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Introduction
The methods of varicose vein ablation exhibit variability contingent upon the operators, while the timing, interval, and methodologies employed for post-operative follow-up also diverge based on the preferences of clinicians. Notably, a paucity of established research exists concerning follow-up practices. In the past, the Union Internationale de Phlébologie (UIP) consensus on ultrasound examination subsequent to varicose vein surgery was documented in 2011 (1). More recently, new guidelines for chronic venous disease (CVD) have been put forth by both the society for vascular surgery (SVS) and European society for vascular surgery (ESVS) (2,3). This review aims to consolidate and elucidate the specifics of postoperative follow-up procedures following varicose vein ablation.
Postoperative ultrasound follow-up period
Immediate postoperative observation is typically conducted within a week to a month following surgery, primarily aimed at verifying the success of the ablation procedure (1). During this immediate postoperative period, ultrasound is utilized to confirm the presence of an incompetent saphenous vein at the ablation site. Additionally, ultrasound serves to identify potential complications such as deep vein thrombosis (DVT) or endothermal heat-induced thrombosis (EHIT). In instances where the staged procedure is planned, not a one-step procedure, ultrasound may be employed to determine the subsequent stage of treatment. For instance, sclerotherapy may be administered concurrently with saphenous vein ablation or scheduled at a distinct time interval following saphenous vein ablation. In cases involving saphenous-preserving varicose vein surgeries, such as Cure Conservatrice et Hémodynamique de l’Insuffisance Veineuse en Ambulatoire (CHIVA) or Ambulatory Selective Varicose Vein Ablation under Local Anesthesia (ASVAL), it becomes imperative to verify the proper removal of the shunt post-surgery (4).
Late follow-up, typically conducted after 1 month, focuses on varicose vein recurrence and assesses the long-term outcomes of the surgery. The follow-up periods are categorized as short-term (less than 1 year), mid-term (2 to 3 years), and long-term (more than 5 years) (1). A long-term follow-up proves sufficient for evaluating varicose vein recurrence. Short-term recurrence often serves as a predictor for long-term recurrence, which tends to occur gradually beyond the first year. In a study tracking 130 lower extremities over 5 years, ultrasound revealed a swift occurrence of groin recurrence within the first year (59%), followed by a gradual increase to 82% at the 5-year mark (5). Another study involving endovenous laser ablation on 499 great saphenous veins in 423 patients demonstrated that most recurrences manifested before 9 months. Sustained complete saphenous vein occlusion at 1 year resulted in the majority of cases remaining obliterated for 3 to 5 years (6). Furthermore, a duplex study conducted 1 and 5 years after saphenofemoral junction (SFJ) ligation, analyzing 100 lower extremities, demonstrated a 1-year duplex ultrasound sensitivity of 80% and specificity of 91% in predicting 5-year recurrence (7).
Recurrent varices after surgery (REVAS)
To ascertain REVAS, follow-up ultrasound is employed to confirm the proper ligation of the sapheno-femoral junction (SFJ) or sapheno-popliteal junction (SPJ). Successful removal of the vein can be verified along the stripped saphenous vein track, and the ligation site of perforator veins is also confirmed. It is essential to check for recurrence at the primary reflux point. A systematic recording of recurrent varicose veins is facilitated through the use of a systematic sheet, where details such as topographical site, recurrence source, nature of the source, contribution factor, etc., can be documented using the REVAS sheet (8).
Escape points from the deep vein can be assessed using the Valsalva or compression maneuver. Reflux in tributary veins not connected with the deep vein can be examined with the compression maneuver. Neovascularization, defined as the “presence of multiple new, small tortuous veins in anatomic proximity to a previous venous intervention” in the vein-term consensus (1), may manifest as multiple new, small, tortuous veins at the site of a previous venous intervention. These veins may emerge de novo or result from the dilation of existing veins not initially visible on ultrasound. At times, reflux is observed to connect with the lymph node venous network, leading to reflux into the tributary veins (1). Another mechanism of neovascularization involves the absorption over time of stump thrombosis formed after stripping, causing the reappearance of reflux. In most cases, neovascularization after stripping exhibits a thin wall, a serpentine pattern, and lacks valves. It can be associated with non-saphenous lesions or pelvic veins (9).
