Page 1517 · Tessari microfoam injection for telangiectasia, reticular veins & small varicosities
Successful sclerotherapy begins not with a needle but with a magnifying lamp and a diameter gauge. Spider veins (telangiectasia), feeder reticular veins, and small varicosities are pathophysiologically related but mechanically distinct targets — thin-walled capillary-adjacent vessels versus thicker-walled subdermal venules — and each requires a different sclerosant concentration to achieve full-thickness endothelial injury without either failing to close the vessel or overtreating it into a pigmented, ropey scar.
Spider veins arise from progressive dilation of the intradermal venous plexus, frequently fed by an underlying incompetent reticular vein or, less visibly, by a deeper saphenous reflux point. Chronic venous hypertension — from valve failure, hormonal influence (estrogen relaxes venous smooth muscle), prolonged standing, or genetic predisposition — transmits retrograde pressure down through reticular veins into the superficial dermal plexus, causing the vessels to dilate, become tortuous, and eventually visible through the skin as fine red (arteriolar-adjacent, papillary dermis) or blue (venular, deeper reticular dermis) threads.
Before treatment, the vessel network is mapped by inspection and transillumination, occasionally with handheld Doppler or duplex ultrasound if a larger feeding reticular vein or saphenous incompetence is suspected. Treating a spider vein in isolation without addressing its feeding reticular vein is a common cause of early recurrence — the feeder must be identified and treated first, working from largest-caliber vessel down to the finest telangiectasia ("proximal to distal, large to small").
A sclerosing agent works by chemically denaturing the vascular endothelium on contact — but the dose-response relationship is not linear across vessel calibers. A concentration sufficient to injure the thin single-cell-layer endothelium of a 0.2mm telangiectasia will, in a 4mm reticular vein, simply dilute in the larger blood volume and fail to reach the wall in an effective dose, while the same concentration used correctly in a capillary would be needlessly aggressive if used undiluted in a fine vessel — driving hyperpigmentation, matting, or skin necrosis if extravasated.
Clinicians therefore titrate polidocanol (or sodium tetradecyl sulfate) concentration to vessel size: the smallest effective concentration is always preferred, since efficacy plateaus above a threshold while complication risk continues to rise with concentration. This dose-titration principle — not "more is better" but "match the dose to the target" — is the single most important judgment call in a sclerotherapy session.
Rule of thumb used in most European and North American protocols: 0.25–0.5% polidocanol for spider veins under 1mm, 0.5–1% for larger telangiectasia and small reticular feeders, 1–2% for reticular veins 2–4mm, and up to 3% (or the equivalent STS concentration) for small varicosities 4–8mm. Concentrations above this range are reserved for larger truncal veins treated under ultrasound guidance.
Candidates are screened for deep vein thrombosis history, known hypercoagulable states, pregnancy, allergy to the sclerosant, and — importantly — patent foramen ovale (PFO) or migraine with aura, both of which raise the (still rare) risk of transient visual or neurological disturbance from foam bubbles reaching the systemic circulation. A brief history and, in higher-risk cases, a discussion of foam volume limits per session is standard practice before the first injection.
Liquid sclerosant alone is diluted and washed away by flowing blood within seconds of injection, limiting its contact time with the vessel wall. Converting the same drug into a microfoam — a dense suspension of gas microbubbles stabilized in a thin sclerosant liquid film — solves this problem directly: foam displaces blood rather than mixing with it, and dramatically increases the surface area of drug in contact with the endothelium.
Developed by Lorenzo Tessari in 2000, the technique requires only two Luer-lock syringes, a three-way stopcock, and room air (or, in some protocols, CO2/O2 blends to reduce bubble-related side effects):
1. One syringe is filled with 1 part liquid sclerosant (e.g. 1mL of 1% polidocanol); the second is filled with 4 parts room air (4mL). 2. Both syringes are connected to the two side ports of a three-way stopcock, with the open port closed or capped. 3. The plungers are pushed alternately, forcing the air-liquid mixture back and forth through the narrow stopcock channel roughly 15–20 times. 4. Turbulent shear at the stopcock orifice breaks the air into progressively finer microbubbles, which the surfactant properties of the sclerosant molecule (polidocanol is itself a surfactant) stabilize into a thin lamellar foam. 5. The result is a white, dense, low-viscosity microfoam with a bubble diameter of roughly 100–250 micrometers — small enough to pass through a fine needle, large enough to displace blood effectively.
