All EMS presentations
GIClinical presentation

Diarrhea

A streamlined, differential-led presentation for rapid clinical review.

Clinical snapshot

Twenty-second review

  • Diarrhea accelerates intestinal fluid and electrolyte loss through infectious, inflammatory, medication, malabsorptive, or ischemic mechanisms and may cause dehydration.
  • Blood, severe pain, peritonism, shock, recent antibiotics, immune compromise, or profound weakness raises concern for complicated disease.
  • Keep overflow around fecal impaction in the differential; overlapping or concurrent illness remains possible.
  • For diarrhea, trends and combinations of findings are more informative than one isolated vital sign.
Differentials

Compare the clinical patterns

The repeated material is grouped inside each possibility. Open only the condition you need.

Serious3 conditions
ColitisTime-sensitive high-risk possibility

HPI

Clarify duration/frequency; blood or melena; abdominal pain.

Signs & symptoms

Blood, fever, severe pain, immune compromise, or poor perfusion.

Focused exam

Inspect for distension, scars, hernia, emesis, or blood; auscultate and palpate gently for focal tenderness, guarding, or rigidity; Assess hydration, perfusion, and relevant chest, flank, pelvic, or rectal-history clues.

Brief pathophysiology

Colitis may cause diarrhea through a time-sensitive process capable of rapid physiological deterioration.

Vital-sign pattern

What the trend may show

Possible pattern

Volume loss may first appear as tachycardia or postural symptoms; hypotension is a later sign. Fever or blood loss changes the likely cause and risk.

Heart rate (bpm)

May rise

Tachycardia may reflect volume depletion, fever, or distress.

Blood pressure (mmHg)

May fall

Relative or orthostatic change can precede resting hypotension.

Pulse pressure (mmHg)

May narrow

Reduced stroke volume can narrow pulse pressure as depletion worsens.

Temperature (°C)

Variable

Fever supports infection; hypothermia may occur in severe illness.

Front-load in the triage report

  • Colitis: Blood, fever, severe pain, immune compromise, or poor perfusion.
  • Duration/frequency.
  • Blood or melena?
GI bleedTime-sensitive high-risk possibility

HPI

Clarify blood or melena; abdominal pain; vomiting.

Signs & symptoms

Blood, fever, severe pain, immune compromise, or poor perfusion.

Focused exam

Assess hydration, perfusion, and relevant chest, flank, pelvic, or rectal-history clues; Assess hydration, abdomen, stool description, skin, temperature, medication and travel history, and functional impact.

Brief pathophysiology

GI bleed may cause diarrhea through a time-sensitive process capable of rapid physiological deterioration.

Vital-sign pattern

What the trend may show

Possible pattern

Hemorrhage is a trend diagnosis: tachycardia and narrowing pulse pressure may precede hypotension. Age, pregnancy, medications, and pacing can blunt expected responses.

Heart rate (bpm)

Often rises

Tachycardia is a common compensatory response but may be absent.

Pulse pressure (mmHg)

May narrow

Narrowing pulse pressure can reflect reduced stroke volume.

Blood pressure (mmHg)

May fall late

A normal pressure does not exclude significant compensated hemorrhage.

MAP (mmHg)

May fall

A falling trend supports worsening perfusion; interpret with mental status and skin signs.

Front-load in the triage report

  • GI bleed: Blood, fever, severe pain, immune compromise, or poor perfusion.
  • Blood or melena?
  • Abdominal pain.
SepsisTime-sensitive high-risk possibility

HPI

Clarify abdominal pain; vomiting; fever.

Signs & symptoms

Blood, fever, severe pain, immune compromise, or poor perfusion.

Focused exam

Assess hydration, perfusion, and relevant chest, flank, pelvic, or rectal-history clues; Assess hydration, abdomen, stool description, skin, temperature, medication and travel history, and functional impact.

Brief pathophysiology

Sepsis may cause diarrhea through a time-sensitive process capable of rapid physiological deterioration.

Vital-sign pattern

What the trend may show

Possible pattern

No single vital sign diagnoses sepsis. New tachypnea, abnormal temperature, tachycardia, or falling pressure—especially with altered mentation or poor perfusion—supports organ dysfunction and urgency.

