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Coagulogram: how to properly prepare for a blood clotting analysis
What is a coagulogram and why is it prescribed?
Coagulogram is a laboratory study that allows you to assess blood clotting efficiency. It is prescribed to identify risk thrombosis, bleeding, complications during surgery, pregnancy or taking anticoagulants.
The standard coagulogram profile includes:
prothrombin time (PTT)
activated partial thromboplastin time (APTT)
fibrinogen
INR (International Normalized Ratio)
antithrombin III, D-dimer — if necessary
The analysis is sensitive to many external and internal factors, therefore precise preparation is a prerequisite for reliable results.
Who needs a coagulogram?
patients before surgery
when planning pregnancy or its complications (preeclampsia, gestosis)
people with varicose veins, thrombosis, stroke in history
with unexplained bleeding, tendency to bruise
patients taking blood-thinning or clotting medications
with liver diseases, autoimmune conditions or cancer processes
Preparing for a coagulogram: step-by-step instructions
48 hours before analysis
Give up alcohol
Limit fatty foods
Do not change your usual diet abruptly.
If possible, stop taking medications that affect clotting (only with the approval of a doctor)
In 24 hours
Avoid physical exertion, prolonged standing, or hypothermia
Minimize stressful situations
Refrain from visiting the sauna or intense sports.
On the day of analysis
Donate blood on an empty stomach: 8–12 hours without food
Don't drink coffee, tea, juices - only clean water
Do not smoke for 2–3 hours
Do not take medication in the morning (unless agreed with your doctor)
Arrive at the laboratory sit quietly for 10–15 minutes in advance
Table: How different factors affect the result of a coagulogram
| Factor | Impact on the result | What to do |
|---|---|---|
| Coffee, tea | Increased vascular tone, change in PTC | Do not use |
| Smoking | Vasoconstriction, platelet activation | Stay for 2 hours. |
| Physical activity | Increased fibrinogen | Rest before submission |
| SARS, temperature | Increased D-dimer, coagulation disorders | To be handed over after recovery |
| Stress, insomnia | Fluctuations in hormonal levels, changes in APTT | Ensure peace in the morning |
| Taking medications (NSAIDs, hormones) | Distortion of almost all indicators | Notify doctor or temporarily cancel |
Important notes for specific groups
Pregnant women: a coagulogram is performed several times during pregnancy. Preparation is standard, but it is important to report any complications from previous pregnancies (hypertension, gestosis, cesarean section).
Cancer patients: the risk of thrombosis is higher, so it is worth clarifying which parameters will be evaluated (for example, D-dimer, antithrombin III).
Patients on warfarin: Do not stop the drug on your own. Your doctor or laboratory should know the date and time of your last dose.
Proper preparation for a coagulogram is not just a “formality before the analysis.” It is a way to avoid false diagnoses, incorrect prescription of drugs, and undesirable consequences during treatment. If you are in doubt about any point, be sure to consult a doctor or laboratory technician before donating blood.
