• Before surgery, wait at least 10 to 12 hours after the last dose of LMW heparin is administered before a spinal/epidural catheter is placed. • After surgery, when there is adequate surgical site hemostasis, wait at least six to eight hours after catheter removal before resuming treatment with LMW heparins. LMW heparin – We discontinue LMW heparin 24 hours before the planned surgery or procedure, based on a biologic half-life of most subcutaneous LMW heparins of approximately three to five hours [ 7,58,62 ].