- May 27
Microsclerotherapy: Technique, Aftercare and How to Reduce Complications
- Haroun Gajraj
- Microsclerotherapy
- 0 comments
By Dr. Haroun Gajraj | VeinCare Academy | May 2026
This review of Microsclerotherapy is written for healthcare professionals who perform microsclerotherapy for leg telangiectasias and reticular veins. It summarises current evidence and guideline-based practice relating to sclerosant pharmacology, concentration selection, injection technique, post-procedural care, compression therapy, postsclerotherapy pigmentation and the recognition and management of complications.
🎥 Prefer video? Watch the full 30-minute clinical guide on YouTube: "Microsclerotherapy Masterclass: Professional Injection Techniques & Aftercare for Leg Spider Veins" →
Contents
Introduction
Sclerosants used in microsclerotherapy
Recommended concentrations for C1 disease
Injection technique for telangiectasias
Injection technique for reticular veins
Technical errors and extravasation
Positioning, ergonomics and procedural workflow
Aftercare and compression therapy
Postsclerotherapy pigmentation
Serious complications and referral thresholds
Key clinical points
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References
1. Introduction
Microsclerotherapy is the treatment of telangiectasias and small reticular veins by intraluminal injection of a liquid sclerosant using a fine needle. It remains the standard intervention for C1 venous disease because it allows selective treatment of cosmetically or symptomatically troublesome superficial veins while using very small sclerosant volumes [1][10].
Its biological basis is endothelial injury. Detergent sclerosants disrupt the endothelial membrane, initiating platelet activation, local thrombosis, inflammation and subsequent fibrosis of the treated vessel [1][11]. Although the principle is straightforward, clinical outcomes are highly dependent upon concentration selection, accuracy of injection, treatment of feeding reticular veins where appropriate, and management of the post-treatment inflammatory and thrombotic response [1][9][10].
2. Sclerosants Used in Microsclerotherapy
The principal sclerosants used in contemporary microsclerotherapy are polidocanol (POL) and sodium tetradecyl sulfate (STS) [1][10][11]. Both are detergent sclerosants, but they differ in physicochemical properties and practical handling characteristics. Polidocanol is a non-ionic surfactant with mild local anaesthetic properties, while STS is an anionic surfactant [1][11].
Comparative experimental and clinical literature indicates that STS is more potent than polidocanol at equivalent percentage concentrations, which explains why lower concentrations are recommended for STS in guideline documents [1][10]. In practical terms, many clinicians regard STS as approximately two- to three-fold more active than polidocanol for a given nominal concentration, although exact equivalence is not fixed and depends on vessel size, technique and contact time [1][10].
Polidocanol is generally associated with less injection discomfort and may be more forgiving in minor extravasation, whereas STS may produce greater tissue irritation and, when injected outside the target vessel or into an arteriole, may carry a greater risk of necrosis [1][9][11]. Both agents should be regarded as prescription medicines that require immediate access to facilities and expertise for recognition and management of anaphylaxis [1][10][11].
3. Recommended Concentrations of Sclerosants for C1 Disease
The European guidelines for sclerotherapy in chronic venous disorders remain the principal consensus reference for concentration selection [10]. For telangiectasias, typical recommended liquid concentrations are STS 0.1–0.2% and polidocanol 0.25–0.5% [1][10]. For reticular veins, commonly recommended ranges are STS up to 0.5–0.75% and polidocanol 0.5–1.0% [1][10].
These ranges should not be interpreted as targets to be reached routinely. The central principle is to use the lowest concentration that produces reliable endothelial injury within the target vessel without excessive perivascular inflammation [1][9][10]. This is particularly important in cosmetic C1 disease, where technical success is judged not only by vessel clearance but also by the avoidance of pigmentation, matting, ulceration and patient dissatisfaction [8][9][10].
4. Injection Technique for Telangiectasias
Telangiectasias lie in the superficial dermis and therefore require very superficial needle placement [1][10]. One of the commonest early technical errors is to place the needle too deep, producing either failed injection or dermal extravasation [1][9].
Standard practice is to use a very fine needle, typically in the 27–32G range, with 30G commonly used for thread veins [1][10]. Many experienced practitioners favour a slight bend of the needle, permitting near-parallel alignment with the skin surface and facilitating intraluminal entry into superficial vessels [1]. Stretching the skin to stabilise the vessel and supporting the syringe to minimise unwanted hand movement are essential practical steps [1].
