Can inter-observer consistency be achieved in the laparoscopic assessment of the peritoneal carcinomatosis index score in peritoneal metastasis? A pilot study

Abstract Objectives The main prognostic factor for peritoneal metastasis (PM) is the complete resection of the disease during cytoreductive surgery. Accurate patient selection is therefore essential for determining eligibility for this type of surgery. The peritoneal carcinomatosis index (PCI) is a widely used tool for assessing the extent of carcinomatosis. This study aimed to evaluate the inter-observer reproducibility of PCI assessments via laparoscopy and identify factors influencing this reproducibility. Methods Between November 2020 and November 2022, 25 laparoscopic PCI assessment videos were reviewed by six surgeons from two centers. The total PCI score, regional PCI scores, and the number of visualized PCI areas were recorded. Inter-observer concordance was analyzed. Results The median PCI score was 12 out of 39 (range 0–39), and the median number of visualized PCI regions was 10 out of 13 (range 1–13). The intraclass correlation coefficient (ICC) for the total PCI score was 0.846 (95 % CI 0.738, 0.927). A history of abdominal surgery significantly impacted PCI assessment reproducibility (p=0.029). Conclusions This study found a high inter-observer concordance in laparoscopic PCI assessments. Previous abdominal surgery negatively affected reproducibility, highlighting a challenge in evaluating the PCI in these patients.