{"id":118,"date":"2025-10-01T20:43:59","date_gmt":"2025-10-01T20:43:59","guid":{"rendered":"https:\/\/cmcdeploytwo.co.nz\/vsoanz\/?page_id=118"},"modified":"2025-10-16T03:23:39","modified_gmt":"2025-10-16T03:23:39","slug":"deep-venous-thrombosis-dvt","status":"publish","type":"page","link":"https:\/\/cmcdeploytwo.co.nz\/vsoanz\/index.php\/deep-venous-thrombosis-dvt\/","title":{"rendered":"Deep Venous Thrombosis (DVT)"},"content":{"rendered":"<div class=\"wpb-content-wrapper\">[vc_row full_width=&#8221;stretch_row&#8221; content_placement=&#8221;middle&#8221; equal_height=&#8221;yes&#8221; rtl_reverse=&#8221;yes&#8221; remove_bottom_col_margin=&#8221;true&#8221; columns_right=&#8221;yes&#8221; wpex_bg_color=&#8221;#03a3de&#8221; min_height=&#8221;350px&#8221;][vc_column width=&#8221;1\/2&#8243;]<style>.vcex-image.vcex_69d07920c71bc .vcex-image-img{object-position:right top;}<\/style><figure class=\"vcex-image vcex-module vcex-fill-column vcex_69d07920c71bc\"><div class=\"vcex-image-inner wpex-relative wpex-w-100 vc_custom_1760585015804\"><img width=\"1210\" height=\"657\" src=\"https:\/\/cmcdeploytwo.co.nz\/vsoanz\/wp-content\/uploads\/2025\/10\/Deep-Venous-Thrombosis_DVT_-copy.webp\" class=\"vcex-image-img wpex-align-middle wpex-w-100\" alt=\"\" loading=\"lazy\" decoding=\"async\" srcset=\"https:\/\/cmcdeploytwo.co.nz\/vsoanz\/wp-content\/uploads\/2025\/10\/Deep-Venous-Thrombosis_DVT_-copy.webp 1210w, https:\/\/cmcdeploytwo.co.nz\/vsoanz\/wp-content\/uploads\/2025\/10\/Deep-Venous-Thrombosis_DVT_-copy-300x163.webp 300w, https:\/\/cmcdeploytwo.co.nz\/vsoanz\/wp-content\/uploads\/2025\/10\/Deep-Venous-Thrombosis_DVT_-copy-1024x556.webp 1024w, https:\/\/cmcdeploytwo.co.nz\/vsoanz\/wp-content\/uploads\/2025\/10\/Deep-Venous-Thrombosis_DVT_-copy-768x417.webp 768w\" sizes=\"auto, (max-width: 1210px) 100vw, 1210px\" \/><\/div><\/figure>[\/vc_column][vc_column width=&#8221;1\/2&#8243;][vc_column_text css=&#8221;.vc_custom_1759351435113{padding-top: 20px !important;padding-bottom: 20px !important;}&#8221; color=&#8221;#fefefe&#8221;]\n<h1><strong>Deep Venous<\/strong><br \/>\nThrombosis (DVT)<\/h1>\n[\/vc_column_text][\/vc_column][\/vc_row][vc_row css=&#8221;.vc_custom_1759015527111{margin-top: 60px !important;}&#8221;][vc_column][vc_tta_tour controls_size=&#8221;md&#8221; active_section=&#8221;1&#8243;][vc_tta_section title=&#8221;What is a deep vein or venous thrombosis (DVT)?&#8221; tab_id=&#8221;1759012899351-dcaaabe1-cd5c8990-cefe&#8221;][vc_column_text css=&#8221;&#8221;]\n<h2 class=\"wp-block-heading\">What is a deep vein or venous thrombosis (DVT)?<\/h2>\n<p>There are two main groups of veins in the legs: the superficial veins and the deep veins.\u00a0 When blood clots form in the deep veins, this is known as a\u00a0<strong>D<\/strong>eep\u00a0<strong>V<\/strong>ein\u00a0<strong>T<\/strong>hrombosis or\u00a0<strong>D<\/strong>eep\u00a0<strong>V<\/strong>enous\u00a0<strong>T<\/strong>hrombosis (DVT). These terms mean the same.\u00a0 The deep veins cannot be seen externally.\u00a0 The superficial veins can be seen through the skin and sometimes form\u00a0<a href=\"https:\/\/vascular-society.nz\/varicose-veins\/\" target=\"_blank\" rel=\"noreferrer noopener\" data-type=\"page\" data-id=\"90\">varicose veins<\/a>\u00a0when they become enlarged.\u00a0 Superficial veins can sometimes develop blood clots. This is called phlebitis or superficial thrombophlebitis.\u00a0 Thrombosis can actually take place in any of the veins throughout the body, but is most frequent in the legs.<\/p>\n<p>DVT in the legs can be divided into 3 main types classified by their location.\u00a0 Firstly ilio-femoral DVT affects the major vein in the pelvis (iliac vein) draining the leg and may also involve the femoral vein in the thigh.\u00a0 Femoro-popliteal vein DVT predominantly affects the femoral vein in the thigh and the popliteal vein behind the knee.\u00a0 Calf vein (tibial vein) DVT predominantly affects the smaller deep veins in the lower leg. These divisions are largely arbitrary and DVT may affect all of these veins or segments of a vein that don\u2019t readily fit into this classification.\u00a0 The divisions are useful in terms of assessing the severity and risk of complications. Ilio-femoral DVTs are likely to present with the most severe symptoms and the highest risk of subsequent complications and calf vein DVTs with the lowest risk of complications.[\/vc_column_text][\/vc_tta_section][vc_tta_section title=&#8221;What are the symptoms of a deep venous thrombosis?&#8221; tab_id=&#8221;1759012899354-da1d8fff-c0988990-cefe&#8221;][vc_column_text css=&#8221;&#8221;]\n<h2 class=\"wp-block-heading\">What are the symptoms of a deep venous thrombosis?<\/h2>\n<p>Many patients may have minimal or no symptoms and this is known as a silent DVT.\u00a0 These patients may never know they have had a DVT.<\/p>\n<p>The main symptoms of a DVT are\u00a0<strong>pain<\/strong>\u00a0and\u00a0<strong>swelling<\/strong>\u00a0in the affected leg, particularly in the calf.\u00a0 The calf may be slightly red and tender.\u00a0 These symptoms can vary widely in their severity and are also not very specific.