TPI's & soft-tissue injections are analogous to EMGs. Here is what the AANEM says:
What are the risks associated with performing an EMG on a patient taking Coumadin?
Bleeding and hematoma are potential risks of needle EMG in patients with or without disorders of hemostasis. There is limited data regarding the incidence of clinically significant bleeding complications from needle EMG and additional risks in patients who are receiving antiplatelet or anticoagulant therapy or who suffer from thrombocytopenia or clotting factor deficiencies. Additionally, the use of subcutaneous partially fractionated heparin (e.g. Lovenox®) is becoming more commonplace. The degree of anticoagulation is not readily measurable, which may also result in increased risk of hemorrhagic complications. Some practitioners utilize vapocoolant spray to improve hemostasis, although there are no studies assessing the utility of this technique. Likewise, no data indicates that various needle parameters (e.g. gauge, monopolar vs. concentric, etc.) present different risks for bleeding complications. In a retrospective, uncontrolled study of patients who were not receiving anticoagulants, 14 asymptomatic paraspinal muscle hematomas were identified by MRI in 5 of 45 muscles. In a survey of 47 electrodiagnostic laboratories with ACGME-approved fellowships, 3 laboratories reported a single instance of serious bleeding complications (requiring intervention) occurring in anticoagulated patients.31 One laboratory reported two instances of serious bleeding complications. In the only prospective study, subclinical hematomas were visualized by ultrasonography in 3 of 209 muscles. There was no statistical difference in hematoma rates in subjects taking anti-platelet or anticoagulant therapy compared to control subjects. 40 There are few published case reports of bleeding complications following needle EMG. These include a 64-year-old man anticoagulated with coumadin (prothrombin time = 28s [control = 12.4s], partial thromboplastin time = 68 [26]). He developed subcutaneous bleeding following needle EMG examination with a drop in hematocrit from 43 to 29%, resulting in angina and requiring blood transfusion.13 There are two cases of hematoma and compartment syndrome affecting the calf27 (73-year-old man with recent aspirin usage) and forearm60 (34-year-old woman with no bleeding risks). There is an additional report of calf hematoma and pseudoaneurysm in an 81-year-old woman with an INR = 2.5. 53 The risks and benefits of needle EMG examination should be considered in patients with known disorders of hemostasis, and needle EMG should be performed with added caution. Each case should be considered individually with regard to the potential benefits of the study relative to the risks of intramuscular hemorrhage or other bleeding. If the decision is made to perform needle EMG in such a patient, it is advisable to first examine small, superficial muscles to watch for bleeding problems. Prolonged pressure over the needle site will usually produce hemostasis.
Excerpt from the AANEM position statement
Intra-articular joint injections - shoulder, hip, and knee - are different. The risk of a hemarthrosis, while small, is nevertheless real. Because the evidence on what to do doesn't exist we should probably use 'shared decision making' and leave the choice to the patient/family about whether or not to bridge them prior to the injection. Not documenting the offer to bridge in your consent, IMO, a sin of omission in the event of a hemarthrosis.
I've had both a knee hemarthrosis and significant hematoma formation with an EMG.
