Ultra Sonographic Study of Kidney Changes Following Experimental Cryogenic Partial Nephrectomy in a Rabbit Model

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Background and Objective: Treatment of some limited kidney neoplasms is a partial kidney resection called a partial nephrectomy. One of the concerns in partial nephrectomy is severe and uncontrolled hemorrhage that sometimes results in kidney removal. Cryosurgery is one of the less invasive methods for the management of small kidney lesions, during which the controlled freezing of unwanted tissues will eventually lead to necrosis and gradual destruction of the lesion.The advantages of the cryosurgery method are easy implementation, no thermal ischemia damage during the operation, and no need to cut and suture the kidney parenchyma. Materials and Methods: In this experimental intervention research, the caudal pole of the left kidney of 9 adult female rabbits was subjected to cryogenic partial nephrectomy through a lateral laparotomy. Rabbits were evaluated by ultrasound on 1, 3, 7, 14, 21, and 28 days after surgery to record and observe the extent of kidney damage and healing in the Sagittal and Dorsal sections. Several parameters, such as kidney length dimensions, size of the caudal cortex, and cranial cortex of the kidney, were measured and recorded. Results: Kidney length on days 1, 21, and 28 was significantly less than day 0. On the 7th day after surgery, 2 separate areas, damaged and frozen necrotic tissue (caudal cortex) and healthy and normal kidney tissue were visible. The size of the caudal cortex from day 14 onwards was significantly less than day 0. The process of significant changes in the caudal cortex of the kidney started from day 14 of surgery and the border between dead and living tissue (Line of Demarcation) was distinguishable as a transition zone. On the 21st day after surgery, both the length of the kidney and the caudal cortex decreased significantly compared to day 0. Gradual loss of the caudal pole of the kidney (caudal cortex, the place where cryosurgery was performed directly) showed the applicability of cryosurgery in surgeries during which the tumor was removed (tumor ablation). On the 28th day after surgery, due to gradual necrosis and the loss of the caudal pole of the kidney, the kidney looked like a bitten apple, and the results of changes in the dimensions of the kidney (caudal cortex and length of the kidney) indicated necrosis of the caudal pole of the kidney, which finally led to the shrinking of the kidney. Conclusion: Ultrasonographic study of kidney injury and healing showed that cryosurgery, in addition to tumor ablation, would also have the ability to remove peripheral tissues (partial nephrectomy).