\u00a0 It can be difficult to make the diagnosis of DVT on the symptoms alone, because many other unrelated disorders can also cause similar symptoms.<\/p>\n<p>In mobile patients who present with symptoms suspicious of a DVT, 75% (3 of every 4 patients) will not have a DVT (<a href=\"http:\/\/www.bmj.com\/content\/329\/7470\/821.pdf+html\" target=\"_blank\" rel=\"noreferrer noopener\">Fancher TL et al, 2004<\/a>).<\/p>\n<figure id=\"Risk factors for DVT\" class=\"wp-block-table\">\n<table>\n<tbody>\n<tr>\n<th scope=\"col\">High risk groups for DVT<\/th>\n<\/tr>\n<tr>\n<td>Previous DVT<\/td>\n<\/tr>\n<tr>\n<td>Previous pulmonary embolus<\/td>\n<\/tr>\n<tr>\n<td>The elderly<\/td>\n<\/tr>\n<tr>\n<td>Malignant disease<\/td>\n<\/tr>\n<tr>\n<td>Extensive trauma\/extensive surgery<\/td>\n<\/tr>\n<tr>\n<td>Obesity<\/td>\n<\/tr>\n<tr>\n<td>Abdominal or pelvic surgery rather than upper limb or head and neck surgery<\/td>\n<\/tr>\n<tr>\n<td>Contraceptive pill<\/td>\n<\/tr>\n<tr>\n<td>Congestive heart failure. Myocardial infarction<\/td>\n<\/tr>\n<tr>\n<td>Underlying thrombophilia<\/td>\n<\/tr>\n<\/tbody>\n<\/table><figcaption>Risk factors for developing DVT<\/figcaption><\/figure>\n<p>Occasionally DVT can be very severe and affect the deep and superficial veins.\u00a0 In these circumstances the venous drainage from the limb may be so impaired that venous gangrene can develop.\u00a0 There is often an underlying cause for this event, such as an underlying cancer or clotting disorder. It can be a very difficult situation to treat.[\/vc_column_text][\/vc_tta_section][vc_tta_section title=&#8221;What is the economy class syndrome?&#8221; tab_id=&#8221;1759014772115-45b909ba-03388990-cefe&#8221;][vc_column_text css=&#8221;&#8221;]\n<h2 class=\"wp-block-heading\">What is the economy class syndrome?<\/h2>\n<p>The development of a DVT following a long flight has been called the economy class syndrome (<a href=\"http:\/\/www.ncbi.nlm.nih.gov\/pubmed\/2900413\" target=\"_blank\" rel=\"noreferrer noopener\">Cruikshank JM et al, 1988<\/a>).\u00a0 The first such recorded event was in 1946 on a non-stop flight lasting 14 hours (<a href=\"http:\/\/www.nejm.org\/doi\/full\/10.1056\/NEJM195401282500404\" target=\"_blank\" rel=\"noreferrer noopener\">Homans J, 1954<\/a>). The economy class syndrome has now expanded to refer to any flight related DVT especially when travelling economy class because of the more limited leg room. A recent study has reported on nearly 9.5 million people who arrived in Western Australia from international flights between 1981 and 1999.\u00a0 Over the same period 246 patients were admitted with a first DVT\/PE (lung clot) within 14 days of arrival.\u00a0 The risk of requiring admission with a DVT\/PE in this study was 26 travellers in 1,000,000 (0.000026%) overall.\u00a0 Interestingly, the risks for non-Australian citizens were greater than for Australian citizens (33 per million for non-Australian versus 9.6 per million for Australian).\u00a0 The study also found a definite 12% increased risk of DVT\/PE in passengers on long haul flights.\u00a0 It is important to remember that this is only a tiny increase in risk (0.00002912%), as the absolute risk is so low.\u00a0 In comparison the authors quote a risk of dying in a motor vehicle accident as about 100 times greater than the risk of dying from a pulmonary embolism\/DVT after a long haul flight (<a href=\"http:\/\/www.bmj.com\/content\/327\/7423\/1072.pdf+html\" target=\"_blank\" rel=\"noreferrer noopener\">Kelman et al 2003<\/a>).<\/p>\n<p>A pooled analysis of all studies in the medical literature found an 18% higher risk of clots for each 2 hour increase in travel duration using any mode of transport. There was a 26% higher risk of clots for every 2 hours of air travel. One problem the authors noted was the variability and inconsistency in the reported literature (<a href=\"http:\/\/annals.org\/article.aspx?articleid=744631\" target=\"_blank\" rel=\"noreferrer noopener\">Chandra et al, 2009<\/a>).[\/vc_column_text][\/vc_tta_section][vc_tta_section title=&#8221;Does deep venous thrombosis occur at other times?&#8221; tab_id=&#8221;1759014806183-f54d1997-de0b8990-cefe&#8221;][vc_column_text css=&#8221;&#8221;]\n<h2 class=\"wp-block-heading\">Does deep venous thrombosis occur at other times?<\/h2>\n<p>DVT is not only associated with air travel but has been recorded after any long period of immobility, such as a long car or rail journey or more commonly during a period in hospital, particularly in severely ill patients during prolonged periods of immobility.\u00a0 It is rare following air travel and much more commonly occurs in patients who have\u00a0<strong>not<\/strong>\u00a0been on a recent flight.<\/p>\n<p>Deep venous thrombosis can occur in 20% of patients undergoing major surgery and over 40% of patients undergoing major orthopaedic (bone) surgery.[\/vc_column_text][\/vc_tta_section][vc_tta_section title=&#8221;Risk factors for deep venous thrombosis&#8221; tab_id=&#8221;1759014827533-6ef99622-00a98990-cefe&#8221;][vc_column_text css=&#8221;&#8221;]\n<h2 class=\"wp-block-heading\">Risk factors for deep venous thrombosis<\/h2>\n<p>Ultimately the formation of a venous thrombosis is an imbalance in the inter-relationship between the clotting ability of the blood, changes in the wall of the vein and changes in blood flow in the vein especially stasis (Virchow\u2019s triad).