An apparatus includes an injector, a first fluid conduit, a second fluid line, and a control module. The injector includes a body, a flexible cannula, a flexible needle, and a sensor. The needle is configured to translate relative to the cannula. The sensor is operable to detect a position of the needle relative to the cannula. The first and second fluid lines are coupled with the needle. The control module is in communication with the sensor, with the first fluid conduit, and with the second fluid conduit. The control module is configured to provide delivery of a first fluid through the first conduit to the needle based on a signal from the sensor. The control module is further configured to provide delivery of a second fluid through the second conduit to the needle.