Consider checking aXa activity level if <12 hours (low-dose LMWH). An acceptable level of residual aXa activity remains undetermined, therefore we suggest aXa value of ≤0.1 IU/mL.

In patients receiving high (therapeutic) doses of LMWH, we recommend delay of at least 24 hours prior to needle/catheter placement.

Consider checking aXa activity level if <24 hours particularly in elderly patients (age >75 years) and patients with renal insufficiency (CrCl ≤30 mL/min) (high-dose LMWH). An acceptable level of residual aXa activity remains undetermined, therefore we suggest aXa value of ≤0.1 IU/mL.

Antiplatelet or oral anticoagulant medications administered in combination with LMWH increases the risk of neuraxial hematoma. We recommend against concomitant administration of medications affecting hemostasis, such as antiplatelet drugs, standard heparin, or dextran, regardless of LMWH dosing regimen when there is an indwelling neuraxial catheter.

Twice-daily low dose LMWH: We recommend the first dose of LMWH be administered the following day and at least 12 hours after needle/catheter placement. Indwelling catheters should be removed prior to initiation of LMWH. Administration of LMWH should be delayed for 4 hours after catheter removal.

Single daily low dose LMWH: We recommend the first postoperative LMWH dose should be administered at least 12 hours after needle/catheter placement. The second postoperative dose should occur no sooner than 24 hours after the first dose. Indwelling neuraxial catheters do not appear to represent increased risk and may be maintained. However, no additional hemostasis altering medications should be administered due to the additive effects. The catheter should be removed 12 hours after the last dose of LMWH. Subsequent LMWH dosing should occur at least 4 hours after catheter removal.

Single or twice-daily high (therapeutic) dosing LMWH: High-dose LMWH may be resumed 24 hours after non-high-bleeding-risk surgery and 48–72 hours after high-bleeding-risk surgery. We recommend that indwelling neuraxial catheters be removed 4 hours prior to the first postoperative dose and the first postoperative dose should be at least 24 hours after needle/catheter placement, whichever is greater.

NSAIDs appear to represent no added risk for the development of major bleeding after regional anesthetic techniques. NSAIDs (including aspirin) do not create a level of risk that will interfere with the performance of neuraxial or deep plexus/peripheral blocks. In patients receiving these medications, we do not identify specific concerns as to the timing of single-injection or catheter techniques, postoperative monitoring, or the timing of neuraxial catheter removal.

Based on labeling and surgical/procedural experience, the suggested time interval between discontinuation of thienopyridine therapy and needle placement is 5–7 days for clopidogrel, and 7–10 days for prasugrel.

Neuraxial and deep plexus/peripheral catheters should not be maintained with prasugrel due to the rapid onset. However, since the antiplatelet effect is not immediate with clopidogrel, they may be maintained for 1–2 days, provided a loading dose of the antiplatelet agent is not administered.