The foam is mechanically unstable and coalesces back toward liquid within about two minutes, so it is prepared immediately before injection and used promptly.
Three mechanisms explain foam's clinical superiority over liquid sclerosant injection:
• Blood displacement: foam is far less dense than blood and displaces the blood column ahead of it rather than diluting into it, keeping the sclerosant concentration at the wall close to the prepared concentration rather than being cut by a factor of 5–10 as liquid sclerosant would be.
• Increased surface area: the microbubble interface dramatically increases the total surface area of drug-air interface in contact with the endothelium per milliliter injected, compared to a liquid column of the same volume.
• Visibility under ultrasound: the gas-liquid interface of foam is strongly echogenic, letting the treating clinician watch the foam fill the target vein in real time under duplex ultrasound — confirming correct intraluminal placement and observing the foam-to-spasm transition directly, something liquid sclerosant (echo-poor) cannot offer.
Because of this efficiency, foam sclerotherapy achieves closure with roughly 3–4 times less total sclerosant drug mass than the equivalent liquid technique, which also reduces total chemical exposure and complication risk per session.
Randomized trials comparing foam versus liquid polidocanol for reticular and small varicose veins consistently show higher closure rates with foam (roughly 75–85% versus 40–60% for liquid at comparable concentrations) at one-year follow-up, which is why foam has become the default technique for anything larger than the finest telangiectasia.
Injection technique differs by vessel depth and caliber. The finest surface telangiectasia are cannulated under direct vision with a 30-gauge needle at a shallow angle; reticular veins and small varicosities, which lie deeper and are harder to palpate reliably, are increasingly injected under real-time duplex ultrasound guidance to confirm the needle tip and the foam column both remain intraluminal throughout the injection.
For telangiectasia visible at the skin surface, the vessel is entered at a shallow 10–30 degree angle with the bevel up, watching for the characteristic "flash" of blood entering the hub or the visible blanching of foam displacing blood along the vessel as gentle, slow pressure is applied to the syringe plunger. Correct intraluminal placement is confirmed by watching the foam column advance along the vessel path under the skin — if instead a firm wheal balloons up at the injection site, the needle has extravasated and the injection is stopped immediately to avoid a chemical burn.
Small aliquots (as little as 0.1–0.2mL) are injected per site along the vessel's length, and gentle digital pressure just proximal to the injection point can help direct the foam distally along the target vessel and away from unwanted collateral spread.
Reticular veins and small varicosities lying below the visible dermal plexus are treated under real-time duplex ultrasound: the probe locates the vessel in cross-section, the needle is advanced under direct sonographic view until the tip is confirmed within the lumen, and the foam injection is watched in real time as an expanding echogenic (bright white) front filling and distending the vein.
Ultrasound guidance both increases first-pass injection accuracy for vessels too deep or small to reliably palpate and lets the operator watch for early signs of foam tracking into a deep vein connection, allowing the injection to be paused or redirected. It has become standard of care for anything beyond the most superficial telangiectasia in most vascular and dermatologic practices.
Total injected foam volume per treatment session is capped (commonly around 10mL of foam, i.e. roughly 2mL of liquid sclerosant precursor) to limit total drug exposure and reduce the small but real risk of bubble-related neurological symptoms; larger vein territories are treated over multiple staged sessions rather than in one sitting.
Polidocanol and sodium tetradecyl sulfate are both detergent-class sclerosants: amphiphilic surfactant molecules that insert into and disrupt the lipid bilayer of endothelial cell membranes on contact, denaturing surface proteins and causing cell death. The foam vehicle ensures this chemical injury is delivered along the full length and circumference of the vessel wall rather than washed away, triggering an acute inflammatory cascade that closes the lumen within minutes to hours of injection.
