Abstract
Objectives
While ambulatory phlebectomy and sclerotherapy are established treatments for varicose tributaries, they possess inherent limitations regarding invasiveness and technical consistency. This study aimed to evaluate the safety and clinical feasibility of tributary varicose vein ablation (VVA). The primary endpoint was the safety of VVA based on postoperative complications. Secondary endpoints included the target vessel occlusion rate and the reduction of subcutaneous induration.
Methods
This multicenter prospective study included 311 limbs (240 patients) with saphenous-type varicose veins treated with VVA across four institutions. A 1470 nm diode laser and radial fiber were used with a standardized energy density of 25 J/cm. Early complications were assessed at 1 week (n = 311). For the longitudinal analysis of induration and skin hyperpigmentation, 283 limbs that completed the 6-month follow-up were evaluated. Changes in categorical paired data were analyzed using McNemar’s test. Factors associated with persistent pigmentation were analyzed using the unpaired t-test.
Results
The target vessel occlusion rate was 99.6% at 6 months. At 1 week, no instances of skin burns or infections were recorded. One case (0.3%) of pulmonary embolism occurred but resolved with anticoagulation. Subcutaneous induration was observed in 81.6% of limbs at 1 month (mean diameter: 4.92 ± 2.34 mm) but significantly regressed by 6 months (26.1%, 2.50 ± 1.66 mm; p < .001). Persistent minor nerve injury was rare (0.7% at 6 months). The incidence of subcutaneous induration significantly decreased from 81.6% at 1 month to 26.1% at 6 months (p < .001). Skin hyperpigmentation remained at 16.3% at 6 months (p = .451).
Conclusions
VVA using a radial fiber is a safe and effective alternative that overcomes the limitations of traditional phlebectomy and sclerotherapy. By ensuring thermal delivery exclusively within the target vessels, the procedure provides a reproducible and standardized approach for the comprehensive management of varicose veins.
Keywords
Introduction
In the treatment of lower extremity varicose veins, performing concomitant treatment of tributaries in addition to the incompetent saphenous trunk is effective in achieving early symptomatic improvement and reducing the rate of re-intervention.1,2 While ambulatory phlebectomy and sclerotherapy are commonly employed, they present challenges such as surgical invasiveness or technical difficulty in cases with significant tissue adhesions.
To address these limitations, several investigators previously explored endovenous laser ablation specifically for tributary veins (varicose vein ablation; VVA).3–5 However, these early attempts did not lead to the widespread adoption of VVA as a standard procedure. This lack of continuity was largely due to unsatisfactory outcomes, including concerns regarding unavoidable thermal injury—such as skin burns and nerve injury—associated with older laser systems and suboptimal energy delivery.
In recent years, the introduction of radial fibers has enabled more uniform and controlled thermal delivery. 6 Utilizing these technological advancements, Utoh et al. reported favorable outcomes in their study where symptomatic tributaries were treated with endovenous laser ablation using a radial fiber. 7 Despite these promising results, high-quality evidence regarding the safety and reproducibility of VVA in a multicenter clinical setting remains scarce. Establishing a standardized protocol is essential for the widespread adoption of this technique. Therefore, we conducted this multicenter prospective study to re-evaluate the safety and clinical feasibility of VVA using a standardized protocol across multiple specialized facilities.
Methods
Study population and design
The primary endpoint of this study was safety, defined as the incidence of major and minor complications within 6 months postoperatively. Secondary endpoints included the clinical feasibility of VVA, assessed by the target vessel occlusion rate and the regression of subcutaneous induration and hyperpigmentation at 1 and 6 months.
This multicenter prospective study was conducted across four specialized institutions: Kumamoto Vascular Clinic, Waki Day Surgery Clinic, Yamamoto Vein Clinic, and Suzuki Medical Clinic. We enrolled patients with saphenous-type varicose veins who underwent treatment between December 15, 2024, and April 15, 2025.
Indications for treatment followed the established guidelines for endovenous ablation 8 ; specifically, patients with primary varicose veins demonstrating reflux of ≥ 0.5 s in the saphenous veins associated with symptoms of venous stasis. The study specifically focused on cases where VVA was performed. For inclusion in this study, the performance of VVA on at least one tributary was required; the concomitant use of other treatment modalities (e.g., ambulatory phlebectomy or sclerotherapy) for other segments or tributaries in the same limb was permitted.
Follow-up assessments for adverse events were scheduled at 1 week, 1 month, and 6 months postoperatively. Following the pre-defined criteria, patients who were lost to follow-up at 1 week or 1 month were excluded from the final analysis to ensure the robustness of the short-term safety evaluation.