Aspiration is not feasible in most telangiectasias owing to their size [1][10]. Consequently, correct placement is inferred visually. Successful injection is indicated by blanching of the target vessel; in contrast, blanching of the surrounding skin, pain, or the appearance of a raised pale bleb indicates extravasation or dermal injection and should prompt immediate cessation [1][9][10]. Injection should be slow, low pressure and low volume, with treatment confined to a small field from each puncture site [1][10].
5. Injection Technique for Reticular Veins
Reticular veins are larger and lie slightly deeper, usually at the dermal-subdermal junction [1][10]. The needle angle is correspondingly steeper than for telangiectasias, generally in the shallow range of approximately 5–10 degrees [1][10].
In contrast to telangiectasias, gentle aspiration may be used in reticular veins to confirm intraluminal placement [1][10][11]. A small flash of dark venous blood at the hub supports correct positioning, although blood should not be drawn deeply into the syringe because it can dilute or partly inactivate the sclerosant [11].
Again, low volume and low pressure are important. The operator should stop if resistance develops, if the tissue rises, or if blanching affects the skin rather than the vessel [1][9]. Some practitioners briefly hold the needle in position or apply compression over the segment after injection to prolong endothelial contact before dilution and washout [1].
6. Technical Errors and Extravasation
Bleb formation is the classic sign of dermal extravasation and is one of the commonest technical problems in microsclerotherapy [1][9]. It presents as a raised, pale or white intradermal swelling and may be accompanied by stinging or pain. The appropriate response is immediate cessation of injection followed by dispersive massage [1][9][12].
The severity of consequences depends on sclerosant concentration, volume and speed of recognition. With very small volumes of low-concentration polidocanol, clinically important tissue loss is unlikely if extravasation is identified early [1][9]. However, recurrent blebs should be interpreted as a marker of technical imprecision and should prompt review of needle angle, skin tension, support of the syringe and plunger pressure.
A particularly important distinction is that between blanching of the vessel, which is the intended endpoint, and blanching of the skin, which may indicate perivascular injection, veno-arteriolar reflex vasospasm or inadvertent arterial entry [1][9][10]. This distinction should be emphasised during training because failure to recognise it early is a preventable cause of skin injury [9][12].
7. Positioning, Ergonomics and Procedural Workflow
The guideline literature pays relatively little attention to ergonomics, but microsclerotherapy is a fine-motor procedure in which operator comfort has direct consequences for precision [1]. The patient should be positioned supine, lateral or prone as required, with good lighting and, where useful, magnification or transillumination [1][10].
In practical terms, an adjustable couch, a wheeled stool and a mobile work surface improve control and reduce cumulative musculoskeletal strain. A systematic treatment sequence — for example anterior leg, then lateral and medial aspects, then posterior surfaces — reduces unnecessary repositioning and promotes consistent documentation. Although these measures are based mainly on expert practice rather than comparative trials, they are relevant because fatigue and poor posture plausibly degrade injection accuracy during longer sessions [1].
8. Aftercare and Compression Therapy
Immediately after microsclerotherapy, erythema, bruising, itching, local tenderness and visible trapped thrombus are all common and usually reflect the intended biological response to endothelial injury and thrombosis [1][9][11]. Patients should be counselled in advance that treated veins often look worse before they look better. This expectation management is clinically important because early visual deterioration is a frequent cause of avoidable concern despite technically successful treatment [8][9].
Ambulation after treatment is widely advised in order to maintain flow in the deep venous system and reduce venous stasis [1][10][11]. Adequate hydration and avoidance of prolonged immobility are also sensible precautionary measures, particularly in those with additional thrombotic risk factors [10][11].
Compression after liquid sclerotherapy for C1 disease remains debated. A randomised trial by Rabe et al. showed that 23–32 mmHg stockings worn for 3 weeks improved vessel disappearance after treatment of telangiectasias and reticular veins [3]. Earlier controlled work by Weiss et al. suggested that compression improves outcomes and that benefit may be related to duration [4]. By contrast, Kern et al. reported no discernible clinical benefit from one week of compression compared with no compression after C1 sclerotherapy [5].
