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Deivasigamani et al. Mini-invasive Surg 2023;7:9 https://dx.doi.org/10.20517/2574-1225.2022.99 Page 5 of 19

percutaneous placement of cryoprobes is more challenging. CA can be used to treat renal tumors up to
three to four centimeters in size. The location of the tumor affects whether additional precautions are
required to protect nearby structures. To reduce the risk of collateral tissue damage to vulnerable tissues,
such as the colon, a 1-2 cm buffer is advised. Some anterior tumors can be treated percutaneously using
patient repositioning and adjuvant displacement techniques. One such technique is hydro-dissection, which
[12]
involves the injection of fluid through a small-diameter catheter implanted under imaging guidance .
When the tumor is more central and closer to larger vessels, these vessels may provide a heat sink effect
making it more difficult for the target lesion to reach cytocidal temperatures and require more aggressive
treatment with larger or additional cryoprobes and a wider ice ball margin . When tumors are close to the
[22]
urinary collecting system, there is a small risk of thermal injury to the urinary collecting system that could
potentially lead to downstream stricture or urine leak/fistula. To reduce this risk, retrograde pyeloperfusion
can be utilized by the instillation of warm saline into the urinary collecting system via a ureteral catheter,
thus preserving these crucial structures without significantly impairing the ablation treatment
effectiveness . Nevertheless, importantly, ice ball extension into normal kidney tissue has not been linked
[23]
to intrarenal collecting system injury, and it was previously demonstrated in a porcine model that insertion
of the cryoprobe into the renal pelvis with intentional thermal injury did not cause urinary fistula
development.

PERIPROCEDURAL ADVANTAGES
The frozen tissue or ice ball can be monitored using ultrasound or CT imaging, facilitating real-time
monitoring and assessment of the ablated region . Highly vascular lesions like angiomyolipoma may be
[24]
effectively ablated with CA because it has a less pronounced heat sink effect that dampens temperature
variations and is less likely to injure the urinary collecting system than heat-based methods like RFA [20,25] . In
addition, the procedure can often be safely repeated if needed in the future should tumor recurrence occur.
Another setting where CA may be advantageous is in obese patients because increased perinephric fat that
makes a surgical approach more challenging can actually make CA easier by providing additional space
between the SRM and adjacent vulnerable organs .
[20]

PERIPROCEDURAL DISADVANTAGES
The primary drawback of CA relative to other ablative modalities is lengthier procedure timeframes,
although the overall procedural length depends on patient factors including tumor size, tumor location, and
perinephric fat, as well as the method of CA (open, LCA, or PCA), the cryoablation system and the imaging
system used, and the proceduralist’s experience. Additionally, the facility must acquire and store the gases
[20]
required for cooling, which may raise the financial and logistical expenses associated with conducting CA .
Postoperative bleeding from the target site or probe tract might be less likely to occur with RFA due to the
coagulation effect of extreme heat .
[20]
ROLE OF BIOPSY IN CRYOABLATION
Percutaneous renal tumor biopsy (RTB) is contentious in SRM management due to the risk of
complications, diagnostic inaccuracy or nondiagnostic sampling, and the limited influence on medical
management decisions. The most common complications following RTB include renal hematoma (4.9%),
[26]
significant pain (1.2%), and gross hematuria (1%) . Needle tract seeding is of theoretic risk of RTB that has
been reported in some case series [27,28] . However, an access sheath at the time of RTB and CA can be used to
permit many multiple needles to pass through the lesion with only a single pass through the skin, decreasing
the theoretic risk of needle tract seeding. Elderly or weak patients who will be handled conservatively
regardless of RTB findings and young or healthy individuals who would be reluctant to accept the potential