Data collection and outcome measures
In order to ensure consistency across multiple centers, a single, specific assessment site for VVA was prospectively designated for each treated limb. Only adverse events judged to be directly related to this pre-determined VVA site were included in the primary safety analysis. Assessment items and their diagnostic criteria were categorized by follow-up timing as follows:
At 1 week: • Skin burns: Defined as full-thickness skin necrosis at the ablation site. • Pain: Defined as any discomfort severe enough to require the consideration of analgesic prescription. • Ecchymosis: Defined as subcutaneous hemorrhage exceeding 1/4 of the treated area around the assessment site. • Superficial thrombophlebitis: Defined as localized inflammatory clinical signs over a thrombosed treated vein requiring medical intervention. • Infection/Cellulitis: Defined as spreading skin and/or fat infection requiring antibiotic treatment. • Proximal deep vein thrombosis or pulmonary embolism: Confirmed by ultrasonography or contrast-enhanced computed tomography.
At 1 and 6 months: • Target vessel patency: Defined as the presence of blood flow or a non-occluded lumen exceeding 1/4 of the original vessel diameter at the assessment site. • Nerve injury: Defined as any neurological abnormality, including persistent hypoesthesia, paresthesia, or neuralgia along the treated segment. • Subcutaneous induration: Defined as distinctly palpable induration at the assessment site. The maximum diameter of the treated vein measured by ultrasound was recorded as the induration size. • Hyperpigmentation: Defined as linear skin discoloration remaining along the course of the ablated vein.
Procedures and laser settings
The treatment consisted of endvenous laser ablation for saphenous veins and concomitant treatment for tributary veins. The laser system comprises a 1470 nm diode laser system (LEONARDO 1470; Biolitec, Bonn, Germany) with a slim radial fiber (ELVeS Radial 2ring slim fiber, diameter 1.27 mm; Biolitec) This system was applied to both the saphenous trunks and tributaries. Ablation parameters for the saphenous veins and the administration of perioperative prophylactic anticoagulation were left to the discretion of each institution for each case. In VVA, the target vein was punctured using a 16-gauge indwelling needle. The laser fiber was inserted through the cannula to the desired position. Following the administration of tumescent local anesthesia (TLA) around the vessel, ablation was performed at a power of 5W and a pullback speed of 0.2 cm/sec, equivalent to a linear endovenous energy density (LEED) of 25 J/cm.
Statistical analysis
Statistical analyses were performed using EZR (Saitama Medical Center, Jichi Medical University, Saitama, Japan), which is a graphical user interface for R. Regarding early postoperative complications, analysis was performed on patients who completed the 1-week follow-up. For the longitudinal evaluation of late complications such as subcutaneous induration and skin hyperpigmentation, only the patients who completed the full 6-month follow-up were included. To ensure the reliability of paired comparisons, cases with missing data at the 6-month mark were excluded.
To optimize the clinical assessment, the presence or absence of subcutaneous induration and skin hyperpigmentation was dichotomized for analysis. The incidence of these complications at each time point was compared using McNemar’s test. Furthermore, the change in the physical size of the induration over time was evaluated as a continuous variable and analyzed using the paired t-test. P-values less than 0.05 were considered statistically significant. Furthermore, the associations between persistent pigmentation and clinical factors (preoperative vein diameter and postoperative induration size) were analyzed using the unpaired t-test.
Results
Patient characteristics and flow
A total of 502 limbs in 421 patients underwent treatment across the four facilities during the study period. The flow of limbs through the study is summarized in Figure 1. Among these, endovenous laser ablation (EVLA) for the saphenous trunks was performed in 405 limbs, 312 of which received concomitant VVA. After excluding one limb due to loss to follow-up at 1 week, early postoperative complications were evaluated in the remaining 311 limbs (from 275 patients). To allow for longitudinal assessment of postoperative complications between 1 and 6 months using McNemar’s test, the final comparative analysis was restricted to 283 limbs (from 250 patients) for which complete follow-up data were available at both time points. The follow-up rate for this cohort at 6 months was 91.0% (283/311 eligible limbs). CONSORT diagram for trail
Baseline patient and limb characteristics (n = 311).
Some limbs involved treatment of multiple saphenous veins. CEAP, Clinical-Etiology-Anatomy-Pathophysiology.
