Chronic venous disease (CVD) can cause a range of symptoms, including leg pain, swelling, and skin changes, and can lead to more serious complications such as venous ulcers and deep vein thrombosis. Superficial vein reflux is the most prevalent abnormality in patients with CVD (1). There are various patterns of reflux involving saphenous and nonsaphenous veins (NSV). While saphenous vein reflux is the most prevalent and well-studied condition, the latter is often misdiagnosed or not recognized altogether leading to incomplete or erroneous treatment. NSV refer to the veins that are not part of the great saphenous vein or small saphenous vein but occur in any of the other veins in the leg, including deep non axial veins, perforator veins and tributaries.

The prevalence of non-saphenous vein reflux is not well-established, but emerging evidence suggests that it may be more common than previously thought. Studies have shown that non-saphenous vein reflux may be present in up to 9∼35% of patients with chronic venous insufficiency, indicating that it is a significant and under-recognized problem (2-5).

Current treatments for venous reflux typically focus on the great saphenous vein and small saphenous vein, with minimally invasive procedures such as thermal and non-thermal ablation techniques. However, these treatments may not be efficient for NSV reflux, which may require different interventions (5,6). Differentiating between saphenous and NSV reflux is crucial for accurate diagnosis and appropriate treatment. Misdiagnosis or inappropriate treatment can lead to suboptimal outcomes.

This paper aims to present the different patterns of non-saphenous vein reflux and clinical presentation, the diagnostic methods and treatment options to improve NSV recognition and optimize clinical outcomes.

NSV reflux is found in different part of the lower limb such as the posterolateral thigh, vulvar, gluteal, sciatic nerve, sartorial/subsartorial area, popliteal fossa, and knee veins (4). Accurate diagnosis and appropriate treatment are crucial for optimal outcomes in patients with NSV reflux. The appearance and prevalence of each type of NSV can vary, and a thorough physical examination and imaging studies are necessary to make an accurate diagnosis.

The prevalence of NSV reflux is reported to be about 10% in untreated patients and 20% in those with recurrent varicose veins (4,7,8). It is most often found in females who had at least 2 pregnancies (4). Nonsaphenous vein reflux often co-exists with pelvic venous disease (9). When pelvic reflux decompressed through pelvic escape points or uncompensated obstruction of the left renal vein or common iliac vein affects the lower extremities, it may result in NSV reflux of the lower extremities. Therefore, in female patients with NSV reflux should undergo complete history taking on pelvic symptoms. When the source of NSV reflux is suspected to originate from the pelvis, evaluation of the abdominal and pelvic veins with imaging modalities including duplex ultrasound (DU), intravascular ultrasound (IVUS) computed tomography venography (CTV), magnetic resonance venography (MRV) or conventional venography can be performed. The current gold standard for diagnosis of pelvic venous disorder remains venography, but DU has been widely accepted as the first-line test to identify pelvic venous reflux and/or obstruction with high sensitivity (10,11). To evaluate and exclude the source of reflux, the following structures need to be included: the inferior vena cava, iliac veins, renal veins, gonadal veins, and the peri- and trans-uterine plexus.

1) Clinical presentation

The clinical presentation of patients with NSV reflux is similar to those with saphenous veins signs and symptoms with a few exceptions due to location of the NSV. Most patterns present with CEAP C1 to C3 but 10% have skin damage C4∼C6. When these veins are associated with pelvic reflux or with saphenous veins or both, signs and symptoms are more intense. Only few papers have addressed this issue and therefore more work is needed. Examples of different presentations are shown in Fig. 1.

Figure 1. Clinical presentation of varicosities resulting from the non-saphenous vein in the lower extremity. (A) Vulvar vein: the varicose veins course medially to the saphenofemoral junction and connect with veins of the pelvic floor. In this particular example, the connections are most often with deep internal pudendal veins and/or the obturator vein. (B) Gluteal vein: the varicosities usually run posteriorly, as seen in this figure, and pierce the gluteal fascia to unite with gluteal veins. (C) Sciatic nerve veins: this vein runs posteriorly and extends in a different direction. The varicose vein typically enters the fascia a few centimeters above the popliteal skin crease and connects with veins around the sciatic nerve. These veins can be localized in the thigh or often, in females with previous pregnancies, can extend to the pelvis to unite with the inferior gluteal veins. (D) Posterolateral thigh perforator vein: this is the longest perforator of the lower extremity. The varicosities run from the lateral or posterior-lateral calf to the thigh and enter the fascia lata, usually at the middle of the thigh. (E) Sartorial or subsartorial vein: this vein usually enters the fascia at the upper part of the knee. (F) Popliteal fossa vein: the varicosities are in the posterior posteromedial or posterolateral calf and penetrate the fascia at the popliteal skin crease or higher, uniting with the popliteal vein lateral and superior to the saphenopopliteal junction. (G) Atypical perforating vein: atypical perforators are found in the different area such as the lower thigh, lateral knee, calf and sometimes perforators through the bone as in this example.

