Editing Varicose veins (section)

== Causes ==
[[File:Varicose veins-en.svg|thumb|upright=1.3|How a varicose vein forms in a leg. Figure A shows a normal vein with a working valve and normal blood flow. Figure B shows a varicose vein with a deformed valve, abnormal blood flow, and thin, stretched walls. The middle image shows where varicose veins might appear in a leg.]]
[[File:Blausen 0891 VaricoseVein.png|thumb|Comparison of healthy and varicose veins]]

Varicose veins are more common in women than in men and are linked with [[heredity]].<ref>{{cite journal | vauthors = Ng MY, Andrew T, Spector TD, Jeffery S | title = Linkage to the FOXC2 region of chromosome 16 for varicose veins in otherwise healthy, unselected sibling pairs | journal = Journal of Medical Genetics | volume = 42 | issue = 3 | pages = 235–239 | date = March 2005 | pmid = 15744037 | pmc = 1736007 | doi = 10.1136/jmg.2004.024075 }}</ref> Other related factors are [[pregnancy]], [[obesity]], [[menopause]], [[Senescence|aging]], prolonged standing, leg injury and abdominal straining. Varicose veins are unlikely to be caused by crossing the legs or ankles.<ref>{{cite web|url=http://www.dukehealth.org/health_library/health_articles/myth-or-fact-crossing-your-legs-causes-varicose-veins|title=Myth or Fact: Crossing Your Legs Causes Varicose Veins| vauthors = Griesmann K |publisher=Duke University Health System|date=March 16, 2011|access-date=March 1, 2014|archive-url=https://web.archive.org/web/20140305174414/http://www.dukehealth.org/health_library/health_articles/myth-or-fact-crossing-your-legs-causes-varicose-veins|archive-date=2014-03-05|url-status=dead}}</ref> Less commonly, but not exceptionally, varicose veins can be due to other causes, such as [[Post-thrombotic syndrome|post-phlebitic obstruction]] or incontinence, venous and arteriovenous malformations.<ref>{{cite book | vauthors = Franceschi C | date = 1996 | chapter = Physiopathologie Hémodynamique de l'Insuffisance veineuse |page = 49 | title = Chirurgie des veines des Membres Inférieurs | series = AERCV editions 23 | location = Paris }}</ref>

[[Chronic venous insufficiency|Venous reflux]] is a significant cause. Research has also shown the importance of pelvic vein reflux (PVR) in the development of varicose veins. Varicose veins in the legs could be due to ovarian vein reflux.<ref>{{cite journal |last1=Hobbs |first1=J. T. |title=Varicose veins arising from the pelvis due to ovarian vein incompetence |journal=International Journal of Clinical Practice |date=14 September 2005 |volume=59 |issue=10 |pages=1195–1203 |doi=10.1111/j.1368-5031.2005.00631.x |pmid=16178988 |doi-access=free }}</ref><ref>{{cite journal | vauthors = Giannoukas AD, Dacie JE, Lumley JS | title = Recurrent varicose veins of both lower limbs due to bilateral ovarian vein incompetence | journal = Annals of Vascular Surgery | volume = 14 | issue = 4 | pages = 397–400 | date = July 2000 | pmid = 10943794 | doi = 10.1007/s100169910075 }}</ref> Both ovarian and internal [[iliac vein]] reflux causes leg varicose veins. This condition affects 14% of women with varicose veins or 20% of women who have had vaginal delivery and have leg varicose veins.<ref>{{cite journal | vauthors = Marsh P, Holdstock J, Harrison C, Smith C, Price BA, Whiteley MS | title = Pelvic vein reflux in female patients with varicose veins: comparison of incidence between a specialist private vein clinic and the vascular department of a National Health Service District General Hospital | journal = Phlebology | volume = 24 | issue = 3 | pages = 108–113 | date = June 2009 | pmid = 19470861 | doi = 10.1258/phleb.2008.008041 }}</ref> In addition, evidence suggests that failing to look for and treat pelvic vein reflux can be a cause of recurrent varicose veins.<ref>{{cite journal | vauthors = Ostler AE, Holdstock JM, Harrison CC, Fernandez-Hart TJ, Whiteley MS | title = Primary avalvular varicose anomalies are a naturally occurring phenomenon that might be misdiagnosed as neovascular tissue in recurrent varicose veins | journal = Journal of Vascular Surgery. Venous and Lymphatic Disorders | volume = 2 | issue = 4 | pages = 390–396 | date = October 2014 | pmid = 26993544 | doi = 10.1016/j.jvsv.2014.05.003 | doi-access = free }}</ref>

There is increasing evidence for the role of incompetent [[perforator vein]]s (or "perforators") in the formation of varicose veins.<ref>{{cite journal | vauthors = Whiteley MS | title = Part one: for the motion. Venous perforator surgery is proven and does reduce recurrences | journal = European Journal of Vascular and Endovascular Surgery | volume = 48 | issue = 3 | pages = 239–242 | date = September 2014 | pmid = 25132056 | doi = 10.1016/j.ejvs.2014.06.044 | doi-access = free }}</ref> and recurrent varicose veins.<ref>{{cite journal | vauthors = Rutherford EE, Kianifard B, Cook SJ, Holdstock JM, Whiteley MS | title = Incompetent perforating veins are associated with recurrent varicose veins | journal = European Journal of Vascular and Endovascular Surgery | volume = 21 | issue = 5 | pages = 458–460 | date = May 2001 | pmid = 11352523 | doi = 10.1053/ejvs.2001.1347 | doi-access = free }}</ref>

Varicose veins could also be caused by [[Hyperhomocysteinemia#Causes|hyperhomocysteinemia]] in the body, which can degrade and inhibit the formation of the three main structural components of the artery: [[collagen]], [[elastin]] and the [[proteoglycans]]. [[Homocysteine]] permanently degrades [[cysteine]] [[disulfide]] bridges and [[lysine]] [[amino acid]] residues in [[proteins]], gradually affecting function and structure. Simply put, homocysteine is a 'corrosive' of long-living proteins, i.e. [[collagen]] or [[elastin]], or lifelong proteins, i.e. [[fibrillin]]. These long-term effects are difficult to establish in clinical trials focusing on groups with existing artery decline. [[Klippel–Trenaunay syndrome]] and [[Parkes Weber syndrome]] are relevant for [[differential diagnosis]].{{citation needed|date=February 2021}}

Another cause is chronic alcohol consumption due to the vasodilatation side effect in relation to gravity and blood viscosity.<ref>{{cite book | veditors = Ayala C, Spellberg B | title = Pathophysiology for the Boards and Wards | edition = 4th| publisher = Lippincott Williams & Wilkins | date = 2009 | isbn = 978-0-7817-8743-7 }}</ref>