Fibrinolysis: clot breaks down after it forms
Fibrinolysis is about clot breakdown after clot formation — not the explanation for every bleeding pattern. A lysis signal becomes meaningful only when read with timing, the surgical field, and physiology.
Key points
- Fibrinolysis is about clot breakdown after clot formation, not every bleeding pattern.
- Lysis signals should be interpreted with timing, surgical field, physiology, and antifibrinolytic exposure.
- Treatment decisions should follow the bleeding pattern, institutional protocol, and reassessment.
When to use this page
During perioperative or major bleeding, when a viscoelastic test shows a lysis signal and you are deciding whether clot breakdown is contributing to the bleeding.
What fibrinolysis means
Fibrinolysis describes a clot forming and then breaking down. It is not the explanation for every diffuse bleeding pattern, and a lysis signal should be considered with timing and the surgical context rather than read as a standalone diagnosis.
What lysis signals may suggest
LY30, ML, a lysis index, or equivalent signals suggest a pattern that should be interpreted with timing and clinical bleeding. Read them against the test platform and local reference ranges, and consider whether the clot was strong enough for lysis to be assessed meaningfully.
- Interpret LY30 / ML / lysis index with the test platform and local reference ranges
- Consider whether clot formation was adequate before reading the lysis signal
- A lysis signal suggests a pattern to interpret, not a fixed diagnosis
When fibrinolysis becomes clinically important
Fibrinolysis can matter in trauma, major bleeding, obstetric hemorrhage, liver disease, and CPB-related situations, depending on institutional context. The clinical signal is ongoing bleeding with evidence of clot breakdown — not simply that bleeding is present.
Bleeding does not by itself mean lysis
A lysis signal is interpreted against clot formation and the bleeding pattern. Antifibrinolytic therapy is a decision to interpret with timing, prior exposure, and institutional protocol — not a reflex applied to all bleeding.
An action frame
- Confirm the bleeding pattern
- Confirm the lysis signal and its timing
- Review prior tranexamic acid or antifibrinolytic use
- Correct physiology and confirm source control
- Consider antifibrinolytic therapy according to local protocol
- Reassess bleeding and repeat testing when appropriate
What not to miss
- Surgical bleeding can coexist with a lysis signal
- Low fibrinogen or low platelet contribution may dominate the picture
- A normal lysis signal does not explain all bleeding
Take-home message
A lysis signal is meaningful only when interpreted with clot formation, bleeding pattern, timing, and physiology. Fibrinolysis is important, but it is not the universal explanation for perioperative bleeding.
Clinical content by Kozo Watanabe, MD View profile →
Verify your decision
Lysis signal with ongoing bleeding → use the ROTEM trigger guide to read the lysis pattern alongside clot formation and timing, then reassess bleeding after any antifibrinolytic decision.
Open the ROTEM trigger guide →Continue learning
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