2) Duplex examination

The examination starts with the patient in the standing position. The limbs are inspected by rotating in all the different planes to locate the veins. This facilitates ultrasound assessment as the veins of interest are localized. Imaging is typically performed with linear array transducers, however, in few patients a convex transducer may be used to track the connection of the NSV with the deep system. The methods of examining deep, superficial, tributary, and perforator veins have been previously described. The test is performed with patient in the standing position. If the patient cannot stand for the whole test, only the areas of groin are examined in the standing position and the rest of the test is performed with the patient sitting. For the NSV that are found in the pelvic floor, gluteal area, and posterior thigh, the ultrasound is performed with the patient standing. Topography and characteristics of different NSVs are described in detail below. Reflux in the NSV is defined as a retrograde flow >0.5 seconds.

3) Vulvar veins

Vulvar varicosities are dilated veins in the labia majora and labia minora. It affects up to 22%∼34% of women with varicose veins of the pelvis, 18∼22% of pregnant women, and up to 50% of women with a history of multiple pregnancies (12). In pregnant women, dilated veins typically disappear in the postpartum period for most patients, while they persist in only 20% of patients (13). Women with vulvar varicose veins may or may not have pelvic symptoms and typical vulvar symptoms include heaviness, aching, throbbing, and itching (14). Peri- or trans-uterine plexus or left ovarian vein reflux is the common source of reflux, and reflux through the internal pudendal vein from iliac vein occlusion can be another potential source of reflux. These veins usually run medial to sapheno-femoral junction having a medial or posteromedial course in the thigh. They can be independent or connect with great saphenous vein. Veins in vulvar region are connected with deep internal pudendal vein (imaged through P point) and the obturator vein (imaged through O point). One other vein in the groin area is the inguinal (image through I point) that connects with the anterior saphenous vein or the GSV but does not connect with NSV in the limb. Fig. 1A demonstrates clinical presentation related to the vulvar vein reflux. Ultrasound image of varicosities caused by vulvar vein reflux is depicted in Fig. 2.

Figure 2. Vulvar veins connecting with the deep internal pudendal vein higher in the pelvis. Multiple varicosities extend from the vulvar veins to the medial thigh.

4) Gluteal veins

Gluteal vein reflux is a less common type of non-saphenous vein reflux, the veins may be visible at the posterior thigh (4). Though rare, it may cause sciatic nerve compression symptoms (15). When this type of reflux is suspected, ultrasonographic evaluation of the dilated veins followed to the gluteal area is required to demonstrate connections with the pelvic vein and reflux deeper to the gluteal fascia (image through G point) (10). The gluteal vein may rarely connect with thigh extension of small saphenous vein. Fig. 1B demonstrates clinical presentation of varicosities related to the gluteal vein reflux.

5) Sciatic and tibial nerve veins

Sciatic nerve vein reflux affects the veins within and around the sciatic nerve. Sciatic nerve vein is the most common location of the refluxing vein associated with nerves (16). Varicosities associated with tibial nerve are less common when found are most often seen in continuity with the sciatic nerve veins. Varicosities associated with peroneal vein is not described. The symptoms and the superficial topography were similar for both nerves as well as the relief of the symptoms after treatment. Sciatic or tibial nerve vein reflux can cause pain, swelling, and discomfort in the affected leg by nerve irrigation or from the superficial varicosities. Normal nerve veins are not easily identified by DU due to their small size, and enlargement of these veins is often associated with the presence of reflux in superficial veins. Veins within the sciatic nerve do not have valves. Therefore, when the perinerve veins become incompetent blood from the nerve vein drain in the refluxing varicosities. In most patients sciatic nerve veins are found in continuity with refluxing inferior gluteal veins. Fig. 1C demonstrates clinical presentation of varicosities related to the sciatic vein reflux. Ultrasound image of varicosities caused by sciatic nerve veins reflux is depicted in Fig. 3.

Figure 3. Sciatic nerve veins. Multiple varicosities with reflux inside and outside the sciatic nerve.

