Thrombotic Thrombocytopenic Purpura (TTP)

Elective surgery waits - TTP is a hematologic emergency managed in the ICU, not a comorbidity you work around. Plasma exchange is usually stopped once platelets hold above 150,000/microL for more than 48 hours with normalizing LDH and no new organ dysfunction; that is the earliest sensible window for an elective case.

Confirm the picture before you plan - peripheral smear for schistocytes (more than 1%), platelet count (often under 30,000/microL), LDH, unconjugated bilirubin, reticulocyte count, haptoglobin, and ADAMTS13 activity under 10%. A normal PT/PTT and a negative direct Coombs are what separate TTP from DIC and from autoimmune hemolysis. The PLASMIC score above 5 predicts severe ADAMTS13 deficiency when the assay will not come back in time.

Platelet transfusion is restrictive - reserve platelets for overt bleeding or immediately before an invasive procedure. Oklahoma registry data showed no difference in death or severe neurologic injury with transfusion, but this is not a routine preop top-up. Packed red cells are given for a clinical indication as usual.

Neuraxial is off the table in an acute episode - platelet counts in an untreated presentation typically run under 30,000/microL.

Plasma exchange logistics - exchange runs daily through a central venous catheter at about one plasma volume (roughly 40 mL/kg), with plasma as the replacement fluid so ADAMTS13 is repleted. Schedule surgery around sessions; exchange strips clotting factors and drugs. Catheter-related bloodstream infection, catheter-associated venous thrombosis, TRALI, and anaphylaxis are the reported complications, and fluid overload and arrhythmias occur during treatment.

Steroids are running - prednisone 1 mg/kg/day in neurologically intact patients, or methylprednisolone 1000 mg daily for three days in the severely ill. Continue the steroid perioperatively.

Caplacizumab means bleeding - this anti-VWF A1 fragment blocks platelet adhesion and raises bleeding risk; it is continued subcutaneously for 30 days after exchange stops. Clinically significant bleeding warrants stopping the drug and giving VWF concentrate.

Immunosuppression - rituximab (375 mg/m2 weekly for four doses), cyclophosphamide, cyclosporine, and vincristine are used in refractory disease, and splenectomy in relapse. Treat these patients as immunocompromised for line and airway technique.

Check the heart - serum troponin above 0.25 ng/mL at diagnosis carries a threefold higher risk of death or treatment refractoriness. Get a baseline troponin and ECG; coronary microthrombosis is a leading cause of death.

Document the neuro exam - headache, focal deficits, seizures, confusion, and vertigo are the dominant symptoms, and brain MRI is used to gauge end-organ damage. A written preinduction baseline is the only way to interpret a postop change.

Kidneys are usually the lesser problem - creatinine is generally below 2 mg/dL and renal involvement may be limited to proteinuria or hematuria; pronounced renal failure should push you toward hemolytic uremic syndrome (HUS) instead. Still avoid a second nephrotoxic hit.

Pregnancy - pregnancy is a recognized trigger, and HELLP syndrome and pre-eclampsia sit in the differential. Get hematology involved before committing to a neuraxial technique for delivery.

TTP is a thrombotic microangiopathy caused by severe deficiency of ADAMTS13, the protease that cleaves ultra-large von Willebrand factor (VWF) multimers. Deficiency is congenital (ADAMTS13 mutation) or, more commonly, acquired from an autoantibody, with pregnancy, HIV, estrogen-containing contraceptives, and several drugs as triggers. Uncleaved multimers pile up on endothelium, grab platelets, and seed microthrombi in arterioles and capillaries.

The result is the classic pentad: fever, thrombocytopenia, microangiopathic hemolytic anemia with schistocytes, renal dysfunction, and neurologic dysfunction. CNS and kidneys are hit hardest, and cardiac microthrombosis can cause myocardial infarction and sudden death. Platelets fall from consumption, not from a coagulopathy — PT and PTT are typically normal, which is what separates TTP from DIC. Untreated mortality is roughly 90%, falling to 10% to 20% with prompt plasma exchange.