Reverse flow cleaning method for medical devices

A method of cleaning the lumens of a medical device comprising:

• a) providing a medical device with a first lumen and a second lumen, said first and second lumens each having a proximal end and a distal end, and said distal end of at least one of said lumens open to a drain at about atmospheric pressure;
• b) providing a cleaning fluid;
• c) causing said cleaning fluid to flow at a positive pressure through said first and second lumens in a first fluid flow path, said first fluid flow path starting at said proximal end of said first lumen;
• and
• d) causing said cleaning fluid to reverse flow at a positive pressure through said first and second lumens in a second fluid flow path, said second fluid flow path starting at said proximal end of said second lumen, wherein at least part of said second fluid flow path is opposite said first fluid flow path.