Bilioenteric anastomoses were common interventions before the rise of minimal invasion procedures, specifically, before endoscopic retrograde cholangiopancreatography. During a choledochoduodenostomy (CDS) the distal part of the common bile duct is excluded from the bile drainage and behaves as a “sump,” a poorly drained part that works as a reservoir which is responsible of the development of complications of the bilio-pancreatic tract. The consequent sump syndrome is a rare medical complication that presents a diversity of symptoms, for which there is no well-defined diagnostic algorithm. We present the case of a 72-year-old male patient with multiple comorbidities. He presented to the ER because of recurrent episodes of cholangitis; after having obtained the patient’s medical records, lab and image studies, the latter showed pneumobilia. After considering all the results plus the pneumobilia we suspect the presence of this uncommon complication of CDS. The patient was subjected to an unsuccessful endoscopic treatment followed by surgery, after which he showed signs of improvement and adequate evolution till hospital discharge.