What is the initial workup and management for an inpatient with suspected appendicitis?

Initial Workup for Inpatient with Suspected Appendicitis

For non-pregnant adults with suspected appendicitis, obtain an abdominal CT scan with intravenous contrast as the initial imaging modality, followed by prompt surgical consultation and administration of broad-spectrum antibiotics covering aerobic gram-negative organisms and anaerobes. 1, 2

Clinical Assessment

Initial evaluation should identify:

• Characteristic abdominal pain with migration to the right lower quadrant 1, 2
• Localized right lower quadrant tenderness and guarding 1, 3
• Laboratory evidence of acute inflammation (elevated white blood cell count) 1, 4
• Anorexia, nausea, or intermittent vomiting 3
• Low-grade fever 3

These clinical findings should be used to risk-stratify patients and guide decisions about imaging and management. 2 While the classic constellation of symptoms identifies approximately 90% of appendicitis cases, clinical diagnosis alone has historically resulted in unacceptably high negative appendectomy rates of up to 25%. 1, 5

Diagnostic Imaging Strategy

For Non-Pregnant Adults

Obtain helical CT of the abdomen and pelvis with intravenous contrast as the first-line imaging study. 1, 2 This modality demonstrates superior diagnostic accuracy with 90.8% sensitivity and 94.2% specificity. 4

• IV contrast is usually appropriate, though CT without IV contrast also has high diagnostic accuracy and may be appropriate in certain circumstances 1
• CT is superior to ultrasound in adults, where ultrasound has only 87.1% sensitivity and 89.2% specificity, with a median of 68% of studies yielding equivocal or indeterminate results 1, 4, 6

For Pregnant Patients

Begin with abdominal ultrasound as the initial imaging modality. 1, 2 All female patients of childbearing potential should undergo pregnancy testing prior to imaging. 1, 2

• If the patient is in the first trimester, use ultrasound or MRI instead of CT to avoid ionizing radiation 1, 2
• If ultrasound is equivocal and clinical suspicion persists, proceed to MRI rather than CT 1
• Laparoscopy or limited CT scanning may be considered if non-radiation imaging does not define the pathology 1

For Pediatric Patients

Obtain ultrasound as the initial imaging modality to avoid radiation exposure. 1 Imaging should be performed for all children when the diagnosis is uncertain, particularly those aged <3 years. 1

• If initial ultrasound is equivocal and clinical suspicion persists, obtain MRI or CT as subsequent imaging rather than repeating ultrasound 1
• CT with IV contrast is usually appropriate after equivocal ultrasound, though CT without IV contrast may be appropriate 1

Management of Imaging Results

If Imaging is Positive

Immediately initiate antimicrobial therapy and obtain surgical consultation for appendectomy. 1, 2

• Appropriate antibiotics must cover facultative and aerobic gram-negative organisms plus anaerobes 1, 2
• Options include piperacillin-tazobactam monotherapy or combination therapy with cephalosporins or fluoroquinolones plus metronidazole 3
• Operative intervention should be performed as soon as reasonably feasible 2
• Both laparoscopic and open appendectomy are acceptable, with approach dictated by surgeon expertise 2

If Imaging is Negative but Symptoms Persist

Arrange mandatory 24-hour follow-up to ensure resolution of signs and symptoms due to the measurable risk of false-negative results. 1, 2, 7, 5

• Do not discharge patients with persistent symptoms after negative imaging without structured follow-up 5
• Consider observation and supportive care with or without antibiotics if clinical suspicion persists 1

If Imaging is Equivocal or Indeterminate

Admit for 24-hour observation with serial examinations if clinical suspicion remains. 5 Careful follow-up is mandatory, with possible hospitalization if the index of suspicion is high. 1, 2, 7

• Depending on the clinical situation, observation may be appropriate instead of subsequent imaging 1
• If strong clinical suspicion persists after equivocal imaging, exploratory laparoscopy or laparotomy may be considered if subsequent imaging would delay appropriate management 1
• Because CT is highly accurate, immediate additional imaging studies beyond CT are usually not necessary 1

High-Risk CT Findings

Identify patients at higher risk for treatment failure with antibiotics-first approach:

• Appendiceal diameter ≥7 mm 3
• Presence of appendicolith (conglomeration of feces in appendiceal lumen) 3
• Appendiceal diameter >13 mm 3
• Mass effect 3

These findings are associated with approximately 40% treatment failure rate with antibiotics alone and should prompt surgical management in patients fit for surgery. 3

Critical Pitfalls to Avoid

Do not rely on clinical examination alone in nonspecific presentations, as the negative appendectomy rate without imaging can reach 25%. 1, 5

Do not delay antibiotics in confirmed or strongly suspected cases, as this increases the risk of complications. 2

Do not discharge patients with negative imaging but persistent symptoms without structured 24-hour follow-up, as false-negative imaging results occur. 7, 5

Do not fail to obtain imaging in all female patients and children with uncertain diagnosis, as clinical diagnosis is particularly unreliable in these populations. 1, 2