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APPENDICITIS

A Complete Medical Education - From First Principles to Independent Practice

Sources: Sabiston Textbook of Surgery 21e | Fischer's Mastery of Surgery 8e | Schwartz's Principles of Surgery 11e | Tintinalli's Emergency Medicine | Bailey & Love's Short Practice of Surgery 28e | Sleisenger & Fordtran's Gastrointestinal & Liver Disease | Cochrane Review 2024 | Lancet Gastroenterol 2025

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SECTION 1: DEFINITION

• Most common surgical emergency worldwide
• Lifetime risk: 6-7% in the general population
• ~300,000 hospitalizations annually in the United States
• Incidence: 100 per 100,000 person-years in North America
• Peak incidence: Ages 10-30 years (second decade of life most affected)
• Less common under age 4 and over age 60

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SECTION 2: CAUSES & RISK FACTORS

The Fundamental Cause: Luminal Obstruction

Causes of Luminal Obstruction

Risk Factors

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SECTION 3: CLASSIFICATION / TYPES

APPENDICITIS
│
├── UNCOMPLICATED (Simple / Acute Non-perforated)
│     ├── Early (Catarrhal) - mucosal inflammation only
│     └── Suppurative - full-wall inflammation, pus in lumen
│
└── COMPLICATED
      ├── Gangrenous - transmural necrosis, black/green appendix
      ├── Perforated - hole in the wall, contents leak out
      │     ├── Locally contained → Appendiceal Phlegmon
      │     │     (inflammatory mass, no discrete pus)
      │     ├── Locally contained → Periappendiceal Abscess
      │     │     (walled-off pus collection)
      │     └── Free perforation → Diffuse Peritonitis (life-threatening)
      └── Appendiceal Mass (Plastron)

• Uncomplicated: Can be treated with antibiotics alone OR surgery
• Complicated with phlegmon/abscess: Usually antibiotics first, drain if needed, surgery later
• Free perforation with peritonitis: Emergency surgery NOW

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SECTION 4: RELEVANT ANATOMY & PHYSIOLOGY

Where is the Appendix?

Positions of the Appendix (and why they matter clinically)

Blood Supply

• Appendicular artery - a branch of the ileocolic artery (from superior mesenteric artery)
• It is an end artery - meaning no collateral circulation. Once it gets obstructed or thrombosed, ischemia is rapid and irreversible.

The Appendix is Not Vestigial!

1. Mucosal-associated lymphoid tissue (MALT) - active immune function, peaks in teens
2. Gut microbiome reservoir - acts as a "safe house" for beneficial bacteria to repopulate the colon after diarrheal illness
3. Neuroendocrine cells - relevant to carcinoid tumors

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SECTION 5: PATHOPHYSIOLOGY

Step-by-Step: Cause → Process → Symptoms → Complications

STEP 1: OBSTRUCTION
Fecalith / lymphoid hyperplasia blocks the appendiceal lumen
            ↓
STEP 2: PRESSURE BUILD-UP
Mucus continues to be secreted (the cells don't know the exit is blocked)
Intraluminal pressure rises
Law of Laplace: increased pressure → increased wall tension
            ↓
STEP 3: VASCULAR COMPROMISE
Rising wall tension compresses venous drainage first
→ Venous and lymphatic outflow obstruction
→ Mucosal edema and ischemia
→ SYMPTOM: Vague periumbilical/central pain (visceral pain - T10 dermatome)
            ↓
STEP 4: BACTERIAL TRANSLOCATION
Normal colonic bacteria (E. coli, Bacteroides, Klebsiella) breach the ischemic mucosa
→ Bacterial overgrowth within the appendix
→ Acute inflammatory response
→ SYMPTOM: Fever, nausea, vomiting, anorexia, leukocytosis
            ↓
STEP 5: TRANSMURAL INFLAMMATION
Inflammation spreads through all layers to reach the serosal surface
Irritates the adjacent parietal peritoneum
→ SYMPTOM: Pain MIGRATES from periumbilical → Right Lower Quadrant
(This migration is the hallmark symptom - it occurs because pain switches from
visceral [vague, central] to somatic [sharp, localized])
            ↓
STEP 6: GANGRENE AND PERFORATION
Arterial supply is eventually compromised → transmural necrosis
Wall becomes gangrenous (black/green discoloration)
→ COMPLICATION: Perforation (hole forms in the wall)
            ↓
STEP 7: PERFORATION CONSEQUENCES
   ├── Omentum + loops of bowel wall off the area
   │     → Phlegmon (inflammatory mass, no discrete pus)
   │     → Appendiceal Abscess (walled-off pus)
   └── Omentum fails to contain
         → Free perforation → Diffuse peritonitis → Septic shock

