| Characteristic | Female, N = 311 | Male, N = 321 | Overall, N = 631 |
|---|---|---|---|
| Race | |||
| White | 24 (77%) | 25 (78%) | 49 (78%) |
| Black | 1 (3.2%) | 3 (9.4%) | 4 (6.3%) |
| Hispanic/Latino | 3 (9.7%) | 2 (6.3%) | 5 (7.9%) |
| Asian | 1 (3.2%) | 1 (3.1%) | 2 (3.2%) |
| Other | 2 (6.5%) | 1 (3.1%) | 3 (4.8%) |
| Ethnicity | |||
| Not Hispanic/Latino | 27 (87%) | 29 (91%) | 56 (89%) |
| Hispanic/Latino | 4 (13%) | 3 (9.4%) | 7 (11%) |
| Prematurity | 9 (29%) | 6 (19%) | 15 (24%) |
| Age of patient (days) | 6 (2, 30) | 2 (1, 21) | 4 (1, 27) |
| Echogenicity (right) | |||
| None | 20 (65%) | 14 (44%) | 34 (54%) |
| Mild | 9 (29%) | 8 (25%) | 17 (27%) |
| Moderate | 1 (3.2%) | 7 (22%) | 8 (13%) |
| Severe | 1 (3.2%) | 3 (9.4%) | 4 (6.3%) |
| Echogenicity (left) | |||
| None | 15 (56%) | 9 (41%) | 24 (49%) |
| Mild | 8 (30%) | 5 (23%) | 13 (27%) |
| Moderate | 3 (11%) | 5 (23%) | 8 (16%) |
| Severe | 1 (3.7%) | 3 (14%) | 4 (8.2%) |
| Unknown | 4 | 10 | 14 |
| Echogenicity (overall) | |||
| None | 18 (58%) | 12 (38%) | 30 (48%) |
| Mild | 9 (29%) | 9 (28%) | 18 (29%) |
| Moderate | 3 (9.7%) | 8 (25%) | 11 (17%) |
| Severe | 1 (3.2%) | 3 (9.4%) | 4 (6.3%) |
| Ultrasound probe | |||
| 9L | 4 (14%) | 2 (7.4%) | 6 (11%) |
| L2-9 | 3 (11%) | 1 (3.7%) | 4 (7.3%) |
| L8-18i | 1 (3.6%) | 0 (0%) | 1 (1.8%) |
| M6-15 | 1 (3.6%) | 0 (0%) | 1 (1.8%) |
| ML4-20 | 3 (11%) | 0 (0%) | 3 (5.5%) |
| ML6-15 | 15 (54%) | 24 (89%) | 39 (71%) |
| S4-10 | 1 (3.6%) | 0 (0%) | 1 (1.8%) |
| Unknown | 3 | 5 | 8 |
| Congenital heart disease | 13 (42%) | 7 (22%) | 20 (32%) |
| Exam type | |||
| US Abdomen Complete | 21 (68%) | 20 (63%) | 41 (65%) |
| US Abdomen - RUQ | 5 (16%) | 11 (34%) | 16 (25%) |
| Other | 5 (16%) | 1 (3.1%) | 6 (9.5%) |
| Follow-up ultrasound | 9 (29%) | 8 (25%) | 17 (27%) |
| Echogenicity at follow-up | |||
| No | 7 (78%) | 5 (63%) | 12 (71%) |
| Mild | 2 (22%) | 1 (13%) | 3 (18%) |
| Moderate | 0 (0%) | 2 (25%) | 2 (12%) |
| Unknown | 22 | 24 | 46 |
| 1 n (%); Median (IQR) | |||
Transient echogenicity of neonatal renal papillae: updating normal age range with current ultrasound technology
Statistical analysis
Placeholder for description of analysis methods.
Patient characteristics
The study population included 63 patients. Their characteristics are summarized in Table 1. Overall echogenicity is defined as the maximum degree of severity between the right and left renal pyramids.
Factors correlated with echogenicity
The distributions of factors like age of patient, prematurity, congenital heart disease, and ultrasound probe are summarized by degree of severity of echogenicity (right, left, and overall) in Table 2.
