Monitoring of bladder pressure, known as cystometry, is a key diagnostic tool in urodynamic studies of patients that exhibit lower urinary tract symptoms. Over the past few years, there has been an increased interest in ambulatory urodynamics due to the increased convenience and more realistic monitoring environment. This paper presents an ultra-low power implantable wireless platform, UP-Link, for long-term ambulatory bladder pressure monitoring. The proposed platform, which is built using off-the-shelf components and uses the MICS (Medical Implant Communication Service) radio frequency band for communication, enables more cost-effective and rapid development compared to existing ASIC-based solutions. The UP-Link platform is powered by two coin cell batteries with a total capacity of 560mAh and has an estimated battery life of several months to years. Results obtained through in vitro experiments demonstrate that the pressure data measured using UP-Link shows excellent agreement (0.995 using the intraclass correlation coefficient method) with measurements obtained using a commercial pressure gauge. An accelerated battery-life test was also performed, the results of which validate our lifetime estimates. The longevity of the UP-Link platform enables ambulatory urodynamic studies at much longer time scales than current practice.