Why does pain migrate? (The key pathophysiology question)

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SECTION 6: CLINICAL FEATURES

The Classic Presentation (Textbook, ~50-60% of cases)

1. Anorexia (loss of appetite) - often first symptom
2. Nausea/vomiting (follows pain onset - important!)
3. Vague periumbilical or central abdominal pain
4. Pain migrates to the right lower quadrant over 4-24 hours
5. Low-grade fever (38-38.5°C)
6. Local tenderness at McBurney's point

Clinical Pearl: Vomiting before pain suggests gastroenteritis. In appendicitis, PAIN ALWAYS COMES FIRST, vomiting follows.

Symptoms - With Explanations

Signs - With Explanations

Atypical Presentations - Never Miss These!

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SECTION 7: HISTORY TAKING

The 7 Key Questions and Why They Matter

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SECTION 8: DIFFERENTIAL DIAGNOSIS

RLQ Pain - "The Great Imitator" Differential

RIGHT LOWER QUADRANT PAIN
│
├── GASTROINTESTINAL
│     ├── Mesenteric adenitis - most common mimic in children
│     ├── Meckel's diverticulitis - "rule of 2s"
│     ├── Terminal ileitis (Crohn's disease)
│     ├── Cecal diverticulitis
│     ├── Intestinal obstruction
│     ├── Intussusception (children)
│     └── Epiploic appendagitis
│
├── GENITOURINARY
│     ├── Ureteric colic (right kidney stone)
│     ├── Urinary tract infection
│     └── Pyelonephritis
│
├── GYNECOLOGICAL (females)
│     ├── Ectopic pregnancy (MUST RULE OUT FIRST)
│     ├── Ovarian torsion
│     ├── Ruptured ovarian cyst
│     ├── Pelvic inflammatory disease (PID)
│     ├── Mittelschmerz (mid-cycle ovulation pain)
│     └── Endometriosis
│
├── MUSCULOSKELETAL
│     ├── Psoas abscess
│     └── Rectus sheath hematoma
│
└── SYSTEMIC
      ├── Diabetic ketoacidosis (periumbilical pain)
      ├── Henoch-Schonlein purpura (children)
      └── Right lower lobe pneumonia (referred pain)

How to Distinguish Key Differentials

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SECTION 9: INVESTIGATIONS

Approach to Investigation

No single test can diagnose or exclude appendicitis - investigations complement clinical judgment.

Basic Blood Tests

Clinical Pearl: Normal WBC does NOT exclude appendicitis - up to 20% of cases have normal WBC, especially early on and in the elderly.

Urinalysis

• May show mild pyuria or microscopic hematuria (appendix lies near ureter)
• Does NOT confirm UTI/urolithiasis automatically
• Frank bacteriuria + dysuria → consider UTI, but don't miss appendicitis

Pregnancy Test (beta-hCG)

• MANDATORY in all females of childbearing age
• Rules out ectopic pregnancy before any imaging with radiation

Imaging

Ultrasound (USS) - First Line in Children & Pregnant Women

• Sensitivity: 75-90%; Specificity: 85-95% (operator-dependent)
• Limitation: Cannot always visualize the appendix (obesity, bowel gas)
• Can rule out ovarian pathology in females

CT Scan - Gold Standard for Adults

• Sensitivity: 92-97%; Specificity: 93-96%
• Concern: Radiation exposure (especially in young patients, children, pregnant women)
• Use low-dose CT where available

