Development of a novel difficulty scoring system for laparoscopic liver resection procedure in patients with intrahepatic duct stones

Table 1 Characteristics of 46 patients with intrahepatic duct stones

Variables	Training group (n = 46)	Validation group (n = 34)	P value
Age, years	61 (49-73)	52 (40-64)	0.690
Sex (male/female)	11/35	25/9	0.795
BMI, kg/m2 (IQR)	21.9 (20-24.4)	22.8 (20.4-24.2)	0.514
Previous biliary surgery, n (%)	21 (45.7)	12 (35.3)	0.355
ASA score ≥ 3, n (%)	16 (34.8)	12 (35.3)	0.491
History of hypertension, n (%)	8 (17.4)	4 (11.8)	0.489
History of diabetes, n (%)	2 (4.3)	1 (2.9)	0.745
History of coronary artery heart disease, n (%)	0 (0)	2 (5.9)	0.098
History of lung diseases, n (%)	5 (10.9)	1 (2.9)	0.186
Location of stones (TL/TR)	22/24	29/5	0.001
Number of stones ≥ 3, n (%)	44 (95.7)	34 (100)	0.221
Distal bile duct atrophy, n (%)	24 (52.2)	27 (79)	0.013
Diameter of common bile duct, cm (IQR)	1.5 (1.2-1.8)	1.1 (0.8-1.4)	0.001
Maximum diameter of intrahepatic duct, cm (IQR)	1.4 (1-1.6)	1.5 (1.2-1.8)	0.028
Maximum stone size, cm (IQR)	1 (0.6-1.5)	0.9 (0.6-1.2)	0.225
Platelet count, 109/L (IQR)	156 (79-233)	190 (119-261)	0.015
White blood cell count, 109/L (IQR)	7.7 (4.6-10.8)	6.1 (3.9-8.3)	0.008
Red blood cell count, 109/L (IQR)	4.2 (3.6-4.8)	4.4 (3.8-5)	0.654
Alanine aminotransferase, U/L (IQR)	59 (25-189)	33 (21-90)	0.066
Aspartate aminotransferase, U/L (IQR)	43 (27-136)	49 (20-117)	0.446
Total bilirubin, μmol/L (IQR)	22.4 (14.9-44.9)	18.7 (13-31.6)	0.149
Prothrombin time, s (IQR)	11.4 (10.5-12.3)	10.9 (10.1-11.7)	0.311

BMI: Body mass index; TL: Type left; TR: Type right; ASA: American Society of Anesthesiologists; IQR: Interquartile range.

Table 2 Independent factors predicting surgical difficulty by multiple linear regression

Independent variables	P value
Location of stones	0.002
Number of stones ≥ 3	0.037
Stone located in the bile ducts of several grades
Primary bile duct	0
Secondary bile duct	0.022
Tertiary bile duct	0.004
Previous biliary surgery less than twice	< 0.001
Distal bile duct atrophy	< 0.001

Table 3 The multiple linear regression model calculates the constants of the variables of the coefficient

Variables	Variables category	Coefficient
Location of stones	TL	0
	TR	1107.1
Number of stones ≥ 3	No	0
	Yes	170.5
Stone located in the bile ducts of several grades	Primary bile duct	0
	Secondary bile duct	134.2
	Tertiary bile duct	181.8
Previous biliary surgery less than twice	No	0
	Yes	182.8
Distal bile duct atrophy	No	0
	Yes	137.7

TL: Type left; TR: Type right.

Table 4 Difficulty factor score classification associated with laparoscopic liver resection

Variables	Variables category	Score
Location of stones	TL	0
	TR	1
Number of stones ≥ 3	No	0
	Yes	2
Stone located in the bile ducts of several grades	Primary bile duct	0
	Secondary bile duct	1
	Tertiary bile duct	2
Previous biliary surgery less than twice	No	0
	Yes	2
Distal bile duct atrophy	No	0
	Yes	1
Total score
≤ 3: Low difficulty
4-5: Medium difficulty
≥ 6: High difficulty

TL: Type left; TR: Type right.

Table 5 Postoperative outcomes of laparoscopic liver resection in three levels of difficulty, n (%) (mean ± SD)

Variables	Low (n = 24)	Medium (n = 7)	High (n = 3)	P value
Surgical times, min	292	355	401	0.034
Blood loss, mL	187	307	500	0.002
Postoperative hospital stays, day	8	9	9	0.269
Intraoperative blood transfusion	1 (4.2)	1 (14.3)	2 (66.7)	0.007
Hospital costs, CNY	47540	53956	52507	0.336
Clavien-Dindo classification ≥ 3	1 (4.2)	1 (14.3)	2 (66.7)	0.007
Postoperative alanine aminotransferase, U/L	169	352	320	0.002

CNY: China yuan.