The Bottom Line

Hemostasis is the process of stopping bleeding during and after surgery. Your dermatologist uses several techniques—including medicated numbing injections, pressure, electrocautery (a small electrical tool), and absorbable agents—to keep your surgical field clear and your wound safe. Good bleeding control leads to better-looking scars and lowers infection risk. If you take blood thinners, tell your doctor before any skin procedure.

What Is Hemostasis and Why Does It Matter?

Hemostasis simply means stopping bleeding. During any skin surgery—whether a biopsy, excision, or Mohs procedure—your dermatologist must control bleeding throughout the procedure. Here’s why it matters to you as a patient:

  • Visibility: A clear, blood-free field allows the surgeon to see exactly what they are cutting and closing, which reduces the chance of error.
  • Healing: Blood pooling under a wound (called a hematoma) can push wound edges apart, delay healing, and increase infection risk.
  • Scarring: Wounds that close cleanly without blood pooling tend to produce thinner, less visible scars.
  • Safety: Significant bleeding that is not controlled can rarely cause complications—especially in patients on blood-thinning medications.

How Bleeding Is Controlled: The Main Techniques

1. Epinephrine in the Numbing Injection

The local anesthetic your doctor injects almost always contains a small amount of epinephrine (adrenaline). Epinephrine causes blood vessels in the area to constrict (narrow), dramatically reducing bleeding before the first incision is even made. This is why your surgeon will usually wait 5–10 minutes after injecting before starting—giving the epinephrine time to work fully. The effect typically lasts 30–60 minutes.

You may notice your skin looks pale or blanched in the treated area. That is the epinephrine working. It is completely normal and temporary.

2. Direct Pressure

Applying firm, sustained pressure with sterile gauze is one of the simplest and most effective ways to stop bleeding from small vessels. Your surgeon will often press gauze soaked in dilute epinephrine directly onto the wound for 2–3 minutes. You may see them just holding the gauze in place—this is intentional, not stalling.

3. Electrocautery (the “Buzzing Tool”)

Electrocautery is a handheld device that uses electrical current to heat tissue and seal bleeding vessels. It is the most commonly used hemostasis tool in skin surgery. If you have had a skin procedure before, you may have heard a brief buzzing or sizzling sound and smelled something like burning hair—that was electrocautery at work.

There are two types used in dermatology:

  • Electrofulguration/electrodesiccation: A spark that dries and destroys tissue; used for very small surface bleeders
  • Bipolar or monopolar electrosurgery: Uses current passed between two points to precisely seal a blood vessel; used for larger or deeper vessels

Electrocautery is done carefully and sparingly near wound margins because too much heat can damage surrounding tissue and affect how the margins look under the microscope—which matters for skin cancer surgery.

4. Suture Ligation

For larger blood vessels that cauterization alone cannot seal, your surgeon may tie the vessel with a small absorbable suture (a stitch that dissolves over time). This is sometimes called “tying off” a bleeder and is a reliable method for significant vessels in deeper tissue.

5. Topical Hemostatic Agents

When oozing from many small vessels persists, surgeons may apply a topical agent directly to the wound. Common options include:

  • Aluminum chloride: A styptic solution that works well on surface oozing
  • Gelatin sponge (Gelfoam): A dissolvable material that provides a scaffold for clot formation
  • Microfibrillar collagen or thrombin: Biochemical agents that actively trigger the clotting cascade
  • Ferric subsulfate (Monsel’s solution): Commonly used after shave biopsies; turns the wound a yellow-brown color as it works—this is normal

What Patients on Blood Thinners Need to Know

If you take anticoagulants or antiplatelet medications, your dermatologist needs to know before any procedure. Common medications in this category include:

  • Warfarin (Coumadin)
  • Apixaban (Eliquis), rivaroxaban (Xarelto), dabigatran (Pradaxa)
  • Aspirin, clopidogrel (Plavix)
  • High-dose fish oil (omega-3 supplements)
  • NSAIDs like ibuprofen and naproxen

Most guidelines now recommend continuing prescription anticoagulants for routine skin surgery rather than stopping them—the risk of stopping these medications (stroke, blood clot) often outweighs the extra bleeding risk during a minor skin procedure. Your surgeon has techniques to manage bleeding effectively even on blood thinners. However, this is a decision made together between you, your dermatologist, and the doctor who prescribed the blood thinner.

Over-the-counter supplements like fish oil and vitamin E can also thin the blood. Ask your doctor whether to pause these before surgery.

When to See a Dermatologist

  • You need a skin procedure and are on blood thinners—discuss this at your pre-op appointment
  • After a skin procedure, your wound soaks through its dressing and does not stop bleeding after 15 minutes of firm, continuous pressure
  • A painful lump or expanding bruise develops under or near your wound in the first 24–48 hours (may be a hematoma)
  • You have a history of a bleeding disorder and are planning any dermatologic surgery

Frequently Asked Questions

Is it normal to see some blood after skin surgery?

Yes. A small amount of blood or pink-tinged fluid on your bandage in the first 24 hours is completely normal. What you should watch for is active, continuing bleeding that soaks through a fresh bandage within 30 minutes even with sustained pressure. That warrants a call to your doctor.

Why did my skin look white after the numbing injection?

That is the epinephrine in the anesthetic constricting the blood vessels. It is temporary and harmless. Normal skin color and sensation return within a few hours as the medication wears off.

Can I take aspirin before my skin surgery?

If you take aspirin for heart disease or stroke prevention, do not stop it without talking to the doctor who prescribed it. Your dermatologist can manage the slightly increased bleeding with their hemostatic techniques. If you take aspirin only for general wellness with no medical need, your dermatologist may ask you to hold it for 5–7 days before the procedure.

What is the dark or yellowish stuff on my wound?

If you had a shave biopsy or superficial procedure, you may notice a dark yellow-brown crust. This is likely from a hemostatic agent called Monsel’s solution (ferric subsulfate) that was applied during the procedure. It is not infection—it will wash away over a week or so as the wound heals.

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  2. Otley CC. Continuation of medically necessary aspirin and warfarin during cutaneous surgery. Mayo Clin Proc. 2003;78(11):1392-1396.
  3. Alam M, Goldberg LH. Serious adverse vascular events associated with perioperative interruption of antiplatelet and anticoagulant therapy in dermatologic surgery. Dermatol Surg. 2002;28(11):992-998.
  4. Pollack SV. Wound healing and management. Dermatol Clin. 1989;7(3):639-648.
  5. Connolly SM, et al. AAD/ACMS/ASDSA/ASMS appropriate use criteria. J Am Acad Dermatol. 2012;67(4):531-550.

Trusted Resources

Always consult a board-certified dermatologist or dermatologic surgeon for diagnosis and treatment recommendations specific to your situation.