Monoclonal gammopathy of undetermined significance (MGUS) characterized by refractory lower gastrointestinal postoperative bleeding with coagulopathy.

Bleeding is a common complication after lower gastrointestinal surgery, and cases due to coagulation dysfunction are rare. The current authors encountered a 54-year-old Chinese man with refractory bleeding after endoscopic rectal polypectomy, and multiple endoscopic and surgical interventions failed to control that bleeding. An APTT mixing test could not be corrected and there was no evidence of autoimmune-related disease, so the presence of nonspecific antibodies was considered. After empiric therapy with a cyclophosphamide and glucocorticoid, APTT was corrected and gastrointestinal bleeding stopped. Based on laboratory results and therapeutic results, the patient was ultimately diagnosed with prolonged APTT induced by monoclonal gammopathy of undetermined significance (MGUS). MGUS and coagulopathy characterized by a prolonged APTT has rarely been reported. Here, studies noting elevated monoclonal immunoglobulins and coagulopathy have been reviewed. If a prolonged APTT of undetermined significance cannot be corrected with an APTT mixing test and if autoimmune-related factors are excluded, then plasma cell-related diseases such as MGUS need to be considered.