Cryosurgery
Koroush S. Haghighi, David L. Morris
The goal of hepatic cryosurgery is complete destruction of tumors for curative or palliative reasons as an alternative to resection where resection is not feasible.
Indications and Contraindications Indications Malignant liver tumors in the case of:
■ Cirrhosis – if risk of resection is excessive
■ Bilobar disease where resection would not leave enough hepatic parenchyma
■ Debulking of neuroendocrine tumors
■ As an adjunct to resection (i.e., resect one side and cryoablate the other side)
■ Edge cryotherapy when resection margins are less than 1cm
Contraindications ■ Non-resectable extrahepatic disease (except neuroendocrine tumors)
■ High number of lesions (i.e., > nine lesions; other centers may consider > five lesions as a contraindication)
■ Tumors >5cm
■ Synchronous bowel resection and hepatic cryoablation (increased risk of liver abscess)
Preoperative Investigation and Preparation for the Procedure
In addition to the preoperative investigations before liver resections:
■ In the case of neuroendocrine tumors: H1 and H2 blockers and somatostatin (double existing dose or 100 mg twice daily if not on it) 48h preoperatively
■ Bowel preparation (facultative)
■ Make sure there is liquid N2in the machine
Procedure
STEP 1 Evaluation of the tumor
In order to exclude extrahepatic disease, the procedure is started with a diagnostic laparoscopy or a mini-laparotomy. The liver is examined bimanually and the tumors are investigated by ultrasound with respect to number, size and distance of bile ducts and vascular structures. Next, the lesser sac is opened and suspicious lymph nodes are sent for histological examination. Heated bed blankets should be used to prevent
hypothermia.
STEP 2 Insertion of the probe and applying cryotherapy
Access to the liver is gained by a bilateral subcostal or triradiate incision. For safety reasons, the probes need to be checked for leaks under water with liquid N2running.
Using ultrasound guidance (A-1), the probes (3–10mm in diameter) can be inserted at the center of the tumor (A-2).
A-1
A-2
STEP 2 (continued) Insertion of the probe and applying cryotherapy
For larger tumors multiple probes in a predetermined relationship are used (B).
Cryosurgery can also be combined with a partial hepatectomy. In such cases an edge probe is used to destroy the remnant tumor at the resection surface. This probe does not need to be inserted into the liver (C).
The iceball made by cryoablation should extend ≥1cm beyond the tumor margin.
This should be demonstrated with ultrasound guidance. Since it is not possible to see through the ice, the posterior margin is visualized by ultrasound from behind the liver.
After demonstration of a 1-cm margin, we thaw passively and wait for 1cm to thaw out and then refreeze. Twin freeze-thaw cryotherapy lowers local recurrence rate.
A single cryoablation cycle takes approximately 7–10min, depending on the size of the lesion.
B
C
STEP 3 Removing the probes
Before the probe can be taken out, it has to be rewarmed with warmed nitrogen gas.
Then, the probe can gently be pulled out of the liver, and the tract can be filled with surgical or alternate hemostatic foams.
STEP 4 Cracks
The changes in temperature can cause fractures in the liver which can cause bleeding.
These “cracks” need to be managed by liver sutures and packs.
Postoperative Tests Prediction of Cryoshock
■ Full blood count (FBC), looking for thrombocytopenia particularly on day 3
■ Liver function test (LFT), especially aspartate aminotransferase (AST), highest rise day 1
■ Kidney function tests
Postoperative Complications Cryoshock
Cryoshock is a syndrome of multiorgan failure including renal impairment, pulmonary edema, coagulopathy, and disseminated intravascular coagulation. The incidence of cryoshock is around 1% and is only seen with large volume distraction and especially with the complete twin freeze-thaw technique.
Hepatic Abscess
Very rare, except with synchronous bowel resection and cryoablation.
Pleural Effusion
Common, especially during right-sided hepatic ablation.
Biloma or Biliary Leak Biliary Strictures
Biliary strictures can occur but are very rare within the liver. The main risk is for large lesions in segment IV lying at the bifurcation of the PVS.
Tricks of the Senior Surgeon
■ Do not wash the lesion or the abdominal cavity with warm saline to speed thawing, as this can result in dramatic cracking.
■ Make sure there is liquid N2in the machine before you start the procedure.
■ Use multiple probes for multiple lesions simultaneously to increase the speed of procedure. However, single lesions are better treated by one large probe than several small probes due to the risk of cracking between small probes.
■ Large lesions need more than one probe.
■ Before closing the abdomen, make sure the iceball has thawed completely and there is no bleeding from any cracks.
■ Aim for a high urine output (intra- and postoperatively) to prevent kidney failure.