<\/p>\n<p>Usually a combination of factors lead to the development of a DVT.\u00a0 Some of these factors can be described as external factors.\u00a0 For instance a combination of immobility and cramped seats, with the front of the seat pressing on the calf, may be important in the economy class syndrome.\u00a0 Aircraft cabin pressure may also play a role.\u00a0 There do seem to be factors related particularly to air travel which cause activation of the coagulation system (<a href=\"http:\/\/www.medicine.wisc.edu\/~williams\/airtravelcoag.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Schreijer AJM et al, 2006<\/a>).\u00a0 A UK government report (Sunday Times, September 2nd, 2001) has investigated factors which could influence the development of DVT during air travel.\u00a0 It has indicated that decreased cabin pressure and altered sleep patterns because of jet lag may be important in the development of DVT.\u00a0 They have suggested that more studies to investigate the links between air travel and DVT should be funded.<\/p>\n<p>Immobility is also important in patients undergoing surgery.\u00a0 The combination of a long surgical operation and a prolonged period of bedrest will increase the risk of DVT. A recent study has also highlighted the increased risk of DVT for up to 12 weeks after surgery, even minor surgery, in middle-aged women (<a href=\"http:\/\/www.bmj.com\/content\/339\/bmj.b4583.pdf+html\" target=\"_blank\" rel=\"noreferrer noopener\">Million Women Study, 2009<\/a>).<\/p>\n<p>Apart from these external factors there may also be internal factors which increase the likelihood of an individual person developing a DVT.\u00a0 Important risk factors include age over 40 years, pregnancy, presence of cancer, hormone therapy (hormone replacement therapy, the oral contraceptive pill) and dehydration.<\/p>\n<p>If you have had a previous DVT then you are always at a slightly increased risk of a further DVT, particularly soon after your first DVT.\u00a0 The risk of recurrent DVT is about 11% at one year increasing to 40% overall at 10 years. This risk of recurrent DVT does decrease with time but seems to be more likely if the original DVT was unprovoked (<a href=\"http:\/\/biblioteca-innsz.org.mx:8080\/xmluiNutricion\/bitstream\/handle\/123456789\/9861\/2970.pdf?sequence=1\" target=\"_blank\" rel=\"noreferrer noopener\">Labropoulos, 2010<\/a>).\u00a0 The risk of recurrence appears to be less in patients who develop a post-operative DVT.<\/p>\n<p>If you have had a previous DVT or have blood disorders that make clotting more likely then they also put you at increased risk.\u00a0 At least 30% of patients with DVT and no obvious cause will have thrombophilia on testing.\u00a0 Factor V Leiden is the commonest abnormality and found in 12-30% of patients who have a DVT.<\/p>\n<p>May-Thurner syndrome is a poorly recognised cause of left sided ilio-femoral DVT.\u00a0 It is a condition in which the left common iliac vein in the pelvis is compressed by the right common iliac artery which passes in front.\u00a0 Elegant studies using magnetic resonance venography have confirmed the association with ilio-femoral DVT (<a href=\"http:\/\/www.ncbi.nlm.nih.gov\/pubmed\/15472584\" target=\"_blank\" rel=\"noreferrer noopener\">Fraser DGW et al, 2004<\/a>).\u00a0 They have also shown that thrombus (clot) is less likely to resolve and the vein to re-open in the presence of this syndrome (<a href=\"http:\/\/www.ncbi.nlm.nih.gov\/pubmed\/15472585\" target=\"_blank\" rel=\"noreferrer noopener\">Fraser DGW et al, 2004<\/a>).[\/vc_column_text][\/vc_tta_section][vc_tta_section title=&#8221;Why is thrombosis important?&#8221; tab_id=&#8221;1759014855534-cd1bf395-e3558990-cefe&#8221;][vc_column_text css=&#8221;&#8221;]\n<h2 class=\"wp-block-heading\">Why is thrombosis important?<\/h2>\n<p>Thrombosis is important to recognise because it may be dangerous in two ways.<\/p>\n<p>Firstly, if a piece of blood clot breaks off from the veins in the legs and travels along the veins to the lungs (pulmonary embolism, PE) it can be fatal in a small number of people.\u00a0 Even if it is not fatal such a blood clot can make you very seriously ill.\u00a0 Pulmonary embolism causes symptoms such as shortness of breath, chest pain, cough, coughing up blood (haemoptysis), and collapse.\u00a0 Most patients with PE have no leg symptoms at diagnosis (<a href=\"http:\/\/www.ncbi.nlm.nih.gov\/pmc\/articles\/PMC1352055\/pdf\/bmj33200215.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Blann AD, Lip GYH, 2006<\/a>).<\/p>\n<p>Secondly, after a clot has formed in the legs it can damage the valves in the veins or block the veins.\u00a0 In either case this may cause problems in the legs in the future (see chronic venous insufficiency). It has been estimated that up to 90% of patients with ilio-femoral DVT will subsequently develop signs and symptoms of chronic venous insufficiency with up to 15% developing venous ulcers. As the blood clot clears from the leg and venous blood flow resumes the flow is likely to be abnormal with reflux or reverse flow developing and increasing with time.