<p>The needle comprises a handle housing (2) which has a distal end section (D). The end section has an internal thread (6) by which it is screwed to the hollow threaded socket on the inlet of the endoscopic instrumentation duct. The catheter is inserted through the hollow threaded socket. The hollow bar (4) has a scale (15) co-operating with marking (16) on the handle housing for reading the length by which the hollow puncture needle (5) protrudes distally out of the catheter. The handle housing contains a guide tube (10). The hollow bar and guide tube slide telescopically inside each other.</p>
