HOW I DO – Deep Vein Thrombosis – PART – 10
HOW I DO – Deep Vein Thrombosis – PART – 10
(All the articles published in past are available at www.shyamhemoncclinic.com/blog/)
Question: In last part, we covered some important points related to surgical clearance for patients with high aPTT. 1. Most patients with high aPTT, with normal PT, have a congenital bleeding disorder. Most common being Hemophilia. Don’t forget the APLA syndrome where aPTT is high, but patient actually has a thrombotic tendency rather than bleeding. 2. Degree of aPTT does not always correlate well with bleeding risk. 3. All high aPTT related bleeding can not be managed with FFP. Hence it is must to have a diagnosis and plan prepared before any elective procedure or surgery. 4. First evaluation is to repeat aPTT. As these tests are very sensitive, and hence errors at several levels. Fresh sample is preferred, directly collected at the laboratory. Preferably expert team regularly working on these issues i.e. specialty hematology laboratory. 5. Second test is a mixing study, to see if we are dealing with a factor deficiency or an inhibitor. 6. In general, repeat testing is recommended before labeling anyone with a specific factor deficiency. Using a freshly collected sample again. 7. Choose your lab carefully. Many subspecialties in pathology too!!
We have discussed at length related to bleeding. But we have more people dying from thrombosis now than from bleeding. In fact, deep vein thrombosis and pulmonary embolism, commonly referred to as VTE (venous thromboembolism), is the Number 1 Preventable cause of Death in hospitalized patients. Modern lifestyle, obesity, age, cancer etc are significant risk factors for development of deep vein thrombosis. Can we talk about this issue?
Answer: Certainly. This is a huge area of concern, and hence a lot of research too. So many new medicines have been developed in last 2 decades that we use regularly for VTE.
Let us start with when to suspect VTE. And how to make a diagnosis.
Many patients with VTE do not have classical signs and symptoms. Hence it is important to know high risk subsets e.g. recent Knee or Hip replacement surgery, immobile for a long duration due to any reason, obesity, cancer, major surgery especially involving pelvis, older age, pregnancy, history of VTE in past. If there is unexplained leg edema, pain, redness (either distal leg or thigh) ; shortness of breath, chest pain, drop in oxygen saturation. Any of these should lead to a suspicion for deep vein thrombosis with or without pulmonary embolism. Every patient will not have dramatic symptoms, but DVT is a potential emergency, as it can lead to pulmonary embolism. And as you rightly pointed out earlier, pulmonary embolism is the number 1 cause of preventable death in hospitalized patients. Hence if you suspect DVT, a venous doppler must be obtained same day. Occasionally, DVT can happen in veins of arm, abdomen, chest also. But most common is lower extremity. If you have symptoms suggestive of pulmonary embolism, then contrast CT scan of chest is to be obtained urgently. ECHO has additional value. And if CT is not feasible right away, ECHO can add to the suspicion. Allowing you to start empiric anticoagulation quickly. D dimer is not diagnostic, but if negative, in a case with low suspicion, it helps to rule out pulmonary embolism. It has no other value, including no value for follow up.
We were taught about Homan’s sign for diagnosis of DVT during medical school days. It is proven beyond doubt now that this is very unreliable. And one must not exclude DVT based on absence of this sign. It involves dorsiflexing foot by doctor to see if it elicits pain in calf.
Above discussion applies to both inpatients and outpatients. But if you suspect DVT, or PE, urgent action and almost always hospitalization is required. At least initially.
Que: What precautions do I need before starting anticoagulation?
Ans:. History – ensure patient does not have an absolute contraindication for anticoagulation e.g. recent intracranial bleeding, GI bleeding, ongoing bleeding, major trauma. Must check minimum CBC, PT, aPTT, Creatinine, SGPT. To ensure no severe thrombocytopenia, baseline coagulation abnormalities, major organ dysfunction. We see a fair number of patients where anticoagulation is started before obtaining these basic tests. At least a blood sample should be collected, before any anticoagulation. Even if all tests are not available, one must know platelet count before starting. This is only in a case of major emergency. Otherwise wait for all the tests mentioned above. Most patients will be low risk for bleeding. And anticoagulation should be started.
Some will have absolute contraindication as above, where you have to plan for IVC filter or other measures depending on site of thrombosis etc. Some patients will have risk factors for bleeding, but not absolute contraindications. In such patients, it is an individualized decision making. And it is better to discuss the risks and benefits with patient or immediate relatives. Since there is no right answer is here. And either decision can have severe consequences. For example, no anticoagulation can lead to death from pulmonary embolism. Frequently without major warning signs, a massive pulmonary embolism can be fatal. Whereas bleeding is frequently more disturbing, and may require a lot of interventions and cost, but in a monitored setting, it is rare to have a fatal sudden bleed. Except intracranial bleed, which does not happen without specific risk factors.
April 12th 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