• Average Subcutaneous Anti-Xa Blood Levels [ Time Frame: approximately 3 months ] [ Designated as safety issue: No ]
  Blood levels taken from the first and last visits (when available) were combined to get an average. The anti-Xa test reports the low molecular weight heparin concentration in the blood.
  
  

• Percent Difference of Each Participant's Subcutaneous Anti-Xa Levels [ Time Frame: 6 time points (for each participant) in approximately 3 months ] [ Designated as safety issue: No ]
  Anti-Xa subcutaneous blood levels are displayed in percent difference to show normal fluctuations of anti-Xa levels without using the port. A percent difference is calculated by the current value has the previous value subtracted from it; this new number is divided by the absolute value of the previous value; then this new number is multiplied by 100. This allows each set of data to be compared to itself. Anti-Xa tests measure the concentration of low molecular weight heparin in the blood.
  
  
• Percent Difference of Each Participant's Anti-Xa Levels Without Port and Day One of Using the Port [ Time Frame: approximately 3 months ] [ Designated as safety issue: No ]
  Comparing subcutaneous baseline (without port) anti-Xa levels with day one of using the port. A percent difference is calculated by the current value has the previous value subtracted from it; this new number is divided by the absolute value of the previous value; then this new number is multiplied by 100. This allows each set of data to be compared to itself. Anti-Xa tests measure the concentration of low molecular weight heparin in the blood.
  
  
• Percent Difference of Each Participant's Anti-Xa Blood Levels Between Day 1 and Day 7 [ Time Frame: 7 days ] [ Designated as safety issue: No ]
  Comparing anti-Xa levels from the first day of using the port and the last day of using the port. A percent difference is calculated by the current value has the previous value subtracted from it; this new number is divided by the absolute value of the previous value; then this new number is multiplied by 100. This allows each set of data to be compared to itself. Anti-Xa tests measure the concentration of low molecular weight heparin in the blood.
  
  
• Standard Deviation of Participant's Own Glomerular Filtration Rate (GFR) [ Time Frame: 6 time points in approximately 3 months ] [ Designated as safety issue: Yes ]
  GFR was calculated from a creatinine blood level to establish a safe renal function that would validate anti-Xa levels. Low molecular weight heparin is primarily cleared from the body by the kidneys. Any condition that decreases kidney function can potentially decrease LMWH clearance, increasing its concentration in the blood and increasing the potential for excessive bleeding.
  
  

Subcutaneous ports have recently been used to administer Low Molecular Weight Heparin (LMWH) to patients for the prevention or treatment of venous thromboembolism; however, no studies have been performed to evaluate the ports' reliability in delivering this type of drug. Hence, it is not known whether absorption of the drug is constant over the seven-day lifespan of the port. Although the use of subcutaneous ports is not currently the standard of care, health care providers are more frequently using this as an alternative method to direct injection of LMWH, particularly in pediatric patients.

The main advantage of subcutaneous ports is the decreased number of needle sticks when using the ports to administer the medication. However, it is possible that, due to potential repeated bleeding into the subcutaneous space at the port site or other factors, drug absorption may decrease over the seven day lifespan of the port, resulting in a decrease of plasma drug level. Subtherapeutic LMWH levels and, hence, ineffective anticoagulation may result. This study's aim is to determine if the current use of subcutaneous ports is a safe, effective and reliable way of administering LMWH for the purpose of anticoagulation.