Abstract: Embodiments disclosed herein are directed to connections systems including a port, a catheter, a cathlock and an adapter. The adapter can be coupled with a proximal end of the catheter and a cathlock can co-operate with the adapter to secure the catheter to the port in a fluid tight engagement. One of the cathlock or the adapter can threadably engage the port and employ mechanical advantage to radially compress the catheter and ensure a fluid-tight seal. The system can further include an insertion tool configured to facilitate securing the adapter to the catheter or securing the adapter or cathlock to the port. The adapter can be provided as a separate structure or coupled to the cathlock. Engagement of the adapter with the catheter can be signaled with an audible click. Optionally the adapter can include a skirt configured to compress the catheter onto the adapter stem.