MRI - Preferred in Pregnancy

• No radiation; excellent soft tissue detail
• Sensitivity/Specificity comparable to CT
• Limitation: Less available, longer scan time, more expensive

Diagnostic Scoring Systems

The Alvarado Score (MANTRELS)

• 1-4: Low risk - appendicitis unlikely; observe/discharge
• 5-6: Moderate risk - CT imaging recommended
• 7-8: High risk - likely appendicitis; surgical consultation
• 9-10: Very high risk - appendicitis almost certain; take to OR

Appendicitis Inflammatory Response (AIR) Score

• Score 0-4: Low risk (appendicitis unlikely)
• Score 5-8: Intermediate risk (imaging recommended)
• Score 9-12: High risk (appendicitis very likely)

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SECTION 10: DIAGNOSIS

Diagnostic Criteria

Diagnostic Approach Flowchart

Patient presents with RLQ pain
            ↓
Step 1: RULE OUT IMMEDIATELY DANGEROUS CONDITIONS
• Positive beta-hCG → Ectopic pregnancy workup
• Hemodynamic instability → Resuscitate + urgent surgery/gynecology
            ↓
Step 2: CLINICAL ASSESSMENT
• History: migration of pain, anorexia, vomiting after pain
• Exam: McBurney's tenderness, guarding, rebound, Rovsing's, psoas sign
• Calculate Alvarado/AIR score
            ↓
            ├── Alvarado 7-10 (High Risk) → Surgical consultation → OR
            │
            ├── Alvarado 5-6 (Intermediate Risk) → CT Scan
            │         ├── CT Positive → Surgery
            │         └── CT Negative/Equivocal → Observe, repeat exam
            │
            └── Alvarado 1-4 (Low Risk) → USS first (children/pregnancy)
                        ├── USS positive → Surgery
                        └── USS negative/equivocal → CT or observe
            ↓
Step 3: SPECIAL POPULATIONS
• Children: USS first → CT only if USS inconclusive
• Pregnant: USS first → MRI if USS inconclusive (avoid CT)
• Elderly: Low threshold for CT (atypical presentation, rule out malignancy)

Acceptable Negative Appendectomy Rate

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SECTION 11: COMPLICATIONS

Complications in Order of Severity

• Children <5 years: Up to 90-100% (cannot communicate symptoms early)
• Adults: ~20-25% at presentation
• Elderly >65 years: 30-70%

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SECTION 12: RED FLAGS & EMERGENCIES

Dangerous Signs - Do Not Miss!

Admission Criteria - Admit ALL patients with:

• Clinical/scoring system diagnosis of appendicitis
• High or intermediate Alvarado score pending imaging
• Perforation or peritonitis (regardless of score)
• Pregnancy with suspected appendicitis
• Extremes of age (children, elderly) with RLQ pain
• Failure to improve on observation

Referral Criteria

• Refer to surgery: All confirmed or highly suspected cases
• Refer to gynecology: If ectopic pregnancy or ovarian torsion suspected
• Refer to ICU: Septic shock, multi-organ dysfunction

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SECTION 13: MANAGEMENT

Treatment Goals

1. Relieve the obstruction (ultimately by removing the appendix)
2. Control infection (antibiotics)
3. Prevent/treat complications
4. Restore normal physiology

Management Algorithm Overview

APPENDICITIS CONFIRMED
        ↓
INITIAL MANAGEMENT (ALL CASES)
• IV access + fluid resuscitation (crystalloids)
• Nil by mouth (NPO)
• IV antibiotics (broad-spectrum)
• Analgesia (do NOT withhold - myth that analgesia masks signs)
• Monitor vital signs + urine output
        ↓
        ├── UNCOMPLICATED → Surgery vs Antibiotics alone (shared decision)
        │
        ├── COMPLICATED (Phlegmon/Abscess) → Antibiotics ± percutaneous drainage
        │                                         Interval appendectomy 6-8 weeks later
        │
        └── PERFORATION WITH PERITONITIS → Emergency Surgery

Non-Drug Treatment

1. Surgical Treatment - Appendectomy

• Three small incisions (umbilicus + 2 lower abdominal ports)
• Advantages: Shorter hospital stay, faster recovery, lower wound infection rate, better cosmesis, better visualization in obese patients
• Time to surgery: Should not be delayed >6 hours if possible

