If resistance is encountered and the catheter cannot advance despite obtaining a flashback of blood, do not force it, as the needle tip may be stuck against a valve or the vein’s wall.

Obtaining a flashback of blood does not necessarily mean the catheter can advance, as the needle tip may be stuck against a valve or the vein’s wall.

Here are the steps to consider:

• Retraction and repositioning: Carefully retract the needle slightly before gently trying to advance the catheter again. This minor adjustment helps to reposition the needle within the vein, allowing the catheter to move forward smoothly. If it appears that the catheter-needle assembly is not inserted deep enough, consider advancing the assembly sightly deeper at a low angle into the lumen of the vein. Only then attempt to thread the catheter over the needle.
• Adjust the insertion angle: Use the correct insertion angle. Upon obtaining a flashback, lower the angle of the needle-catheter system to be almost parallel to the skin before advancing further. This adjustment aligns the catheter with the vein, facilitating smoother entry.

VIDEO: https://youtu.be/M3GUm5oVjeE 

• Consider using the “Floating technique” when you suspect that the catheter may be stopped by a valve:

1. Start by inserting the needle deep enough to secure the catheter’s tip within the vein.
2. Pull back the needle slightly, exposing part of the catheter.
3. Slowly flush while cautiously advancing the catheter. 
4. Continue flushing and advancing until the catheter is entirely inside the vein.

• Flushing the catheter helps to open valves, fills and widens the vein, and reduces the risk of puncturing through the other side of the vein.

Video: https://youtu.be/Rx0xj1UN7AI 

Video: https://youtu.be/2Y1O-FMG4-o