Splenic vein resection together with the pancreatic parenchyma versus separated resection after isolation of the parenchyma during distal pancreatectomy (COSMOS-DP trial): Study protocol for a randomised controlled trial

Background: In distal pancreatectomy (DP), it is customary to ligate and divide the splenic vein after isolating it from the pancreatic parenchyma. This is considered essential to prevent disruption of the stump of the splenic vein and consequent intra-abdominal haemorrhage in the event of pancreatic fistula (PF). However, this procedure can be technically demanding, especially when the vein is firmly embedded in the pancreatic parenchyma. The objective of the COSMOS-DP trial is to confirm the non-inferiority of resection of the splenic vein embedded in the pancreatic parenchyma compared with the conventional technique of isolating the splenic vein before resection during DP using a mechanical stapler. Methods: Patients with diseases of the pancreatic body and tail whose pancreatic parenchyma and splenic vein can be divided concurrently during open or laparoscopic DP are considered eligible for inclusion. This study is designed as a multicentre prospective randomised phase III trial. Eligible patients will be centrally randomised to either Arm A (resection of the splenic vein after isolation from the pancreatic parenchyma) or Arm B (co-resection of the vein together with the pancreas). This study aims to establish the non-inferiority of the safety of Arm B compared with that of Arm A; the primary endpoint is the incidence of PF (ISGPF grade B/C). Discussion: The COSMOS-DP trial will establish the safety of this procedure, such that it can be recommended with more confidence. The use of this procedure will likely result in significant reductions in operative time and blood loss during DP.