Comment to: Ultrasonography study on the segmental aplasia of the great saphenous vein by Oguzkurt L. Phlebology 2013 [Epub ahead of print].

Stefano Ricci

Abstract

This is a prospective study to assess the frequency and anatomic distribution of the segmental absence or aplasia of the GSV using ultrasonography. 670 limbs of 335 consecutive patients who had signs and symptoms related to venous insufficiency of the leg were evaluated. Venous clinical severity scores ranged from 0 to 20The GSV was examined for its diameter, its relation with the fascial compartments and venous reflux on both legs. Diagnosis of segmental absence of the GSV was established when ultrasonography showed that the saphenous vein left the compartment and there was not any other saphenous vein in it. If a normal diameter or smaller than normal diameter vein remained in the compartment all along its course, this was not considered segmental aplasia and excluded from the study. Segmental aplasia was classified into three subgroups.
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.
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 always present in its mid portion below or above the knee . It was found in 223 of 670 limbs (33%) in the whole patient population. It was type 1 in 59%, type 2 in 29%, and type 3 in 12% of the patients. It was 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, and 65 of 194 limbs (33.5%) with GSV insufficiency and 44 of 141 limbs (31.2%) with normal GSV on the left side.
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.
Aplasic segment of the GSV may prevent progression of any kind of endovenous device such as surgical stripper, laser fiber, or radiofrequency ablation probe. 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. This vein was named as accessory saphenous vein or tributary vein. An alternative term such as the saphenous connecting vein or bridging vein regarding its function or the saphenous bow regarding its shape might be more appropriate.
The etiology of segmental aplasia or hypoplasia of the GSV is unknown. It was assumed to be due to a developmental prevalence of vessels with the most favorable hemodynamic condition over the greater vessels that underwent atrophy.

Comment by Stefano Ricci

Veins anatomy studied through ultrasonography made a great advancement in the knowledge of phlebologists. The suggestion of the saphenous eye by Bailly in 19931 made easy the GSV identification, leading to better comprehension of the multiple aspects of varices pathology. Several studies followed, summarized in 2006 by Cavezzi et al.2
This paper repeats the observation of GSV aplasia, but do not add useful data to the current knowledge of the subject, except for that GSV aplasia is as frequent in normal subjects as in varicose patients, in contradiction to other Authors’ analysis. This report could be interesting like all the divergent opinions, if it was performed following the guidelines suggested by previous authors, but this is not the case. For example, as correctly reported, saphenous fascia was difficult to understand around the knee region. For this reason Ricci and Cavezzi (cited as ref. 8) suggested to employ the Tibial-gastrocnemious angle sign to state if an examined vein in that area could be assigned as GSV, but no mention of this sign can be found in this study, probably missing several cases. Concerning the GSV aplasia in its most proximal part, replaced completely by the AASV, the authors did never encounter this condition, but, again, to distinguish the AASV from the GSV Bailly, in 1993, suggested to employ the Alignment sign, also ignored in the study (cited in ref. 2).
In citing references, aplasia and hypoplasia cases are mixed up, suggesting ambiguous conclusions. Concerning the name of the connecting vein, collateral vein was suggested in the same n. 8 citation, according to Oxford dictionary collateral definition: side by side, parallel, subordinate but from same source, contributory, connected but aside from main subject.

Reply by the Author (Oguzkurt)

