- The patient has adequate coagulation function as defined by international normalized ratio (INR) ≤ 1.5 and partial thromboplastin time (PTT) ≤ 1.5 x the ULN. Patients on full-dose anticoagulation must be on a stable dose of oral anticoagulant or low molecular weight heparin, and if on warfarin must have an INR between 2 and 3 and have no active bleeding or pathological condition that carries a high risk of bleeding (eg, tumor involving major vessels or invading the rectal lumen, or known varices)