Cranial extension of the small saphenous vein: when caudal flow is normal

Abstracts

A extensão cranial da veia safena parva se destaca pelas inúmeras variações anatômicas e diferentes padrões de fluxo que podem ser observados, descritos em trabalhos envolvendo dissecções pós-morte ou cirúrgicas, flebografias e Doppler, que denotam a formação embriológica mais precoce e complexa em relação à safena magna. A observação de um tipo específico de extensão cranial da safena parva onde o sentido das valvas é contrário ao habitualmente observado foi primeiramente caracterizada por Carlo Giacomini, sendo o fluxo caudal nesses casos de aspecto normal sem sinal de incompetência valvar. Este artigo demonstra os padrões anatômicos e de fluxo que podem ser caracterizados na veia safena parva, contribuindo para que aspectos normais do seu fluxo não sejam confundidos com incompetência valvar.

Veia; Doppler; refluxo

REVIEW ARTICLE

Cranial extension of the small saphenous vein: when caudal flow is normal

André Paciello Romualdo; Roberto de Moraes Bastos; Mathias Fatio; Alessandro Cappucci; Solange Augusta Munhoz Mariana; Érika Narahashi; Alberto Lobo Machado; Eduardo Hideki Tokura

Fleury Medicina e Saúde, São Paulo, SP, Brazil

Correspondence

ABSTRACT

Cranial extension of the small saphenous vein is of special interest due to the number of anatomical variations and different blood flow patterns observed, which have been described in investigations including postmortem or surgical dissections, phlebographies, and Doppler studies, indicating an earlier and more complex embryological development in relation to the great saphenous vein. A specific type of cranial extension of the small saphenous vein, where a reverse flow is often observed in the valves, was first characterized by Carlo Giacomini. In these veins, caudal flow is normal, with no evidence of valvular incompetence. This article describes anatomical and blood flow patterns found in the small saphenous vein, thus contributing to avoid that normal blood flow aspects are misinterpreted as valvular incompetence.

Keywords: Vein, Doppler, reflux.

Introduction

Doppler ultrasound investigation is an important diagnostic tool for detection of vascular pathologies, particularly in relation to the veins of the lower limbs. Among several venous segments, the cranial extension of the small saphenous vein is of special interest due to the number of anatomical variations and different blood flow patterns observed, and a correct understanding of its anatomy and physiology is essential to an accurate diagnosis.

The objective of this study is to point out that, among the possible anatomical variations described, a particular one shows caudal blood flow, an aspect that could be a characteristic of Doppler ultrasound investigation.

History

Josef Hyrtl was the first anatomist to describe the cranial extension of the small saphenous vein, in 1864, when he coined the term "femoral-popliteal vein" for a superficial vein in the posterior thigh. In 1936 this term was included in a guide for anatomical terminology, the Jenaer Nomina Anatomica, being replaced with "posterior subcutaneous femoral vein" and, afterwards, with "medial marginal vein" as the official nomenclature in later editions of Nomina Anatomica.^1,2

Among all nineteenth-century anatomists, Carlo Giacomini stood out because of a study conducted in 1873,³ when he described new types of small saphenous vein termination and their relationship with thigh fasciae, demonstrating that they were the very same saphenous vein running in the upper genicular segment rather than anomalous superficial veins as previously suggested, concluding that "the ascending branch of the small saphenous vein, rather than being considered an anomaly due to its extreme frequency, should be considered a normal state."³ Another original contribution was the discovery of two valvular arrangements in opposite directions: the first one allows only cranial flow when there is an intersaphenous anastomosis, and the second one allows caudal flow toward the saphenopopliteal junction, acting as a tributary of the proximal thigh segment.¹

The current term cranial extension of the small saphenous vein has arisen from a consensus reached by radiologists, vascular surgeons and anatomists during the 14th World Congress of the International Union of Phlebology, held in Rome in 2001, being recognized by official bodies on anatomy, the International Federation of Associations of Anatomists and the Federative Committee on Anatomical Terminology.^4,5 According to this consensus document, the term cranial extension of the small saphenous vein comprehends any saphenous vein termination above the popliteal flap, including the Giacomini vein.

