Relationship between tumor location and pain level in CT-guided percutaneous microwave ablation of hepatocellular carcinoma

Objective To investigate the relationship between tumor location and pain level in computed tomography( CT)- guided percutaneous microwave ablation( MWA) of hepatocellular carcinoma( HCC) under local anesthesia. Methods A total of 42 tumors in 35 HCC patients were given CT- guided percutaneous MWA under local anesthesia after transcatheter hepatic arterial chemoembolization. The 35 patients were divided into two groups based on the distance from the tumor to the Glisson's capsule and / or the branch of the portal vein. Group A( 19 tumors out of 16 patients) had a distance of ≤5 mm from the tumor to the Glisson's capsule and / or the branch of the portal vein,and group B( 23 tumors out of 19 patients) had a distance of > 5 mm from the tumor to both the Glisson's capsule and the branch of the portal vein. The pain levels of the two groups were evaluated by visual analogue scale( VAS). The tumor size,baseline VAS score,intraoperative VAS score( the highest VAS score during MWA),relative VAS score( intraoperative VAS score minus baseline VAS score),the highest tolerated MWA power,ablation time,and meperidine hydrochloride dose were recorded and compared between the two groups. The comparison was made by Mann- Whitney U test. Results The 16 cases in group A had significantly higher intraoperative VAS score and relative VAS score than the 19 cases in group B( 3. 25 ± 0. 68 vs 2. 74 ± 0. 73,P = 0. 042; 3. 00 ± 0. 52 vs 2. 47 ± 0. 61,P = 0. 009). It showed that the patients whose tumor was close to the Glisson' s capsule had a greater pain level than the patients whose tumor was away from the Glisson's capsule. The dose of meperidine hydrochloride in group A was significantly higher than that in group B( 78. 1 ± 20. 2 mg vs 64. 5± 17. 3 mg,P = 0. 039). After treatment with high dose of meperidine hydrochloride,groups A and B showed no significant differences in the highest tolerated MWA power and ablation time( 73. 8 ± 15. 4 W vs 75. 8 ± 17. 7 W,P > 0. 05; 6. 6 ± 1. 8 min vs 6. 4 ± 2. 1 min,P >0. 05). Conclusion The patients who have a longer distance between the tumor and the Glisson's capsule and the branch of the portal vein suffer greater pain in MWA therapy. Additional meperidine hydrochloride can help complete the MWA treatment.