Three-dimensional reconstruction of the lower limb's venous system in human fetuses using the computer-assisted anatomical dissection (CAAD) technique.

OBJECTIVE: The aim of the present study was to show the feasibility and describe the first results of a 3D reconstruction of the venous network of the lower limbs in human fetus using the computer-assisted anatomical dissection (CAAD) technique. MATERIALS AND METHODS: We used limbs from two human fetuses, respectively, 14 and 15 weeks gestation old. Specimens were fixed in 10% formalin, embedded in paraffin wax and serially sectioned at 10 m. The histological slices were stained using HES and Masson Trichrome for soft tissues identification. Immunolabeling techniques using the Protein S-100 marker and the D2-40 marker were used to identify nerves and vessels, respectively. Stained slices were aligned manually, labeled and digitalized. The segmentation of all anatomical structures was achieved using the WinSurf(®) software after manual drawing. RESULTS: A 3D interactive vectorial model of the whole leg, including skin, bone, muscles, arteries, veins, and nerves was obtained. In all limbs, we observed the presence of a big axial vein traveling along the sciatic nerve. In addition, the femoral vein appeared as a small plexus. Although this is a common anatomical feature at the end of organogenesis, this feature is observed in only 9% of adults. Usually interpreted as an "anatomical variation of the femoral vein" it should be considered as a light truncular malformation. These observations bring further support to our proposed "angio-guiding nerves" hypothesis. CONCLUSION: This preliminary study shows that the CAAD technique provided an accurate 3D reconstruction of the fetal leg veins anatomy. It should bring a new insight for the understanding of the different steps of development of the human venous system.

Anatomy and embryology of the small saphenous vein: nerve relationships and implications for treatment.

The aim of this paper is to describe the anatomical relations of the small saphenous vein (SSV) in order to define the high-risk zones for the treatment of chronic venous disease. The SSV runs in the saphenous compartment demarcated by two fascia layers: a muscular fascia and a membranous layer of subcutaneous tissue. The clinician should be keenly aware of the anatomical pitfalls related to the close proximity of nerves to the SSV in order to avoid their injury: At the ankle, the origin of the SSV is often plexiform, located deep below the fascia, and the nerve is really stuck to the vein. The apex of the calf is an area of high risk due to the confluence of nerves which perforate the aponeurosis. Moreover, the possible existence of a 'short saphenous artery' which poses a high risk for injection of a sclerosing agent due to a highly variable disposition of this artery surrounding the SSV trunk. For this reason, procedures under echo guidance in this area are mandatory. The popliteal fossa is probably a higher risk zone due to the vicinity of the nerves: the small saphenous arch is close to the tibial nerve, or sometimes the nerve of the medial head of the gastrocnemius muscle. In conclusion, before foam injection or surgery, a triple mapping of the small saphenous territory is mandatory: venous haemodynamical mapping verifying the anatomy that is highly variable, nerve mapping to avoid trauma of the nerves and arterial mapping. This anatomical study will help to define the main high-risk zones.

Embryology and three-dimensional anatomy of the superficial venous system of the lower limbs.

OBJECTIVES: The purpose of this study is to better understand the anatomy of the venous network of the lower limbs by using new imaging techniques, particularly the three-dimensional modelling by computerized tomographic (CT) venography. This new tool is combined with anatomical dissection techniques and the results of Duplex ultrasound imaging. METHODS: The embryogenesis of the venous network, which explains the main variations of the venous system, and a description using the new terminology of the veins. RESULTS: Physiologically, the muscular veins play a crucial role, owing to the effect of the muscular pumps by their aspiration power on the superficial system via the perforators. They always act at the same level. This explains the fixity of the main perforator veins and the interest of their anatomical knowledge. CONCLUSION: The new imaging techniques and treatments dedicated to the venous system of the lower limbs make their descriptive anatomy increasingly useful. It will be the basis of a common language between radiologists, phlebologists and surgeons.

The thigh extension of the small saphenous vein: a hypothesis about its significance, based on morphological, embryological and anatomo-comparative reports.