These data explain the current guideline position: compression after liquid sclerotherapy of C1 veins carries a weak recommendation based on moderate-quality evidence [10]. A balanced interpretation is that compression may be beneficial in selected patients — particularly those with prior pigmentation, troublesome trapped thrombus or coexisting venous disease — but the evidence does not justify portraying it as universally essential for all cosmetic thread vein treatments [3][5][10].
9. Postsclerotherapy Pigmentation
Postsclerotherapy pigmentation is the commonest cosmetically significant adverse effect of microsclerotherapy [6][9]. In their histological study, Goldman, Kaplan and Duffy demonstrated that the predominant pigment is haemosiderin deposited following red cell extravasation and degradation rather than purely melanocytic post-inflammatory change [6]. They reported that pigmentation commonly follows treatment of small leg veins and that spontaneous clearance is frequent, although persistence may occur [6].
Later evidence has refined this understanding. A multicentre randomised trial by Scultetus et al. showed that early microthrombectomy reduced postsclerotherapy pigmentation and improved clinical outcomes, supporting the concept that retained intraluminal thrombus is an important source of iron deposition and staining [2]. This is clinically useful because it identifies one of the few modifiable post-procedural steps that can materially influence pigmentation risk.
The risk of pigmentation is increased by higher sclerosant concentrations, excessive local inflammatory injury, residual thrombus and poor technical control [6][8][9]. Prevention therefore begins with concentration discipline and precise injection, but should also include review at 1–2 weeks for evacuation of retained coagulum when appropriate [2][9].
With respect to treatment of persistent pigmentation, evidence remains limited and heterogeneous. For the melanin component of post-inflammatory hyperpigmentation, Kerscher et al. demonstrated that thiamidol (isobutylamido-thiazolyl-resorcinol), a selective tyrosinase inhibitor, significantly reduced post-inflammatory hyperpigmentation in a controlled clinical study [7]. Although this evidence derives from dermatological PIH rather than sclerotherapy-specific cohorts, the mechanistic rationale is relevant where melanin contributes to residual discoloration. For persistent established pigmentation, energy-based options such as IPL with radiofrequency have also been reported to improve post-sclerotherapy pigmentation in selected patients [8].
10. Serious Complications and Referral Thresholds
Serious complications of microsclerotherapy are uncommon, but they are the principal reason why training, concentration discipline and emergency preparedness matter [1][9][10]. Skin necrosis may follow significant extravasation, veno-arteriolar reflex vasospasm or inadvertent intra-arterial injection [8][9][12]. Warning signs include sudden disproportionate pain, immediate intense blanching of the skin, or ischaemic change extending beyond a minor superficial bleb [8][9][12].
Where these features occur, injection should cease immediately. Massage may help disperse sclerosant if extravasation has occurred, but suspected arterial injection should be managed as an emergency with urgent referral to hospital-level care [9][12].
Allergic reactions are rare but potentially life-threatening. Clinics performing sclerotherapy must therefore have protocols, resuscitation equipment and drugs for the immediate management of anaphylaxis [1][10][11]. Neurological disturbances, more often reported after foam than liquid sclerotherapy, are usually migraine-like rather than thromboembolic stroke, but they can be alarming to patients and require pre-procedure counselling [11]. Deep vein thrombosis and pulmonary embolism are rare in microsclerotherapy when low doses are used, but prudent case selection and encouragement of early mobilisation remain important [10][11][13].
11. Key Clinical Points
Microsclerotherapy remains the standard intervention for telangiectasias and small reticular veins [1][10].
The principal sclerosants are polidocanol and STS; STS is more potent and therefore used at lower concentrations [1][10].
For telangiectasias, typical liquid concentrations are STS 0.1–0.2% or polidocanol 0.25–0.5%; for reticular veins, STS up to 0.5–0.75% or polidocanol 0.5–1.0% [1][10].
The desired endpoint is blanching of the vessel; blanching of the skin is a warning sign to stop [1][9][10].
Compression after C1 liquid sclerotherapy has some supportive evidence but remains controversial and should be individualised [3][4][5][10].
Early microthrombectomy reduces postsclerotherapy pigmentation in small veins and should be considered where retained thrombus is present [2].
