NHA Certified Phlebotomy Technician (CPT)Collection RoutineMedium
A phlebotomy technician is attempting to draw blood from a patient and notices that the evacuated tube fills slowly and then stops. The vein is still visible and appears stable. Which of the following is the most likely cause?
- AThe tourniquet was applied too loosely.
- BThe vacuum in the evacuated tube has been lost.
- CThe needle has gone completely through the vein.
- DThe needle is partially out of the vein.
Show answer & explanationAnswer & explanation
Correct answer: D. The needle is partially out of the vein.
If the tube fills slowly and then stops, but the vein is still visible and stable, it often indicates that the needle has partially withdrawn from the vein. The bevel may be partially out, or it may be pressed against the vein wall.
Why the other options are wrong
- A. A loosely applied tourniquet would result in no or very slow blood flow from the start, not a slow fill followed by a complete stop in a visible, stable vein.
- B. Loss of vacuum in the tube would prevent any blood from entering, or it would stop immediately, not a slow fill then stop. This is a possibility if the tube was faulty.
- C. If the needle went completely through the vein, blood flow would likely stop abruptly or a hematoma would form, rather than a slow fill and stop.
Troubleshooting Slow/Stopped Flow
Systematic steps to identify and correct issues when blood flow is inadequate or stops during venipuncture.
- First check needle position relative to vein.
- Consider if the tube vacuum is compromised.
- Assess tourniquet application and patient position.
- Never 'fish' for the vein; gentle repositioning or withdrawing is safer.
Memory trick: Slow flow? Check the angle, then the tube, then the tourniquet.