Prolonged activated partial thromboplastin time with no clear explanation.

: Evaluation of bleeding risk before operation includes history of bleeding, complete blood count and basic coagulation tests, prothrombin time and activated partial thromboplatin time (aPTT). In this article, we present a patient with colon cancer who presented with asymptomatic prolonged aPTT of 72-100 s, while past a PTT values were within normal limits. aPTT was corrected in vitro by mixing with normal plasma. Further laboratory workup excluded coagulation factors deficiencies or an acquired inhibitor to coagulation factors. The patient underwent uncomplicated laparoscopic anterior resection of a recto-sigmoid carcinoma after receiving fresh frozen plasma and correction of aPTT. Further investigation revealed a rare disorder of an acquired prekallikrein deficiency. We describe the patient's clinical presentation, laboratory workup and review the literature of contact phase proteins deficiency.