<\/p>\n<p>In a Canadian study looking at patients after DVT, over 40% of patients developed some changes of chronic venous insufficiency. The risk of developing chronic venous insufficiency was greater when clots occurred in the iliac and femoral veins, if patients were overweight, if the patient had suffered previous thrombosis and if the patients were older women (<a href=\"http:\/\/www.medsp.umontreal.ca\/IRSPUM_DB\/pdf\/20528.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Kahn et al 2008<\/a>). Those patients with the most severe changes at one month after their DVT were most likely to have ongoing problems over the longer term.[\/vc_column_text][\/vc_tta_section][vc_tta_section title=&#8221;Can the economy class syndrome (DVT) be prevented?&#8221; tab_id=&#8221;1759014887716-648cb14b-00198990-cefe&#8221;][vc_column_text css=&#8221;&#8221;]\n<h2 class=\"wp-block-heading\">Can the economy class syndrome (DVT) be prevented?<\/h2>\n<p>For the majority of people going about their normal business there is no need to take any special precautions to reduce the risk of DVT.\u00a0 Prevention is important if you are known to be at high risk of DVT or are to undertake an activity which could put you at increased risk.<\/p>\n<p>DVT can be prevented by taking sensible precautions.\u00a0 The most important preventive measure is activity. Standing up, stretching and taking a brief walk every hour during air travel will help to reduce your risk.\u00a0 It is important not to become dehydrated \u2013 so drink water or soft drinks regularly.\u00a0 This will also aid mobility!<\/p>\n<p>It is important to exercise the calves of the legs when sitting.\u00a0 The calves can be gently exercised when sitting by pressing the front of the feet onto the floor and moving the heels up and down off the floor.<\/p>\n<p>If you are at particular risk of DVT, then it may be sensible to take 150mgs of aspirin before your flight.\u00a0 Aspirin can cause irritation of the stomach and can rarely lead to bleeding from the stomach.\u00a0 It is important not to take aspirin, unless you know you are safe to do so and have had no previous problems with vomiting blood or peptic ulcers.<\/p>\n<p>Graduated compression stockings are particular types of stocking that provide maximum compression around the ankle area.\u00a0 The compressive effect then lessens further up the leg.\u00a0 This improves venous flow in the deep veins. A<a href=\"http:\/\/onlinelibrary.wiley.com\/store\/10.1002\/14651858.CD001484.pub2\/asset\/CD001484.pdf?v=1&amp;t=hf2wyq8l&amp;s=7813db74db63846bba070bcd30226be866484d73\" target=\"_blank\" rel=\"noreferrer noopener\">\u00a0Cochrane review<\/a>\u00a0has concluded after an analysis of multiple studies that graduated compression stocking alone and in combination with other preventive measures significantly reduce the risk of DVT in hospitalised patients. Stockings are also useful for airline passengers in terms of reductioon of both DVT risk and leg swelling. It is important that the stockings are fitted correctly. If you have varicose veins around the knee level it may be better to use above knee stockings. One study also found that significant problems developed such as skin breaks, ulcers and blisters when stockings were used in patients after they had suffered a stroke so it is important to make an individual assessment of benefit (<a href=\"http:\/\/www.medicine.wisc.edu\/~williams\/compression_stockings_trial.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">CLOTS 2009<\/a>).<\/p>\n<p>Many patients undergoing surgery have injections of low dose (prophylactic) heparin under the skin once or twice per day to reduce the risk of blood clots forming. These patients can also have pneumatic cuffs fitted to the calfs or feet which intermittently inflate and deflate throughout surgery.\u00a0 This encourages the flow of blood in the veins of the legs, and helps to prevent long periods where the blood in the veins is slow moving and may lead to thrombosis. There are detailed guidelines available in Australia and New Zealand to assist in using methods to prevent post-operative thrombosis.<\/p>\n<p>A recent randomised trial (<a href=\"http:\/\/bvi.ecssrv.net\/files\/2011\/11\/Lancet2001.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Scurr et al 2001<\/a>) has produced some unexpected results.\u00a0 Volunteers were allocated to wearing or not wearing below knee stockings during long flights, returning within 6 weeks.\u00a0 Scanning of the veins and blood tests were performed within 48 hours of return to detect DVT.\u00a0 In the group not wearing stockings a high incidence of silent DVT was detected (1 in 10).\u00a0 Volunteers wearing stockings did not suffer any DVTs.\u00a0 This study has been criticised on various grounds, especially the fact that DVT was so common in the group not wearing stockings.\u00a0 All the DVTs detected were very small and present in the calf veins which is an area where the ultrasound scan can have difficulty being accurate.