Please select the eligibility criteria that correspond to the clinical trial below.
Title: A Pilot Study to Determine the Feasibility of Conducting a Randomized Clinical Trial Comparing Fondaparinux Sodium (Arixtra) Once Daily With Enoxaparin (Lovenox®) Twice Daily With Respect to Preventing VTE After Bariatric Surgery in Obese Patients
Brief Summary: This pilot study is designed to determine the feasibility of conducting a randomized clinical trial comparing fondaparinux sodium (Arixtra) once daily with enoxaparin (Lovenox®) twice daily with respect to preventing deep vein thrombosis (DVT) and pulmonary embolism (PE) after bariatric surgery in obese patients.


Options:
A: Inclusion Criteria:

1. Men or women 18 years or older.
2. Body mass index (BMI) of 35kg/m2 or greater.
3. Undergoing laparoscopic bariatric surgery, i.e., laparoscopic sleeve gastrectomy, laparoscopic Roux-en Y gastric bypass or laparoscopic duodenal switch.

Exclusion Criteria:

1. History of previous deep vein thrombosis.
2. History of previous pulmonary emboli.
3. History of documented clotting/coagulation disorder.
4. History of cancer.
5. Weight \< 50 kg or \> 200 kg or unable to fit in MRI scanner.
6. Presence of metallic foreign bodies
7. Recent history of smoking (within the last year).
8. History of venous stasis disease.
9. History of obesity hypoventilation syndrome.
10. Patients who are unable to lay flat for extended periods of time or are claustrophobic.
11. Patients who have a pacemaker, an implanted defibrillator or certain other implanted or electronic or metallic devices (implanted medical or metallic devices, shrapnel, or metal).
12. History of hypersensitivity reaction to anticoagulation products.
13. History of HIT (Heparin Induced Thrombocytopenia.
14. History of Renal Insufficiency (Creatinine Clearance \< 50).
15. Active clinically significant bleeding.
16. Acute bacterial endocarditis.
17. BMI \> 60.
18. Patients with metallic foreign body or implant (unable to have an MRV study).
B: The inclusion criteria are:

1. laboratory confirmed diagnosis of SARS-CoV-2 via reverse transcriptase polymerase chain reaction as per the World Health Organization protocol or by nucleic acid based isothermal amplification.Positive test prior to hospital admission OR within first 5 days (i.e. 120 hours) after hospital admission;
2. admitted to hospital for COVID-19;
3. one D-dimer value above ULN (5 days (i.e. 120 hours) of hospital admission) and either: a) D-Dimer ≥2 times ULN; or b) D-dimer above ULN and oxygen saturation ≤ 93% on room air;
4. ≥18 years of age;
5. informed consent from the patient (or legally authorized substitute decision maker).

The exclusion criteria are:

1. pregnancy;
2. hemoglobin \<80 g/L in the last 72 hours;
3. platelet count \<50 x 10\^9/L in the last 72 hours;
4. known fibrinogen \<1.5 g/L (if testing deemed clinically indicated by the treating physician prior to the initiation of anticoagulation);
5. known INR \>1.8 (if testing deemed clinically indicated by the treating physician prior to the initiation of anticoagulation);
6. patient already on intermediate dosing of LMWH that cannot be changed (determination of what constitutes an intermediate dose is to be at the discretion of the treating clinician taking the local institutional thromboprophylaxis protocol for high risk patients into consideration);
7. patient already on therapeutic anticoagulation at the time of screening (low or high dose nomogram UFH, LMWH, warfarin, direct oral anticoagulant (any dose of dabigatran, apixaban, rivaroxaban, edoxaban);
8. patient on dual antiplatelet therapy, when one of the agents cannot be stopped safely;
9. known bleeding within the last 30 days requiring emergency room presentation or hospitalization;
10. known history of a bleeding disorder of an inherited or active acquired bleeding disorder;
11. known history of heparin-induced thrombocytopenia;
12. known allergy to UFH or LMWH;
13. admitted to the intensive care unit at the time of screening;
14. treated with non-invasive positive pressure ventilation or invasive mechanical ventilation at the time of screening (of note: high flow oxygen delivery via nasal cannula is acceptable and is not an exclusion criterion).
15. imminent death according to the judgement of the most responsible physician
16. enrollment in another clinical trial of antithrombotic therapy involving pre-intensive care unit hospitalized patients
C: Inclusion Criteria:

1. Positive SARS-CoV-2 diagnostic (on pharyngeal swab of deep airways material)
2. Positive pressure ventilation (either non-invasive or invasive) from \> 24 hours
3. Invasive mechanical ventilation from \< 96 hours
4. P/F ratio \< 150
5. D-dimer level \> 6 x upper limit of local reference range
6. PCR \> 6 fold upper limit of local reference range

Exclusion Criteria:

1. Age \< 18 years
2. On-going treatment with anticoagulant drugs
3. Platelet count \<100.000/mmc
4. History of heparin-induced thrombocytopenia
5. Allergy to sodium enoxaparine or other LMWH, unfractionated heparin or metylprednisolone;
6. Active bleeding or on-going clinical condition deemed at high risk of bleeding contraindicating anticoagulant treatment
7. Recent (in the last 1 month prior to randomization) brain, spinal or ophthalmic surgery
8. Chronic assumption or oral corticosteroids
9. Pregnancy or breastfeeding or positive pregnancy test. In childbearing age women, before inclusion, a pregnancy test will be performed if not available;
10. Clinical decision to withhold life-sustaining treatment or "too sick to benefit";
11. Presence of other severe diseases impairing life expectancy (e.g. patients are not expected to survive 28 days given their pre-existing medical condition);
12. Lack or withdrawal of informed consent.
D: Inclusion Criteria:

* Patients with confirmed symptomatic PE and/or DVT who have been treated for 6 to 12 months and did not interrupt anticoagulation for longer than 1 week

Exclusion Criteria:

* Legal lower age limitations (country specific) Indication for therapeutic-dosed anticoagulants Indication for antiplatelet therapy or a conventional non-steroid anti-inflammatory drug (NSAID) Hepatic disease which is associated with coagulopathy leading to a clinically relevant bleeding risk Calculated creatinine clearance \< 30 mL/min

Answer: A