Cirugia Nefrouretral

Nephroureteral surgery is not relatively common in dogs and cats. This type of surgery may encompass nephrotomy, nephrectomy, or ureterocystostomy. Indications for surgery include unresponsive pyelonephritis, abscessation of the kidney, neoplasia, severe trauma, ureteral conditions that cause irreversible hydronephrosis. Diagnostics are key to determining the need and potential consequences of surgery. The patient status should also be considered carefully as many of these cases may be unstable as a result of their disease process. Proper perioperative management is important and the patients need to be maintained on fluids and monitored carefully throughout their hospitalization.

If neoplasia is suspected, do not forget to evaluate for metastasis as this may alter the course of treatment. In cats, renal lymphoma is the most common primary renal tumor and it is readily diagnosed with an aspirate. These tumors generally do not require surgery, as they can be responsive to chemotherapy. On the other hand, renal carcinomas are the most common tumors in dogs and account for up to 85% of primary renal malignancies. These tumors benefit from nephrectomy.

Excretory urograms or intravenous pyelograms can provide a qualitative assessment of each kidney and will help define anatomic structures. Keep in mind that it will not provide any quantitative information about renal function. Ultrasonography performed by a trained person can be very useful as well to help evaluate the extent and look for intra-abdominal metastasis. CT with contrast will further aid the surgeon in evaluating for metastasis, planning for surgery and knowing what vascular anomalies might be present.

Calculi occurring at the level of the kidney are typically not removed surgically unless a complete obstruction is suspected, there is worsening azotemia, or unresponsive pyelonephritis. Calculi occur as a result of a supersaturation of calculogenic substances, which can occur for a variety of reasons. Calcium oxalate nephroliths are the most common. Clinical signs can vary from none to nonspecific vomiting, lethargy, and anorexia. Potential findings include renomegaly, hematuria, pyelonephritis, and nonspecific abdominal pain. Surgical treatment of nephroliths may involve nephrotomy, pyelolithotomy, or nephrectomy. A nephrectomy is usually reserved for those patients that have a severe infection, are severely hydronephrotic, or the kidney is non-functional. When a nephrotomy is performed the surgeon must choose between a bisectional nephrotomy and an intersegmental nephrotomy. The intersegmental approach is thought to be less traumatic (and more time consuming), but no advantage has been found when studies evaluated glomerular filtration rates after surgery. Nephrotomies may inherently cause a decrease in glomerular filtration rate until the kidney has had time to recover, therefore appropriate management postoperatively cannot be underestimated, particularly if the contralateral kidney is not normal.

Treatment of renal trauma is highly variable depending on the extent and type of injury. The immediate concern for the surgeon will be minimizing blood loss. Ultimately, the concern will be renal function. Treatment is many times nephrectomy, but occasionally renal parenchyma may be repaired and nephrectomy avoided. Common injuries include parenchymal fractures, capsular tears, perirenal or renal hematomas, vascular avulsion, crush injuries, and renal prolapse.