\u00a0 Despite this it is clear that this finding requires further detailed studies to either confirm or refute the findings. This study also demonstrated that care must be taken with compression stocking and particularly the tight retaining band in the upper calf. This can cause phlebitis after prolonged compression of underlying varicose veins.[\/vc_column_text][\/vc_tta_section][vc_tta_section title=&#8221;How is Deep Venous Thrombosis diagnosed?&#8221; tab_id=&#8221;1759351791403-26f4bf80-0d95&#8243;][vc_column_text css=&#8221;&#8221;]\n<h2 class=\"wp-block-heading\">How is Deep Venous Thrombosis diagnosed?<\/h2>\n<p>The diagnosis of DVT may be suspected by the symptoms and signs in an individual patient and the circumstances of the patient.\u00a0 For instance, pain and swelling in one calf, in a patient after major surgery or a long flight, will raise a suspicion of DVT, which will require exclusion with further tests.\u00a0 The same symptoms that develop following a game of squash are more likely to be due to a muscle injury.\u00a0 Clinical diagnosis alone is unreliable and inaccurate and further tests are required.<\/p>\n<figure id=\"attachment_123\" aria-describedby=\"caption-attachment-123\" style=\"width: 300px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-123\" src=\"https:\/\/cmcdeploytwo.co.nz\/vsoanz\/wp-content\/uploads\/2025\/10\/Thrombus-in-the-vein-.jpg\" alt=\"Thrombus in the vein\" width=\"300\" height=\"404\" srcset=\"https:\/\/cmcdeploytwo.co.nz\/vsoanz\/wp-content\/uploads\/2025\/10\/Thrombus-in-the-vein-.jpg 300w, https:\/\/cmcdeploytwo.co.nz\/vsoanz\/wp-content\/uploads\/2025\/10\/Thrombus-in-the-vein--223x300.jpg 223w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-123\" class=\"wp-caption-text\">Thrombus in the vein<\/figcaption><\/figure>\n<p>The main test used to exclude or diagnose DVT is Duplex ultrasound scanning. This is a simple, painless test with a high degree of accuracy. Ultrasound can demonstrate clot within the deep veins. It is particularly accurate in the larger veins of the leg. The image on the left is an ultrasound scan showing thrombus (the blood clot) with some blood flowing around the clot.<\/p>\n<p>In the calf veins ultrasound is more difficult, but can be accurate in experienced hands. Unfortunately ultrasound can be time consuming and costly. As the majority of tests will be normal, clinicians are trying to find ways to reduce the number of normal scans performed. One way to do this is to measure D-dimer levels on a blood test.<\/p>\n<p>Measurement of D-dimer (a marker of coagulation or blood clotting) in blood is gaining increasing popularity as a rapid and inexpensive screening test. This test is especially useful for ruling out DVT if the results are normal. In a patient at low or moderate risk, a normal D-dimer test can safely rule out DVT (Fancher TL, 2004). If the D-dimer is abnormal, then confirmation of DVT using Duplex scanning is important. This is because other situations where blood clotting occurs can lead to an increase in D-dimer levels. No test is foolproof, and in a patient with a high risk of DVT and a normal D-dimer Duplex scanning should be performed.<\/p>\n<p>Other tests such as venography and plethysmography are much less commonly used today, but venography is the most accurate test in the diagnosis of DVT.[\/vc_column_text][\/vc_tta_section][vc_tta_section title=&#8221;Can deep venous thrombosis be treated?&#8221; tab_id=&#8221;1759352035950-c5e3ba36-4f76&#8243;][vc_column_text css=&#8221;&#8221;]\n<h2 class=\"wp-block-heading\">Can deep venous thrombosis be treated?<\/h2>\n<p>Fortunately, a DVT can be treated and the risk of immediate serious complications can be reduced.\u00a0 The main treatment is anticoagulation and compression stockings.<\/p>\n<p>Anticoagulation is a treatment that thins the blood making it less likely to clot.\u00a0 This is usually started using an injection (heparin) which is continued for between 5 and 10 days. This is because heparin acts very rapidly helping reduce the risk of further problems as soon as it is started.\u00a0 When heparin is started after a clot has formed, it is started at a higher (therapeutic) dose.\u00a0 Most patients today receive low molecular weight heparin (LMWH) as it can be given as a once or twice daily dose and is as effective as the older unfractionated heparins which require daily monitoring with blood tests.<\/p>\n<p>While still having heparin, a further treatment with warfarin is started.\u00a0 Warfarin also thins the blood, but it can be taken in a tablet form.\u00a0 These tablets act more slowly and it often takes 4 or 5 days before the blood is thinned sufficiently so that the heparin can be stopped.\u00a0 Warfarin is continued for between 3-6 months and requires regular monitoring of blood clotting tests to make sure it is working properly.\u00a0 If you have had more than one DVT it may be important to remain on warfarin for the rest of your life. Warfarin is very inconvenient to take because of the regular monitoring that is required. There are newer drugs becoming available and undergoing trials which may replace warfarin over the next 5-10 years.