Microsclerotherapy Injection Technique: The 5-Step Protocol for Spider Veins

By Dr. Haroun Gajraj | VeinCare Academy | 26th August 2026

Dr. Haroun Gajraj is GMC-registered Vascular Specialist, Founder & Board Member of the British Association of Sclerotherapists (BAS).

Unlike textbook reviews or consensus summaries, this guide outlines the refined injection protocol I developed over thirty years of treating telangiectasias and reticular veins.

Microsclerotherapy looks deceptively straightforward from the outside, but the margin between excellent vessel clearance and complications like telangiectatic matting, excessive post-sclerotherapy pigmentation, or tissue extravasation is decided in seconds at the needle tip.

Guidelines tell you what to inject, but they rarely describe the injection technique in detail: how to stabilise the skin, how to interpret vessel blanching, and how to check for extravasation or skin blanching.

The structured protocol below distills these clinical nuances into a reliable, repeatable routine for daily practice.

TL;DR: Microsclerotherapy Injection Protocol

• The Core Mantra ("Low, Slow, Low, Low, Hold"): Inject a Low volume of Low concentration sclerosant at a Slow speed with Low pressure, followed by a 10-second stationary Hold to maximize endothelial contact time before dilution.

• Needle Mechanics & Stability: Bend a 30-gauge needle 10°–15° with the bevel up to advance flat along the epidermis while applying two-handed skin counter-traction.

• Visual Endpoints: Target crisp vessel blanching. Stop immediately if skin blanching, wheal formation (a bleb), or acute discomfort occurs to prevent extravasation injury.

• Complication Mitigation: Treat underlying reticular feeder veins before fine telangiectasias, use the lowest effective sclerosant strength to prevent matting, and immediately massage any inadvertent blebs to disperse solution.

1. Preparation for Microsclerotherapy: Diagnosis & Patient Selection

Flawless injection technique cannot rescue poor preparation:

• Rule out underlying truncal reflux and treat feeder reticular veins first before addressing fine telangiectasias.

• Photograph baseline appearance from standardised angles.

• Confirm patient eligibility and set clear expectations that veins typically look worse (bruised, inflamed) before looking better.

2. The Core Injection Mantra: Low, Slow, Low, Low, Hold

When injecting telangiectasia, this five-point mantra ensures every critical safety and efficacy variable is controlled:

• Low Volume of Sclerosant: Inject only what is required to achieve localised blanching (limiting treatment to roughly a 2×2 cm area per injection site). Flooding the capillary bed increases the risk of telangiectatic matting.

• Slow Injection: Injecting rapidly is associated with more complications. A slow push allows you to observe the column of blood being displaced along the vessel lumen.

• Low Concentration: Telangiectasias sit superficial in the dermis and cannot tolerate aggressive solutions. Using low concentrations (e.g., 0.25%–0.5% Polidocanol or 0.1%–0.2% Sodium Tetradecyl Sulfate) achieves endothelial destruction without inducing skin necrosis or reactive matting. Stronger solutions were associated with more post-sclerotherapy pigmentation.

• Low Pressure: Never force a syringe plunger. High-pressure injections are associated with more telangiectatic matting.

• Hold: Once the desired volume is delivered, keep the needle and syringe plunger still for 10 seconds. This ensures that the sclerosant makes contact with the endothelium for longer before it is "washed away" and inactivated by contact with blood.

3. Why the 10-Second Hold Matters

Sclerosants destroy the vessel by chemically disrupting the endothelial cell lining.

If the needle is withdrawn the instant the plunger stops, blood instantly rushes back into the vessel, washing away or diluting the active solution before adequate endothelial contact occurs. Holding the needle stationary for 10 seconds maintains local sclerosant concentration at the target site, enhancing the inflammatory cascade needed for vessel fibrosis and eventual reabsorption.

4. Visual Feedback: Vessel Blanching vs. Skin Blanching

During injection, keep your eyes locked on the needle tip and surrounding skin, not on the syringe barrel:

• Vessel Blanching (Target Endpoint): The vessel clears instantly as sclerosant displaces blood within the lumen. Maintain a slow flow and complete the 10-second hold.

• Skin Blanching / Bleb (Warning Sign): The surrounding skin turns pale, raises into a wheal (bleb), or the patient reports sharp pain. Stop immediately. Massage the area gently with a sterile swab to disperse any extravasated sclerosant.

5. Needle Positioning and Skin Traction

Reticular veins and telangiectasia are small and require accurate injection with the skin stabilised under tension

Skin Tension: Use the non-injecting hand to pull the skin taut. A flat skin surface prevents superficial vessels from rolling away from the bevel of the needle.

• Bevel Up, Shallow Angle: Bend a 30-gauge needle 10° to 15° with the bevel facing up. This allows the needle shaft to lie almost flat against the skin surface.

• Ergonomic Stability: Rest your injecting hand against the patient's leg for stability, avoiding unsupported hand movements.

6. A Framework for Clinical Precision

This 5-step protocol is not a substitute for formal clinical training. It is a systematic framework designed to keep volume, pressure, speed, concentration, and contact time aligned at every single injection point.

Watch the Full Clinical Demonstration

To see these injection angles, skin stretching techniques, and needle-holding maneuvers demonstrated in real time on clinical cases, watch the step-by-step masterclass tutorial below:

Watch: Microsclerotherapy Masterclass – Professional Injection Techniques & Aftercare

(Includes video footage of reticular vein cannulation, managing blebs, post-procedure compression advice, and topical treatments for post-sclerotherapy pigmentation)

Master Leg Spider Vein Treatment: Hands-On Training

Reading about injection technique is valuable, but mastering the tactile feedback, skin stretching, and needle angles requires direct, supervised clinical practice.

If you are a healthcare professional looking to safely and confidently introduce cosmetic vein treatments to your practice, join our comprehensive, hands-on training workshop at the EK clinic.

Explore the Hands-On Microsclerotherapy Training Course

• Direct Clinical Supervision: Practice needle placement, skin stabilisation, and real-time blanching assessment on live patients.

• Complication Prevention: Learn how to identify feeder reticular veins, avoid extravasation, and manage post-treatment pigmentation.

• Practice Integration: Gain the clinical protocols and operational confidence needed to deliver predictable results from day one.

This educational article is written and regularly reviewed by Dr Haroun Gajraj, a GMC-registered vein specialist who has treated thousands of patients with vein disease and has trained many doctors and nurses in microsclerotherapy, radiofrequency thermocoagulation, and related cosmetic vein procedures. Dr Gajraj is the founder and board member of the British Association of Sclerotherapists. You can view his current GMC registration and independent patient reviews on iWantGreatCare for further information about his clinical background.

Clinicians remain responsible for assessing each patient, obtaining informed consent, explaining risks and alternatives, and working within the scope of their professional registration and regulatory guidance.

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© VeinCare Academy | Dr. Haroun Gajraj | veincare.academy
This article is intended for qualified healthcare professionals. All clinical decisions should be based on individual patient assessment, primary medical literature and current professional guidelines.