Dear editor,

I agree with your comment on following the guidelines published to date. It would have been better if we could comment on the tibiogastrocnemius sign and alignment sign in our study. However, both signs are well known to us before and during this study.3 The tibiogastrocnemius sign is important when the GSV could not be identified by ultrasonography around the knee. The sign can also be useful to demonstrate whether the GSV is patent, hypoplasic or aplasic in the same region. However, the sign is not the only way to diagnose if there is hypoplasia or aplasia of the GSV around the knee. We examined the vein from above to below and from below the above all along its course in each patient. Absence of the GSV in the saphenous compartment beyond the point where a vein leaves the compartment was diagnostic for segmental aplasia. One does not need to follow the tibiogastrocnemius sign. We believe there was no case missed or misdiagnosed in this respect. In their series considering the tibiogastrocnemius sign, Ricci et al.4 found the total prevalence of hypoplasia or aplasia as 29% (types D and E). Our study showed that segmental aplasia only had a prevalence of 33%. This higher rate could also support the fact that that we did not miss cases of segmental aplasia by not depending on the tibiogastrocnemius sign for definition of segmental aplasia of the GSV.
In our study, we did not encounter segmental aplasia in the most proximal and most distal parts of the GSV. It was always present in its mid portion below or above the knee. We were again aware of the study of Bailly, in 1993, suggesting to employ the alignment sign to distinguish the anterior accessory great saphenous vein (AASV) from the GSV. Alignment sign simply explains that GSV is always more medial to the femoral vessels and any vessel similar to GSV but aligned with the femoral vessels should be called the AASV. Sometimes, there is only one vein in the proximal thigh, which aligns with the femoral vessels. This condition was called the complete replacement of the GSV by the AASV. Although there is mention of this subject in the proximal thigh, we could find only one report about it.5
The condition was seen in only one of 674 limbs studied (1 of 84 limbs with segmental hypoplasia). Therefore, it is rare and it is not surprising that we did not see it. The alignment sign, we believe, is again important but should not be the only determinant to diagnose complete replacement of the GSV by the AASV. One needs to see that the GSV goes out of the saphenous compartment leaving no vein or a very narrow vein in the saphenous compartment proximal to this point.
Concerning the name of the vein, not only collateral vein, but also accessory saphenous vein, and tributary vein were used by the same authors in three different publications. The name tributary is probably a misnomer, because a tributary of the saphenous vein drains blood from some part of the subcutaneous tissues to the saphenous vein. There are two defined accessory veins of the GSV, which are the anterior and posterior accessory saphenous veins. This collateral vein is different from each of the defined accessories. The name collateral may fit to the Oxford dictionary definition. However, the vein that forms a bow or bridge between the two sides of the GSV is a specific vein. It is very common but not known well. It would be better to give a specific name for it. Saphenous bridge or saphenous bow is quite descriptive and defines a venous segment that leaves and re-enters the saphenous compartment in case of segmental hypoplasia or aplasia of the GSV.
In the pioneering work on segmental hypoplasia and aplasia with ultrasonography and anatomical investigations,6 segmental hypoplasia was seen in 23% and aplasia in 17.6 of 121 limbs studied. The anatomical study with histological dissections, hypoplasia was seen in 18.8% and aplasia in 15.6% of 32 cadaveric limbs. Hypoplasia in the cadaveric limbs was defined as narrowing of the vein. The caliber of the vein could not be measured because of artifacts derived from the postmortem changes. They stated that in 17.4% limbs, the segment of the GSV was so narrow to be visible only by the use of microscopical devices. Therefore, one may misdiagnose some of the hypoplasia cases as aplasia with ultrasonography. In the other important study with ultrasonography,5 the authors mentioned on the segmental hypoplasia of the GSV but there was no mention on the segmental aplasia in the population studied. Segmental hypoplasia was seen in 12% of patient with varicose disease and 25% of normal population (P>0.001). The authors reported that they used the term hypoplasia to emphasize the point that the vein is present but is very narrow. However, in the same article they reported that segmental hypoplasia was diagnosed when no ascending vein could be clearly identified within the saphenous compartment. Segmental hypoplasia and aplasia are confusing on ultrasonography.
We need studies with large patient population using high-resolution ultrasonography arrays that aim to define both segmental aplasia and hypoplasia of the GSV at the same study. We believe most of these cases are actually aplasia and not hypoplasia with ultrasonography.

Levent Oguzkurt, MD
Baskent University School of Medicine
Department of Radiology, Ankara, Turkey

References

1. Bailly M. Cartographie CHIVA. In: Encyclopedie Medico-Chirurgicale. Paris: Editions Techniques; 1993. pp 43-161-B, 1-4.
2. Cavezzi A, Labropoulos N, Partsch H, et al. Duplex ultrasound investigation of the veins in chronic venous disease of the lower limbs – UIP consensus document. Part II. Anatomy. Eur J Vasc Endovasc Surg 2006;31:288-99.[PubMed]
3. Oguzkurt L. Ultrasonographic study of the lower extremity superficial veins. Diagn Interv Radiol 2012;18:423-30.[PubMed]
4. Ricci S. Echo-anatomy of long saphneous vein in the knee region: proposal of a classificaiton in five anatomical pattern. Phlebology 2002;16:111-6.[Abstract]
5. Caggiati A, Mendoza E. Segmental hypoplasia of the great saphenous vein and varicose disease. Eur J Vasc Endovasc Surg 2004;28:257-61.[PubMed]
6. Caggiati A, Ricci S. The caliber of the human long saphenous vein and its congenital variations. Ann Anat 2000;182:195-201.[PubMed]

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