[\/vc_column_text][\/vc_tta_section][vc_tta_section title=&#8221;Other treatments for DVT&#8221; tab_id=&#8221;1759352066357-54b1e83f-37d2&#8243;][vc_column_text css=&#8221;&#8221;]\n<h2 class=\"wp-block-heading\">Other treatments for DVT<\/h2>\n<p><strong>Compression stockings \u2013<\/strong>\u00a0these are graduated compression stockings and are routinely recommended as they can help with symptomatic relief of swelling and discomfort.\u00a0 They also increase blood flow in the veins.\u00a0 In association with elevation of the affected limb they can provide very effective symptomatic relief.<\/p>\n<p>Stockings can also be used to reduce the risk of developing a DVT in patients at risk.\u00a0 Thigh or calf length stockings are effective.<\/p>\n<p><strong>Filters \u2013\u00a0<\/strong>sometimes pieces of blood clot break off from the DVT and travel to the lungs causing pulmonary embolism.\u00a0 Treatment with anticoagulation is sufficient in the majority of patients to halt this process.\u00a0 In some patients anticoagulation is dangerous or fails to stop pulmonary embolism and in these circumstances a filter can be used to protect the lungs.\u00a0 The filter is a metallic sieve which is placed in the inferior vena cava (the major vein draining the legs and trunk) and this stops clots (emboli) reaching the lungs.\u00a0 Filter usage varies considerably between different centres and surprisingly a clinical trial of filters failed to show a survival benefit (<a href=\"http:\/\/www.nejm.org\/doi\/pdf\/10.1056\/NEJM199802123380701\" target=\"_blank\" rel=\"noreferrer noopener\">Decousus H et al, 1998<\/a>).<\/p>\n<p><strong>Thrombolysis \u2013\u00a0<\/strong>actively dissolving the DVT using enzymes is attractive as it could lead to rapid resolution of symptoms and prevent damage to the venous valves and the vein walls.\u00a0 It may be most useful in patients with major DVT and the most effective technique is to use a catheter (tube) placed directly into the clot and deliver the enzyme directly to the clot. The main risk of treatment relates to bleeding in other organs such as the brain, although this occurs in only a small percentage of patients.\u00a0 It is not a routine treatment as yet and major trials (CaVent, ATTRACT, CAVA) are underway to confirm its relative benefit and safety, but it may have an important role in treating major DVT in large veins.<\/p>\n<p><strong>Surgery \u2013\u00a0<\/strong>surgery is used infrequently, but can be helpful in the presence of massive DVT especially where the limb may be at risk.\u00a0 Anticoagulation is still essential.[\/vc_column_text][\/vc_tta_section][vc_tta_section title=&#8221;Are there long term complications from a DVT?&#8221; tab_id=&#8221;1759352108921-bbc8a131-5ec2&#8243;][vc_column_text css=&#8221;&#8221;]\n<h2 class=\"wp-block-heading\">Are there long term complications from a DVT?<\/h2>\n<p>There can be long term complications from a DVT.<\/p>\n<p>In many patients as the blood clot is reabsorbed by the body the valves lining the deep veins are damaged.\u00a0 This can lead to abnormal reverse flow (reflux) in the deep veins. Over many years this can lead to high pressures in the veins around the ankle and lower calf.\u00a0 In some people this may lead to the development of leg ulcers and chronic venous insufficiency.\u00a0 This is called the post-thrombotic syndrome or post-phlebitic limb.\u00a0 This syndrome develops in about 43-47% of patients (<a href=\"http:\/\/www.dkmic.de\/bibliothek\/literatur\/26.%20Management%20of%20deep%20vein%20thrombosis%20and%20prevention%20of%20post-thrombotic%20syndrome.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Strijkers et al, 2011<\/a>) with a first time proximal (in the larger veins, above the lower leg) DVT even with standard treatment, and some sources quote rates up to 60%.\u00a0 The post-thrombotic syndrome is likely to be much worse if blockages remain in the veins and are not cleared by the body\u2019s natural mechanisms. The incidence of post-thrombotic syndrome can be reduced by wearing below knee graduated compression stockings (Kyrle and Eichinger, 2005). Either Class 1 or Class II stockings will be helpful. Pain and swelling is reduced initially and with longer term use (1-2 years) the incidence of severe post-thrombotic syndrome is also significantly reduced by about 50% at 2 years.<\/p>\n<p>Sometimes the blood clot cannot be reabsorbed by the body and the deep veins remain permanently blocked.\u00a0 In these unusual circumstances the superficial veins enlarge to form varicose veins, so that blood can drain from the legs.\u00a0 It is important that these superficial varicose veins are not removed, because they are acting as an important pathway for blood to drain from the leg.