Hello Blood & Clots/CanadiEM community!
Before we post our blog series on thrombosis and bleeding, we encourage you to test your initial knowledge by going through a few brief case scenarios. These cases were originally posted as part of our needs assessment in Fall 2016, and you can find the answers after each question below.
The first few quizlets can be found here: Quizlet 1, Quizlet 2, Quizlet 3, Quizlet 4.
All the content from the Blood & Clots series can be found here.
-Blood & Clots Editorial Team
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A 71 year old female presents with several weeks of right leg swelling. This has been progressive and persistent swelling. She denies symptoms of chest pain, pleurisy, and shortness of breath. Her PMHx includes hypothyroidism, hypertension, GERD, and depression. Her medications include el-troxin, bisoprolol, pantoprazole, Effexor.
Vital signs are stable and examination of the right leg reveals pitting edema to the mid-shin and tenderness to palpation of the calf. An ultrasound confirms diagnosis of deep vein thrombosis (DVT) involving the popliteal vein and femoral vein of the right leg. Her lab parameters are: Hb 107 g/L, Plt 179 x109, creatinine clearance (CrCl) 56 mL/min (calculated by Cockcroft-Gault). Additional history reveals no provoking factors such as trauma, immobilization or recent surgery. There is no history of malignancy and no previous bleeding concern. She reports 30 lb weight loss over the last 6 months.
Question 1: What treatment options are available for this patient?
A) Low-molecular-weight-heparin (LMWH) in combination with vitamin K antagonist (VKA) with target INR of 2.0-3.0
B) IV unfractionated heparin (UFH) in combination with vitamin K antagonist (VKA) with target INR of 2.0-3.0
C) Rivaroxaban 15 mg BID X 3 weeks then 20 mg daily
D) Apixaban 10 mg BID X 7 days then 5 mg BID
E) LMWH for 5 days then dabigatran 150 mg twice daily
Answer to Question 1
A, C, D, or E) LMWH bridging to Warfarin; Rivaroxaban; Apixaban; or Dabigatran
IV heparin would be indicated if the patient had severe renal failure with creatinine clearance < 30 mL/min. This also requires admission to hospital.
All other options are acceptable as our patient is stable and does not require admission. One practical consideration is that LMWH injections and warfarin are burdensome. Meanwhile both rivaroxaban and apixaban can be started as oral options, without the need for LMWH. Both of these direct oral anticoagulants are available via Limited Use codes in Ontario for a 6 month duration.
Stay tuned for a future post in the next few months that will delve into anticoagulant selection for VTE in greater depth!
Question 2: Because this was an unprovoked DVT, you want to perform malignancy screening on your patient. What tests should you consider?
A) Complete history and physical examination, routine investigations: CBC, electrolytes, renal function, LFTs, chest X-ray
B) Upper and lower endoscopy
C) Mammography/pap smear
D) CT scan of the abdomen
E) Fecal occult blood test
Answer to Question 2
A, B, C) History and physical exam/routine labs/CXR; endoscopy; mammogram and pap smear
The SOME trial (PMID: 26095467) compared limited screening to limited screening plus abdominal CT scan in patients with first unprovoked VTE. Limited screening included: Complete history and physical examination, routine investigations: CBC, electrolytes, renal function, LFTs, CXR and age and gender appropriate screening if not performed during the year prior to VTE diagnosis. In our patient mammography is appropriate; Pap smear is recommended in women between age 18 to 70 who have ever been sexually active. Addition of CT abdomen to limited screening was not clinically significant in identifying occult cancers. Given this patient’s post-menopausal anemia, referral for endoscopy is reasonable.
Question 3: Due to the presence of anemia in your post-menopausal patient, a colonoscopy has been arranged. She is anticoagulated with rivaroxaban 20 mg daily. How to you manage her anticoagulation around the time of procedure?
A) Continue anticoagulant
B) Measure INR the day before surgery and base decision on the result
C) Hold rivaroxaban 5 days before the procedure and given low molecular weight heparin bridging
D) Hold rivaroxaban starting on pre-op day 1
E) Hold rivaroxaban starting on pre-op day 2
Answer to Question 3
D) Hold Rivaroxaban starting on Pre-Op Day 1
INRs are not used to evaluate the anticoagulant effect of rivaroxaban. Continuing anticoagulation is at the discretion of the endoscopist and one does not anticipate the possibility of biopsies. The patient’s CrCl is above 50 mL/min and the colonoscopy is classified as a low-risk bleeding procedure, so the patient needs to miss one dose of anticoagulation (pre-op day 1). The half-life of rivaroxaban in patients with CrCl >50 mL/min is 7-10 hours. If CrCl < 50 mL/min then it is suggested to miss 2 doses of rivaroxaban (hold rivaroxaban starting on pre-op day 2).