Abstract
Purpose
To assess the frequency and anatomic distribution of the segmental aplasia of the great saphenous vein (GSV) using ultrasonography in patients who presented with a clinical etiologic anatomic and pathophysiologic (CEAP) score 1 and above.
Materials and Methods
A prospective study on 670 limbs of 335 consecutive patients evaluated for segmental aplasia of the GSV with ultrasonography. The difference of segmental aplasia of the GSV between patients with and without GSV insufficiency was searched.
Results
Segmental aplasia of the GSV was found in 223 of 670 limbs (33%). Segmental aplasia of the GSV was seen in 65 of 189 limbs (34.4%) with GSV insufficiency and 45 of 146 limbs (30.8%) with normal GSV on the right side (P = 0.52), and 65 of 194 limbs (33.5%) with GSV insufficiency and 44 of 141 limbs (31.2%) with normal GSV on the left side (P = 0.72).
Conclusion
Segmental aplasia of the GSV was seen in one-third of patients who had a CEAP score 1 and above. The frequency of the segmental aplasia was almost the same in the right and the left limbs and was similar in patients with or without GSV insufficiency.
Introduction
The great saphenous vein (GSV) takes its origin from the medial marginal vein of the foot and ends at the saphenofemoral junction. All along its course, the GSV is located between the deeply situated muscular fascia and superficially situated saphenous fascia. The space formed by the two fascias is called the saphenous compartment which is continuous from the thigh to the leg.1–3 The superficial and deep fascias around the GSV form the “Egyptian eye” appearance that can easily be identified by anatomic dissection and ultrasonography and was considered a marker to identify the GSV. 2 Any vein running outside the saphenous fascia is considered an accessory or a tributary to the GSV. 1
The caliber of the normal GSV in the saphenous compartment increases progressively from the leg to the groin due to the confluence of the tributary veins. However, the GSV can be very small in diameter or cannot be seen at all within the saphenous compartment.4,5 The former condition is called hypoplasia and the latter condition is called aplasia of the GSV. Both are usually segmental in the course of the vein. In both cases, there is usually a connecting vein that leaves the saphenous compartment where hypoplasia or aplasia of the GSV begins, ascends cranially running parallel to the compartment, and enters the compartment where hypoplasia or aplasia ends. This connecting vein was called a tributary to the saphenous vein or the saphenous accessory vein.4,5 Although the segmental aplasia or hypoplasia of the GSV is very common, there are few studies on the subject. It can be clinically important as the aplasic or hypoplasic segment may prevent extension of reflux from the proximal saphenous vein to the distal one. 4 In addition, segmental hypoplasia is found significantly more common in patients with varicose veins than in normal subjects. 4 The purpose of this prospective study is to assess the frequency and anatomic distribution of the segmental absence or aplasia of the GSV using ultrasonography.
Materials and methods
Patients
In one-year period, 670 limbs of 335 consecutive patients who had signs and symptoms related to venous insufficiency of the leg were evaluated in our outpatient clinic. All subjects gave their informed consent to participate to the study which was approved by the institutional review board. All the procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation and with the Helsinki Declaration (http://www.wma.net/en/30publications/10policies/b3/index.html). All patients older than 18 years of age who applied to our outpatient clinic with the complaint of varicose veins or symptoms related to venous insufficiency were enrolled to the study. Forty-two patients who had any kind of vascular malformation, superficial or deep venous thrombosis, any kind of previous varicose vein treatment, or trauma or surgery to the leg that could possibly influence lower extremity venous anatomy in the past history or during the current ultrasonography examination were excluded from the study. Patients who presented to our clinic for reasons other than lower extremity venous complaints were not included as we do not routinely examine those patients with ultrasonography while they were standing.