Table 2: Predictors of echogenicity of renal pyramids.
| Characteristic | None, N = 301 | Mild, N = 181 | Moderate, N = 111 | Severe, N = 41 | p-value2 |
|---|---|---|---|---|---|
| Age of patient (days) | 22 (2, 34) | 3 (1, 19) | 1 (1, 3) | 2 (2, 3) | 0.006 |
| Prematurity | 7 (23%) | 7 (39%) | 0 (0%) | 1 (25%) | 0.10 |
| Congenital heart disease | 12 (40%) | 5 (28%) | 3 (27%) | 0 (0%) | 0.5 |
| Ultrasound probe | 0.3 | ||||
| 9L | 6 (24%) | 0 (0%) | 0 (0%) | 0 (0%) | |
| L2-9 | 1 (4.0%) | 1 (6.7%) | 2 (18%) | 0 (0%) | |
| L8-18i | 1 (4.0%) | 0 (0%) | 0 (0%) | 0 (0%) | |
| M6-15 | 1 (4.0%) | 0 (0%) | 0 (0%) | 0 (0%) | |
| ML4-20 | 2 (8.0%) | 0 (0%) | 1 (9.1%) | 0 (0%) | |
| ML6-15 | 14 (56%) | 13 (87%) | 8 (73%) | 4 (100%) | |
| S4-10 | 0 (0%) | 1 (6.7%) | 0 (0%) | 0 (0%) | |
| Unknown | 5 | 3 | 0 | 0 | |
| 1 Median (IQR); n (%) | |||||
| 2 Kruskal-Wallis rank sum test; Fisher’s exact test | |||||
| Characteristic | None, N = 341 | Mild, N = 171 | Moderate, N = 81 | Severe, N = 41 | p-value2 |
|---|---|---|---|---|---|
| Age of patient (days) | 17 (2, 33) | 5 (2, 22) | 1 (1, 2) | 2 (2, 3) | 0.037 |
| Prematurity | 9 (26%) | 5 (29%) | 0 (0%) | 1 (25%) | 0.4 |
| Congenital heart disease | 15 (44%) | 3 (18%) | 2 (25%) | 0 (0%) | 0.13 |
| Ultrasound probe | 0.5 | ||||
| 9L | 6 (21%) | 0 (0%) | 0 (0%) | 0 (0%) | |
| L2-9 | 1 (3.6%) | 2 (13%) | 1 (13%) | 0 (0%) | |
| L8-18i | 1 (3.6%) | 0 (0%) | 0 (0%) | 0 (0%) | |
| M6-15 | 1 (3.6%) | 0 (0%) | 0 (0%) | 0 (0%) | |
| ML4-20 | 2 (7.1%) | 0 (0%) | 1 (13%) | 0 (0%) | |
| ML6-15 | 17 (61%) | 12 (80%) | 6 (75%) | 4 (100%) | |
| S4-10 | 0 (0%) | 1 (6.7%) | 0 (0%) | 0 (0%) | |
| Unknown | 6 | 2 | 0 | 0 | |
| 1 Median (IQR); n (%) | |||||
| 2 Kruskal-Wallis rank sum test; Fisher’s exact test | |||||
| Characteristic | None, N = 241 | Mild, N = 131 | Moderate, N = 81 | Severe, N = 41 | p-value2 |
|---|---|---|---|---|---|
| Age of patient (days) | 17 (2, 30) | 2 (1, 4) | 2 (1, 5) | 2 (2, 3) | 0.014 |
| Prematurity | 5 (21%) | 6 (46%) | 0 (0%) | 1 (25%) | 0.090 |
| Congenital heart disease | 12 (50%) | 5 (38%) | 2 (25%) | 0 (0%) | 0.2 |
| Ultrasound probe | 0.2 | ||||
| 9L | 6 (30%) | 0 (0%) | 0 (0%) | 0 (0%) | |
| L2-9 | 1 (5.0%) | 1 (9.1%) | 2 (25%) | 0 (0%) | |
| ML4-20 | 1 (5.0%) | 0 (0%) | 1 (13%) | 0 (0%) | |
| ML6-15 | 12 (60%) | 9 (82%) | 5 (63%) | 4 (100%) | |
| S4-10 | 0 (0%) | 1 (9.1%) | 0 (0%) | 0 (0%) | |
| Unknown | 4 | 2 | 0 | 0 | |
| 1 Median (IQR); n (%) | |||||
| 2 Kruskal-Wallis rank sum test; Fisher’s exact test | |||||
It is clear that the degree of echogenic renal pyramids (each side and overall) is negatively correlated with patient age. The boxplots of patient age by echogenicity of renal pyramids are shown in Figure 1.
