From the Guidelines

No, a patient who takes 40mg of Lovenox (enoxaparin) twice a day (BID) should not receive an epidural 12 hours after the last dose.

According to the guidelines, for planned manipulation of an epidural or spinal catheter (insertion, removal), Enoxaparin should be avoided/held for 24 hours BEFORE planned manipulation and should be resumed no earlier than 2 hours FOLLOWING manipulation 1.
The American Society of Clinical Oncology clinical practice guideline update also recommends that when neuraxial anesthesia or analgesia is planned, prophylactic doses of once-daily LMWH should not be administered within 10 to 12 hours before the procedure/instrumentation (including epidural catheter removal) 1.
The Association of Anaesthetists of Great Britain & Ireland recommends a minimum of 12 hours after the last dose of LMWH sc prophylaxis before performing a neuraxial block, and 4 hours after block performance or catheter removal for the next drug dose 1.

The patient is taking 40mg of Lovenox (enoxaparin) twice a day (BID), which is a higher dose than the typical once-daily dose.
The guidelines and recommendations are based on once-daily dosing, and the patient's twice-daily dosing may increase the risk of bleeding.

Based on the guidelines and recommendations, it is recommended to wait at least 24 hours after the last dose of Enoxaparin before performing an epidural, and to resume Enoxaparin no earlier than 2 hours after the procedure.
The patient's twice-daily dosing and the increased risk of bleeding should be taken into consideration when making a clinical decision.
It is essential to weigh the benefits of epidural analgesia against the risks of bleeding and to consider alternative pain management options if necessary.

From the Research

The patient is taking 40mg of Lovenox (enoxaparin) twice a day (BID) and wants to receive an epidural 12 hours after the last dose.
According to the study 2, the anti-Xa heparin level was measured in patients who received twice-daily enoxaparin, and the results showed that the level was > or = 0.20 U/ml in 5 patients and > or = 0.10 U/ml in 7 patients at the time of catheter removal, which was on average 10.4 hours after the preceding LMWH dose.
Another study 3 reported a case of a patient who developed an epidural hematoma while receiving enoxaparin postoperatively with an indwelling epidural catheter, suggesting that the use of enoxaparin with an epidural catheter may increase the risk of bleeding complications.
However, a study 4 found that enoxaparin administration within 24 hours of caesarean section appears to be reasonable, regardless of epidural anesthesia, and no patient developed a spinal epidural hematoma.
It is essential to consider the timing of the last dose of enoxaparin and the patient's individual risk factors for bleeding complications before administering an epidural.

Enoxaparin has been associated with bleeding complications, including hemorrhage, thrombocytopenia, and local reactions 5.
A study 6 found that the incidence of hemorrhagic complications differed significantly between patients who received different doses of enoxaparin, with higher doses associated with a higher risk of bleeding.
The risk of bleeding complications should be carefully evaluated in patients receiving enoxaparin, especially when considering the use of an epidural catheter.

The decision to administer an epidural to a patient taking enoxaparin should be made on a case-by-case basis, considering the patient's individual risk factors and the timing of the last dose of enoxaparin 2.
Clinicians should be aware of the potential risks of bleeding complications associated with enoxaparin and take steps to minimize these risks, such as monitoring the patient's anti-Xa heparin level and being vigilant for signs of bleeding 3, 5.