HOW I DO – DVT – Specific Sites – PART – 17
HOW I DO – DVT – Specific Sites – PART – 17
(All the articles published in past are available at www.shyamhemoncclinic.com/blog/)
Question: In last part, we covered additional important points related to DVT/PE 1. Duration of anticoagulation for DVT with a transient risk factor, is 3 months only. And they do not require testing for hereditary etiology. 2. Those without a transient risk factor, need much longer anticoagulation. With some new data to show role for even lower dose anticoagulation for extended periods. At the least, aspirin, for prolonged periods, if anticoagulation is not feasible. No test, including D DIMER is useful in deciding when to stop or reduce dose. 3. For significant pulmonary embolism, same principles apply for duration of anticoagulation. Except for incidentally detected subsegmental emboli, who do not need anticoagulation, unless they are high risk for DVT e.g. active cancer. 4. Goal INR for all indications is between 2-3. We also discussed reversal of warfarin – for those with bleeding and for those with high INR but no bleeding. We discussed reversal of DOAC also, with specific antidote as first choice. If not available, PCC. Dialysis for dabigatran. 5. For OBESE patients, standard DOAC dosing can be used up to 120 kg weight. 6. When to treat DVT as outpatient from day one. 7. Stick to one DOAC as far as possible, so that whole team is familiar with right dosing and administration details.
Are there any other important points related to DVT/PE that we need to highlight?
Answer: Yes this is a very wide topic. But let us briefly review Thrombosis of Specific Sites. Since most common DVT site is leg, most articles, guidelines are about leg DVT. But other sites need different evaluation and planning.
- Distal leg (Calf) DVT – Risk of pulmonary embolism is extremely low with distal dvt i.e. beyond popliteal vein. All the risk that we have been talking about, is related to Proximal DVT. Hence, these can be observed, without any anticoagulation, with serial monitoring by venous doppler, once a week. If they do not progress within two weeks, risk of extension to proximal dvt then is very low. As these thromboses resolve in about 30 percent of cases spontaneously, some advocate serial monitoring.
However, since about 70% do progress to proximal dvt, some advocate anticoagulation, as for proximal dvt. In practice, we look at risk benefit ratio, like in most medical settings. If bleeding risk is high, and/or no other risk factors for dvt, monitoring is preferred. Also provided patient is reliable for monitoring. If bleeding risk is low, or strong risk factors for dvt, like active cancer, start anticoagulation. Duration is same as for proximal dvt.
Incidentally detected, small dvt or with minimal symptoms, and no risk factors, are the ones that can be avoided anticoagulation by serial monitoring. That is the goal, to avoid treatment for those with low risk.
- Upper Extremity (arm) DVT – this is another controversial area. When I was in fellowship, most considered this low risk for pulmonary embolism, and hence were not anticoagulated or only for a short time. For those who have dvt associated with a central line or PICC line, removal of catheter and a short anticoagulation is perhaps still ok. When need for a central line/PICC is critical, and replacement is not easy, we keep line and anticoagulate.
However for others without such obvious local factor, now they are considered same as leg proximal dvt, and treated accordingly with standard dose and duration of anticoagulation.
- Cerebral Venous Sinus Thrombosis – CVTS – This is not as common as leg dvt, but certainly not rare. A potentially serious site. However, if patient is diagnosed in time, most people have excellent neurological recovery, generally complete. With standard anticoagulation as for leg dvt i.e. LMWH in acute phase, followed by DOAC or Warfarin after initial few days. Interestingly, duration of anticoagulation required is short here i.e. 3 to 6 months, or some give 12 months. And relapse is rare. Evaluation includes standard risk factors for dvt. But mostly no obvious risk factors exist, such as immobilization, surgery, cancer, hereditary etiology. We find very high homocysteine levels in India as one associated factor more frequently however. Possibly due to low vitamin B12 levels. Also, our most common patients are young adults. Frequently with erratic eating habits. In western studies, homocysteine levels are about 15-30 when they say high, and is considered a very weak risk factor for dvt in general. But mine and other Indian colleagues experience is that in India, we see very high levels upwards of 100-150. This may be important and true association.
- Mesenteric Vein Thrombosis – This site is more likely to lead to serious morbidity or mortality compared with cerebral venous sinus thrombosis. Common complication is small intestine gangrene, requiring removal of a large portion, leading to significant morbidity, depending on length removed. Of course, many can be treated with anticoagulation alone, if no gangrene, diagnosed and treated in time. This site has more frequent association with Myeloproliferative Neoplasm for some reason. Hence, even with normal CBC, we test for these especially JAK 2 mutation. Patients may present with dvt, up to two years before they develop full signs of MPN. Other risk factors for dvt of course are to be looked at as usual. If they survive first event, second event is potentially fatal or very morbid. Hence lifelong anticoagulation is advisable. Even if no risk factor is found.
Some patients are diagnosed with chronic thrombosis. Their management is not clear. In most cases we observe, unless there is a significant risk factor for recurrence. Then we anticoagulate long term.
November 8th 2025
Dr Chirag A. Shah; M.D. Oncology/Hematology (USA), 9998084001. Diplomate American Board of Oncology and Hematology. Ahmedabad. drchiragashah@gmail.com www.shyamhemoncclinic.com