Ablation settings for the saphenous veins varied by institution and individual case. In principle, the parameters were set between 6.5 and 8 W and 40–100 J/cm; however, for segments in the distal lower leg which are close to nerves, lower settings of 5–6.5 W and 20–50 J/cm were employed. The mean total treatment time for both saphenous and tributary veins was 26.66 ± 10.73 min per limb. No patients received perioperative anticoagulation. Duplex ultrasound at 1 month postoperatively confirmed complete occlusion of the saphenous vein from the tributary branching point to the deep venous junction in all cases.
The mean diameter of the target tributary veins at the pre-designated assessment sites was 6.10 +/− 2.35 mm, and the mean number of punctures for VVA was 3.34 +/− 2.52 per limb. In addition to VVA, concomitant procedures were performed as needed, including ambulatory phlebectomy in 42 limbs (13.5%) and sclerotherapy in 36 limbs (11.6%).
Safety and adverse events at 1 week
Early postoperative complications at 1 Week (n = 311).
All events were assessed specifically at the pre-designated Varicose Vein Ablation (VVA) site; DVT, deep vein thrombosis; PE, pulmonary embolism.
One case (0.3%) of pulmonary embolism occurred in a 67-year-old female who had undergone bilateral GSV-EVLA combined with VVA. She had no history of venous thromboembolism (VTE) or predisposing thrombophilic conditions; therefore, perioperative prophylactic anticoagulation was not administered. At the 1-week follow-up visit, while duplex ultrasound detected neither deep vein thrombosis (DVT) nor endovenous heat-induced thrombosis (EHIT), the patient reported mild dyspnea. Subsequent contrast-enhanced CT confirmed a pulmonary embolism. The patient was successfully treated with anticoagulation therapy and recovered without sequelae.
Clinical outcomes and long-term follow-up (1 and 6 months)
Clinical outcomes and adverse events (1 and 6 Months) (n = 283).
*, p-values were calculated using the paired t-test; **, p-values were calculated using McNemar’s test.
The progression of physical findings was as follows: • Subcutaneous induration: At 1 month, subcutaneous induration was present in 231 limbs (81.6%), with a mean diameter of 4.92 +/− 2.34 mm. By 6 months, the prevalence significantly decreased to 26.1% (74/283 limbs), and the mean diameter significantly reduced to 2.50 +/− 1.66 mm (p < .001 via paired t-test). • Hyperpigmentation: Linear discoloration along the treated vein was observed in 52 limbs (18.4%) at 1 month and 46 limbs (16.3%) at 6 months. • Nerve Injury: Minor neurological abnormalities (hypoesthesia or localized paresthesia) were noted in 8 limbs (2.8%) at 1 month. This number decreased to 2 limbs (0.7%) at 6 months, both of which were mild and did not require permanent clinical intervention.
Factors associated with persistent pigmentation
Comparison of clinical factors between resolved and persistent hyperpigmentation at 6 months.
Discussion
Historical context and technological evolution
Ambulatory phlebectomy has long been considered the gold standard for tributary treatment. However, its invasive nature and technical challenges in cases with significant tissue adhesions have led to the exploration of endovenous alternatives. Early attempts at Varicose Vein Ablation (VVA) established the feasibility of the procedure but failed to gain widespread clinical acceptance.3–5 This lack of continuity was largely due to the use of older-generation laser systems, which were associated with an unavoidable risk of thermal injury to surrounding tissues—such as skin burns and nerve injury—regardless of the surgeon’s skill or experience.
Our study demonstrates that modern VVA, utilizing a 1470 nm diode laser and radial fiber, successfully overcomes these historical limitations. By adopting a standardized, low-energy protocol (5W, 25 J/cm) and ensuring precise intravascular navigation, we achieved a high occlusion rate (99.6% at 1 month) without a single instance of skin burns. Our technique ensured that thermal energy was delivered exclusively within the target convoluted vessels, thereby avoiding unintentional injury to surrounding extra-vascular tissues. This contrast with previous literature underscores that the perceived “failure” of early VVA was due to the technological constraints of that era. With the current widespread availability of radial fibers, the focus of VVA has shifted from basic feasibility to the establishment of safe, reproducible, and standardized surgical protocols.
Subcutaneous induration
One of the most significant findings in this study is the clinical progression of subcutaneous induration. While indurations were observed in 81.6% of limbs at 1 month, their incidence and size significantly decreased by the 6-month follow-up (p < .001). In saphenous EVLA, these indurations are typically sequestered within the deep fascia and remain imperceptible to the patient. In VVA, however, their superficial location makes them easily palpable, which may cause patient anxiety. Our data provide a clear clinical timeline: these indurations represent a transient inflammatory phase of venous fibrosis rather than a permanent complication. Therefore, we emphasize that thorough preoperative counseling regarding the temporary nature of these indurations is essential for patient satisfaction.
