A medical instrument system comprises an imaging probe including a distal tip terminating at a first distal end of the imaging probe and a lens disposed at the first distal end. The imaging probe including a first sealing feature on an external surface of the imaging probe. The medical instrument also comprises an elongated medical instrument including a distal portion terminating at a second distal end and including a working channel configured to slidably receive the imaging probe. The working channel including a second sealing feature on a surface of the working channel. The first sealing feature and the second sealing feature are shaped and configured to contact one another to prevent the passage of fluid between the first and second sealing features.