Purpura, Thrombotic Thrombocytopenic

TTP rare (1:1,000,000). Adult, pregnancy may be a predisposing factor. Survival 80% at 6 mo; 90% mortality if untreated.

Periop risks

Rarely reported in pregnancy or postsurgically (case reports point to cardiac/urologic complications). Refer pt for splenectomy if medical therapy fails. Risks include MAHA with variable neurologic deficits and renal dysfunction combined with thrombocytopenia.

Preop drugs, therapies (plasma exchange, steroids, rituximab)

CNS/renal dysfunction

Thrombocytopenia (although usual quantitative platelet transfusion triggers do not apply)

Severe MAHA characterized by thrombocytopenia, variable multisystem organ involvement (particularly CNS and kidney); may be considered part of the spectrum of HUS. Differential in pregnancy from HELLP.

Low ADAMTS13 activity (<10%), a metalloprotease that cleaves multimers of von Willebrand factor, thus leading to increased intravascular platelet aggregation in high-shear environments.

May be associated with ticlopidine or malignancy.

Has been described after cardiac, vascular, and abdominal surgery.

Parity of RCTs; combination of therapies

• Plasmapheresis (exchange): Daily, more NB than plasma infusion (platelet-poor FFP) usually with rapid clinical response in days (failed Rx within 4–7 d)

• Steroids: Adjuvant (methylprednisolone 10 mg/kg/d better than 1 mg/kg/d). Potentially suppress production of anti-ADAMTS13 autoantibodies.

• Rituximab: Monoclonal Ab against CD20 Ag on B lymphocytes; used to treat refractory or relapsing TTP. Optimal dosing, timing, and side effects based on case series.

• Splenectomy: For failed medical response, prevention of relapse (small series).

• Avoid platelet transfusion.