Table 2.
Univariate analysis of the association of surgical and postoperative factors with ultrasound image grade
| Variable | Grade 1 (n=29) | Grade 2 (n=41) | Grade 3 (n=15) | P value |
|---|---|---|---|---|
| Surgical method | 0.226 | |||
| RPN | 23 (79.3) | 35 (85.4) | 14 (93.3) | |
| LPN | 6 (20.7) | 6 (14.6) | 1 (6.7) | |
| Surgical approach | 0.942 | |||
| Retroperitoneal | 20 (69) | 29 (70.7) | 10 (66.7) | |
| Transperitoneal | 9 (31) | 12 (29.3) | 5 (33.3) | |
| Seniority of surgeona | 0.357 | |||
| Junior | 5 (17.2) | 6 (14.6) | 0 (0) | |
| Middle | 11 (37.9) | 15 (36.6) | 8 (53.3) | |
| Senior | 13 (44.9) | 20 (48.8) | 7 (46.7) | |
| Resection rangeb | 0.025c | |||
| Standard excision | 28 (96.6) | 33 (80.5) | 11 (73.3) | |
| Expanded excision | 1 (3.4) | 8 (19.5) | 4 (26.7) | |
| Layers | 0.206 | |||
| One | 8 (27.6) | 3 (7.3) | 3 (20) | |
| Two | 21 (72.4) | 38 (92.7) | 12 (80) | |
| WIT (min) | 17.34±6.56 | 19.83±6.81 | 18.33±3.96 | 0.266 |
| Operative time (min) | 163.28±38.51 | 152.07±32.56 | 148±26.24 | 0.267 |
| Decrease of eGFR (%) | 8.55 (1.91-18.42) | 12.2 (6.2-27.85) | 7.84 (3.1-34.07) | 0.182 |
| Decrease of Hbd (%) | 10.07 (6.55-14.49) | 11.64 (7.57-14.91) | 15.5 (9.92-17.78) | 0.038e |
| Increase of Cr (%) | 18.18 (3.2-30.48) | 18.97 (9.82-33.98) | 22.06 (7.08-44.8) | 0.440 |
| Length of stay (day) | 7.16±2.1 | 7.06±1.63 | 6.56±1.33 | 0.679 |
| Time to extubation (day) | 4.57±1.88 | 4.52±1.06 | 5.17±0.75 | 0.212 |
| Complicationf | 0.474 | |||
| No | 13 (44.8) | 14 (34.1) | 4 (26.7) | |
| Grade I | 14 (48.4) | 21 (51.2) | 9 (60) | |
| Grade II | 1 (3.4) | 6 (14.6) | 2 (13.3) | |
| Grade III | 1 (3.4) | 0 | 0 | |
| Pathology | 0.241 | |||
| Malignant tumor | 24 (82.8) | 26 (63.4) | 9 (60) | |
| Benign tumor | 4 (13.8) | 13 (31.7) | 4 (26.7) | |
| Else | 1 (3.4) | 2 (4.9) | 2 (13.3) | |
| Extravasation | 0.002g | |||
| No (one day) | 19 (65.5) | 26 (63.4) | 2 (13.3) | |
| Yes (over one day) | 10 (34.5) | 15 (36.6) | 13 (86.7) | |
| LOE | 1 (1-2) | 1 (1-2.5) | 2 (2-3) | 0.006h |
Abbreviations: GUIs, grades of US images; RPN, robotic partial nephrectomy; LPN, laparoscopic partial nephrectomy; WIT, warm ischemia time; eGFR, estimated glomerular filtration rate; Hb, hemoglobin; Cr, creatinine; LOE, length of extravasation. Notes: Numbers are n (%) or mean ± standard deviation (SD) or median (Interquartile range);
seniority of surgeon, junior, <3 years of experience of RPN, middle, 3-5 years, senior, >5 years;
resection range, standard excision included strategic sharp dissection through normal parenchyma and removing a 5 mm rim of healthy tissue along with the tumor, expanded excision included a >5 mm rim of normal parenchyma adjacent to the tumor;
Mann-Whitney U test;
decrease of Hb (%) meant the decrease of Hb on the first day after surgery, and it is the same with the change of eGFR and Cr.
Kruskal-Wallis test, post hoc multiple comparisons showed statistical difference between grade 1 and 3 group (P=0.033);
Clavien-Dindo classification system;
Chi-square test.
Kruskal-Wallis test, post hoc multiple comparisons showed a statistical difference between grade 1 and 3 group (P=0.005), grade 2 and 3 group (P=0.025).