[\/vc_column_text][\/vc_tta_section][vc_tta_section title=&#8221;Useful DVT links&#8221; tab_id=&#8221;1759014929506-4e94bf49-783d8990-cefe&#8221;][vc_column_text css=&#8221;&#8221;]\n<h2 class=\"wp-block-heading\">Useful DVT links<\/h2>\n<p><a href=\"http:\/\/en.wikipedia.org\/wiki\/Deep_vein_thrombosis\">http:\/\/en.wikipedia.org\/wiki\/Deep_vein_thrombosis<\/a><\/p>\n<p><a href=\"http:\/\/www.nhs.uk\/conditions\/deep-vein-thrombosis\/Pages\/Introduction.aspx\">http:\/\/www.nhs.uk\/conditions\/deep-vein-thrombosis\/Pages\/Introduction.aspx<\/a><\/p>\n<p><a href=\"http:\/\/www.outcomes-umassmed.org\/dvt\/\">http:\/\/www.outcomes-umassmed.org\/dvt\/<\/a><\/p>\n<p><a href=\"http:\/\/aviationmedicine.com\/articles\/index.cfm?fuseaction=displayArticle&amp;articleID=33&amp;navID=67&amp;contentID=67\" target=\"_blank\" rel=\"noreferrer noopener\">http:\/\/www.aviationmedicine.com<\/a>\u00a0\u2013 Excellent site on relationship of DVT to air travel with exhaustive references<\/p>\n<p><a href=\"http:\/\/www.airhealth.org\/\">http:\/\/www.airhealth.org\/<\/a><\/p>\n<p><a href=\"http:\/\/www.economyclasssyndrome.net\/\">http:\/\/www.economyclasssyndrome.net\/<\/a><\/p>\n<p><a href=\"http:\/\/www.nlm.nih.gov\/medlineplus\/ency\/article\/000156.htm\">http:\/\/www.nlm.nih.gov\/medlineplus\/ency\/article\/000156.htm<\/a><\/p>\n<p><a href=\"http:\/\/www.publications.parliament.uk\/\">http:\/\/www.publications.parliament.uk<\/a><\/p>\n<p><a href=\"http:\/\/www.medicine.ox.ac.uk\/bandolier\/\">http:\/\/www.medicine.ox.ac.uk\/bandolier\/<\/a><\/p>\n<p><a href=\"http:\/\/www.medicine.ox.ac.uk\/bandolier\/band17\/b17-1.html\" target=\"_blank\" rel=\"noreferrer noopener\">http:\/\/www.medicine.ox.ac.uk\/bandolier\/band17\/b17-1.html \u2013\u00a0<\/a>Evidence base for low molecular weight heparins<\/p>\n<p><a href=\"http:\/\/www.medicine.ox.ac.uk\/bandolier\/band16\/b16-4.html\" target=\"_blank\" rel=\"noreferrer noopener\">http:\/\/www.medicine.ox.ac.uk\/bandolier\/band16\/b16-4.html<\/a>\u00a0\u2013 Evidence base for graduated compression stockings in prevention of DVT<\/p>\n<p><a href=\"http:\/\/www.sign.ac.uk\/guidelines\/fulltext\/36\/section2.html\" target=\"_blank\" rel=\"noreferrer noopener\">http:\/\/www.sign.ac.uk\/guidelines\/fulltext\/62\/index.html<\/a>\u00a0\u2013 Scottish guidelines on prophylaxis of venous thromboembolism<\/p>\n<p><a href=\"http:\/\/www.sign.ac.uk\/guidelines\/fulltext\/36\/section2.html\" target=\"_blank\" rel=\"noreferrer noopener\">http:\/\/www.sign.ac.uk\/guidelines\/fulltext\/36\/section2.html<\/a>\u00a0\u2013 Guidelines on treatment of venous thromboembolism<\/p>\n<p><a href=\"http:\/\/hcd2.bupa.co.uk\/fact_sheets\/mosby_factsheets\/Deep_Vein_Thrombosis.html\">http:\/\/hcd2.bupa.co.uk\/fact_sheets\/mosby_factsheets\/Deep_Vein_Thrombosis.html<\/a><\/p>\n[\/vc_column_text][\/vc_tta_section][vc_tta_section title=&#8221;References&#8221; tab_id=&#8221;1759015003224-6e58c0d1-e0df8990-cefe&#8221;][vc_column_text css=&#8221;&#8221;]\n<h2>References<\/h2>\n<p><a href=\"http:\/\/www.bmj.com\/content\/329\/7470\/821.pdf+html\" target=\"_blank\" rel=\"noreferrer noopener\">Fancher TL, White RH, Kravitz RL. Combined use of rapid D-dimer testing and estimation of clinical probability in the diagnosis of deep vein thrombosis: systematic review.<\/a>\u00a0Brit Med J 2004; 329: 821-829.<br \/>\n<a href=\"http:\/\/www.ncbi.nlm.nih.gov\/pubmed\/2900413\" target=\"_blank\" rel=\"noreferrer noopener\">Cruickshank JM, Gorlin R, Jennett B. Air travel and thrombotic episodes: the economy class syndrome.<\/a>\u00a0Lancet 1988; 11: 497-98.<br \/>\n<a href=\"http:\/\/www.nejm.org\/doi\/full\/10.1056\/NEJM195401282500404\" target=\"_blank\" rel=\"noreferrer noopener\">Homans J. Thrombosis of the deep leg veins due to prolonged sitting.<\/a>\u00a0New Engl J Med 1954; 250: 148-149.<br \/>\n<a href=\"http:\/\/www.medicine.wisc.edu\/~williams\/airtravelcoag.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Schreijer AJM et al. Activation of coagulation system during air travel: a crossover study.<\/a>\u00a0Lancet 2006; 367: 832-38.<br \/>\n<a href=\"http:\/\/www.bmj.com\/content\/339\/bmj.b4583.pdf+html\" target=\"_blank\" rel=\"noreferrer noopener\">Sweetland S et al. Duration and magnitude of the potoperative risk of venous thromboembolism in middle-aged women: prospective cohort study.<\/a>\u00a0Brit Med J 2009; 339: b4583 .<br \/>\n<a href=\"http:\/\/www.bmj.com\/content\/327\/7423\/1072.pdf+html\" target=\"_blank\" rel=\"noreferrer noopener\">Kelman CW, Kortt MA, Becker NG et al. Deep vein thrombosis and air travel: record linkage study.<\/a>\u00a0Brit Med J 2003; 327: 1072-76.<br \/>\n<a href=\"http:\/\/onlinelibrary.wiley.com\/store\/10.1002\/14651858.CD001484.pub2\/asset\/CD001484.pdf?v=1&amp;t=hf2wyq8l&amp;s=7813db74db63846bba070bcd30226be866484d73\" target=\"_blank\" rel=\"noreferrer noopener\">Sachdeva A, Dalton M, Amaragiri SV, Lees T. Elastic compression stockings for prevention of deep venous thrombosis.<\/a>\u00a0Cochrane Rev 2010, Issue 7.<br \/>\n<a href=\"http:\/\/www.medicine.wisc.edu\/~williams\/compression_stockings_trial.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">CLOTS Trial Collaboration. Effectiveness of thigh-length graduated compression stocking sto reduce the risk of deep vein thrombosis after stroke (CLOTS Trial 1): a multicentre, randomised controlled trial.<\/a>\u00a0Lancet 2009; 373: 1958-1965.<br \/>\n<a href=\"http:\/\/bvi.ecssrv.net\/files\/2011\/11\/Lancet2001.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Scurr JH, Machin SJ, Bailey-King S et al. Frequency and prevention of symptomless deep vein thrombosis in long haul flights: a randomised trial.<\/a>\u00a0 Lancet 2001; 357: 1485-89.