• The primary outcome measure is self-reported comfort score based on a visual analogue scale (VAS). Patients will complete a 10-point VAS. Patients will complete a VAS at the time of injection.
  

• On the day of the procedure, bruising at injection sites will be evaluated.
  
• Patients will document in a diary each injection before and after the surgery or invasive procedure. On the day of surgery or procedure abdominal bruising measurement will be obtained. A digital photo will be take of the injection site.
  

Increasing Patient Comfort and Compliance: The Bridging Anticoagulation Clinic strives to provide the highest quality of care to patients who require temporary interruption of warfarin therapy. An important component of optimizing patient care is minimizing patient discomfort with perioperative administration of short-acting anticoagulants (LWMH or UFH) used for bridging therapy, which, in turn, may optimize patient compliance with this treatment. This issue is especially relevant for patients who are receiving out-of-hospital treatment with LMWH or UFH because about 85% of such patients will be taught to self-administer this medication. This study seeks to determine if there is less discomfort and bruising associated with self-injection of LMWH than with UFH.

Minimizing Injection Site Bruising: No studies, to our knowledge, have assessed the characteristics or clinical importance of bruising in patients receiving subcutaneous LMWH or UFH. Thus, there is no evidence to support any association between bruising and discomfort. To bridge this gap in knowledge, we will document each injection site during the course of the study and measure the amount of bruising observed using a standardized photographic methodology. Injection site bruising has the potential to cause medical problems if an injection site hematoma develops, which can become infected or can cause long-term discomfort.