Case 3.4 – Post Operative Fever [SDL]

A. History Taking

1. Symptoms Assessment

• Fever characteristics: Onset, duration, pattern (continuous vs. intermittent), maximum temperature recorded
• Associated symptoms:
  • Respiratory: Cough, sputum production, dyspnea, pleuritic chest pain
  • Urinary: Dysuria, frequency, urgency, loin pain, hematuria
  • Abdominal: Abdominal pain, nausea, vomiting, diarrhea
  • Wound-related: Pain, discharge, redness at surgical site
  • Constitutional: Rigors, sweating, malaise, headache
• Leg symptoms: Pain, swelling, tenderness (DVT risk given history)

2. Operative Details

• Type of hysterectomy (abdominal vs. vaginal vs. laparoscopic)
• Duration of surgery
• Intraoperative complications
• Blood loss and transfusion requirements
• Antibiotic prophylaxis given

3. Post-operative Course

• Fluid balance and urine output
• Pain management and mobility
• Time of urinary catheter removal
• Presence of drains or other devices
• Current medications including compliance with heparin

4. Relevant Past Medical History

• Asthma: Control, recent exacerbations, current medications
• DVT history: When, treatment received, residual symptoms
• Previous surgeries and complications
• Drug allergies
• Smoking history

B. Physical Examination

General Examination

• Vital signs: Temperature, heart rate, blood pressure, respiratory rate, oxygen saturation
• General appearance: Level of distress, hydration status, color
• Mental status: Alertness, orientation, confusion

Detailed Physical Examination Checklist

System/Area	Specific Examination Points	Key Findings to Note
Respiratory System	• Inspection: Respiratory rate, pattern, use of accessory muscles • Palpation: Chest expansion, tactile fremitus • Percussion: Note areas of dullness • Auscultation: Breath sounds, crackles, bronchial breathing, pleural rub	Signs of pneumonia, atelectasis, pulmonary embolism, or bronchospasm
Cardiovascular System	• Heart rate and rhythm • Heart sounds (normal, murmurs, gallop) • Jugular venous pressure • Peripheral pulses • Capillary refill time	Tachycardia, new murmurs, signs of endocarditis, hemodynamic instability
Abdominal/Surgical Site	• Wound inspection: Erythema, swelling, discharge, dehiscence • Palpation: Tenderness, guarding, rebound tenderness • Presence of surgical drains and output characteristics • Bowel sounds • Organomegaly • Pelvic examination if indicated	Wound infection, intra-abdominal abscess, peritonitis, pelvic collection
Urinary System	• Suprapubic tenderness • Costovertebral angle tenderness • Urethral discharge • Catheter site if present	Urinary tract infection, pyelonephritis, catheter-related infection
Lower Limbs	• Inspection: Swelling, color changes, varicosities • Palpation: Calf tenderness, warmth, cord-like structures • Measure calf circumference bilaterally • Homan's sign (limited value) • Pedal pulses	Deep vein thrombosis (especially relevant given history)
Venous Access Sites	• Examine all IV sites, central lines • Look for erythema, purulence, tracking • Palpate for tenderness	Phlebitis, line-related sepsis
Skin/Pressure Areas	• Check sacrum, heels, buttocks • Look for rashes, lesions • Examine for signs of drug reaction	Pressure sores, cellulitis, drug eruptions
ENT/Oral Cavity	• Throat examination • Sinus tenderness • Oral mucosa • Dental hygiene	Pharyngitis, sinusitis, dental abscess

C. Investigations

1. Blood Tests

• Full Blood Count (FBC): White cell count, differential count, hemoglobin, platelets
• C-reactive protein (CRP) and ESR: Markers of inflammation
• Urea and Electrolytes (U&E): Renal function, dehydration, electrolyte imbalance
• Liver Function Tests (LFTs): Hepatic involvement, drug reactions
• Coagulation studies: Especially if anticoagulation adjustment needed
• Blood cultures: At least 2 sets from different sites if temperature ≥38.3°C or sepsis suspected
• Lactate: If sepsis suspected (marker of tissue hypoperfusion)