On contact, the sclerosant's hydrophobic tail inserts into the endothelial cell membrane while its hydrophilic head remains at the surface, progressively disrupting membrane integrity, denaturing surface adhesion proteins, and ultimately causing cell lysis and detachment. As the endothelial lining is stripped away, the underlying subendothelial collagen and basement membrane are exposed directly to flowing (or, ideally, foam-displaced) blood — a highly thrombogenic surface that immediately begins recruiting platelets.
Because foam maintains a higher effective sclerosant concentration at the wall for longer than liquid, it achieves more complete, full-thickness endothelial denudation circumferentially around the vessel — the key determinant of durable closure versus a vessel that merely thromboses temporarily and later recanalizes.
Almost immediately upon foam contact, the vessel's smooth muscle (in reticular veins and varicosities, which retain a muscular media, more than in capillary-adjacent telangiectasia) undergoes a reflex spasm — a protective vasoconstrictive response to chemical and mechanical irritation that narrows the lumen and further concentrates the sclerosant against a smaller wall surface area. Clinically, this is often visible as the treated vessel visibly blanching, narrowing, and sometimes disappearing from view within the treatment session itself, well before the slower biological injury cascade has completed.
Over the following minutes to hours, the combination of endothelial loss, exposed thrombogenic collagen, and local inflammatory mediator release (histamine, prostaglandins, cytokines from injured endothelial and mast cells) produces localized edema of the vessel wall and initiates a fibrin-platelet thrombus that occludes the residual lumen — converting the vessel from a patent, blood-filled channel into a solid, non-conducting cord.
Known complications at this stage stem directly from the injury mechanism: transient hyperpigmentation (hemosiderin deposition from extravasated red cells, seen in up to 10–30% of treated vessels, usually resolving over 6–12 months), telangiectatic matting (paradoxical growth of new fine vessels, thought to reflect an angiogenic response to the inflammatory injury, in roughly 1–5% of sessions), and rare transient visual disturbance or migraine-like symptoms from foam microbubbles reaching the cerebral circulation via a PFO, occurring in well under 1% of sessions but the reason PFO and migraine-with-aura history is screened beforehand.
Closing the vessel chemically is only half the treatment — how the vessel heals over the following weeks determines the cosmetic outcome. Graduated external compression, applied immediately after injection and maintained for days to weeks, apposes the injured vessel walls together, preventing the residual lumen from refilling with blood (recanalization) and minimizing the hemosiderin staining that causes brown post-sclerotherapy pigmentation.
Immediately after injection, the treated vessel is chemically injured but still mechanically patent — its walls have not yet been forced together, and left alone, blood can re-enter the injured lumen, dilute the residual thrombus, and allow at least partial recanalization, the single most common cause of an unsatisfying result or early recurrence. Compression solves this mechanically rather than chemically: an external bandage or graduated compression stocking (typically 20–30mmHg) presses the vessel walls into direct apposition, so that when the fibrin-platelet plug organizes it does so across a collapsed, empty lumen rather than a blood-filled one.
Compression also reduces the volume of blood trapped within the treated vessel at the time of injury, which directly reduces the amount of hemosiderin (iron-containing pigment from breakdown of trapped red blood cells) deposited in the surrounding dermis — the principal cause of the brownish post-treatment staining that is the most common cosmetic complaint after sclerotherapy.
Over the days following treatment, the occluding thrombus within the vessel is progressively organized and replaced by fibroblast-driven connective tissue, converting what was a blood-filled channel into a solid fibrous cord with no lumen — the biological end point of successful sclerotherapy. This fibrotic cord is gradually resorbed and remodeled by the body over subsequent weeks, and the vessel — no longer carrying blood, no longer visible as a red or blue line — fades progressively from view as it is broken down.
Fine telangiectasia typically show visible improvement within 3–6 weeks; larger reticular veins and small varicosities, carrying a greater volume of thrombus to organize, take longer — commonly 6 to 16 weeks — and larger or undertreated vessels not uncommonly require a second treatment session at that point to complete closure of any residually patent segment.
Patients are counseled that the treated vessel typically looks slightly worse (bruised, sometimes firm and tender to touch as a palpable cord) in the first 1–2 weeks before gradually fading — this transient appearance reflects the expected thrombosis-to-fibrosis process, not treatment failure, and premature concern at this stage is one of the most common sources of patient anxiety after an otherwise successful session.