Please select the eligibility criteria that correspond to the clinical trial below.
Title: BARIVA:Short Versus Extended Prophylaxis of Rivaroxaban for Venous Thromboembolism After Bariatric Surgery
Brief Summary: The aim of this study is to investigate the efficacy and safety of rivaroxaban in obese patients undergoing bariatric surgery.

The objectives are to assess the safety and feasibility of venous thromboembolism (VTE) prophylaxis and lung embolism with Rivaroxaban 10mg as an oral anticoagulant. After bariatric surgery patients receive the study medication Xarelto 10mg QD for 7, resp. 28 days.

All clinically thromboembolic events will be assessed by ultrasound or CT, respectively, as soon as apparent. In addition, patients are screened for VTE at day 28 by ultrasound to detect clinically inapparent thromboses.

In a subgroup of study patients (patients from the University Hospital Inselspital, Bern) PK/PD parameters are assessed following the last intake of rivaroxaban at day 28.


Options:
A: Inclusion Criteria:

* Patients with scheduled elective bariatric surgery or redo surgery after bariatric interventions
* Written informed consent

Exclusion Criteria:

* DVT and/or PE in the patient history
* Myocardial infarction, transient ischemic attack or stroke within 6 months of study entry
* Uncontrolled hypertension
B: Inclusion Criteria:

1. Subject (or legally authorized representative) provides written informed consent prior to initiation of any study procedures.
2. Understands and agrees to comply with planned study procedures.
3. Male or non-pregnant female adult ≥18 years of age at time of enrollment.
4. Subject consents to randomization within 72 hours of hospital admission or transfer from another facility within 72 hours of index presentation.
5. Subjects with a positive COVID-19 diagnosis by nasal swab or serologic testing.
6. Hospitalized with a requirement for supplemental oxygen.
7. Have:

   * Either a D- Dimer \> 4.0 X ULN, OR
   * Sepsis-induced coagulopathy (SIC) score of ≥4

Exclusion Criteria:

1. Indications for therapeutic anticoagulation
2. Absolute contraindication to anticoagulation including:

   1. active bleeding,
   2. recent (within 1 month) history of bleed,
   3. dual (but not single) antiplatelet therapy,
   4. active gastrointestinal and intracranial cancer,
   5. a history of bronchiectasis or pulmonary cavitation,
   6. Hepatic failure with a baseline INR \> 1.5,
   7. CrCl \< 15ml/min,
   8. a platelet count \< 25,000,
   9. a history of heparin-induced thrombocytopenia (HIT) within the past 100 days or in the presence of circulating antibodies,
   10. contraindications to enoxaparin including a hypersensitivity to enoxaparin sodium, hypersensitivity to heparin or pork products, hypersensitivity to benzyl alcohol,
   11. pregnant female,
   12. inability to give or designate to give informed consent,
   13. participation in another blinded trial of investigational drug therapy for COVID-19
C: Inclusion Criteria:

1. Adults ≥ 18 years old;
2. Evaluated in the emergency unit with probable or confirmed infection by COVID-19;
3. Time between symptoms and inclusion ≤ 07 days \*;
4. Present mild or moderate signs and symptoms, with no clear indication for hospitalization;
5. Present at least 2 risk factors for complication:

   * 65 years
   * Hypertension
   * Diabetes mellitus
   * Asthma
   * Chronic Obstructive Pulmonary Disease (COPD) or other chronic lung diseases
   * Smoking
   * Immunosuppression
   * Obesity (BMI\> 30)
   * History of non-active cancer
   * Bed restriction or reduced mobility (≥50% of the wake time without walking)
   * Previous history of VTE
   * Use of oral hormonal contraceptives

Exclusion Criteria:

1. Patients \<18 years old;
2. Hospitalization indication upon first medical care;
3. Positive test for influenza in the first visit;
4. Any known liver disease associated with coagulopathy; INR (International Normalized Ratio) \> 1.5;
5. Pregnant, lactating or with the possibility of becoming pregnant and without using an adequate contraceptive method;
6. High risk of bleeding; History of bronchiectasis or pulmonary cavitation, Significant bleeding in the last 3 months, Active gastroduodenal ulcer, history of recent bleeding (within 3 months) or a high risk of bleeding;
7. Stroke within 1 month or any history of hemorrhagic or lacunar stroke or any intracranial bleeding or any intracranial neoplasia, brain metastasis, arteriovenous malformation or brain aneurysm;
8. Severe heart failure with left ventricular ejection fraction \<30% (echocardiogram or other validated method previously documented) or symptoms of heart failure class III or IV of the New York Heart Association (NYHA);
9. Estimated glomerular filtration rate (eGFR) \<30 mL / min;
10. Clinical indication for dual antiplatelet therapy or anticoagulation therapy (VTE, atrial fibrillation / flutter, mechanical valve prosthesis);
11. Marked thrombocytopenia (platelets \<50,000 / mm3);
12. Non-cardiovascular disease that is associated with a poor prognosis, for example, active cancer (excluding non-melanoma skin cancer) defined as cancer without remission or requiring active chemotherapy or adjuvant therapies such as immunotherapy or radiation therapy or that increases the risk of an adverse reaction to the evaluated interventions;
13. History of hypersensitivity or known contraindication to rivaroxaban;
14. Systemic treatment with strong inhibitors of Cytochrome P450 3A4 (CYP3A4) and glycoprotein p (Pgp) (for example, systemic azole antimycotics, such as ketoconazole and human immunodeficiency virus \[HIV\] protein inhibitors, such as ritonavir) or strong inducers of CYP 3A4, that is, rifampicin, rifabutin, phenobarbital, phenytoin and carbamazepine;
15. Current treatment being tested;
16. Concomitant participation in another study with experimental drugs in the context of COVID;
17. Use of chloroquine or hydroxychloroquine associated with azithromycin;
18. Active cancer;
19. Other contraindications to rivaroxaban;
D: 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).

Answer: A