• Grid-iron incision (or transverse) over McBurney's point
• Still used when laparoscopy unavailable or in complex cases
• First described by McBurney in 1894

• Increasingly performed at specialized centers
• No definitive advantage over laparoscopic

2. Non-Operative Management (Antibiotics Alone)

• APPAC Trial (2015, JAMA): 530 patients, antibiotic-alone efficacy 72.7% at 1 year vs 100% for appendectomy
• CODA Trial (2020, NEJM): Antibiotics non-inferior to appendectomy at 30 days; 29% needed appendectomy within 90 days
• Cochrane Review (2024, PMID 38682788): Antibiotics effective in 63-80% at 1 year; higher complication rate in those who eventually needed surgery after antibiotic failure
• Individual Patient Data Meta-Analysis (Lancet Gastroenterol 2025, PMID 39827891): Antibiotic treatment viable alternative for uncomplicated appendicitis; appendicolith predicts failure

• Confirmed uncomplicated appendicitis (no fecalith on CT, no perforation)
• Patient preference after informed discussion
• Patient unable to undergo surgery (high operative risk)

• Appendicolith present on imaging (high risk of failure and complications)
• Complicated appendicitis (perforated, gangrenous)
• Diffuse peritonitis
• Patient unable to return for follow-up
• Immunocompromised patients
• Patient preference for definitive surgery

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SECTION 14: PHARMACOLOGY OF IMPORTANT DRUGS

Antibiotic Therapy - The Foundation of Medical Management

• Escherichia coli (most common - 64.6%)
• Bacteroides fragilis (key anaerobe)
• Pseudomonas aeruginosa (16.4%)
• Klebsiella pneumoniae
• Enterococcus species

Drug Options - Pre-operative and Non-operative

REGIMEN 1: Piperacillin-Tazobactam (Pip-Tazo) - "Tazocin"

REGIMEN 2: Second-Generation Cephalosporin (e.g., Cefuroxime or Cefoxitin) + Metronidazole

• Mechanism: Beta-lactam; inhibits cell wall synthesis (PBP binding)
• Dose: 1.5 g IV TDS (three times daily)
• Covers: Gram-positives, gram-negatives
• Does NOT cover anaerobes (needs metronidazole added)

• Mechanism: Prodrug; reduced intracellularly by ferredoxin to cytotoxic radicals that damage bacterial DNA
• Dose: 500 mg IV/orally TDS (or 1 g IV loading dose, then 500 mg TDS)
• Covers: Anaerobes (Bacteroides fragilis, Clostridium), protozoa
• Side effects: Metallic taste, nausea, peripheral neuropathy (with prolonged use), disulfiram-like reaction with alcohol
• Contraindications: First trimester pregnancy (teratogenicity concerns); alcohol use
• Monitoring: Neurological symptoms with prolonged use

REGIMEN 3: Ciprofloxacin + Metronidazole (Penicillin-allergic patients)

• Mechanism: Fluoroquinolone; inhibits DNA gyrase (topoisomerase II) and topoisomerase IV, preventing bacterial DNA replication
• Dose: 400 mg IV BD (or 500 mg oral BD if oral route available)
• Covers: Gram-negative rods including Pseudomonas; does NOT cover anaerobes
• Side effects: Tendon rupture (Achilles), QT prolongation, photosensitivity, peripheral neuropathy, seizures (rare), cartilage damage in growing children
• Contraindications: Children <18 years (generally avoided), pregnant/breastfeeding, concurrent QT-prolonging drugs
• Monitoring: QTc interval, tendon pain

Duration of Antibiotics

Analgesia

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SECTION 15: TREATMENT ALGORITHM

By Severity

════════════════════════════════════════════════════════
 LEVEL 1: MILD / UNCOMPLICATED APPENDICITIS
════════════════════════════════════════════════════════
Alvarado 5-9, CT showing appendicitis, no perforation, 
no phlegmon, no abscess