Persistent hyperpigmentation
Regarding the mechanism of skin hyperpigmentation, previous studies on sclerotherapy have suggested that the primary cause is not inflammatory melanin deposition, but rather the extravasation of hemoglobin from the treated vessel. 9 Our findings strongly support this hypothesis; the significant associations between persistent hyperpigmentation and both larger preoperative vein diameter and greater postoperative induration size suggest that a higher volume of intravascular thrombus—acting as a reservoir of hemoglobin—leads to more pronounced pigmentary changes. These results indicate that the degradation of extravasated hemoglobin into hemosiderin is the predominant factor in the development and persistence of pigmentation following endovenous ablation. Unlike inflammatory post-hyperpigmentation caused by melanin, which is primarily cleared through epidermal turnover and relatively rapid macrophage phagocytosis, hemosiderin exists as insoluble iron-protein complexes within the dermis. 10 The metabolic processing and clearance of these iron deposits by macrophages are significantly slower, often spanning several months to years. This biological characteristic likely explains why no significant reduction in the incidence of pigmentation was observed within the 6-month observation period of this study.
Safety and rare complications
Regarding serious complications, we recorded one case (0.3%) of pulmonary embolism in a 67-year-old female who had undergone bilateral GSV-EVLA combined with VVA. Although the concomitant truncal treatment makes it difficult to isolate VVA as the sole trigger, this event highlights the inherent risks of any endovenous intervention. Nevertheless, the overall complication profile in our 311-limb cohort was comparable to reported rates for ambulatory phlebectomy. 11 The high safety profile, including the complete absence of skin burns and a very low rate of persistent nerve injury (0.7% at 6 months), supports the clinical feasibility of this procedure as a standardized surgical option for comprehensive venous management.
Clinical significance of concomitant treatment for tributary veins
It is well-documented that some tributary varicose veins may regress spontaneously following the successful ablation of the saphenous trunk. However, the extent and timing of such regression are often unpredictable, and many patients desire more immediate symptomatic relief or cosmetic improvement. This study focuses specifically on the safety and efficacy of Varicose Vein Ablation (VVA) in cases where proactive intervention for tributaries was deemed necessary. While a comparative study between VVA and conservative observation of tributaries remains a subject for future research, our data demonstrate that VVA can be performed safely as a concomitant or secondary procedure.
Study limitations
While this prospective study provides robust data on the clinical feasibility of VVA, there are some limitations. First, the follow-up period was limited to 6 months, which may not be sufficient to evaluate long-term recurrence rates. Second, the study did not include a direct randomized comparison with ambulatory phlebectomy. However, the multi-institutional nature of this study and the standardized protocol strengthen the generalizability of our findings.
Conclusion
This multicenter prospective study demonstrates that varicose vein ablation (VVA) using a radial fiber and a standardized low-energy protocol (25 J/cm) is a safe and effective treatment for tributary veins. Our technique ensured that thermal energy was delivered exclusively within the target convoluted vessels, thereby avoiding unintentional injury to surrounding extra-vascular tissues. This precision allowed for high occlusion rates without instances of skin burns or permanent nerve injury. Although subcutaneous induration occurs frequently in the early postoperative period, our data confirm that it significantly regresses within 6 months. Therefore, VVA represents a minimally invasive, reproducible, and standardized alternative to ambulatory phlebectomy, offering a precise and reliable surgical option for the comprehensive management of lower extremity varicose veins.
Footnotes
Ethical considerations
The study protocol was reviewed and approved by the Institutional Review Board of Kumamoto Vascular Clinic (Approval No. 024-02). All procedures were performed in accordance with the ethical standards of the 1964 Declaration of Helsinki and its later amendments.
Consent to participate
Written informed consent was obtained from all individual participants included in the study.
Consent for publication
The authors give their consent for the publication of identifiable details, which can include photographs and/or videos and/or case history and/or details within the text (“Material”) to be published in the above Journal and Article.
Author contributions
TY, OS and JU conceived and designed the study. TY, JU, OS, SS and NW performed the surgical procedures and data collection. TY analyzed the data. TY wrote the initial draft of the manuscript. All authors reviewed and approved the final version of the manuscript.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Declaration of conflicting interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Data Availability Statement
The datasets generated and analyzed during the current study are not publicly available due to privacy and ethical restrictions related to patient data. However, the data are available from the corresponding author upon reasonable request and with permission from the institutional review board.
Guarantor
TY. Takashi Yamamoto takes full responsibility for the integrity of the work as a whole, from inception to published article.