2. Microbiological Samples

• Urine: Dipstick and microscopy, culture and sensitivity
• Wound swabs: If wound appears infected or discharging
• Sputum culture: If productive cough present
• Vaginal swabs: If vaginal discharge or concern for pelvic infection
• Drain fluid: Send for culture if drains in situ

3. Imaging

• Chest X-ray: Essential to exclude pneumonia, atelectasis, pleural effusion
• Abdominal/Pelvic Ultrasound: To detect collections, abscesses, hematomas
• CT Abdomen/Pelvis with contrast: If clinical suspicion of intra-abdominal pathology
• Doppler Ultrasound of lower limbs: If clinical suspicion of DVT
• CT Pulmonary Angiography (CTPA): If pulmonary embolism suspected

4. Other Investigations

• ECG: Tachycardia assessment, exclude cardiac ischemia
• Arterial blood gas: If respiratory compromise or sepsis suspected

D. Immediate Management

• Continue monitoring vital signs (minimum 4-hourly, more frequently if unstable)
• Ensure adequate hydration (IV fluids if poor oral intake)
• Regular analgesia to facilitate mobility and respiratory effort
• Encourage deep breathing exercises and mobilization
• Continue thromboprophylaxis as prescribed
• Document findings clearly and escalate if deteriorating
• Consider early warning score (e.g., NEWS2) to track clinical trajectory

1. Respiratory Causes ("Wind")

Common in immediate post-operative period (24-48 hours)

• Atelectasis: Most common cause of fever in first 48 hours post-operatively. Due to hypoventilation, poor respiratory effort, pain
• Pneumonia: Hospital-acquired pneumonia (HAP), aspiration pneumonia, ventilator-associated pneumonia
• Pulmonary embolism: May present with fever along with dyspnea and pleuritic chest pain
• Pleural effusion: Especially if complicated or infected (empyema)
• Bronchospasm/Asthma exacerbation: Particularly relevant for Mrs Davis

2. Urinary Tract Causes ("Water")

Common days 3-5 post-operatively

• Urinary tract infection (UTI): Most common after urinary catheterization. Risk increases with duration of catheterization
• Catheter-associated UTI (CAUTI): Single most common healthcare-associated infection
• Urinary retention: Can predispose to infection

3. Wound and Surgical Site Causes ("Wound")

Common days 5-7 post-operatively (but can occur earlier)

• Superficial surgical site infection (SSI): Skin and subcutaneous tissue
• Deep SSI: Fascia and muscle layers
• Organ/space SSI: Any part of anatomy manipulated during surgery
• Specific to hysterectomy: Vaginal cuff infection/abscess, pelvic abscess or collection, pelvic cellulitis, infected hematoma
• Necrotizing fasciitis: Rare but life-threatening, rapid progression

4. Venous Thromboembolic Disease ("Walking")

Typically days 7-10 but can occur earlier

• Deep vein thrombosis (DVT): Particularly relevant for Mrs Davis given her history. Low-grade fever common. May be clinically silent
• Pulmonary embolism (PE): Can present with fever, dyspnea, pleuritic chest pain, tachycardia
• Superficial thrombophlebitis: At IV cannulation sites

5. Intravascular Device-Related Infections

• Peripheral IV catheter-related: Phlebitis, thrombophlebitis
• Central line-associated bloodstream infection (CLABSI)
• Catheter-related bacteremia/sepsis

6. Drug-Related Fever ("Wonder Drugs")

Can occur at any time

• Drug fever: Antibiotics (beta-lactams, sulfonamides), anticonvulsants, allopurinol
• Transfusion reactions: If blood products administered
• Contrast media reactions

