28 |
|
29 |
10.26 |
8.49 |
6.64 |
|
30 |
10.55 |
8.84 |
6.99 |
|
31 |
10.90 |
9.20 |
7.35 |
|
32 |
11.19 |
9.55 |
7.71 |
|
33 |
11.54 |
9.91 |
7.99 |
|
34 |
11.97 |
10.26 |
8.34 |
|
35 |
12.25 |
10.55 |
8.70 |
|
36 |
12.54 |
10.97 |
9.06 |
|
37 |
12.82 |
11.26 |
9.41 |
|
38 |
13.18 |
11.61 |
9.69 |
|
39 |
13.53 |
11.97 |
10.12 |
|
40 |
13.82 |
12.25 |
10.41 |
Figure 4, page 397
line for +2 SD in mm =
= (0.3298462 * (week)) + 0.6601538
line for mean in mm =
= (0.3483077 * (week)) – 1.618308
line for -2 SD in mm =
= (0.3424835 * (week)) – 3.281055
|
|
Length in mm |
||
|---|---|---|---|
|
week |
+2.0 SD |
Mean |
- 2.0 SD |
|
27 |
28.39 |
21.37 |
13.88 |
|
28 |
29.80 |
22.78 |
15.29 |
|
29 |
31.20 |
24.02 |
16.54 |
|
30 |
32.45 |
25.27 |
17.78 |
|
31 |
33.70 |
26.52 |
19.03 |
|
32 |
35.10 |
27.77 |
20.28 |
|
33 |
36.50 |
29.02 |
21.84 |
|
34 |
37.75 |
30.26 |
23.09 |
|
35 |
39.00 |
31.51 |
24.34 |
|
36 |
40.40 |
32.92 |
25.58 |
|
37 |
41.65 |
34.32 |
26.83 |
|
38 |
43.06 |
35.57 |
28.24 |
|
39 |
44.30 |
36.82 |
29.64 |
|
40 |
45.55 |
38.06 |
30.89 |
Figure 3, page 397
line for +2 SD in mm =
= (1.319055 * (week)) – 7.127626
line for mean in mm =
= (1.28169 * (week)) – 13.20741
line for -2 SD in mm =
= (1.30508 * (week)) – 21.34508
Specialty: Urology
ICD-10: ,
