Acute Appendicitis

Summary

Acute appendicitis is inflammation of the vermiform appendix, representing the most common surgical emergency worldwide. Classic presentation is abdominal pain migrating from periumbilical to RLQ, anorexia, and low-grade fever. Perforation risk increases significantly after 48-72 hours. Diagnosis is clinical, supported by CT imaging. Treatment is laparoscopic appendectomy, though antibiotics-only may be appropriate for uncomplicated cases.

Key Facts

Critical Alerts

• Perforation risk increases significantly after 48-72 hours of symptom onset
• Elderly and immunocompromised patients may present atypically with minimal pain
• Pregnant women - appendix migrates cephalad; consider in RUQ pain
• Children - higher perforation rates due to delayed diagnosis
• Antibiotics alone may be appropriate for uncomplicated cases in select patients

Key Diagnostics

Emergency Treatments

(Integrated into Clinical Presentation above)

Red Flags

Life-Threatening Conditions

High-Risk Features

• Duration >48 hours: Perforation rate increases significantly
• Extremes of age: <5 years or >65 years have higher complication rates
• Immunocompromised: HIV, chemotherapy, transplant patients
• Diabetes mellitus: May mask symptoms, higher complication rates
• Obesity: Difficult examination, delayed diagnosis

Clinical Scoring Systems

Alvarado Score (MANTRELS):

Interpretation:

• 0-4: Appendicitis unlikely, observe or discharge
• 5-6: Possible appendicitis, CT imaging recommended
• 7-8: Probable appendicitis, surgical consultation
• 9-10: Highly probable, consider surgery without imaging

Laboratory Studies

Imaging Studies

CT Abdomen/Pelvis with IV Contrast:

• Sensitivity: 94-98%
• Specificity: 95-98%
• Findings: Appendix >6mm diameter, fat stranding, appendicolith, abscess
• Advantages: Excellent for complications, alternative diagnoses
• Disadvantages: Radiation exposure, contrast reactions, cost

Ultrasound:

• Sensitivity: 75-90% (operator dependent)
• Specificity: 85-95%
• Findings: Non-compressible appendix >6mm, target sign, periappendiceal fluid
• Advantages: No radiation (ideal for pregnancy, children), bedside availability
• Disadvantages: Limited by body habitus, operator experience, bowel gas

MRI:

• Sensitivity: 90-95%
• Specificity: 95%
• Best Use: Pregnancy when US inconclusive
• Advantages: No radiation, excellent soft tissue contrast
• Disadvantages: Time, availability, cost

Imaging Algorithm

1. Reproductive-age women: Beta-hCG → Pelvic US → CT if inconclusive
2. Children: Ultrasound first → CT if inconclusive
3. Pregnant patients: US → MRI → CT only if diagnosis still unclear and critical
4. Adult males, post-menopausal women, obese patients: CT first-line

Condition Explanation

• "Your appendix is a small finger-shaped pouch attached to your large intestine. It has become infected and inflamed, which is causing your pain."
• "This is the most common reason for emergency abdominal surgery."
• "Treatment usually involves removing the appendix surgically, which prevents it from rupturing and causing more serious infection."

Post-Operative Instructions

Activity:

• Light activity for 1-2 weeks (laparoscopic) or 4-6 weeks (open)
• No heavy lifting >10 lbs for 2-6 weeks depending on approach
• May shower after 48 hours; avoid submerging in water for 2 weeks
• Return to work: 1-2 weeks (desk job) or 4-6 weeks (physical labor)

Diet:

• Advance from clear liquids to regular diet as tolerated
• Stay well hydrated
• Fiber intake to prevent constipation

Wound Care:

• Keep incisions clean and dry
• Steri-strips will fall off on their own in 7-10 days
• Watch for signs of infection: redness, swelling, drainage, fever

Warning Signs Requiring Return

• Fever >38.5°C (101.3°F)
• Increasing abdominal pain
• Redness, swelling, or pus from incision sites
• Inability to keep liquids down for >24 hours
• No bowel movement for >3-4 days
• Severe nausea/vomiting
• Difficulty breathing or chest pain

Special Populations

Pediatric Patients

• Higher perforation rates: 30-75% (especially <5 years) due to delayed diagnosis
• Presentation: Often atypical; diarrhea common; less reliable history
• Imaging: Ultrasound preferred; CT only if inconclusive
• Treatment: Laparoscopic appendectomy when possible

Elderly Patients (>65 years)

• Higher mortality: 5-10% vs <1% in younger adults
• Atypical presentation: Less pain, less fever, delayed presentation
• Higher perforation rate: 40-70% at presentation
• Imaging: Low threshold for CT; always consider malignancy
• Postoperative: Higher complication rates, longer recovery

Pregnant Patients

• Incidence: 1 in 1500 pregnancies
• Challenges: Appendix migrates upward; leukocytosis normal in pregnancy
• Imaging: Ultrasound → MRI preferred; CT only if necessary
• Treatment: Surgical appendectomy at any gestational age
• Fetal mortality: 4% uncomplicated; up to 36% if perforated
• Avoid tocolytics: Not shown to prevent preterm labor post-appendectomy

Immunocompromised Patients

• Higher risk of complications: Delayed healing, abscess formation
• Atypical presentation: May lack fever, leukocytosis, significant pain
• Lower threshold for imaging and surgery
• Broaden antibiotic coverage: Consider antifungal in severe cases

Obese Patients (BMI >35)

• Diagnostic challenges: Difficult physical examination
• Imaging: CT often necessary; higher radiation doses needed
• Surgical considerations: Higher conversion to open, longer operative time
• Postoperative: Higher wound complications, VTE risk

Performance Indicators

Documentation Requirements

• Time of symptom onset
• Vital signs and resuscitation efforts
• Physical examination findings including peritoneal signs
• Laboratory results (WBC, differential, CRP)
• Imaging findings and interpretation
• Alvarado or risk score documentation
• Antibiotic timing and choice with rationale
• Surgical consultation time and findings
• Informed consent discussion
• Disposition plan and follow-up arrangements

Quality Improvement Initiatives

• Standardized imaging pathways to reduce radiation and negative appendectomy
• Antibiotic stewardship: de-escalation after culture results
• Enhanced recovery after surgery (ERAS) protocols
• Same-day discharge protocols for uncomplicated laparoscopic appendectomy

Key Clinical Pearls

Diagnostic Pearls

• "The hungry patient doesn't have appendicitis": Anorexia is present in >90%
• Pain precedes vomiting: Opposite sequence suggests gastroenteritis
• Migration of pain is key: Periumbilical → RLQ is classic evolution
• Normal WBC doesn't exclude appendicitis: 10-20% have normal counts
• Right shift matters: >75% neutrophils increases likelihood
• CRP >50 suggests complicated disease: Helpful for risk stratification
• Never forget beta-hCG: Ectopic pregnancy is life-threatening

Treatment Pearls

• Don't withhold analgesia: It improves rather than obscures diagnosis
• Antibiotics before surgery: Reduces surgical site infections
• Laparoscopic is preferred: Even in perforation and abscess
• Timing isn't emergent for uncomplicated: 24-hour window acceptable
• Antibiotics alone is an option: For uncomplicated, informed patients
• Appendiceal mass: Consider delayed surgery after IV antibiotics

Disposition Pearls

• Serial examinations are valid: If diagnosis uncertain, reassess in 6-8 hours
• CT findings change management: Abscess → may warrant drainage first
• Age >40 needs colonoscopy follow-up: Rule out underlying malignancy
• High clinical suspicion + negative CT: Still consider surgical consultation
• Recurrence after antibiotics-only: 20-40% will have recurrent appendicitis