Residual stump
The presence and characteristics of the residual stump following vein stripping can vary depending on the technique employed, specifically whether a flush or high ligation was utilized, and the associated relationship with tributary veins (10). In cases where the terminal valve is competent, the stump receives blood flow from tributary veins, maintaining normal blood flow to the deep veins, and the diameter of the stump may be reduced. However, when reflux is sustained due to an incompetent terminal valve, and reflux may persist through connections to tributary veins, the diameter of the stump may not decrease (11).
Saphenous track
Following saphenous vein stripping, the expectation is that veins should no longer be visible in the saphenous track. However, in instances of saphenous-sparing surgery, normal great saphenous vein (GSV) anatomy may be preserved, and reflux may persist, representing a natural course of the treatment (4).
Below-knee great saphenous vein (BK GSV)
The BK GSV serves to maintain venous outflow through the calf perforator vein. Residual reflux may persist in the BK GSV following treatment of the above-knee (AK) GSV. The management of residual reflux in the BK GSV is a topic of debate. When BK GSV reflux is not linked with tributary reflux, normal outflow can be maintained. Therefore, postoperative measurement of the diameter is beneficial to ensure that venous pressure has been adequately reduced (1). After AK GSV ablation, thrombosis may occur in the BK GSV, then disappear, and reverse flow may be seen again.
Sapheno-popliteal junction (SPJ) and small saphenous vein (SSV)
Given the diverse anatomical variations of the SPJ, confirming its anatomical location before surgery is crucial for subsequent postoperative follow-up (10). Reflux after surgery on the SSV typically manifests during calf compression (systolic) and release (diastolic). However, if it is associated with deep venous insufficiency or obstruction, reflux may also occur during calf compression (systolic). REVAS of the SSV may be linked to various factors, including the perforator vein, gastrocnemius vein, popliteal vein, or incompetence of proximal veins such as the pelvic vein, gluteal vein, and sciatic nerve veins (1).
Perforator vein
The pathological perforating veins in patients with varicose veins, classified under the CEAP clinical grade C2, are defined as perforator veins with an outward flow duration surpassing 500 ms and a diameter exceeding 3.5 mm on ultrasound (2). Blood flow in the perforating veins is naturally bidirectional, yet post-surgery, these veins typically exhibit predominantly antegrade flow and a reduced diameter (12).
Endovascular ablation (EVA)
Recently, EVA has become the primary method, largely replacing stripping surgery. In 2007, the American Venous Forum and the Society of Interventional Radiology recommended the regular monitoring of complications and treatment outcomes through reporting standards for EVA in the treatment of venous insufficiency (13).
Following EVA, the morphological and hemodynamic aspects are monitored at consistent intervals to assess clinical outcomes. In a study tracking 534 patients who underwent EVA, it was found that at the 3-year mark post-EVA, ultrasound recurrence was reported at 17.4%, and clinical recurrence was reported at 9.9%. Of these recurrences, 5.2% required additional treatment. The recurrence patterns were identified as recanalization in 11.6%, neovascularization in 42.6%, disease progression in 6.6%, perforator vein reflux in 2.8%, and new varicose vein formation was reported to be 36.4% (14).
The GSV stump following EVA typically measures within 1~3 cm. Although EHIT is rare, with an incidence of less than 1%, it is crucial to confirm EHIT through immediate ultrasound within at least 1 month after the procedure (1).
The SVS guidelines recommend performing ultrasound within 1 week after the procedure, as most cases of EHIT tend to develop within the first 72 hours. This timely ultrasound assessment is essential for early detection and appropriate management of potential complications (15). The ESVS guidelines concur with the SVS recommendation for ultrasound evaluation within 1 month after the procedure. This aligns with the recognition that conducting ultrasound examinations in this timeframe is crucial for detecting and managing potential complications, including EHIT (3). In general, most cases of EHIT tend to resolve within 4 to 6 weeks with appropriate treatment. Monitoring and managing EHIT during this timeframe are crucial to ensuring a favorable outcome for the patient (16).