Persistent pigmentation is predominantly haemosiderin-related, though a post-inflammatory melanin component may coexist [6][7].
Serious complications are rare, but prompt recognition of necrosis, arterial injury and anaphylaxis is essential [9][10][12].
🎥 Watch the full 30-minute video covering all of these topics: "Microsclerotherapy Masterclass: Professional Injection Techniques & Aftercare for Leg Spider Veins" → [https://youtu.be/QapC2ivzIMw?si=8hs3Iq-xfBuu2Su4]
📖 This article is part of the VeinCare Academy clinical education series for healthcare professionals performing microsclerotherapy. Visit veincare.academy for more.
12. References
Tan M, Shaydakov E, Parsi K, Davies AH, on behalf of UIP. Microsclerotherapy. Phlebology. 2024;39(1):3–13. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC10993627/
Scultetus AH, Villavicencio JL, Kao TC, et al. Microthrombectomy reduces postsclerotherapy pigmentation: multicenter randomized trial. J Vasc Surg. 2003;38(5):896–903. Available at: https://pubmed.ncbi.nlm.nih.gov/14603191/
Rabe E, Schliephake D, Otto J, et al. Compression after sclerotherapy for telangiectasias and reticular leg veins: a randomized controlled study. J Vasc Surg. 2007;45(6):1212–1216. Available at: https://pubmed.ncbi.nlm.nih.gov/17467226/
Weiss RA, Weiss MA. Post-sclerotherapy compression: controlled comparative study of duration of compression and its effects on clinical outcome. Dermatol Surg. 1999;25(2):105–108. Available at: https://pubmed.ncbi.nlm.nih.gov/10037513/
Kern P, Ramelet AA, Wütschert R, et al. Clinical outcome of short-term compression after sclerotherapy for C1 varicose veins. Phlebology. 2021. Available at: https://pubmed.ncbi.nlm.nih.gov/32502730/
Goldman MP, Kaplan RP, Duffy DM. Postsclerotherapy hyperpigmentation: a histologic evaluation. J Dermatol Surg Oncol. 1987;13(5):547–550. Available at: https://pubmed.ncbi.nlm.nih.gov/3571692/
Kerscher M, Glaser K, Williams S, et al. Effective reduction of post-inflammatory hyperpigmentation with the tyrosinase inhibitor isobutylamido-thiazolyl-resorcinol (Thiamidol). Int J Cosmet Sci. 2021;43(3):292–301. Available at: https://pubmed.ncbi.nlm.nih.gov/33559186/
Goldman MP, Sadick NS, Weiss RA. Cutaneous necrosis, telangiectatic matting, and hyperpigmentation following sclerotherapy: etiology, prevention, and treatment. Dermatol Surg. 1995;21(1):19–29. Available at: https://pubmed.ncbi.nlm.nih.gov/7600016/
Guex JJ. Complications of sclerotherapy: an update. Dermatol Surg. 2010;36 Suppl 2:1056–1063. Available at: https://pubmed.ncbi.nlm.nih.gov/20891036/
Rabe E, Breu FX, Cavezzi A, et al. European guidelines for sclerotherapy in chronic venous disorders. Phlebology. 2014;29(6):338–354. Available at: https://pubmed.ncbi.nlm.nih.gov/23559590/
Shaydakov ME, Stansby G, Davies AH. Sclerotherapy. StatPearls. Updated 2024. Available at: https://www.ncbi.nlm.nih.gov/books/NBK599526/
ACE Group. Microsclerotherapy Complications. 2020. Available at: https://uk.acegroup.online/wp-content/uploads/2020/10/ACE-Group-Microsclerotherapy-Complications-v2.5.pdf
Guex JJ, Allaert FA, Gillet JL, Chleir F. Immediate and midterm complications of sclerotherapy: report of a prospective multicenter registry of 12,173 sclerotherapy sessions. Dermatol Surg. 2005;31(2):123–128. Available at: https://pubmed.ncbi.nlm.nih.gov/15762201/
About the author
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, shortwave diathermy 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. It is designed for healthcare professionals and is based on current clinical guidelines, peer‑reviewed research and day‑to‑day practice experience. The information here is general education only and is not a substitute for individual clinical judgement, local protocols or formal training. 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.