The small saphenous vein in its modal pattern flows into the popliteal vein by means of a terminal arch (sapheno-popliteal junction), and frequently gives off an anastomotic branch, ascending on the medial aspect of the thigh, to the great saphenous vein. This branch has often been termed thigh extension of the small saphenous vein. As resulted in this report from autopsy, the venous extension coursed on the midline of the posterior aspect of the thigh, tributary to the deep femoral vein, and the small saphenous vein presented neither a sapheno-popliteal terminal arch, nor evident intersaphenous anastomoses. As a consequence, the small saphenous vein by means of its prolongation continued directly from the calf into the deep femoral vein. In the human embryo the small saphenous vein appears as direct communication with the posterior cardinal vein, and accompanies the developing ischiatic artery and nerve, as the main vein (ischiatic vein) of the lower limb bud. At the end of development, its proximal part persists as inferior gluteal vein. Comparative anatomy indicates that in animals the small saphenous vein is the only superficial vein well developed and that in humans its termination into the popliteal one might be an adaptation to the elongation and relative rigidity of the lower limb. In the horse a posterior vein of the thigh connects the small saphenous with the ischiatic one, and ascends along the ischiatic nerve to anastomose with the deep femoral vein. It would appear also that in the lower animals the small saphenous vein ascends to a higher level on the posterior aspect of the thigh. Thus, a venous extension like that we observed might be an atavism. Therefore, on the basis of these embryological and phylogenetical data, the Authors hypothesized that a small saphenous vein and a thigh extension of such a feature might be regarded as a unique venous channel, wholly axial throughout its course, formed by the small saphenous vein proper in the leg and by a persistent and functional sciatic (ischiatic) vein, which usually disappears, satellite of the ischiatic nerve, in the thigh.

Perforating veins of the shin in human foetuses.

There are 3 groups of perforating veins of the shin: the medial, the lateral and the internal sural perforating veins. Dysfunction of these veins is one of the main factors in venous hypertension. There is a lack of data in the literature concerning perforating veins of the shin in human foetuses. The aim of this study was identification of the perforating veins of the shin in human prenatal development. The material examined included 88 human lower limbs of foetuses (21 males and 23 females) aged from 16 to 38 weeks of intra-uterine life. The perforating veins were dissected under a steromicroscope. The number of perforating veins was analysed in relation to the sex of the foetus and the side of a body. In our study perforating veins of the shin did not show sexual or syntopic dimorphism. Between 2 and 6 Cockett's perforating veins were constantly present. Of these veins 80% divided into ascending and descending branches. Fibular perforating veins were found more often (90.9%) than Boyd's perforating veins (21.6%). Between 1 and 3 fibular perforating veins were observed but in 9% of cases they were entirely absent.

The structure of the cusps of valves in the human foetal great saphenous vein.

The study was performed on 110 great saphenous veins in human foetuses of both sexes aged 9 to 37 weeks. The earliest well-shaped valves were observed in foetuses aged 13 weeks. In these foetuses the number of valves varies from 2 to 7. Consecutive microscopic sections revealed that the developing valves at their origin present thickening of the endothelium which is continuous into the cusps of the valves. The bicuspid cusps are crescent-shaped and both surfaces are lined by endothelium.

Development of valves in the small saphenous vein in human fetuses.

The study was performed on 82 small saphenous veins in human fetuses of both sexes aged 9 to 37 weeks. The earliest valves were observed in 13 week-old fetuses. In fetuses between 13 and 18 weeks old the number of valves increased from 1 to 8. In the older fetuses between 19 and 37 weeks the number of valves varied from 5 to 9 and does not seem to be related to age. During development more valves were found in the upper part of the small saphenous vein. The height of valves increases with age and differs between particular valves of the same vein.

[Superficial veins of the leg]. / Les veines superficielles du membre inférieur.

This clinical work studies the normal pattern of the saphenous veins, their main variations with a short embryological reference. Some pathological cases are described; the perforator veins are very important; the role of the valves at the groin is emphasized.

[The perforating system of the area of the vena saphena magna]. / Sistema perforante del territorio de la vena saphena magna.

An anatomical study of perforating veins system in relation to saphena magna vein had been performed. We had found a great variability of the perforating veins on the lateral aspect of the leg, whereas on the medial side there are 3 perforating veins presents in 100% of the subjects.