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. Patients aged 50 years or older with a positive test for SARS-CoV2 in the past 5 days and eligible for ambulatory treatment.
2. Presence of respiratory symptoms (i.e. cough, sore throat, or shortness of breath) or body temperature \>37.5° C.
3. Ability of the patient to travel to the study center by private transportation, performed either by accompanying person from same household or by the patient him/herself
4. Ability to comply with standard hygiene requirements at the time of in-hospital visit, including a face mask and hand disinfectant.
5. Ability to walk from car to study center or reach it using a wheel chair transport with the help of an accompanying person from the same household also complying with standard hygiene requirements.
6. Ability to self-administer prefilled enoxaparin injections after instructions received at the study center or availability of a person living with the patient to administer enoxaparin.

Exclusion Criteria:

1. Any acute or chronic condition posing an indication for anticoagulant treatment, e.g. atrial fibrillation, prior VTE, acute confirmed symptomatic VTE, acute coronary syndrome.
2. Anticoagulant thromboprophylaxis deemed necessary in view of the patient's history, comorbidity or predisposing strong risk factors for thrombosis:

   1. Any of the following events occurring in the prior 30 days: fracture of lower limb, hospitalization for heart failure, hip/knee replacement, major trauma, spinal cord injury, stroke,
   2. previous VTE,
   3. histologically confirmed malignancy, which was diagnosed or treated (surgery, chemotherapy, radiotherapy) in the past 6 months, or recurrent, or metastatic, or inoperable.
3. Any clinically relevant bleeding (defined as bleeding requiring hospitalization, transfusion, surgical intervention, invasive procedures, occurring in a critical anatomical site, or causing disability) within 30 days prior to randomization or sign of acute bleeding.
4. Intracerebral bleeding at any time in the past or signs/symptoms consistent with acute intracranial hemorrhage.
5. Hemoglobin \<8 g/dL and platelet count \<50 x 109 cells/L confirmed by recent laboratory test (\<90 days).
6. Subjects with any known coagulopathy or bleeding diathesis, including known significant liver disease associated with coagulopathy.
7. Severe renal insufficiency (baseline creatinine clearance \<30 mL/min calculated using the Cockcroft-Gault formula) confirmed by recent laboratory test (\<90 days).
8. Contraindications to enoxaparin therapy, including prior heparin-induced thrombocytopenia and known hypersensitivity.
9. Current use of dual antiplatelet therapy.
10. Participation in other interventional studies over the past 30 days.
11. Non-compliance or inability to adhere to treatment or lack of a family environment or support system for home treatment.
B: Inclusion criteria

* Any operation (elective or emergency) done in an operating theatre by a surgeon.
* All surgical specialties including: acute care surgery, breast surgery, cardiac surgery, colorectal surgery, general surgery, gynaecology, hepatobiliary surgery, neurosurgery, obstetrics, oesophagogastric surgery, ophthalmology, oral and maxillofacial surgery, orthopaedics, otolaryngology, paediatric surgery, plastic surgery, thoracic surgery, transplant surgery, trauma surgery, urology, vascular surgery.
* Day case surgery and inpatient surgery included.
* Any SARS-CoV-2 status (positive at any time, negative, not tested).
* All ages including children and adults.

Exclusion criteria:

Minor procedures (full list will be available in the protocol).
C: 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).
D: Inclusion Criteria:

* Participants must be at high-risk for Coronavirus disease 2019 (COVID-19) disease progression by fulfilling at least one of the following criteria at screening:

  * Presence of chronic pulmonary disease, chronic obstructive pulmonary disease (COPD), pulmonary hypertension
  * Diabetes mellitus (type 1 or type 2), requiring oral medication or insulin for treatment
  * Hypertension, requiring at least one oral medication for treatment
  * Immunocompromised status due to disease (e.g., those living with human immunodeficiency virus with a cluster of differentiation 4 \[CD4\] T-cell count of \<200 per cubic millimeter \[mm\^3\])
  * Immunocompromised status due to medication (e.g., taking 20 milligram \[mg\] or more of prednisone equivalents a day, anti-inflammatory monoclonal antibody therapies, cancer therapies)
  * Any chronic disease that is associated with high risk for severe COVID in the opinion of the site investigator
  * Body mass index ≥35 Kilogram per square meter (kg/m\^2) (based on self-reported weight and height).
* Documented Severe Acute Respiratory Syndrome Coronavirus 2 positive diagnostic test of ≤7 days at the time of screening
* Symptomatic for COVID-19 for ≤72 hours at the time of screening (defined as having at least 2 of the following symptoms of COVID-19 that is of new onset or has worsened from baseline, and include fever, chills, myalgia, arthralgia, headache, fatigue, cough, sore throat, nasal congestion, anosmia, ageusia, nausea, vomiting, or diarrhea. If only two symptoms are present, they cannot both be anosmia and ageusia)
* Capable of giving informed consent, which includes compliance with the requirements and restrictions listed in the inform consent form and in this protocol
* Agree to participate in all remote, in-person or home visits as required in the protocol and provide updated contact information as necessary.
* Female of childbearing potential must agree to practice adequate contraception during the study

Exclusion Criteria:

Participants are excluded from the study if any of the following criteria apply:

* Currently hospitalized or under immediate consideration for hospitalization at screening and Day 1
* Have new onset shortness of breath or increased shortness of breath from pre-COVID-19 (for people with known COPD) at screening and Day 1
* Hypoxemia (oxygen saturation \<94% in ambient air or oxygen saturation below pre-COVID-19 level for people with known COPD) at Day 1
* Require supplemental oxygen (new requirement or increase in requirement from pre-COVID-19 condition) at screening and Day 1
* Have a history of (in the past 3 months) or current active pathological bleeding
* Have a history of hemorrhagic stroke or intracranial hemorrhage
* Have a recent severe head trauma within 30 days which includes concussion, skull fracture or hospitalization for head injury
* Have known intracranial neoplasm, cerebral metastases, arteriovenous malformation or aneurysm
* Have history of pregnancy-related hemorrhage
* Have active gastroduodenal ulcer or other gastrointestinal bleeding diagnosed in the past 3 months
* Currently are in a hemodynamically unstable state
* Currently require thrombolysis or pulmonary embolectomy
* Have history of severe hypersensitivity reaction to Xarelto®
* Currently have a prosthetic heart valve
* Have known diagnosis of triple positive antiphospholipid syndrome
* Have known diagnosis of chronic kidney disease (stage IV or receiving dialysis)
* Have a history of thrombocytopenia or known platelet count \<100,000 cells/mm\^3
* Have history of bronchiectasis and pulmonary cavitation
* Have active cancer (e.g, receiving chemotherapy or treatment for complication of the active cancer)
* Had epidural or neuraxial anesthesia or spinal puncture in the past 2 weeks and plan to undergo these procedures during the study
* Had surgery in the past 4 weeks or plan to undergo surgery during the study
* Currently is pregnant or plans to become pregnant
* Currently is breastfeeding
* Share household with an enrolled participant in this study
* Co-enrollment in any clinical trial that includes prohibited procedures (spinal puncture or surgery) or that includes treatments within the same drug class as rivaroxaban or treatments for which co-administration with rivaroxaban are prohibited. Note that any co-enrollment other than this requires approval by the Sponsor. For any co-enrolled study, the total volume of blood samples collected across the studies should not exceed 275 milliliters (mL) in 4 weeks.
* Currently using and plan to use the following medications during the study

  * Rivaroxaban or drugs in the same class
  * Dual anti-platelets therapy
  * Other anticoagulants
  * Combined Permeability glycoprotein (P-gp) and cytochrome P450 3A (CYP3A) inhibitors and inducers

Answer: C