AimAnastomotic leakage following rectal cancer surgery remains a challenging complication, with a nonhealing rate of approximately 50% at 1 year. Pelvic sepsis may require tertiary treatment that encompasses additional admissions, extensive surgery and other types of interventions. The aim of this study is to analyse the financial burden of pelvic sepsis in a tertiary hospital.MethodFrom 2010 until 2020, all patients referred to a tertiary centre for pelvic sepsis after low anterior resection for rectal cancer were prospectively registered and retrospectively reviewed. The cost analysis adhered to Dutch National Healthcare Institute guidelines and covered hospital‐imposed medical costs from salvage surgery to the last registered intervention, adjusted for inflation and priced in euros.ResultsThis analysis included 126 patients, with an average total cost per patient of €31 131. Salvage surgery accounted for €21 326, with an additional €9805 for reinterventions and readmissions. Salvage surgery comprised nonrestorative surgery in 48% and restorative salvage surgery in the remaining cases. Length of hospital stay averaged 9.6 days on the general ward and 0.8 days in the intensive care unit. Common reinterventions included endoscopic vacuum sponge changes (n = 153), stoma closures (n = 59) and radiological abscess drainages (n = 51). Total costs did not differ significantly between nonrestorative surgery and restorative surgery (mean = €31 950 vs. €30 362, respectively; p = 0.893).ConclusionTreating pelvic sepsis after rectal cancer resection in a tertiary hospital carries a substantial economic burden, averaging €31 131 per patient, and this work helps to quantify the potential economic impact of innovative care to reduce anastomotic leakage.