Background: The standard treatment protocol for PIPAC consists of three procedures. Completion of treatment has been shown to be prognostic of improved survival. The aim of this study was to identify predictors for completion of treatment. Methods: Retrospective multicentric cohort study of patients with peritoneal metastases undergoing PIPAC in three PIPAC expert centers. Per protocol (PP) treatment was defined as patients receiving ≥3 PIPACs and was compared to patients receiving p = 0.001. PP patients had r ascites (410 ± 100 mL vs. 960 ± 188 mL, p = 0.001), no prior history of bowel obstruction (12% vs. 24%, p = 0.028), and more bimodal treatment (39% vs. 13%, p < 0.001). After multiple regression, bimodal treatment was found as an independent predictive factor for completing PP (OR = 4.202, 95%CI [1.813, 10.630], p < 0.001), along with prior bowel obstruction (OR = 0.389, 95%CI [0.153, 0.920], p = 0.037). Conclusion: The absence of ascites and prior bowel obstruction can help to select patients suitable for PIPAC. Best results seem to be achieved when PIPAC is combined with systemic chemotherapy.