Percutaneous drainage of post-operative collections following abdominopelvic surgery has become standard practice and is a routine procedure in many interventional radiology (IR) departments. Such collections are commonly diagnosed on CT studies where the presence of Surgicel ® can mimic an abscess and lead to unnecessary procedures. We present a case where a duodenal perforation was masked by post-operative Surgicel in the gallbladder fossa, which in turn was mistaken for an infected biloma and referred for percutaneous interventional radiology drainage. Careful imaging review, correlation with operative notes and good diagnostic radiological technique led to a correct diagnosis and avoided unnecessary intervention.