Abstract: Placement of a medical device within or in proximity to a substantially fluid filled compartment within a human body is aided by pulse-echo ultrasound and a time-stretching technique. In one embodiment, a small ultrasound transducer is placed near the tip of a catheter intended to be positioned within a ventricle of the brain to drain cerebrospinal fluid. The transducer is electrically pulsed so as to emit sound waves, and then used to receive returning echoes which contain information about structures in front of the transducer. These returning echoes are electronically amplified and processed in such a way that the information represented by the echoes is spread out over a much longer period than the actual acquisition time. This processed information may be presented to an operator visually, via audio feedback and/or via tactile feedback. Embodiments are disclosed where the information is displayed visually through variations in the color or brightness of a light source over time.