7. Intra-abdominal/Pelvic Causes

• Intra-abdominal abscess: Subphrenic, pelvic, or other locations
• Peritonitis: Generalized or localized
• Acalculous cholecystitis: Especially in critically ill patients
• Clostridium difficile colitis: Following antibiotic use

8. Other Infectious Causes

• Parotitis: Due to dehydration, poor oral hygiene
• Sinusitis: Especially if nasogastric tube in place
• Endocarditis: Rare, but consider in persistent bacteremia

9. Non-Infectious Causes

• Tissue trauma from surgery: Physiological inflammatory response (usually resolves within 48 hours)
• Hematoma: Uninfected collections can cause low-grade fever
• Malignant hyperthermia: Rare, occurs during or immediately after anesthesia
• Adrenal insufficiency: In patients on long-term steroids
• Thyroid storm: In patients with hyperthyroidism

Fever (pyrexia) is a complex, coordinated physiological response involving multiple body systems. It represents a regulated increase in core body temperature orchestrated by the hypothalamus in response to pyrogens.

A. Endocrine Characteristics

1. Hypothalamic-Pituitary-Adrenal (HPA) Axis Activation

• Increased cortisol secretion: Stress response to illness, anti-inflammatory effects, metabolic effects, peak levels typically 2-4 times normal
• Elevated ACTH (adrenocorticotropic hormone): Drives cortisol production
• Increased corticotropin-releasing hormone (CRH): Central regulation of stress response

2. Thyroid Hormone Changes

• May see decreased T3 (triiodothyronine) - "sick euthyroid syndrome"
• Increased reverse T3 (rT3)
• Usually normal or slightly decreased TSH
• Adaptive response to conserve energy during acute illness

3. Vasopressin (ADH) Secretion

• Increased antidiuretic hormone: Water retention, concentrated urine, decreased urine output, may lead to hyponatremia if excessive

4. Growth Hormone and IGF

• Elevated growth hormone: Stress-induced secretion
• Decreased IGF-1: Part of acute phase response

5. Gonadotropin Suppression

• Decreased LH and FSH: Reproductive function suppressed during acute illness
• Reduced sex hormone production: Energy conservation mechanism

6. Catecholamine Release

• Increased adrenaline and noradrenaline: From adrenal medulla, contributes to cardiovascular changes, metabolic effects (glycogenolysis, lipolysis)

B. Metabolic Characteristics

1. Increased Metabolic Rate

• Approximately 10-13% increase per 1°C rise in temperature
• Increased oxygen consumption and CO2 production

2. Altered Glucose Metabolism

• Hyperglycemia: Increased hepatic glucose production, insulin resistance, stress hormone effects
• Increased glucose utilization: By immune cells and tissues

3. Protein Metabolism Changes

• Increased protein catabolism: Muscle protein breakdown, negative nitrogen balance
• Acute phase protein synthesis:
  • Increased: CRP, serum amyloid A, fibrinogen, ferritin, haptoglobin
  • Decreased: Albumin, transferrin, transthyretin

4. Lipid Metabolism

• Increased lipolysis: Fat breakdown for energy
• Elevated free fatty acids: Alternative fuel source
• Altered lipid profile: Decreased HDL, increased triglycerides

5. Electrolyte and Mineral Changes

• Hyponatremia: Due to ADH secretion and fluid shifts
• Hypokalemia: Intracellular shift, increased urinary losses
• Hypophosphatemia: Intracellular shift
• Decreased serum iron and zinc: Sequestration (reduces availability to pathogens)

C. Autonomic Characteristics

1. Sympathetic Nervous System Activation

• Cardiovascular effects: Tachycardia, increased cardiac output, peripheral vasoconstriction during "chill phase"
• Pupillary dilation (mydriasis)
• Decreased gastrointestinal motility: Reduced bowel sounds, constipation, nausea

