A catheter assembly comprises a catheter having a wall at least partially defining a lumen. The lumen communicates with an opening in an exterior catheter surface at a distal end of the catheter. A lengthwise portion of the wall is made of a resilient material and is longitudinally extensible. The lengthwise portion of the wall has a diameter that is reduced when the lengthwise portion of the wall is longitudinally extended. The diameter of the lengthwise portion of the wall increases from a reduced condition when the lengthwise portion of the wall resiliently returns from a longitudinally extended condition.
