Comparison of off-clamp microwave scissors-based sutureless partial nephrectomy versus on-clamp conventional partial nephrectomy in a canine model

Abstract

Objectives: To compare the usefulness and safety of off-clamp microwave scissors-based sutureless partial nephrectomy (MSPN) with on-clamp conventional partial nephrectomy (cPN) in dogs.

Methods: We performed off-clamp MSPN using microwave scissors (MWS) in six dogs, and on-clamp cPN in three dogs, in two-stage experiments. The bilateral kidney upper poles were resected via a midline incision under general anesthesia. After 14 days of follow-up, the lower pole resections were performed. The renal calyces exposed during renal resections were sealed and transected using MWS in off-clamp MSPN and were sutured in on-clamp cPN. In the off-clamp MSPN group, the generator's power output of MWS was set as either 50 W or 60 W for each kidney side. We compared the procedure time (PT), ischemic time (IT), blood loss (BL), and normal nephron loss (NNL) between the two techniques using the Mann-Whitney U-test.

Results: We successfully performed 24 off-clamp MSPNs and 12 on-clamp cPNs. The off-clamp MSPN was significantly superior to on-clamp cPN in avoiding renal ischemia (median IT, 0 min vs. 8.6 min, p < 0.001) and reducing PT (median PT, 5.8 min vs. 11.5 min, p < 0.001) and NNL (median NNL, 5.3 mm vs. 6.0 mm, p = 0.006) with comparable BL (median BL, 20.9 ml vs. 23.2 ml, p = 0.804). No bleeding and major urine leakage were noted during the reoperations.

Conclusions: Off-clamp MSPN outperforms on-clamp cPN in lowering the risks of postoperative renal function impairment in dogs.

Keywords: microwaves; off-clamp; partial nephrectomy; renal function; renal ischemia.

Figure 1

The microwave scissors and their generator (right-lower corner).

Figure 2

Off-clamp microwave scissors-based sutureless partial nephrectomy (MSPN) (A–C) and on-clamp conventional partial nephrectomy (cPN) (D–F) for upper pole resections. The excision line was marked at the level of the upper polar line (A,D). The kidney's upper poles were resected using microwave scissors (MWS) (B) without hilar clamping in off-clamp MSPN or using Metzenbaum scissors (E) after hilar clamping in on-clamp cPN. The resected beds were coagulated using MWS without renorrhaphy (C) in off-clamp MSPN, or sutured (F) in cPN.

Figure 3

The hematoxylin and eosin staining of the remnant kidney's upper pole at the two-week follow-up (A), the remnant kidney's lower pole (B), and the resected specimen (C) immediately after off-clamp microwave scissors-based sutureless partial nephrectomy. The area limited by the dashed line indicates the thermal injury zone. The dotted line divides the thermal injury zone into two zones: the near zone and the intermediate zone. The morphology of the renal tissue in the near zone was well maintained for up to two weeks postoperatively (A1, B3). However, the renal tubular cells and glomeruli were slightly smaller than those in the intact zone (B1). The intermediate zone (B2) was characterized by the extravasation of erythrocytes (stars) into interstitial spaces. The renal tubular cells were sporadically ruptured and detached into the lumen (arrowheads). Two weeks postoperatively, the intermediate zone (A2) exhibited coagulative necrosis that was characterized by the disappearance of tubular cells’ nuclei (asterisks), infiltration of macrophages and neutrophils (arrows), and fibrosis formation.

Figure 4

The hematoxylin and eosin staining of the remnant kidney sectioned on coronal (A) and sagittal planes (B) two weeks after on-clamp conventional partial nephrectomy. The areas limited by the dashed line indicate the devascularization zone induced by renorrhaphy (asterisks are suturing holes), which exhibited blood congestion and tissue necrosis (B, right-upper corner) with the infiltration of macrophages and neutrophils, degeneration of renal glomeruli and tubules, and fibrosis. S, superior; I, inferior; R, right; L, left; A, anterior; P, posterior.