2. Thermoregulatory Responses

• During temperature rise (chill phase): Vasoconstriction, piloerection, shivering thermogenesis, seeking warmth
• At fever plateau: Balance between heat production and loss
• During defervescence: Peripheral vasodilation, sweating, increased heat loss

3. Respiratory Changes

• Increased respiratory rate (tachypnea): Compensation for increased metabolic rate, may lead to respiratory alkalosis

4. Skin and Cutaneous Circulation

• Biphasic response: Initial vasoconstriction (cold, pale), later vasodilation (warm, flushed)
• Sweating: Eccrine gland activation during defervescence

5. Renal Effects

• Decreased urine output (oliguria): Due to ADH secretion, reduced renal blood flow, fluid loss through sweating
• Concentrated urine: High specific gravity

D. Behavioral Characteristics

1. Thermoregulatory Behaviors

• During chill phase: Seeking warmth, adding clothing/blankets, curling up
• During hot phase: Seeking cool environment, removing clothing, increased fluid intake

2. Sickness Behaviors

• Malaise and fatigue: Overwhelming tiredness, lack of energy, mediated by cytokines
• Lethargy and somnolence: Increased sleep, reduced activity, conservation of energy
• Social withdrawal: Decreased social interaction, isolation behaviors

3. Appetite and Dietary Changes

• Anorexia (loss of appetite): Reduced food intake, cytokine-mediated, adaptive response
• Taste changes: Altered perception of food
• Nausea: May accompany fever

4. Cognitive and Mood Changes

• Difficulty concentrating: "Brain fog"
• Confusion: Especially in elderly (may indicate delirium)
• Irritability and mood changes: Depression-like symptoms, anxiety, emotional lability
• Altered pain perception: Increased sensitivity or hyperalgesia

5. Motor Function Changes

• Reduced motor activity: Less movement, staying still
• Weakness: Generalized muscle weakness
• Myalgia (muscle aches): Often accompanies fever
• Arthralgia (joint aches)

6. Sensory Changes

• Headache: Very common with fever
• Photophobia: Light sensitivity
• Hyperacusis: Sound sensitivity

Decision-Making Framework

When to START Empirical Antibiotics:

• Signs of sepsis or severe sepsis (use qSOFA or SOFA scores)
• Hemodynamic instability
• Evidence of significant bacterial infection on examination or investigations
• Immunocompromised state
• Deteriorating clinical condition

When to WITHHOLD Antibiotics and Monitor:

• Low-grade fever (\<38.3°C) without other concerning features
• Hemodynamically stable
• Likely non-bacterial cause (atelectasis, physiological surgical response)
• First 48 hours post-op with unremarkable examination

Key Factors for Mrs Davis

Factor	Consideration	Impact on Antibiotic Choice
Type of Surgery	Hysterectomy (gynecological)	Need coverage for Gram-negatives (E. coli, Klebsiella), anaerobes (Bacteroides), Gram-positives
Timing	24 hours post-operative	Early time point - consider non-infectious causes first
Likely Sources	UTI, wound/pelvis, respiratory	Broad-spectrum coverage needed until source identified

RECOMMENDED FIRST-LINE REGIMEN

Alternative Regimens

If Penicillin Allergy:

• Cefuroxime 1.5g IV TDS + Metronidazole 500mg IV TDS
• (Note: 10% cross-reactivity with cephalosporins)

If Severe Penicillin Allergy:

• Ciprofloxacin 400mg IV BD + Metronidazole 500mg IV TDS

If Severe Sepsis/Septic Shock:

• Piperacillin-Tazobactam 4.5g IV TDS or
• Meropenem 1g IV TDS

Management Summary for Mrs Davis

Monitoring and Duration

• Monitor clinical response (temperature, observations, symptoms)
• Review at 48-72 hours when culture results available
• Duration:
  • Uncomplicated UTI: 3-5 days
  • Wound infection: 5-7 days
  • Pelvic infection: 7-14 days depending on severity
• Daily review of need for antibiotics (antimicrobial stewardship)