Methods
Physical examination and ultrasonography examination were undertaken for each subject using a 9-MHz or 13-MHz multifrequency transducers (Antares, Siemens Erlangen, Germany) on both the transverse and longitudinal planes all along the course of the GSV while the patient was standing. All the ultrasonography examinations were performed by the same physician. We preferred to use a 13-MHz frequency transducer unless the patient is very obese. The GSV was examined for its diameter, its relation with the fascial compartments and venous reflux on both legs. Color Doppler and duplex examinations were performed to evaluate the hemodynamic condition of the GSV. The diameter of the GSV was measured 3 cm below the saphenofemoral junction. Reflux was assessed by release after a calf squeeze and Valsalva maneuvers all along the vein. Reflux lasting longer than 0.5 s was diagnostic for GSV insufficiency.
6
The GSV was also evaluated for its relation with respect to the saphenous fascia and the saphenous compartment. The saphenous fascia and the saphenous compartment were usually very constant around the ankle and the groin.
7
However, the saphenous fascia was not well-defined and relation of the GSV to the saphenous compartment was difficult to understand around the knee region.
8
Therefore, diagnosis of segmental absence of the GSV was established when we documented by real-time ultrasonography that the saphenous vein left the compartment and there was not any other saphenous vein in the saphenous compartment (Figure 1). If the saphenous vein left the saphenous compartment but a normal diameter or smaller than normal diameter vein remained in the compartment all along its course, this was not considered segmental aplasia of the saphenous vein and excluded from the study. We observed in some of our patients that a small-diameter GSV extended up in the saphenous compartment while a larger vein left the compartment. We tracked such small-diameter veins all along its course and noticed that most of these veins extended in the saphenous compartment for a few centimeters and ended suddenly by joining a collateral vein or draining into a small perforating vein (Figure 2). This kind of GSV pattern was regarded as segmental aplasia and included in the study. The leaving and re-entry point of the GSV to the saphenous compartment was mapped in detail for both limbs.
In the segmental aplasia, the great saphenous vein leaves the saphenous compartment and there remains no vein in the compartment. Ultrasonography in the longitudinal plane shows that the great saphenous vein leaves the compartment with a smooth angle (a). Ultrasonography in the transverse plane shows the great saphenous vein within the compartment forming the Egyptian eye (b). At a higher level, the compartment is empty and the connecting vein courses in the subcutaneous tissue superficial to the saphenous fascia (white arrows show the saphenous fascia). In some cases of segmental aplasia, the great saphenous vein leaves the compartment but a vein with a normal or smaller than normal diameter remains in the compartment and courses upwards for a while (a, b), then leaves the compartment. If this vein continues up to the point where the connecting vein joins it at a higher level, this is called segmental hypoplasia and not segmental aplasia. However, in most cases, this small-diameter vein also leaves the compartment to join a perforating vein or a subcutaneous vein (c) and does not continue upwards. The saphenous space remains empty (d) consistent with the segmental aplasia of the saphenous vein.
Segmental aplasia was classified into three subgroups according to the location it left the compartment and re-entered (Figure 3):
Type 1: The GSV leaves the saphenous compartment in the leg and joins it at any point in the thigh. Type 2: The GSV leaves the saphenous compartment in the leg and joins it in the leg just below the knee. Type 3: The GSV leaves the saphenous compartment in the thigh and joins it more cranially in the thigh. Segmental aplasia was classified into three subgroups according to the location it leaves the compartment and joins the compartment again at a higher level: (a) Type 1 (b) Type 2, and (c) Type 3 patterns.
Statistical analysis
Data are expressed as the mean ± standard deviation for continuous variables and percentages for categorical variables. Two-sided Student t test was used to compare continuous variables and Chi square test was used to compare categorical variables. A P value < 0.05 was considered to indicate statistical significance. Statistical analysis was performed by using software (SPSS, version 17.0; SPSS, Chicago, IL).
Results
The distribution of CEAP classification.
Frequency and anatomic patterns of the segmental aplasia of the great saphenous vein.
