Please select the eligibility criteria that correspond to the clinical trial below.
Title: A Multi-institutional Trial Comparing Clinical Outcomes Following Low- vs. Standard-dose Abdominal CT as the First-line Imaging Test in Adolescents and Young Adults With Suspected Acute Appendicitis
Brief Summary: To determine whether low-dose (LD) CT is noninferior to standard-dose (SD) computed tomography (CT) as the first-line imaging test in adolescents and young adults in regard to negative appendectomy rate (NAR).


Options:
A: Inclusion Criteria:

1. Adult ≥18 years;
2. Clinical diagnosis of acute uncomplicated appendicitis (AUA) established by clinical care team, supported by any of the following usual care radiological tests (computed tomography (CT), ultrasound (US), and/or magnetic resonance imaging (MRI)). AUA is defined by the usual signs, symptoms, and imaging finding of appendicitis without:

   1. Diffuse peritonitis on clinical exam (i.e., rigid abdomen / four quadrant peritonitis);
   2. Radiologic findings of :

   i. Free air; ii. Walled off fluid collection concerning for an abscess; iii. Significant amounts of intra-abdominal fluid throughout abdomen (i.e., more than trace fluid); or iv. Extent of inflammation or adjacent organ involvement on radiologic imaging such that appendectomy is relatively contraindicated.
3. Ability to provide written or electronic informed consent in English or Spanish.

Exclusion Criteria:

1. 1. Unable or unwilling to return or be contacted for clinical follow-up visits and/or research surveys;
2. Currently incarcerated in a detention facility or in police custody (patients wearing a monitoring device can be enrolled) at baseline/screening;
3. Evidence of severe sepsis or septic shock (e.g., new presumed sepsis-related organ dysfunction, elevated lactate, and/or fluid unresponsive hypotension);
4. Conditions with altered immune response or at risk for bacterial seeding;
5. Immunodeficiency (e.g., absolute neutrophil count \<500/mm3, chronic immunosuppressive drugs, active chemotherapy or plans for chemotherapy in the following 30 days, or known acquired immune deficiency syndrome (AIDS) \[cluster of differentiation 4 (CD4) count \<200 or AIDS-defining illness within the last year\] assessed by patient history);
6. Uncompensated liver failure;
7. Taking medication to treat active inflammatory bowel disease (e.g., Crohn's, ulcerative colitis);
8. Malignancy, not in remission (ongoing chemotherapy patients excluded);
9. Pregnant or expectation of becoming pregnant in the 30 days following baseline/screening;
10. Expected concurrent hemodialysis, peritoneal dialysis, or treatments using indwelling venous catheters;
11. Recent (within 90 days) placement of surgical implant (e.g., pacemaker, joint prosthesis, mechanical valve);
12. Indwelling Left Ventricular Assist Device (LVAD);
13. Patients with another infection (e.g., pneumonia, urinary tract infection) that requires treatment with another antibiotic at baseline/screening;
14. Concurrent illness that would otherwise mandate hospitalization outside of appendicitis and associated symptoms at baseline/screening;
15. Imaging findings of any of the following:

    1. Appendiceal soft-tissue mass;
    2. Imaging features of mucocele or tumor (e.g., appendix measuring ≥ 15mm in diameter and no other CT evidence of appendicitis);
    3. Concern for carcinomatosis on imaging; or
16. Severe allergy or reaction (e.g., immediate urticaria or anaphylaxis) to all of the proposed antibiotics;
17. Prior enrollment in the study or other investigational drug or vaccine while on study treatment;
18. Abdominal/pelvic surgery in the past month; or
19. More than seven hours have transpired since the patient received the first parenteral dose of antibiotics.
B: Inclusion Criteria:

* Emergency department visit with suspected symptoms and signs of acute appendicitis
* Intravenous contrast-enhanced computed tomography examination requested due to suspicion of appendicitis
* Willing to provide telephone or cell phone numbers for follow-up
* Signed informed consent provided prior to study entry

Exclusion Criteria:

* Prior cross-sectional imaging tests to evaluate the presenting symptoms and signs
* Prior history of surgical removal of the appendix
C: Inclusion Criteria:

* Suspected of having acute appendicitis
* Referred for abdomen CT from Emergency Department

Exclusion Criteria:

* Body mass index \< 18.5 kg/m2 (ultrasonography is favored)
* Intravenous contrast-enhancement is contraindicated
D: Before CT scanning

Inclusion Criteria:

* Clinical suspicion of appendicitis
* Age more than 18 years

Exclusion Criteria:

* Clinical signs of generalized peritonitis
* Previous take of antibiotics within the 5 days preceding the presentation
* Allergy or intolerance to lactamases and/or clavulanate potassium
* Corticosteroid or anticoagulant therapy
* Patient with a known inflammatory bowel disease (Crohn's disease or ulcerative colitis)
* Pregnant women
* Patient with iode allergy
* Renal insufficiency (creatinine \> 200 )

CT scanning:

Inclusion Criteria:

* Appendix diameter \> 6 mm

Exclusion Criteria:

* Appendix non visualised
* Signs of localized peritonitis:

  * extradigestive gas
  * fluid collection around the appendix
  * generalized intraperitoneal fluid

Answer: B