Short answer
Thromboelastography, often called TEG, and rotational thromboelastometry, often called ROTEM, are whole-blood viscoelastic hemostasis tests. They show how fast a clot starts, how strong it becomes, and whether it breaks down too fast. Hospitals use them most often in trauma, major surgery, liver transplant, cardiac surgery, obstetric hemorrhage, and other active bleeding settings where quick transfusion decisions matter.
What TEG and ROTEM can show
| Pattern | What it may reflect | Why it matters |
|---|---|---|
| Slow clot initiation | Coagulation factor deficiency, anticoagulant effect, or consumption. | May point toward plasma, factor replacement, or reversal questions. |
| Weak clot strength | Low fibrinogen, low platelets, or platelet dysfunction. | May point toward fibrinogen or platelet support. |
| Excess clot lysis | Hyperfibrinolysis. | May support antifibrinolytic therapy in selected bleeding patients. |
| Heparin-like effect | Medication or sample effect on clotting assays. | Can change how reversal or transfusion is interpreted. |
When clinicians use it
- Major bleeding after trauma or surgery.
- Liver transplant and other high-risk operations.
- Cardiac surgery and massive transfusion settings.
- Obstetric hemorrhage when rapid hemostasis decisions are needed.
- Selected anticoagulant or fibrinolysis questions when standard labs are too slow or incomplete.
Why it is different from PT and aPTT
PT and aPTT are plasma-based tests that measure limited parts of the coagulation cascade. TEG and ROTEM test whole blood and give a more dynamic picture of clot formation, strength, and lysis. Even so, they do not replace platelet count, fibrinogen, PT/INR, aPTT, factor assays, or drug-specific anticoagulant testing. They are complementary tools, not a standalone diagnosis of why someone bleeds.
Questions to ask
- Was the test used for active bleeding, surgery, trauma, transplant, obstetric hemorrhage, or anticoagulant reversal?
- Which system was used: TEG, rapid TEG, platelet mapping, ROTEM, or another viscoelastic assay?
- Was heparinase or a fibrinogen-focused cartridge used if the team needed that answer?
- Did the result change transfusion or medication decisions?
- Were standard labs and clinical bleeding signs reviewed alongside the tracing?
What follow-up may include
Follow-up depends on the clotting pattern rather than the tracing alone. That may mean fibrinogen replacement, platelets, plasma, cryoprecipitate, antifibrinolytic therapy, anticoagulant reversal, or repeat viscoelastic testing after treatment to see whether the clot pattern improved in real time.
FAQ
What is the main difference between TEG and ROTEM?
Both are viscoelastic whole-blood clotting tests. The main difference is the instrument design and the way the sample is activated and measured, not the basic clinical idea.
Can TEG or ROTEM replace PT and aPTT?
No. They add a different view of clotting, but PT, aPTT, fibrinogen, platelet count, and drug-specific tests still matter.
What does low clot strength usually mean?
It can suggest low fibrinogen, low platelets, or platelet dysfunction, but the full clinical context matters.
What does hyperfibrinolysis mean?
It means the clot is breaking down too quickly. In selected bleeding settings, that can support antifibrinolytic treatment decisions.
When is TEG or ROTEM most useful?
It is most useful when bleeding is active and clinicians need fast guidance during trauma, surgery, transplant, or other high-acuity care.
Should I expect this test in routine outpatient workups?
Usually no. It is mainly an acute-care and procedural decision tool rather than a routine wellness or screening test.
Related guides: PT/INR blood test, aPTT blood test, fibrinogen blood test, and platelet function testing.