What is the initial management and treatment for suspected appendicitis?

Initial Management and Workup of Suspected Appendicitis

In adults with suspected appendicitis, obtain CT abdomen and pelvis with IV contrast as the initial imaging modality, administer broad-spectrum antibiotics immediately once diagnosis is confirmed, and arrange urgent surgical consultation for appendectomy. 1, 2

Clinical Assessment and Risk Stratification

Begin by evaluating for characteristic findings that increase likelihood of appendicitis: 2, 3, 4

• Migratory pain from periumbilical region to right lower quadrant (highly suggestive) 3
• Localized right lower quadrant tenderness with rebound or guarding 2, 4
• Fever and laboratory evidence of acute inflammation (elevated WBC) 2, 4
• Positive psoas sign 3

Critical pitfall: Do NOT rely solely on clinical scoring systems (Alvarado, AIR) to exclude appendicitis—studies show 8.4% of patients with appendicitis had low Alvarado scores, and one study found 72% with very low scores (1-4) ultimately had appendicitis. 3 Proceed with imaging even when clinical scores are incomplete or low. 3

Imaging Strategy by Patient Population

Non-Pregnant Adults

Obtain CT abdomen and pelvis with IV contrast as first-line imaging (sensitivity 96-100%, specificity 93-95%). 1, 2, 3

Technical considerations: 1, 3

• IV contrast is strongly preferred and increases sensitivity to 96% 1, 3
• Oral contrast is NOT necessary and may delay diagnosis 3
• CT without IV contrast has high accuracy and may be appropriate in select cases 1

If CT is negative but clinical suspicion persists: Consider observation with supportive care ± antibiotics, or surgical intervention if suspicion remains very high. 1

Children and Adolescents

Start with ultrasound as initial imaging (sensitivity 76%, specificity 95%) to avoid radiation exposure. 1, 3

If ultrasound is equivocal/non-diagnostic and clinical suspicion persists: Obtain MRI or CT rather than repeat ultrasound. 1 CT with IV contrast is usually appropriate after equivocal ultrasound. 1

Important caveat: Ultrasound is highly operator-dependent. Point-of-care ultrasound by emergency physicians/surgeons shows better performance (sensitivity 91%, specificity 97%). 3

Pregnant Patients

Obtain ultrasound as initial imaging modality. 1, 3

If ultrasound is inconclusive: Proceed to MRI without IV contrast (sensitivity 94%, specificity 96%) rather than CT to avoid ionizing radiation, especially in first trimester. 1, 2, 3

MRI is readily available and reasonable as initial imaging if access permits. 1

Antibiotic Therapy

Administer broad-spectrum antibiotics immediately once appendicitis is diagnosed or strongly suspected. 2, 4

Appropriate regimens must cover aerobic gram-negative organisms and anaerobes: 2, 4

• Piperacillin-tazobactam monotherapy, OR
• Cephalosporin + metronidazole, OR
• Fluoroquinolone + metronidazole 4

Critical error to avoid: Delaying antibiotics in confirmed or strongly suspected cases increases risk of complications. 2, 5

Surgical Management

Appendectomy should be performed as soon as reasonably feasible once diagnosis is established. 2, 4, 6

• Both laparoscopic and open appendectomy are acceptable, with approach based on surgeon expertise 2
• Laparoscopic approach is preferred in children 2
• Surgery should occur within 24 hours for uncomplicated appendicitis 2

Complicated Appendicitis

If CT shows perforation, abscess, or phlegmon: 2, 3, 6

• Urgent surgical intervention is required for source control 2, 6
• Large periappendiceal abscess or phlegmon may warrant percutaneous drainage rather than immediate appendectomy 3, 6

High-risk CT findings include: 3, 4

• Appendicolith (fecalith in appendiceal lumen)
• Appendiceal diameter >13 mm
• Mass effect
• Extraluminal air
• Appendiceal wall enhancement defect

Special Populations Requiring Immediate Surgery

Pregnant patients and immunosuppressed patients should undergo timely surgical intervention to decrease risk of complications, even when considering non-operative management in other populations. 6

Non-Operative Management Consideration

In highly selected patients with uncomplicated appendicitis and absence of appendicolith on imaging, antibiotics-first strategy can be discussed as alternative to surgery. 1, 4 However, patients must be counseled that: 1, 4

• Success rate is approximately 63-73% at one year 4, 7
• Risk of treatment failure is approximately 30-40% with high-risk CT findings 4
• Appendectomy remains standard of care with 97% optimal outcome at one year 7

This approach is NOT appropriate for: 4

• Patients with appendicolith on imaging
• Appendiceal diameter >13 mm
• Mass effect on CT
• Pregnant or immunosuppressed patients

Critical Pitfalls to Avoid

• Never administer analgesics (like metamizol) before completing diagnostic evaluation, as this can mask evolving peritonitis 5
• Do not proceed directly to surgery without imaging in patients with incomplete clinical findings—this risks unnecessary surgery (negative appendectomy) and missing alternative diagnoses 3
• Do not assume absence of peritoneal signs excludes appendicitis, especially in atypical presentations 5
• Ultrasound and MRI may incorrectly classify up to half of perforated appendicitis cases as simple appendicitis 3
• In elderly patients, CT with IV contrast is strongly recommended due to higher rates of complicated appendicitis and mortality 3