[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Nursing](https://durgical.com/en/nursing/) › [Medical–surgical nursing](https://durgical.com/en/nursing/areas/med-surg/) › Patients on anticoagulants: bleeding watch, monitoring tests, interactions and teaching

# Patients on anticoagulants: bleeding watch, monitoring tests, interactions and teaching

- Safe practice

Anticoagulants and antiplatelets prevent clots but cause bleeding: the nurse checks the right product, the tests, the bleeding signs and the interactions.

Updated Nov 13, 2026

## Key points

- Before each dose: the correct product and order, bleeding signs, the ordered tests (aPTT for heparin infusion, PT/INR for warfarin) and platelets.
- A marked fall in platelets on heparin can mean heparin-induced thrombocytopenia: stop as the protocol says and inform the doctor at once.
- With neuraxial anaesthesia or a spinal puncture, watch leg strength and sensation: a spinal haematoma can cause paralysis.
- Patients on anticoagulants or antiplatelets avoid NSAIDs and aspirin unless prescribed; check every new medicine, herb or supplement.
- Warfarin: keep vitamin K foods steady, avoid alcohol, attend the INR tests, and report bleeding, a fall or a blow to the head.

## What it is

Anticoagulants and antiplatelets are high-alert medicines: an error or a missed sign can cause serious bleeding or a clot. Before each dose the nurse checks the product and the order, the ordered coagulation tests, the platelet count and any bleeding, and whether a procedure is coming. Unfractionated heparin in infusion is adjusted with the aPTT; warfarin with the PT/INR; low-molecular-weight heparin and the direct oral anticoagulants usually need no routine coagulation test but depend on kidney or liver function. Each drug has a reversal agent the team can use. Teaching covers bleeding signs, injury prevention, a steady diet for warfarin, and checking every new medicine or supplement.

## What it requires

- Double-checking high-alert medicines as the institution requires.
- Bleeding watch: skin, gums, nose, urine, stools, vomit, puncture sites, and vital signs that suggest internal bleeding.
- Monitoring tests ordered for each drug, and platelet and kidney results.
- Interactions with medicines, herbs, alcohol and foods.
- Planning around procedures, surgery and dental work, always under the prescriber's direction.

## How it is applied (and why)

- Verify the product, concentration and order with the second check the institution requires — anticoagulants are high-alert medicines.
- Look for bleeding: skin, gums, nose, urine, stools, vomit and puncture sites — bleeding is the main adverse effect.
- Check pulse and blood pressure and ask about headache, dizziness or weakness — changes can mean internal bleeding.
- Review the ordered test before giving: aPTT for heparin infusion, PT/INR for warfarin, platelets and kidney function — they guide the dose.
- Give subcutaneous heparins with the technique on the subcutaneous injection page — the correct technique protects the site.
- Avoid intramuscular injections and unnecessary punctures — each one can bleed.
- Check every new medicine for interactions and ask about herbs and supplements — many change the effect.
- Ask whether a procedure, surgery or dental work is planned and tell the prescriber — the plan to pause or continue is medical.
- Teach bleeding signs, soft toothbrush, electric razor, fall prevention and the ID card; check teach-back — the patient watches at home.

## In nursing practice

- Call at once for bleeding that does not stop, vomit with blood, black or bloody stools, red or dark urine, or large dark bruises.
- Call at once for a sudden severe headache, confusion, weakness, or a fall with a head knock.
- Call for falling pressure with a rising pulse, or for a test result outside the range the doctor set.
- Call for a marked fall in platelets, or a new clot, while on heparin.
- After neuraxial anaesthesia or a spinal puncture, call for new leg weakness or numbness.

## Common mistakes

- Confusing heparin products or concentrations.
- Giving warfarin without looking at the latest INR, or heparin infusion without the latest aPTT.
- Giving an NSAID to a patient on an anticoagulant without checking with the prescriber.
- Forgetting to ask whether a procedure or surgery is planned.
- Teaching only about the medicine and not about the bleeding signs, falls and other medicines.

## Test yourself

Think of the answer, then tap the question to see it.

## Which test guides an unfractionated heparin infusion and which guides warfarin?

The aPTT guides the heparin infusion; the PT/INR guides warfarin.

## What can a marked fall in platelets on heparin mean?

Heparin-induced thrombocytopenia; heparin is stopped as the protocol says and the doctor is informed at once.

## What dietary advice is given to a patient on warfarin?

Keep the amount of vitamin K-rich foods, such as green leafy vegetables, steady from day to day, avoid alcohol and ask before major diet changes.

## Which symptoms in a patient on an anticoagulant need an urgent call?

Bleeding that does not stop, black or bloody stools, blood in vomit or urine, a sudden severe headache, confusion or a blow to the head.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/nursing/patients-on-anticoagulants-bleeding-watch-monitoring-tests-interactions-and-teac/)

## Elsewhere in DurgiPedia

- [Thrombosis and bleeding: Virchow's triad and hemostatic defects](https://durgical.com/en/physiology/thrombosis-and-bleeding-virchow-s-triad-and-hemostatic-defects/)
- [Bleeding syndromes: platelet vs coagulation pattern](https://durgical.com/en/clinical-exam/bleeding-syndromes-platelet-vs-coagulation-pattern/)

## Connections

## Related 4

- [High-alert medications](https://durgical.com/en/nursing/high-alert-medications/)
- [Subcutaneous injection](https://durgical.com/en/nursing/subcutaneous-injection/)
- [Nursing care in deep vein thrombosis and pulmonary embolism: recognising them, the first response and mobilisation](https://durgical.com/en/nursing/nursing-care-in-deep-vein-thrombosis-and-pulmonary-embolism-recognising-them-the/)
- [Nursing care in atrial fibrillation: apical–radial pulse, stroke warning signs and teaching about anticoagulants](https://durgical.com/en/nursing/nursing-care-in-atrial-fibrillation-apical-radial-pulse-stroke-warning-signs-and/)

## Related conditions 4

- [Deep vein thrombosis](https://durgical.com/en/conditions/deep-vein-thrombosis/)
- [Pulmonary embolism](https://durgical.com/en/conditions/pulmonary-embolism/)
- [Atrial fibrillation](https://durgical.com/en/conditions/atrial-fibrillation/)
- [Heparin-induced thrombocytopenia](https://durgical.com/en/conditions/heparin-induced-thrombocytopenia/)

[← All of nursing](https://durgical.com/en/nursing/)

Educational content for students; it does not replace your institution's protocols, supervised clinical training or a prescriber's order. Dose-calculation examples use made-up numbers: they are educational, not a clinical order.

Sources: [Nursing Pharmacology, 6.12 Blood Coagulation Modifiers](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Pharmacology_(OpenRN)/06%3A_Cardiovascular_and_Renal_System/6.12%3A_Blood_Coagulation_Modifiers) (Open RN (Chippewa Valley Technical College), LibreTexts, 2020); [Taking warfarin (Coumadin): MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/patientinstructions/000292.htm) (MedlinePlus, US National Library of Medicine, 2026); [Nursing Pharmacology, 6.4 Nursing Process Related to Cardiovascular and Renal Medications](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Pharmacology_(OpenRN)/06%3A_Cardiovascular_and_Renal_System/6.04%3A_Nursing_Process_Related_to_Cardiovascular_and_Renal_Medications) (Open RN (Chippewa Valley Technical College), LibreTexts, 2020).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/nursing/patients-on-anticoagulants-bleeding-watch-monitoring-tests-interactions-and-teac/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/nursing/patients-on-anticoagulants-bleeding-watch-monitoring-tests-interactions-and-teac/