6) Posterolateral thigh perforator vein

Posterolateral thigh vein reflux is found in approximately 1% of patients with chronic venous disease (17,18). Due to regression during embryonic life, the veins on the posterior and lateral aspects of the thigh are far less prominent than the saphenous veins (17). When varicosities are found in this area, they usually arise from the posterolateral thigh perforator vein, and connect most often with deep femoral vein, muscular veins of the thigh, and rarely with the femoral vein. Therefore, during ultrasound evaluation, these varicosities should be traced to the perforator, which is usually the source of the reflux. This perforator is the longest one in the lower extremity. The varicosities in this area have always reflux but in some patients the perforator vein is normal. Fig. 1D demonstrates clinical presentation of varicosities related to the posterolateral thigh perforator vein reflux. Ultrasound image of varicosities caused by posterolateral perforator vein reflux is depicted in Fig. 4.

Figure 4. Posterolateral perforator vein of the thigh piercing the fascia at the middle of the thigh and connect with a tributary of the deep femoral vein.

7) Sartorial and subsartorial veins

Sartorial or subsartorial muscle vein reflux is a rare condition that has been reported in case reports (19). Along with atypical varicose veins, tortuous refluxing vein is observed in the thigh, coursing within the sartorius muscle. Due to its unusual course, it should be differentiated from extratruncular venous malformations. Perforating vein or GSV reflux can be observed when the tributaries of these veins receive drainage from the sartorial vein (19). Fig. 1E demonstrates clinical presentation of varicosities related to the sartorial or subsartorial vein reflux. Ultrasound image of varicosities caused by sartorial and subsartorial vein reflux is depicted in Fig. 5.

Figure 5. Sartorial and subsartorial varicose veins. Multiple veins in the sartorius muscle and subsartorial plexus connected with varicosities in the medial knee extending down to the calf.

8) Popliteal fossa vein

Reflux of the vein of the popliteal fossa affects up to about 4% of patients with chronic venous disease (20). It is found superior and lateral to sapheno-popliteal junction and most often extents in the lateral or posterolateral calf. It may appear with the enlarged tributaries of the popliteal fossa or saphenous tributaries when it is connected to the saphenous system. Because of its location this vein can be confused with the small saphenous vein. Fig. 1F demonstrates clinical presentation of varicosities related to the popliteal fossa vein reflux. Ultrasound image of varicosities caused by popliteal fossa vein reflux is depicted in Fig. 6.

Figure 6. Vein of the popliteal fossa. Very tortuous vein piercing the fascia above the popliteal skin crease and diving down to connect with the popliteal vein superior and lateral to SPJ.

9) Atypical varices connecting with uncommon perforator veins

Such veins are found in various locations in the thigh, knee and calf connecting to perforator veins that drain into muscular and bone veins. For example knee perforator vein reflux can be detected with enlargement of the knee tributaries, with prevalence of about 3% of NSV reflux (4). Varicosities in this area typically run laterally or posterolaterally in the knee and calf. As in the case of posterolateral thigh vein in some patients the knee perforator associated with varicosity in this area do not have reflux. Fig. 1G demonstrates clinical presentation of varicosities related to the knee perforator vein reflux. The knee perforators in the lateral aspect may join bone veins. Bone veins are also seen in the tibial area connecting to local varicosities. Ultrasound image of varicosities caused by lateral calf perforator vein reflux is depicted in Fig. 7.

Figure 7. Lateral calf perforator connecting to dilated muscular veins. Varicosities extend down the lateral and posterolateral calf.

10) Treatment

The treatment approach for non-saphenous vein reflux is individualized to each patient and depends on the severity of the condition and the symptoms experienced. Careful planning and ultrasound guidance during procedures are needed. As NSVs are always very tortuous and superficial, endothermal procedures such as radiofrequency ablation or laser treatment has limited role. Foam sclerotherapy and phlebectomy are the treatment of choice for NSV reflux. Pelvic vein reflux is treated with foam sclerotherapy with direct injection using ultrasound or venography (bottom-up technique) in patients without pelvic symptoms, In those with pelvic symptoms or recurrence pelvic and ovarian veins are treated with foam and coils (top down technique).

In case of sciatic nerve vein reflux, sclerotherapy or surgical treatment can be performed. Subfascial ligation and interruption in the lower thigh and popliteal fossa can be the option (16). This can be performed just below the fascia and away from the nerves under duplex scan guidance with subsequent mini-phlebectomy for the epifascial tributaries. At follow-up residual varicosities can be treated with phlebectomies or foam sclerotherapy.

The extent of NSV reflux can be identified by tracing the varicosities to the various connections. As these veins are not included in the routine DU examination protocol, they may be missed leading to incorrect/incomplete treatment. By increasing awareness and understanding of NSV reflux, the diagnosis and management of this condition can be improved, ultimately helping to improve outcomes for patients with venous disease.