INITIAL:
• IV access, NPO, IV crystalloids
• IV antibiotics (cefuroxime + metronidazole OR pip-tazo)
• IV analgesia (morphine + ondansetron)
• Surgical consultation

DEFINITIVE (Patient Choice - Shared Decision):
  Option A: LAPAROSCOPIC APPENDECTOMY
  • Preferred in young patients, fecalith present, 
    females (avoid DDx confusion)
  • Single dose perioperative antibiotics
  • Discharge same day or day 1

  Option B: NON-OPERATIVE (ANTIBIOTICS ALONE)
  • IV antibiotics 48-72h → oral antibiotics 7 days
  • 20-30% will need appendectomy within 1 year
  • NOT appropriate if appendicolith present on CT

════════════════════════════════════════════════════════
 LEVEL 2: MODERATE / COMPLICATED (PHLEGMON OR ABSCESS)
════════════════════════════════════════════════════════
History >3-5 days, palpable mass, CT shows phlegmon 
or well-defined abscess

INITIAL:
• Same as above + strict NPO, nasogastric tube if vomiting
• Broad-spectrum IV antibiotics (pip-tazo or carbapenem)
• Radiology referral for percutaneous drainage if abscess ≥3 cm

MANAGEMENT:
• Antibiotics for 5-7 days IV
• Drain abscess percutaneously if present (interventional radiology)
• If patient stabilizes: switch to oral antibiotics for 7-10 days
• Plan INTERVAL APPENDECTOMY at 6-8 weeks
  (25-50% risk of recurrence; rule out appendiceal malignancy, 
   especially in patients >40 years)

⚠️ Immediate Surgery if:
• Clinical deterioration despite antibiotics
• Signs of free perforation develop
• Bowel obstruction

════════════════════════════════════════════════════════
 LEVEL 3: SEVERE / PERFORATED WITH PERITONITIS
════════════════════════════════════════════════════════
Free perforation, diffuse peritonitis, septic shock

IMMEDIATE RESUSCITATION (Do all simultaneously):
• 2x large-bore IV access
• Aggressive crystalloid resuscitation (30 ml/kg bolus)
• Vasopressors if refractory hypotension (norepinephrine)
• IV pip-tazo 4.5g OR meropenem 1g if septic shock
• Urinary catheter (monitor urine output ≥0.5 ml/kg/h)
• Blood cultures x2 before antibiotics if possible
• ICU liaison / anaesthetics involvement
• Analgesia (IV morphine titrated)

EMERGENCY SURGERY (within 1-2 hours of stabilization):
• Emergency laparoscopic or open appendectomy
• Thorough peritoneal lavage
• Drain placement
• Close in layers; skin may be left open if contaminated

POST-OPERATIVE:
• Continued broad-spectrum antibiotics 5-7 days
• Directed therapy when culture results available
• ICU if haemodynamically unstable

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SECTION 16: REAL-WORLD CLINICAL APPROACH

OPD Approach

1. Triage: Vital signs. Is patient hemodynamically stable? Fever?
2. Rapid clinical assessment: Pain migration? Anorexia? Vomiting?
3. Calculate Alvarado score at the bedside mentally
4. Immediate bloods: FBC, CRP, U&E, LFTs, urinalysis, beta-hCG (females)
5. Imaging: USS if child/pregnant woman; CT if adult with intermediate-high risk
6. Surgical review: All intermediate/high-risk patients
7. Do NOT send home a patient with Alvarado >5 without surgical consultation

Emergency Approach

1. Immediate: ABC assessment. 2 IVCs. Bloods + cultures. Fluid resus.
2. IV antibiotics immediately (don't wait for investigations)
3. Emergency CT if hemodynamically stable enough (confirms perforation, excludes other diagnoses)
4. Surgical team at bedside
5. Emergency theatre - do NOT delay for ward admission/observation

