Pure laparoscopic right hepatectomy: A risk score for conversion for the paradigm of difficult laparoscopic liver resections. A single centre case series

Background: Converted laparoscopic hepatectomies are known to lose some advantages of the minimally-invasiveness, and factors are identified to predict patients at risk. Specific evidence for laparoscopic right hepatectomy is expected of usefulness in clinical practice, given its technical peculiarities. The purpose of the study was the identification of risk factors and the development of a risk score for conversion of laparoscopic right hepatectomy. Materials and Methods: Laparoscopic right hepatectomy performed at a single hepatobiliary surgical center were analyzed. The cohort was split in half to obtain a derivation and a validation set. Risk factors for conversion were identified by uni- and multivariable analysis. A "conversion risk score" was built assigning each factor 1 point and comparing the score with the conversion status for each patient. The accuracy was assessed by the area-under-the-receiver-operator-characteristic-curve. Results: Among 130 operations, 22 were converted (16.9%). Reasons were: 45.5% oncologic inadequacy, 31.8% bleeding, 9.1% adhesions, 9.1% biliostasis, 4.5% anaesthesiological problems. Independent risk factors for conversion were: previous lapamscopic liver surgery (Hazard Ratio 4.9, p 0.011), preoperative chemotherapy Hazard Ratio 6.2, p 0.031), malignant diagnosis (Hazard Ratio 3.3, p 0.037), closeness to hepatocaval confluence or inferior vena cava (Hazard Ratio 4.1, p 0.029), tumor volume (Hazard Ratio 2.9, p 0.024). Conversion rates correlated positively with the score, raising from 0 to 100% when the score increased from 0 to 5 (Spearman: p 0.032 in the derivation set, p 0.020 in the validation set). The risk of conversion showed a sharp increase passing from class 3 to 4, reaching a probability estimated between 60 and 71.4%. The score showed good accuracy (area-under-the-receiver-operator-characteristic-curve 0.82). Conclusion: Specific risk factors for conversion are identified for laparoscopic right hepatectomy. This score may help in standardizing the choice of a pure laparoscopic or open approach for such challenging resections.