Is it safe to do a lumbar puncture on a patient taking plavix? SQ heparin? Aspirin?

According to the American Society of Regional Anesthesia and Pain Medicine, no while on plavix. Thienopyridine derivatives (clopidogrel and ticlopidine) should be discontinued at least 7 days prior to spinal procedures. See image below for their recommendations regarding other antiplatelet and anticoagulant agents.
Click on image to enlarge

Source

Horlocker TT, Benzon H, et al. "Regional anesthesia in the anticoagulated patient: defining the risks (the second ASRA Concensus Conference on Neuraxial Anesthesia and Anticoagulation)" Reg Anesth Pain Med 2003; 28: 172-97