Common Mistakes to Avoid

Clinical Pearls

1. "Pain before vomiting = appendicitis; vomiting before pain = gastroenteritis" - one of the most reliable clinical rules
2. The Alvarado score is your friend - calculate it in every RLQ pain patient
3. A normal CT does not exclude all diagnoses - if clinical suspicion remains high, repeat examination in 6-12 hours
4. The retrocecal appendix is the great impersonator - consider it when you see right flank pain with positive psoas sign but no classic RLQ tenderness
5. Perforation paradox: When the appendix perforates, pain may TEMPORARILY IMPROVE before becoming diffuse - this false improvement is dangerous
6. In pregnancy: Even in the third trimester, >75% of cases still have RLQ pain - don't assume upper quadrant pain

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SECTION 17: PRESCRIPTION EXAMPLES

Example 1: Uncomplicated Appendicitis - Pre-operative

INPATIENT PRESCRIBING CHART

PATIENT: [Name], 22M, 70 kg
DIAGNOSIS: Acute appendicitis (uncomplicated)
ALLERGIES: NKDA

REGULAR MEDICATIONS:
1. 0.9% Normal Saline 1 L IV over 8 hours x2 bags
2. Cefuroxime 1.5 g IV STAT (30 min before incision) - single prophylactic dose
3. Metronidazole 500 mg IV infused over 30 min, STAT (pre-operative)
4. Paracetamol 1 g IV QDS (4 times/day)

PRN (as needed) MEDICATIONS:
5. Morphine 5-10 mg IV PRN every 4 hours (pain score >5/10)
6. Ondansetron 4 mg IV PRN every 8 hours (nausea/vomiting)

POST-OPERATIVE (uncomplicated, no contamination):
• No further antibiotics required if appendix intact
• Paracetamol 1 g oral QDS
• Ibuprofen 400 mg oral TDS (with food) if tolerated

PLAN: Laparoscopic appendectomy

Example 2: Perforated Appendicitis - Emergency

INPATIENT PRESCRIBING CHART

PATIENT: [Name], 45F, 65 kg
DIAGNOSIS: Perforated appendicitis with localized peritonitis
ALLERGIES: NKDA

FLUID RESUSCITATION:
1. 0.9% Normal Saline 1 L IV over 30 min (STAT bolus)
   Then reassess; further 500 mL boluses PRN to UO >0.5 mL/kg/h

ANTIBIOTICS (IV - continue 5-7 days until clinically improving):
2. Piperacillin-Tazobactam 4.5 g IV every 8 hours
   (Infuse over 30-60 minutes)
   [Adjust dose if CrCl <40 mL/min]

ANALGESIA:
3. Morphine 5 mg IV STAT, then 2-5 mg IV every 4h PRN (pain >5)
4. Paracetamol 1 g IV QDS (regular, not PRN)

ANTIEMETIC:
5. Ondansetron 8 mg IV every 8h PRN

MONITORING:
• Hourly vital signs
• Strict fluid balance (IDC + urine output monitoring)
• Daily FBC, CRP, U&E, LFTs
• Blood cultures (if not already taken)

PLAN: Emergency laparoscopic appendectomy as soon as resuscitated/stable
SURGICAL TEAM NOTIFIED: [Time]

Example 3: Non-Operative Management - Uncomplicated Appendicitis

INPATIENT PRESCRIBING CHART - NON-OPERATIVE PATHWAY

Day 1-3 (IV phase):
1. Ertapenem 1 g IV once daily OR
   Ticarcillin-clavulanate 3.2 g IV TDS

Day 3 onwards if improving (oral step-down):
2. Ciprofloxacin 500 mg oral BD + Metronidazole 400 mg oral TDS
   Total duration: 10 days

ANALGESIA:
3. Paracetamol 1g oral QDS
4. Ibuprofen 400mg oral TDS with food
5. PRN Codeine phosphate 30mg oral every 6h (breakthrough pain)

DISCHARGE PLAN (if improving at 48-72h):
• Oral antibiotics to complete 10-day course
• Return precautions: Return to ED immediately if pain worsens, 
  fever develops, or vomiting resumes
• Follow-up in surgical outpatient clinic in 6 weeks
• Plan for interval appendectomy discussion

Common Prescribing Errors

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SECTION 18: PREVENTION

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SECTION 19: PROGNOSIS

Overall Outcomes

Risk Factors for Poor Outcomes

• Delayed presentation (>48-72 hours)
• Extremes of age
• Comorbidities (diabetes, immunosuppression)
• Failure to recognize atypical presentation
• Missed diagnosis in the ED

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SECTION 20: PATIENT COUNSELING

For the Patient (Simple Language)

"Your appendix - a small pouch attached to your intestine in the lower right part of your belly - has become inflamed and infected. It was blocked by hardened material, which caused a build-up of pressure, infected the wall, and could rupture if not treated."

