This prospective case-controlled study conducted through the Institute of Hematology & Blood Diseases Hospital in China is looking to enrol 30 eligible adult patients with ITP who wish to pursue a splenectomy as their next treatment option. The goal of this study is to determine how the immune system in ITP patients benefit from a splenectomy by comparing between those who have had a splenectomy as a result of their ITP with controls (participants who are having a splenectomy for non-ITP reasons). Eligibility includes adults with chronic ITP between the ages of 18-60 years who have failed to maintain a satisfactory platelet response using first and second line therapies. Participants will be offered a splenectomy (provided a safe enough platelet count level can be achieved pre-surgery). Peripheral blood (PB) platelet counts will be collected at various time points during and after the surgery and compared with the control group. Tissue from the spleen will also be analyzed from all enrolled.