Discussion
The current study showed that the segmental aplasia of the GSV was seen in one-third of limbs on each side and was mostly unilateral. It was not seen in the most proximal and most distal parts of the GSV but was always present in its mid portion below or above the knee. In its most common pattern, the GSV left the saphenous compartment below the knee and joined the compartment at some level in the thigh. There was no relation between the presence of segmental aplasia of the GSV and the presence of GSV or SSV insufficiency in the same limb among patients with CEAP scores 1 and above. The GSV can be replaced completely by the anterior accessory great sapheneous vein in rare occasions. Although we did not see this variation in our study population, we have rarely seen it before and after the study enrolment. Therefore, the finding that the GSV was seen in its compartment in proximal limb in all patients was valid only for this study and could not be generalized.
Segmental narrowing or absence of the GSV was rarely mentioned in the literature despite its high incidence in subjects with or without GSV insufficiency.4,5,9,10 The condition could be difficult to establish in venography studies where fascial relations of the GSV could not be demonstrated. Ultrasonography studies conducted before the era of clear definition of fascial relations of the GSV could not easily depict the condition as well. Another reason for unawareness of the condition could also be due to the presence of a connecting vein. This vein ran outside the saphenous compartment in which there was no saphenous vein or a very narrow saphenous vein and connected the normal GSV in the saphenous compartment distally and proximally. This vein could be erroneously considered as the GSV itself. 4 Fascial anatomy is very important for the depiction of the GSV that should be named only for a vein located within the saphenous compartment.1,11,12
The etiology of segmental aplasia or hypoplasia of the GSV is unknown. It was assumed to be due to a developmental defect where vessels with the most favorable hemodynamic condition prevailed over another or others which then underwent atrophy.4,13 The segmental abnormality of the GSV was called aplasia when there was no vein in the saphenous compartment with ultrasonography and hypoplasia when there was a vein in the compartment but of very small diameter. 4 One of the descriptive studies on the subject included ultrasonography examination in 102 normal subjects and stereomicroscopic study in 16 cadavers. The GSV caliber was normal in 59.3%, very narrow (less than 1 mm in diameter) in 23%, and could not be detected in 17.6% of 204 limbs using ultrasonography. 5 A total of 40.6% of the GSV had hypoplasia or aplasia. Anatomical investigation of the narrow segment of the GSV showed a topographic and morphologic structure similar to a normal GSV except its wall which contained a significantly thinner intima and adventitia. Stereomicroscopy of the segment where a GSV could not be seen with ultrasonography showed a small vein with a primordial wall structure with occasionally seen rudimentary valvular folds. 5
The largest ultrasonography study found segmental hypoplasia in 84 of 687 limbs (12%) in normal subjects and in 79 of 320 limbs (25%) in patients with an incompetent GSV. 4 The difference was significant (P < 0.001). The segmental hypoplasia extended from the upper calf to the thigh in 92.8%, was confined to the calf region in 4.8%, and confined to the thigh region in 2.4% of 84 limbs. In two limbs (2.4%), hypoplasia extended up to the groin, where the ascending flow reached the femoral vein by the anterior accessory GSV. The authors considered the presence of GSV hypoplasia as a possible risk factor in the pathogenesis of varicose veins. 4 This hemodynamic overload on the vein bridging the lower and upper parts of the GSV probably accounted for the higher incidence of venous reflux in the presence of segmental hypoplasia. 4 The thin wall with less muscle of this saphenous accessory as well as lack of saphenous fascia as a supporting structure to the vein could also contribute to the reflux. 4 In the current study, we excluded patients who had a normal or narrow-diameter GSV in the saphenous compartment and included only those who had segmental aplasia of the GSV in any segment in the saphenous compartment. We observed higher frequency of segmental aplasia and lower frequency of type 1 anatomy in a limb-based scale. Although we did not find a difference in the frequency of segmental aplasia of the GSV between the two groups, the patient population was different than the study previously described. In the study by Caggiati and Mendoza, 4 the two groups consisted of patients with venous insufficiency and normal subjects without any complaints of venous pathology. Our study did not have a control group consisting of normal subject but patients who presented with any kind of visible venous disease (telengiectasia, reticular veins, or varicose veins; CEAP score 1 or above) or leg complaints probably related to a venous disease.
