Figure 1 shows the patient flow through our study. During the study period, 164 patients with traumatic renal injury were included. Of them, we excluded 16 patients who died within 24 hours after admission and 2 patients who underwent nephrectomy within 24 hours after admission. Thus, 146 patients were eligible for analysis.
Table 1 shows the baseline patient characteristics of this study. The median age was 44 (IQR: 23–66) years, and 68.5% of the patients were male. The most common mechanism was traffic accident in 65 patients (44.5%), followed by fall on the ground and fall down stairs in 41 patients (28.1%), fall from height in 28 patients (19.2%), and sports-related injury in 4 patients (2.7%). Renal injuries were graded as AAST grade I in 33 (22.6%), II in 27 (18.5%), III in 38 (26.0%), IV in 28 (19.2%), and V in 20 (13.7%) patients. The median ISS on admission was 17 (IQR: 12–29). Renal injuries were left-sided in 87 (59.6%) and isolated in 51 (34.9%) patients. Thirty-two patients (21.9%) required renal TAE on admission, and almost all of them (n = 30) had grade III, IV, or V injury (Supplemental Table 1). The median number of CT scans per patient during admission was 3 (IQR: 2–4). The median length of hospital stay was 20 days (IQR: 11–57), and the mortality rate during hospitalization was 6.2%.
Table 1
Baseline Characteristics and Early Complications of the Patients with Traumatic Renal Injury
| All patients |
(n = 146) |
Age, years, median (IQR) | 44 | (23–66) |
Male, n (%) | 100 | (68.5) |
Mechanism of injury, n (%) | | |
Blunt | 142 | (97.3) |
Traffic accident | 65 | (44.5) |
Fall on the ground or fall down stairs | 41 | (28.1) |
Fall from height | 28 | (19.2) |
Sports-related injury | 4 | (2.7) |
Other | 4 | (2.7) |
Penetrating | | |
Stabbing | 4 | (2.7) |
Medication, n (%) | | |
Anticoagulant | 1 | (0.7) |
Antiplatelet | 9 | (6.2) |
Gross hematuria on admission, n (%) | 76 | (52.1) |
ISS, median (IQR) | 17 | (12–29) |
Injured side, n (%) | | |
Right | 60 | (41.1) |
Left | 87 | (59.6) |
Right and left | 1 | (0.7) |
AAST grade, n (%) | | |
I | 33 | (22.6) |
II | 27 | (18.5) |
III | 38 | (26.0) |
IV | 28 | (19.2) |
V | 20 | (13.7) |
Isolated renal injuries, n (%) | 51 | (34.9) |
Renal TAE on admission day, n (%) | 32 | (21.9) |
Number of CT scans during admission, median (IQR) | 3 | (2–4) |
Length of hospital stay, days, median (IQR) | 20 | (11–57) |
Mortality, n (%) | 9 | (6.2) |
Early complications | 30 | (20.5) |
Urinary extravasation, n (%) | 26 | (17.8) |
Diagnosis day, median (IQR) | 2 | (1–5) |
Management, n (%) | | |
Ureteral stent placement | 16/26 | (61.5) |
Nephrostomy | 4/26 | (15.4) |
No procedure | 6/26 | (23.1) |
Vascular complications, n (%) | 9 | (6.2) |
Diagnosis day, median (IQR) | 7 | (1–7) |
Diagnosis, n (%) | | |
Pseudoaneurysm | 8/9 | (88.9) |
Arteriovenous fistula | 1/9 | (11.1) |
Management, n (%) | | |
TAE | 7/9 | (77.8) |
No procedure | 2/9 | (22.2) |
IQR, interquartile range; ISS, Injury Severity Score; AAST, American Association for the Surgery of Trauma; TAE, transcatheter arterial embolization; CT, computed tomography. |
Early complications of traumatic renal injury were found in 30 patients (20.5%). The complications included urinary extravasation in 26 patients (17.8%) and vascular complications in 9 patients (6.2%), with both found in 5 patients (3.4%) (Table 1). All the urinary extravasation were found in patients with renal injury of grade III, IV and V. Sixty percent of the patients with grade V renal injuries developed urinary extravasation (Supplemental Table 1).
The median interval from admission date to the day of diagnosis of urinary extravasation was 2 (IQR: 1–5) days, and 25 patients (96.2%) were diagnosed as having urinary extravasation within 7 days (Table 1). In Kaplan-Meier analysis, the number of days to the diagnosis of urinary extravasation in grade IV-V injuries was statistically significantly shorter than that in grade I-III injuries (p < 0.001) (Fig. 2).
For the management of urinary extravasation, 16 of the 26 (61.5%) affected patients underwent urinary stent placement and 4 had nephrostomy. Of them, 15 patients were treated within 24 hours from the diagnosis. Vascular complications were found in the patients with grade IV-V injuries. The median interval between admission and diagnosis of vascular complications was 7 (IQR: 1–7 days). Of the 9 patients with early vascular complications, 8 had pseudoaneurysms and one had an arteriovenous fistula. Vascular embolization was performed in 7 of these patients (Table 1, Supplemental Table 1).
