Partial nephrectomy is the treatment of choice for managing most renal masses ( ). Relative contraindications include patient factors (strong preference, <10%–20% retained function in the kidney in question), technical factors (ischemia time >45 minutes), and tumor-related factors (encasement of hilum, central collecting system invasion, tumor thrombus, adjacent organ invasion). Tumor size is not, per se, a reason to forego partial nephrectomy.
Hyperfiltration injury . After partial nephrectomy the renal blood flow is delivered to fewer nephrons, resulting in increased glomerular capillary perfusion pressure and single-nephron glomerular filtration rate, a phenomenon termed hyperfiltration . Over decades, hyperfiltration injures the remaining nephrons, and can result in focal segmental glomerulosclerosis with proteinuria and progressive renal failure when the total nephron mass (both kidneys combined) is reduced by >80%.
Renal ischemia and hypothermia . Vascular compression is usually required to reduce bleeding during partial nephrectomy and options include regional ischemia (manual compression, Kaufmann renal compression clamp) and global ischemia (selective renal artery clamping, en bloc hilar clamping). Ischemic times should be as short as possible, ideally <20 minutes if warm ischemia and <35 minutes if cold ischemia. Intravenous mannitol (12.5 g) and furosemide (40 mg) given 5–10 minutes prior to clamping may reduce ischemic injury, though currently no trials have demonstrated this conclusively.
Urothelial carcinoma of the renal collecting system . Prior to considering partial nephrectomy for urothelial carcinoma, the collecting system must be carefully evaluated for multifocality with ureterorenoscopy. Tumors should ideally be unifocal, polar, and not manageable by endoscopy. Neoadjuvant chemotherapy should be strongly considered in such cases.
Preparation and Exposure
Ensure that renal cooling is available. Prepare bolsters by rolling Nu-Knit around a 1 × 5-cm piece of GelFoam and tying the ends with a 4-0 Vicryl. Prepare pledgets by folding Nu-Knit into a double-layered 2 × 5 cm rectangle. (We prefer Nu-Knit because it is absorbable, does not shrink when wet, and has tremendous tensile strength). An ultrasound scanner may be helpful in tumor localization if the tumor is endophytic.
The patient is positioned laterally on the surgical table with the ipsilateral side facing upwards. The contralateral flank is positioned over the break of the table and may additionally be supported with a kidney rest to maximize space in the ipsilateral flank. The patient is secured to the table, ensuring that all pressure points are well padded and that good anesthetic access is maintained.
The kidney is typically approached extraperitoneally through a flank incision through the 10th or 11th intercostal spaces. The bony landmarks are palpated and marked and the incision is made over the lower part of the desired intercostal space taking care to protect the neurovascular bundle running under the ribs. Alternatively, the kidney may be approached peritoneally via midline or subcostal incisions, or in the case of very large tumors, a thoraco-abdominal approach.
Once the retroperitoneal space is exposed, insert a self-retaining retractor, and dissect the kidney free of the perirenal fat (palpable tumors should remain fat covered) ( Fig. 9.1 ). Administer intravenous mannitol and furosemide and then isolate the renal pedicle sufficiently to allow safe application of a vascular clamp. Control the renal vessels with vessel loops. Prior to clamping, a brief “time-out” to check that all equipment is ready may be helpful in improving team situational awareness and reducing warm ischemic time.
Enucleation for Small Cortical Tumors
Score the renal cortex surrounding the tumor with electrocautery. Identify a plane outside of the tumor pseudocapsule and within the normal parenchyma and bluntly dissect it, cutting small vessels if required ( Fig. 9.2 ). We use small tenotomy scissors for this, though other instruments are possible. Renal ischemia is not usually necessary for small tumors, but if bleeding hampers vision, use manual compression or a vascular clamp. Excise the tumor, examine its base, and send for frozen section. Control bleeding vessels with figure-of-eight sutures of 4-0 or 5-0 absorbable monofilament suture. Repair collecting system injuries with same 4-0 suture.
Place a Nu-Knit pledget along each border of the crater and place the bolster into the bottom of the crater. Close the defect with a horizontal mattress using a 2-0 absorbable suture on a large, tapered circle needle (e.g., CTX, GS-25) ( Fig. 9.3 ). Suture through the pledgets, 1–2 cm from the crater ridge, to prevent parenchymal tearing. Apply fibrin glue to crater and tie down mattress sutures. Unclamp as soon as the tumor crater is collapsed, even if 1–2 more mattress sutures are planned. Inspect kidney for bleeding, ischemia, urine leakage, or adjacent trauma.
Replace the perirenal fat around the kidney and close the renal fascia. Leave a closed suction drain in the pararenal space to monitor for delayed bleeding and urine leaks ( Fig. 9.4 ). A Foley catheter is used to monitor urine output. No ureteral catheter or stent is required unless there was a large defect in the collecting system.
Wedge Resection for Large Cortical Tumors
Administer intravenous mannitol and furosemide (Lasix) and then clamp the renal artery with a vascular bulldog. Place a plastic bag or sheet around the kidney and fill it with ice slush if ischemia is anticipated to last more than 20 minutes ( Fig. 9.5 ).