Various medical systems and methods are described, including a medical monitoring system. The medical monitoring system can have a fluid system configured to receive bodily fluid and optically analyze said fluid to determine analyte concentration. The fluid system can have a removable portion. The removable portion can have an opening with a port. The system can also have a container configured to contain anticoagulant. The container can have a portion configured to mate with the port of the removable portion. The container can be further configured to not fit into a conventional luer fitting. An anti-coagulant insertion apparatus is also described. The apparatus can have a syringe, a dock with a port, and an adapter configured to connect the syringe to the port. The dock can also have a tab configured to move with the port.