In a univariate analysis, patients with urinary extravasation showed significant differences in the presence of gross hematuria, renal TAE, AAST renal injury scale, and vascular complications compared with the patients without urinary extravasation (gross hematuria, p < 0.001; AAST grade, p < 0.001; TAE, p = 0.003; vascular complications, p = 0.009). There were no significant differences in the blood tests of blood urea nitrogen and creatinine level between the groups. None of the patients with urinary extravasation had deterioration of blood urea nitrogen and creatinine values, and no patients suffered urinary tract obstruction or postrenal nephropathy (Table 2).
Table 2
Baseline Characteristics and Outcomes Associated with Urinary Extravasation.
| Urinary extravasation (+) | Urinary extravasation (-) | P value |
(n = 26) | (n = 120) |
Age, years, median (IQR) | 52 | (24–77) | 43 | (22–65) | 0.229 |
Male, n (%) | 16 | (61.5) | 84 | (70.0) | 0.485 |
Mechanism of injury, n (%) | | | | | 0.343 |
Blunt | 26 | (100.0) | 116 | (96.7) | |
Fall | 15 | (57.6) | 54 | (45.0) | |
Traffic accident | 9 | (34.6) | 56 | (46.7) | |
Fall on the ground or fall down stairs | 11 | (42.3) | 30 | (25.0) | |
Fall from height | 4 | (15.4) | 24 | (20.0) | |
Sports-related injury | 2 | (7.7) | 2 | (6.3) | |
Other | 0 | (0.0) | 4 | (3.3) | |
Penetrating | | | | | |
Stabbing | 0 | (0.0) | 4 | (3.3) | |
Medication, n (%) | | | | | |
Anticoagulant | 1 | (3.9) | 0 | (0.0) | 0.178 |
Antiplatelet | 2 | (7.7) | 7 | (5.8) | 0.662 |
Gross hematuria on admission, n (%) | 23 | (88.5) | 53 | (44.2) | < 0.001 |
ISS, median (IQR) | 16 | (16–22) | 19 | (10–31) | 0.701 |
Injured side, n (%) | | | | | 0.860 |
Right | 10 | (38.5) | 49 | (40.8) | |
Left | 16 | (61.5) | 70 | (58.3) | |
Right and left | 0 | (0.0) | 1 | (0.8) | |
AAST grade, n (%) | | | | | < 0.001 |
I | 0 | (0.0) | 33 | (27.5) | |
II | 0 | (0.0) | 27 | (22.5) | |
III | 2 | (7.7) | 36 | (30.0) | |
IV | 12 | (46.2) | 16 | (13.3) | |
V | 12 | (46.2) | 8 | (6.7) | |
Isolated renal injuries, n (%) | 17 | (65.4) | 34 | (28.3) | < 0.001 |
Renal TAE on admission day, n (%) | 12 | (46.2) | 20 | (16.7) | 0.003 |
Vascular complication, n (%) | 5 | (19.2) | 4 | (3.3) | 0.009 |
Number of CT scans during admission, median (IQR) | 3 | (2–4) | 2 | (1–3) | 0.008 |
Length of hospital stay, days, median (IQR) | 25 | (16–50) | 18 | (9–59) | 0.290 |
Mortality, n (%) | 3 | (11.5) | 6 | (5.0) | 0.201 |
IQR, interquartile range; ISS, Injury Severity Score; AAST, American Association for the Surgery of Trauma; TAE, transcatheter arterial embolization; CT, computed tomography. |
The multivariable analysis adjusted for age, sex, gross hematuria, and AAST grade (grade I-III or grade IV-V) showed that AAST grade IV-V (adjusted OR: 33.8 [95% CI, 7.12–160], p < 0.001) was statistically significantly associated with the occurrence of urinary extravasation. We observed a trend towards an increased risk of having urinary extravasation in those with gross hematuria (adjusted OR: 3.59 [95% CI, 0.860–15.0], p = 0.080) (Table 3). The complication of urinary extravasation occurred in 56.4% (22/39) of the patients with grade IV-V and gross hematuria.
Table 3
Unadjusted and Adjusted Odds Ratios Comparing Occurrence of Urinary Extravasation
| Crude OR | (95% CI) | P value | Adjusted OR | (95% CI) | P value |
Age | 1.01 | (0.99–1.03) | 0.229 | 1.00 | (0.98–1.02) | 0.836 |
Sex | 0.69 | (0.28–1.66) | 0.485 | 1.05 | (0.33–3.31) | 0.940 |
Gross hematuria on admission | 9.69 | (2.76–34.03) | < 0.001 | 3.59 | (0.86–15.01) | 0.080 |
AAST grade IV or V | 48.00 | (10.60-217.34) | < 0.001 | 33.80 | (7.12-160.59) | < 0.001 |
AAST, American Association for the Surgery of Trauma; OR, odds ratio; CI, confidence interval. |