Another study classified the GSV anatomy in the normal subjects and in subjects with saphenous vein insufficiency as “I” type, “h” type, and “S” type. The “I” type showed normal course of the GSV all along the saphenous compartment. The “h” type showed a tributary ascending parallel to the GSV. The GSV distally was in the saphenous compartment and was often small in caliber or even hypoplasic. The “S” type was the same as the “h” type, but the part of the GSV distal to the confluence with the tributary vein was absent in the saphenous compartment. 13 Distal GSV was hypoplasic or not visualized at all in 43% of patients with saphenous vein insufficiency and 30% of normal subjects. Statistical significance of the difference was not mentioned. Blood flow or reflux continued from the normal GSV to a tributary vein running parallel to the hypoplasic or aplasic part of the GSV distally. 13 In the current study, we did not see any patients with an absent GSV within the saphenous compartment most distally (S type). On the contrary, the saphenous vein or the saphenous eye was normal and quite constant around the groin and around the ankle.
The vein that connects the normal GSV distally and proximally was named as accessory saphenous vein or tributary vein.4,13 According to the most recent terminology, the term accessory saphenous vein is reserved for any venous segment located outside the saphenous compartment and ascending parallel to the GSV both in the leg and in the thigh. The two known accessory veins of the GSV are the anterior and the posterior accessory GSVs.1,2 The vein that connects the upper and lower parts of the GSV within its compartment in case of segmental hypoplasia or aplasia has not been yet defined by the International Interdisciplinary Consensus Committee on Venous Anatomical Terminology yet. 1 A tributary to the GSV usually has smaller distal branches draining some part of the subcutaneous tissue and joins the GSV cranially. However, a tributary usually does not originate from the GSV itself. Therefore, the term accessory saphenous vein or tributary vein actually does not correspond to the vein connecting the normal distal and proximal parts of the GSV. An alternative term for this unique connecting vein such as the saphenous connecting vein or bridging vein regarding its function or the saphenous bow regarding its shape might be more appropriate especially until a definition for terminology is made by consensus. 7
Segmental aplasia of the GSV might have clinical implications. In patients with insufficiency of the GSV in the presence of segmental aplasia, reflux may not extend down to the distal GSV as the GSV is interrupted. Reflux in the proximal GSV may extend downwards to end in a perforator, in another superficial vein or even in the SSV. 4 Aplasic segment of the GSV may also prevent progression of any kind of endovenous device such as surgical stripper, laser fiber, or radiofrequency ablation probe. In case of segmental aplasia of the GSV, care must be taken not to cause thermal damage during endovenous thermal ablation of the insufficient connecting or bridging vein as this vein comes closer to the skin after leaving the saphenous compartment.
There are some limitations of this study. Our patient population did not have a control group consisting of normal subjects. Therefore, we cannot draw a certain conclusion whether segmental aplasia of the GSV has any clinical importance in the pathogenesis of the varicose vein. We did not take into account the cases where there was a small-diameter or normal-sized vein in the saphenous compartment in the presence of a bridging vein connecting the upper and lower parts of the saphenous vein. It could have been better to search the anatomic distribution of all three patterns of the saphenous vein.
Segmental aplasia of the GSV was seen in one-third of patients who presented with the complaints of telengiectasia, reticular veins, or varicose veins or with symptoms of venous insufficiency (CEAP score 1 and above). The frequency of the segmental aplasia was almost the same in the right and the left limbs and was similar in patients with or without GSV insufficiency. In its most common pattern, the GSV left the saphenous compartment below the knee and joined the compartment in the thigh. It was not seen in the most proximal and most distal parts of the GSV.
Footnotes
Declaration of interest
All the authors have no conflict of interest and nothing to disclose.
Ethical approval
The ethics committee of Baskent University approved this study (REC number: KA11/95).
Guarantor
Murat Gedikoglu (Baskent University)
Contributorship
LO researched literature and conceived the study, involved in protocol development, gaining ethical approval, patient recruitment and data analysis, wrote the manuscript, reviewed and edited the manuscript, and approved the final version of the manuscript.