Routine post procedural surveillance
The recent 2022 SVS guidelines suggest early ultrasound to exclude thrombosis, particularly in the post-procedural period. However, the guidelines advise against routine ultrasound surveillance in low or average-risk patients for thrombosis. This recommendation reflects a balance between the need for vigilant monitoring in specific cases and the avoidance of unnecessary procedures in patients at lower risk for thrombosis (2).
With a low incidence of DVT after EVA reported at 0.26%, the consideration of cost-effectiveness is relevant. Given the relatively low occurrence, routine surveillance may not be deemed cost-effective in this context. Decisions about surveillance strategies should be made based on a careful assessment of the risk-benefit ratio, considering the individual patient’s characteristics and potential for complications (17).
Indeed, the data from the survey involving 43,203 patients who underwent endovenous laser ablation highlights the relatively low incidence of DVT and pulmonary embolism (PE) post-procedure. With an incidence of 0.063% for DVT and 0.0067% for PE, the absolute numbers are small. However, the study suggests that while the overall incidence is low, the value of performing postoperative ultrasound for venous thromboembolism (VTE) may be limited (18). Nevertheless, the perioperative detection of VTEs by ultrasound has a potential benefit in initiating early anticoagulant therapy, which could contribute to an improved prognosis. This emphasizes the importance of considering both the incidence of complications and the potential impact of early detection and intervention in making decisions about postoperative surveillance.
Ultrasound after EVA
In the early stages post-EVA, the saphenous vein diameter gradually decreases, a process that takes 6 to 12 months to complete disappearance. As the diameter of the vein may diminish after EVA, Doppler ultrasound settings should be adjusted accordingly to detect low-velocity reflux, considering the possibility that the pressure inducing reflux may have diminished. In cases where a clear connection may not be immediately visible in short-term follow-up, there is ongoing debate about the necessity of long-term follow-up, but it is essential to monitor the progress of the residual stump (1). In later stages, a fibrous cord is formed and is observed as a hyper-echogenic tract on ultrasound. In cases where calf compression may not be as effective, testing for reflux using thigh compressions or the Valsalva maneuver may be beneficial. The adjustments in testing methods and the understanding of the gradual changes post-procedure underscore the complexity and individual variability in post-EVA assessments (19).
When total obliteration is achieved after saphenous vein EVA, ultrasound typically indicates total incompressibility and the absence of color flow. Upon complete vein obliteration, the outer diameter is measured. In cases of partial obliteration, it is recommended to record the internal diameter and measure the length of the obliteration segment (1).
To assess the efficacy of the obliteration, a Valsalva or compression maneuver is performed to check for retrograde flow lasting more than 0.5 seconds. Determining whether reflux is a result of the primary failure of EVA or re-canalization after initial successful obliteration, usually occurring within the first 6 months, requires serial ultrasound imaging. This sequential monitoring is crucial for accurately evaluating the long-term success and durability of the EVA procedure (19).
Foam sclerotherapy
In the case of foam sclerotherapy, recanalization (the reopening or restoration of the treated vein) is more prone to occur compared to some other treatment methods. Therefore, it is recommended to conduct a thorough evaluation of the therapeutic effect and to implement surveillance. Regular monitoring and follow-up assessments are crucial for tracking the long-term outcomes, identifying any signs of recanalization, and ensuring the effectiveness and success of the foam sclerotherapy procedure (20).
Conclusion
Immediate ultrasound within one month following varicose veins treatment is essential for assessing treatment outcomes, detecting potential recurrence, and identifying any complications. Short-term follow-up within the first year is particularly valuable, as it can provide insights that may predict longer-term outcomes. While long-term follow-up may be conducted as needed, it serves a dual purpose of not only monitoring treatment effectiveness and potential recurrences but also contributing to our understanding of the natural course of CVD, which is often associated with aging. This comprehensive approach to follow-up helps in both clinical management and advancing our knowledge of the disease over time.
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