tPA Contraindications: A Clinical Guide to Thrombolytic Eligibility

Tissue plasminogen activator — tPA — dissolves blood clots rapidly and can restore blood flow during an ischemic stroke, heart attack, or pulmonary embolism. Its speed is also its risk: tPA activates the fibrinolytic system broadly, and in certain patients, that activation triggers life-threatening bleeding rather than recovery. tPA contraindications exist to identify those patients before treatment begins, not to restrict care arbitrarily.

Understanding contraindications to tPA matters for clinicians working in emergency, neurology, and critical care settings, and for patients and families who want to understand why a physician may decline to administer this medication in what appears to be a qualifying situation. This article covers absolute and relative contraindications for tPA, the specific checklist applied in stroke, and where thrombolytic contraindications extend beyond ischemic stroke indications.

What tPA Does and Why Contraindication Screening Matters

tPA converts plasminogen to plasmin, which breaks down fibrin — the structural protein in clots. Administered intravenously, it works systemically, meaning it affects clot formation throughout the body, not just at the target thrombus. In a patient with a recent surgical wound, intracranial bleeding, or uncontrolled hypertension, this systemic effect can turn a treatable condition into a fatal hemorrhage. Contraindication screening identifies those risks before the drug is given, when reversal is impossible and bleeding consequences are irreversible.

Absolute Contraindications to tPA

Absolute contraindications to tPA are conditions where the bleeding risk consistently outweighs the potential benefit across virtually all patients. If any absolute contraindication is present, thrombolysis is not given regardless of how severe the presenting condition appears.

Prior Bleeding History

• History of intracranial hemorrhage at any time
• Active internal bleeding (excluding menstruation)
• Bleeding diathesis — known coagulopathy with INR greater than 1.7, aPTT greater than 40 seconds, or platelet count below 100,000/mm³
• Recent (within 3 months) intracranial or spinal surgery, serious head trauma, or prior stroke
• Significant closed-head or facial trauma in the prior 3 months

Timing and Blood Pressure Thresholds

For ischemic stroke, tPA is only approved for administration within 3 hours of last known well time (extended to 4.5 hours for selected patients under AHA/ASA guidelines). Blood pressure must be below 185/110 mmHg at the time of administration — uncontrolled hypertension is an absolute bar because it dramatically increases intracerebral hemorrhage risk during thrombolysis. Glucose below 50 mg/dL or above 400 mg/dL are also absolute thrombolytic contraindications in the stroke setting, as these can mimic stroke and would not benefit from lysis.

Relative Contraindications for tPA

Relative contraindications for tPA require individual risk-benefit analysis rather than automatic exclusion. In some clinical circumstances — a severe, disabling stroke in an otherwise healthy patient with one relative contraindication — the team may proceed after weighing all factors.

• Minor or rapidly improving stroke symptoms
• Major surgery within the prior 14 days
• Recent gastrointestinal or urinary tract hemorrhage within 21 days
• Arterial puncture at a non-compressible site within 7 days
• Seizure at stroke onset (if unclear whether the deficit is ictal rather than ischemic)
• Pregnancy
• Acute myocardial infarction in the prior 3 months

When Clinical Judgment Overrides the Checklist

Relative contraindications to thrombolytic therapy are not automatic vetoes. An experienced stroke neurologist may treat a patient with a relative contraindication if the presenting deficit is severe, the time window is optimal, and no safer alternative exists. These decisions should be made by experienced clinicians in centers equipped to manage hemorrhagic complications, not extrapolated from checklists alone.

tPA Contraindications in Stroke Specifically

tPA contraindications stroke protocols add some stroke-specific criteria not present in cardiac or pulmonary thrombolysis guidelines. These include CT-confirmed intracranial hemorrhage on the pre-treatment scan (mandatory to rule out), large established infarct involving more than one-third of the MCA territory (associated with higher hemorrhagic transformation risk), and prior stroke combined with diabetes as a dual risk factor under the 4.5-hour extended window protocol. The NIHSS score also informs candidacy — patients with very minor deficits (NIHSS 0–5) and patients with very severe deficits may not benefit proportionally from lysis versus the bleeding risk.

Thrombolytic Contraindications Beyond Stroke

Thrombolytics are also used in massive pulmonary embolism with hemodynamic instability, ST-elevation myocardial infarction when percutaneous coronary intervention is unavailable, and peripheral arterial occlusion via catheter-directed delivery. Thrombolytic contraindications in these settings follow similar principles — recent surgery, intracranial pathology, active bleeding — but the time windows and blood pressure thresholds differ by indication.

For STEMI managed with systemic lysis, a prior stroke of any type within 3 months is an absolute contraindication; for PE, the threshold shifts depending on hemorrhagic vs. ischemic stroke history and timing. Clinicians should apply indication-specific screening criteria rather than transferring stroke contraindication lists wholesale to other thrombolytic indications.

Safety recap: tPA contraindication assessment requires a current CT scan, complete medication history, and accurate last-known-well time before administration. Absolute contraindications are non-negotiable; relative ones require documented clinical reasoning. Any facility using tPA must have hemorrhagic complication management protocols in place.