Automated catheter length determination for implantable fluid delivery device

Disclosed are methods and systems for automatically estimating the length of an implantable catheter by measuring the pressure decay response to pumping fluid through the catheter. The decay time for a unit fluid pressure pulse generated within the catheter is proportional to the catheter length, i.e. as the catheter length increases so does the decay time. The catheter length can therefore be estimated based on, e.g., the decay time of the pressure pulse. The estimated catheter length can also be analyzed to determine if it is representative of the actual catheter length, or, e.g., is affected by one or more catheter malfunctions including cuts and occlusions. Systems for automatically estimating the catheter length include an implantable catheter, a pumping mechanism, a pressure sensor configured to measure pressure within the catheter, and a processor that calculates the catheter length from a pressure pulse measured while delivering fluid through the catheter.