"You have two options: surgery to remove the appendix (which cures the problem permanently and takes 1-2 days in hospital), or antibiotics alone for now (which works about 70-80% of the time, but 1 in 4 patients needs surgery within a year anyway). Both are safe. We can discuss which is right for you."

"The surgery is done through 3 tiny keyhole incisions. You'll be under general anaesthesia. It takes 30-60 minutes. Most patients go home the next day. You can return to light activity in 1-2 weeks and full activity in 2-4 weeks."

1. Diet: Start with fluids, advance to normal as tolerated
2. Wound care: Keep incision sites dry for 48 hours
3. Activity: No heavy lifting (>10 kg) for 2 weeks; light walking is encouraged
4. Return to ED immediately if: Fever >38.5°C, severe abdominal pain, wound redness/discharge, vomiting preventing oral intake
5. Follow-up appointment: 2-4 weeks for wound check

"If your pain gets worse, you develop a fever, start vomiting, or feel much worse within the next few days, come back to hospital immediately. This could mean the antibiotics are not working and you need surgery urgently. You must also see us in 6 weeks for a follow-up appointment."

"Your CT scan shows a small calcium deposit inside the appendix - this is called an appendicolith or fecalith. Evidence shows that antibiotics are less likely to work when this is present, and we recommend surgery rather than antibiotics for you."

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QUICK REFERENCE SUMMARY TABLE

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KEY MNEMONICS

• Migration of pain to RLQ (1)
• Anorexia (1)
• Nausea/vomiting (1)
• Tenderness in RLQ (2)
• Rebound tenderness (1)
• Elevated temperature (1)
• Leukocytosis (2)
• Shift to left (1)

• Palpation rebound
• Obturator sign
• Psoas sign
• Elevated temp + rigidity

• In appendicitis: PAIN first, then vomiting
• In gastroenteritis: VOMITING first, then (maybe) pain

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Sources cited: Sabiston Textbook of Surgery 21e (pp. 2038-2065) | Fischer's Mastery of Surgery 8e (pp. 7830-7840) | Schwartz's Principles of Surgery 11e (pp. 1759-1760) | Tintinalli's Emergency Medicine (pp. 563-568) | Bailey & Love's Short Practice of Surgery 28e | Current Surgical Therapy 14e | Cochrane Database Syst Rev 2024 [PMID 38682788] | Lancet Gastroenterol Hepatol 2025 [PMID 39827891] | JAMA Surg 2022 [PMID 35895073]This completes your comprehensive, evidence-based medical teaching on Appendicitis. Here's a brief orientation to what was covered:

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What You Just Learned - At a Glance

1. Foundation: Appendicitis is luminal obstruction → pressure build-up → ischemia → bacterial invasion → perforation
2. The hallmark symptom: Pain migrating from periumbilical → RLQ (visceral to somatic pain shift) - explained mechanistically
3. Clinical scoring: The Alvarado (MANTRELS) score is your practical bedside tool; score ≥7 = high probability
4. Key investigation rule: CT is gold standard for adults; USS first in children/pregnancy; ALWAYS do beta-hCG in women first
5. Modern management controversy: Antibiotics alone are now an accepted alternative for uncomplicated appendicitis (CODA trial 2020; Cochrane 2024) - but appendicolith = surgery preferred
6. Drug knowledge: Pip-tazo covers everything; always add metronidazole to any cephalosporin for anaerobe cover
7. Never miss: Sudden pain relief = possible perforation; rigid abdomen = emergency; elderly and young children perforate at much higher rates

• Pain before vomiting = appendicitis
• Appendicolith on CT = operate, don't gamble on antibiotics
• Always check beta-hCG before any management in females of reproductive age