<br \/>\n<a href=\"http:\/\/biblioteca-innsz.org.mx:8080\/xmluiNutricion\/bitstream\/handle\/123456789\/9861\/2970.pdf?sequence=1\" target=\"_blank\" rel=\"noreferrer noopener\">Labropoulos N, Spentzouris G, Gasparis AP, Meissner M. Impact and clinical significance of recurrent venous thromboembolism.\u00a0<\/a>Brit J Surg 2010; 97: 989-999. .<br \/>\n<a href=\"http:\/\/www.ncbi.nlm.nih.gov\/pubmed\/15472584\" target=\"_blank\" rel=\"noreferrer noopener\">Fraser DGW, Moody AR, Martel A, Morgan PS. Re-evaluation of iliac compression syndrome using magnetic resonance imaging in patients with acute deep venous thromboses.<\/a>\u00a0J Vasc Surg 2004; 40: 604-11.<br \/>\n<a href=\"http:\/\/www.ncbi.nlm.nih.gov\/pubmed\/15472585\" target=\"_blank\" rel=\"noreferrer noopener\">Fraser DGW, Moody AR, Martel A, Morgan PS. Iliac compression syndrome and recanalization of femoropopliteal and iliac venous thrombosis: a prospective study with magnetic resonance venography.<\/a>\u00a0J Vasc Surg 2004; 40: 612-19.<br \/>\n<a href=\"http:\/\/www.ncbi.nlm.nih.gov\/pmc\/articles\/PMC1352055\/pdf\/bmj33200215.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Blann AD, Lip GYH. Venous thromboembolism.<\/a>\u00a0Brit Med J 2006; 332: 215-9.<br \/>\n<a href=\"http:\/\/www.medsp.umontreal.ca\/IRSPUM_DB\/pdf\/20528.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Kahn SR, Schrier I, Julian JA et al. Determinants and time course of the postthrombotic syndrome after acute deep venous thrombosis.<\/a>\u00a0Ann Int Med 2008; 149(10): 698-707.<br \/>\n<a href=\"http:\/\/www.nejm.org\/doi\/pdf\/10.1056\/NEJM199802123380701\" target=\"_blank\" rel=\"noreferrer noopener\">Decousus H, Leizorovicz A, Parent F, et al. A clinical trial of vena caval filters in the prevention of pulmonary embolism in patients with proximal deep-vein thrombosis. Prevention du Risque d\u2019Embolie Pulmonaire par Interruption Cave Study Group.<\/a>\u00a0N Engl J Med 1998 Feb 12; 338(7): 409-15.<br \/>\n<a href=\"http:\/\/www.dkmic.de\/bibliothek\/literatur\/26.%20Management%20of%20deep%20vein%20thrombosis%20and%20prevention%20of%20post-thrombotic%20syndrome.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Strijkers RHW, Cate-Hoek AJ, Bukkems SFFW, Wittens CHA. Management of deep vein thrombosis and prevention of post-thrombotic syndrome.<\/a>\u00a0Brit Med J 2011; 343:d5916 .<br \/>\n<a href=\"http:\/\/www.ncbi.nlm.nih.gov\/pubmed\/15794972\" target=\"_blank\" rel=\"noreferrer noopener\">Kyrle PA, Eichinger S. Deep vein thrombosis.<\/a>\u00a0Lancet 2005; 365: 1163-74.<br \/>\n<a href=\"http:\/\/onlinelibrary.wiley.com\/store\/10.2310\/7060.2000.00047\/asset\/7060.2000.00047.pdf?v=1&amp;t=hf64nut4&amp;s=787200017cd3c5d79e2bce4327cc41d3aabe7b42\" target=\"_blank\" rel=\"noreferrer noopener\">Giangrande PLF. Thrombosis and Air Travel.\u00a0<\/a>\u00a0Aviation Health Institute. 1999.<br \/>\n<a href=\"http:\/\/annals.org\/article.aspx?articleid=744631\" target=\"_blank\" rel=\"noreferrer noopener\">Chandra D, Parisini E, Mozaffarian D. Metaanalysis: Travel and risk for venous thromboembolism.<\/a>\u00a0Ann Int Med 2009; 151(3); 180-90.[\/vc_column_text][\/vc_tta_section][\/vc_tta_tour][\/vc_column][\/vc_row]\n<\/div>","protected":false},"excerpt":{"rendered":"<p>[vc_row full_width=&#8221;stretch_row&#8221; content_placement=&#8221;middle&#8221; equal_height=&#8221;yes&#8221; rtl_reverse=&#8221;yes&#8221; remove_bottom_col_margin=&#8221;true&#8221; columns_right=&#8221;yes&#8221; wpex_bg_color=&#8221;#03a3de&#8221; min_height=&#8221;350px&#8221;][vc_column width=&#8221;1\/2&#8243;][\/vc_column][vc_column width=&#8221;1\/2&#8243;][vc_column_text css=&#8221;.vc_custom_1759351435113{padding-top: 20px !important;padding-bottom: 20px !important;}&#8221; color=&#8221;#fefefe&#8221;] Deep Venous Thrombosis (DVT) [\/vc_column_text][\/vc_column][\/vc_row][vc_row css=&#8221;.vc_custom_1759015527111{margin-top: 60px !important;}&#8221;][vc_column][vc_tta_tour controls_size=&#8221;md&#8221; active_section=&#8221;1&#8243;][vc_tta_section title=&#8221;What is a deep vein or venous thrombosis (DVT)?&#8221; tab_id=&#8221;1759012899351-dcaaabe1-cd5c8990-cefe&#8221;][vc_column_text css=&#8221;&#8221;] What is a deep vein or venous thrombosis (DVT)? There are two main groups of veins in&hellip;<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-118","page","type-page","status-publish","hentry","entry","no-media"],"_links":{"self":[{"href":"https:\/\/cmcdeploytwo.co.nz\/vsoanz\/index.php\/wp-json\/wp\/v2\/pages\/118","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cmcdeploytwo.co.nz\/vsoanz\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/cmcdeploytwo.co.nz\/vsoanz\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/cmcdeploytwo.co.nz\/vsoanz\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/cmcdeploytwo.co.nz\/vsoanz\/index.php\/wp-json\/wp\/v2\/comments?post=118"}],"version-history":[{"count":4,"href":"https:\/\/cmcdeploytwo.co.nz\/vsoanz\/index.php\/wp-json\/wp\/v2\/pages\/118\/revisions"}],"predecessor-version":[{"id":236,"href":"https:\/\/cmcdeploytwo.co.nz\/vsoanz\/index.php\/wp-json\/wp\/v2\/pages\/118\/revisions\/236"}],"wp:attachment":[{"href":"https:\/\/cmcdeploytwo.co.nz\/vsoanz\/index.php\/wp-json\/wp\/v2\/media?parent=118"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}