Sampling cell material
1)Introduce the cannula of the assembled Rotex screw needle biopsy instrument into the puncture canal and guide it up to the edge of the tissue to be sampled (Fig. F), under guidance of biplane fluoroscopy, CT or ultrasound.
2)Rotate the handle of the screw needle clockwise, thereby driving the 16 mm long screwed part into the tissue to be sampled (Fig. G). In the event strong resistance is encountered, rotate the screw needle no more than 5 turns. This is done in order to prevent the screw needle from bending. Pull the needle back into the cannula, push it forward again, and rotate it another 5 turns into the tissue. Repeat this procedure until the full length of the screwed part of the needle has been introduced into the lesion. In lesions with soft material, the screw needle is pushed and pulled in and out of the tissue 2-3 times and then secured in its protected position in the cannula.
3) The helical hub screw of the cannula is, after the screwed part of the needle is driven into the tissue, rotated anti-clockwise until the screwed part is positioned in the protected position of the cannula (Fig. H). The cannula now holds the screw needle, which contains tissue and cell material from the sample in its grooves in a protected position. Increasing resistance to rotation of the helical hub may indicate that the screw needle tip is bent. Forcing rotation of the hub may then lead to further bending of the screw tip. When in doubt, the screw needle should simply be pulled back into the cannula.
4) When sampling has been completed, withdraw the instrument and release the cannula and screw needle from the instrument holder.
