The key to this mini case was the history. The patient had had numerous previous operations without problems. Therefore inherited bleeding disorder is unlikely. The clotting screen had previously been normal so an acquired problem is what we’re dealing with. The patient was on total parentral nutrition and therefore it is likely has central venous access. Heparin flushes are often used for central lines, as in this case.
Heparin potentiates antithrombin and therefore will prolong the thrombin time and the APTT. The reptilase time, using venom from the snake Bothrops atrox, also activates fibrinogen but is not affected by heparin.
Here are the results:
- PT 14s (11-14s)
- APTT 56s (33-40s)
- Fibrinogen (Clauss) 6.9g/L (1.5-4.5g/L)
- Thrombin time 38s (15-19)
- Reptilase time 15s (15-19)
This indicates heparin contamination. The bloods had been taken from a central line with previous heparin flushes. When repeated peripherally the coagulation screen was normal.
It’s important to look at the patient as well as the results. Knowing the patient had previous operations and normal coagulation screens should raise suspicion something is not quite right. Giving the patient fresh frozen plasma to correct erroneous coagulation results would be the wrong thing to do.