Theoretical Risk Factors

One popular hypothesis for the development of varicose veins is Western dietary and defecation habits, which cause an increase in intraabdominal pressure. Population studies have demonstrated that a high-fiber diet is evacuated within an average of 35 hours.24 In contrast, a low-fiber diet has an average transit time of 77 hours. An intermediate diet has a stool transit time of 47 hours.

Defecatory straining induced by Western-style toilet seats has also been cited as a cause of varicose veins, in contrast to the African custom of squatting during defecation.25,26

An association between prostatic hypertrophy, inguinal hernia, and varicose veins may be caused by straining at micturition with a resultant increase in intraabdominal pressure.

Another mechanism for increasing distal venous pressure by proximal obstruction is the practice of wearing girdles or tight-fitting clothing. A statistically significant excess of varicose veins is noted in women who wear corsets compared with women who wear less constrictive garments.

Leg crossing and sitting on chairs are two other potential mechanisms for producing a relative impedance in venous return. Habitual leg crossing is commonly thought to result in extravenous compression, but this has never been scientifically verified.

Most,27 but not all,28 studies have found that obesity is associated with the development of varicose veins. Careful examination of some of these epidemiologic studies shows that when the patient's age is correlated with obesity, the statistical significance is eliminated. Varices may be secondary to decreased exercise and associated medical problems specific to obesity such as hypertension, diabetes, hypercholesterolemia, and sensory impairment.

Finally, it commonly is noted that occupations that require standing for prolonged periods have an increased incidence of varicose veins. This may be exacerbated by tall height, although this factor has not been supported by other studies.

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