Anatomy

The small saphenous vein courses more deeply within the saphenous compartment, delimited by the muscle fasciae, and more superficially within the saphenous vein (Figure 1). At the lower margin of the popliteal fossa, the saphenous compartment ceases to exist because the muscle fascia adheres to the fasciae of the gastrocnemius muscles to insert into the femoral condyles. The popliteal fascia represents the extension of the saphenous fascia, reinforced by the fascial fibers of the gastrocnemius muscles, semitendinosus muscles and biceps femoris.⁶

When extending above the popliteal flap, the small saphenous vein deepens along with the saphenous fascia, thus running into the sulcus between the biceps femoris and semitendinosus muscles through a subfascial route (Figure 2).

The types of small saphenous vein termination have been an object of study for over a century, at first by cadaveric dissection,^3,7 and more recently by Doppler ultrasound examination.^8-12

In general, these studies have confirmed the anatomical aspects proposed by anatomists such as Charles Kosinski,⁷ who in 1926 corroborated the statement by Giacomini in an anatomic study performing dissection on 124 legs, in which small saphenous vein terminations were didactically divided into different patterns, as shown in Figures 3, 4 and 5.

Physiology

Although anatomical aspects of the small saphenous vein have been widely discussed, very little attention has been drawn to the possibility of a reverse blood flow in a specific pattern of cranial extension of the small saphenous vein. Such condition occurs when there is a saphenopopliteal junction and a subfascial-route small-caliber vein that originates from small subcutaneous veins at the upper or mid-third of the posterior thigh (pattern 1A). This extension shows a caudal blood flow, since this vein acts as a tributary of the posterior thigh (Figures 6 and 7). According to Giacomini, "the small saphenous vein shows saphenopopliteal junction [ ] this branch ends in the subcutaneous/subfascial tissue at the upper posterior thigh. [ ] obviously, it carries blood to the small saphenous vein since there was a pair of valves arranged so as to prevent flow in cranial direction."³ This specific pattern was characterized in 14% of the limbs studied by Giacomini and in 23% of the limbs studied through Doppler ultrasound examination by Oliveira et al.⁸ The remaining anatomic studies do not refer to its frequency, whose presence was either omitted or included in the pattern in which an exclusive termination into the popliteal vein occurs.

In intersaphenous segments, valves are arranged so as to carry blood from the small saphenous vein to the great saphenous (patterns 1B, 2B, 2C, and 3A). The Giacomini vein, which is composed of a subfascial and a subcutaneous segment, shows cranial blood flow (Figure 8). According to Giacomini, "valves can be found on the subfascial portion and, usually, 2 or 3 pairs on the subcutaneous portion close to the junction with the great saphenous vein. [ ] these valves are arranged so as to prevent reflux from the great saphenous to the small saphenous vein."³

The other cranial extensions cited by Kosinski,⁷ which end in the deep veins of the thigh (pattern 2A) through the perforating veins or deepening within muscles, always show a cranial blood flow (Figure 9).

Conclusion

Since the 19th century, several anatomic studies have described the various types of small saphenous vein anatomic termination, among which the study by Giacomini stands out, characterizing valve patterns in such venous segments. The observation of a specific type of cranial extension of the small saphenous vein, where a reverse flow is often observed in the valves, should be acknowledged by the examiner, because the characterization of a caudal flow in these cases represents a normal finding rather than a valvular incompetence, a still common misinterpretation.

References

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• 9. Delis KT, Knaggs AL, Khodabakhsh P. Prevalence, anatomic patterns, valvular competence, and clinical significance of the Giacomini vein. J Vasc Surg. 2004;40:1174-83.
• 10. Engel AF, Davies G, Keeman JN. Preoperative localization of the saphenofemoral junction with duplex scanning. Eur J Vasc Surg. 1991;5:507-9.
• 11. Somjen GM, Royle JP, Fell G, Roberts AK, Hoare MC, Tong Y. Venous reflux patterns in the popliteal fossa. J Cardiovasc Surg. 1992;33:85-91.
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Publication Dates

• Publication in this collection
  02 Oct 2009
• Date of issue
  June 2009

History

• Accepted
  21 Jan 2009
• Received
  24 June 2008