Chapter 78 Surgery of the Kidney and Ureter
Biopsy of the kidney often gives the most reliable information regarding the presence of disease and the prognosis for improvement. When renal calculi are removed surgically, a nephrotomy is usually performed. When the renal pelvis and proximal ureter are dilated, a pyelolithotomy may be performed to remove calculi. Removal of the kidney (nephrectomy) is considered because of severe damage due to trauma, neoplasia, infection, or obstruction of the ureter. Reattachment of the ureter to the renal pelvis is extremely difficult without magnification and proper instrumentation and is infrequently attempted in veterinary practice. This disorder is more commonly treated by unilateral nephrectomy and ureterectomy. A ureterotomy may be performed to remove calculi from the lumen of the ureter. Ureteral anastomosis in small dogs and cats is a challenge for veterinarians. Magnification and microsurgical instrumentation are strongly encouraged during this procedure to improve outcome. Ureteroneocystostomy is a feasible treatment option for lesions of the middle and distal ureter and can also be used to treat some cases of ectopic ureter.
ANATOMY
Kidney
• The kidneys are normally found in the retroperitoneal space in a sublumbar location. The cranial pole of the right kidney may be in contact with the liver, and the left kidney is usually found several centimeters caudal to the liver. In dogs, the right kidney is relatively firmly attached by the renal fascia, but both kidneys are mobile in the cat.
• The renal arteries divide into dorsal and ventral branches after arising from the aorta. Each branch divides into five to seven interlobar arteries. The interlobar arteries branch into arcuate arteries at the corticomedullary junction and ultimately give rise to the radial interlobular arteries. Multiple renal arteries may occur on the left side in 13% of dogs and 10% of cats but are rare on the right side. The renal artery may give rise to the ovarian artery, and the left ovarian/testicular veins commonly drain into the renal vein. Multiple renal veins may be present in cats but are uncommon in dogs.
Ureter
• The ureter is a muscular tube that lies within the retroperitoneal space. The ureter carries urine to the bladder by coordinated peristaltic contractions and can dilate up to 17 times its resting diameter during diuresis or obstruction.
• The arterial blood supply of the ureter is longitudinal. Care must be taken not to disturb the arterial blood supply during dissection of the ureter.
RENAL BIOPSY
Surgical Procedure
Technique
3. Make a ventral midline approach to the abdominal cavity and extend the incision cranially to the xiphoid process to facilitate exposure of both kidneys.
5. Examine and palpate the kidneys. If an isolated lesion is present, select an appropriate biopsy site.
6. Obtain single or multiple biopsy samples using a biopsy needle, or perform a nephrotomy to collect a wedge or slice of renal tissue. The technique for biopsy during nephrotomy is discussed in this chapter under Nephrotomy.
7. When a biopsy needle is used, direct the needle away from the pelvis through the cortical region to avoid damaging the pelvis and large vessels, and obtain at least two samples to be sure that a representative one has been taken. Apply pressure to the biopsy site for 5 minutes to promote hemostasis. If bleeding persists, tack the omentum onto the biopsy site with one or two sutures to act as a patch. Mattress or cruciate sutures can also be used in the renal capsule and superficial parenchyma. Tighten sutures just enough to stop bleeding, but avoid capsular tearing.
Postoperative Care and Complications
• Establish diuresis by IV administration of a balanced electrolyte solution at a rate of 90 ml/kg/24 hr for 8 to 12 hours. This helps prevent the formation of blood clots within the renal pelvis.
• Microscopic hematuria, gross hematuria, or both are often observed after renal biopsy and are usually self-limiting.
• Hemorrhage after renal biopsy can become life threatening. If this occurs during a limited approach procedure, surgically expose the kidneys via celiotomy, and place sutures in a mattress pattern through the renal capsule and superficial parenchyma to control hemorrhage. On rare occasions, uncontrollable hemorrhage necessitates nephrectomy.
NEPHROTOMY
Preoperative Considerations
• Nephrotomy is most often performed for removal of renal calculi. Investigate for other calculi within the urinary tract with excretory urography or ultrasonography before surgery.
• Remove large solitary calculi that result in extensive dilation of the renal pelvis by pyelolithotomy (described in other texts).
• Evaluate coagulation function before surgery. Abnormal coagulation may result in prolonged and possibly fatal hemorrhage after surgery. If possible, correct fluid deficits and serum electrolyte abnormalities before surgery.
• If bilateral renal calculi are present, perform nephrotomy as a staged procedure. Perform the second surgery 2 to 4 weeks after the first. Because transient decrease in renal function after nephrotomy is possible, absent or decreased function of the contralateral kidney may preclude nephrotomy. In these instances, pyelolithotomy is greatly preferred.
Surgical Procedure
Technique
5. Examine and palpate the kidneys. Free the affected kidney of its peritoneal attachments, and identify and isolate the renal vasculature.
6. Apply a Rommel tourniquet or vascular forceps to the renal artery and vein. The time at which the vasculature is occluded is noted, and ischemia of the kidney is limited to 30 minutes or less.
7. Make a longitudinal incision through the renal capsule on the greater curvature of the kidney (Fig. 78-1A). Make the incision long enough to allow exposure of the renal pelvis after the renal parenchyma has been divided or incised. Sharply incise the renal parenchyma with a scalpel.
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