A 68-year-old woman with a history of mitral
valve replacement with a mechanical valve was admitted with
abdominal pain. Because of the mechanical valve, she was
chronically on warfarin (a blood thinner). At the time of
admission, her international normalized
ratio (INR) was 1.3, indicating that she was
under-anticoagulated—her blood was not appropriately
"thinned" to prevent possible clots from forming on her mechanical
valve. She was treated with unfractionated heparin, a continuously
delivered intravenous medication, which quickly thinned her blood
Based on her abdominal complaints, a
gastroenterology consultant wished to pursue
esophagogastroduodenoscopy (EGD), a procedure in which a camera is
inserted through the mouth and into the stomach. The
gastroenterologist wanted the patient to be off all blood thinners
to prevent bleeding complications and in case he needed to do
The admitting team caring for the patient wrote
an order to stop the heparin at 5:00 pm on the day before the EGD
as well as an order to restart it 48 hours afterward.
Unfortunately, the order to restart the heparin was missed, and the
heparin was not restarted after the procedure. Four days after the
EGD, the team noticed that the patient's partial thromboplastin
time (PTT), a different marker of blood thinning (one that goes up
in response to heparin), was normal and realized that the patient
was not being anticoagulated appropriately by the heparin. The
heparin was quickly restarted, and the patient was eventually
discharged. She did not suffer any negative consequences, but her
prolonged period off anticoagulants put her at high risk for acute
stroke from blood clots on her mechanical valve.
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