Respiratory rate (breaths/min)

May rise early

Tachypnea is included in NEWS2 and can precede overt hypotension.

Temperature (°C)

High or low

Absence of fever does not exclude sepsis; hypothermia is concerning.

Heart rate (bpm)

Often rises

Tachycardia is common but may be blunted by age or medication.

Blood pressure (mmHg)

May fall

Relative hypotension and trend matter; profound hypotension can be late.

Front-load in the triage report

  • Sepsis: Blood, fever, severe pain, immune compromise, or poor perfusion.
  • Abdominal pain.
  • Vomiting.
Common2 conditions
Infectious gastroenteritisCommon presentation pattern

HPI

Clarify duration/frequency; blood or melena; abdominal pain.

Signs & symptoms

Acute watery stool, contacts, travel, or recent medicines may support the cause.

Focused exam

Inspect for distension, scars, hernia, emesis, or blood; auscultate and palpate gently for focal tenderness, guarding, or rigidity; Assess hydration, perfusion, and relevant chest, flank, pelvic, or rectal-history clues.

Brief pathophysiology

Infectious gastroenteritis may explain the presenting symptoms through a common clinical mechanism, while serial assessment checks for complications or an alternate cause.

Vital-sign pattern

What the trend may show

Possible pattern

Volume loss may first appear as tachycardia or postural symptoms; hypotension is a later sign. Fever or blood loss changes the likely cause and risk.

Heart rate (bpm)

May rise

Tachycardia may reflect volume depletion, fever, or distress.

Blood pressure (mmHg)

May fall

Relative or orthostatic change can precede resting hypotension.

Pulse pressure (mmHg)

May narrow

Reduced stroke volume can narrow pulse pressure as depletion worsens.

Temperature (°C)

Variable

Fever supports infection; hypothermia may occur in severe illness.

Front-load in the triage report

  • Acute watery stool, contacts, travel, or recent medicines may support the cause.
  • Duration/frequency.
  • Blood or melena?
Medication effectCommon presentation pattern

HPI

Clarify blood or melena; abdominal pain; vomiting.

Signs & symptoms

Acute watery stool, contacts, travel, or recent medicines may support the cause.

Focused exam

Assess hydration, perfusion, and relevant chest, flank, pelvic, or rectal-history clues; Assess hydration, abdomen, stool description, skin, temperature, medication and travel history, and functional impact.

Brief pathophysiology

Medication effect may explain the presenting symptoms through a common clinical mechanism, while serial assessment checks for complications or an alternate cause.

Vital-sign pattern

What the trend may show

Possible pattern

Volume loss may first appear as tachycardia or postural symptoms; hypotension is a later sign. Fever or blood loss changes the likely cause and risk.

Heart rate (bpm)

May rise

Tachycardia may reflect volume depletion, fever, or distress.

Blood pressure (mmHg)

May fall

Relative or orthostatic change can precede resting hypotension.

Pulse pressure (mmHg)

May narrow

Reduced stroke volume can narrow pulse pressure as depletion worsens.

Temperature (°C)

Variable

Fever supports infection; hypothermia may occur in severe illness.

Front-load in the triage report

  • Acute watery stool, contacts, travel, or recent medicines may support the cause.
  • Blood or melena?
  • Abdominal pain.
Mimics1 condition
Overflow around fecal impactionImportant alternative presentation

HPI

Clarify duration/frequency; blood or melena; abdominal pain.

Signs & symptoms

Small-volume leakage with constipation history can mimic diarrhea.

Focused exam

Inspect for distension, scars, hernia, emesis, or blood; auscultate and palpate gently for focal tenderness, guarding, or rigidity; Assess hydration, perfusion, and relevant chest, flank, pelvic, or rectal-history clues.

Brief pathophysiology

Overflow around fecal impaction can resemble diarrhea through overlapping symptoms or referred physiology despite a different primary mechanism.

Vital-sign pattern

What the trend may show

Possible pattern

Volume loss may first appear as tachycardia or postural symptoms; hypotension is a later sign. Fever or blood loss changes the likely cause and risk.

Heart rate (bpm)

May rise

Tachycardia may reflect volume depletion, fever, or distress.

Blood pressure (mmHg)

May fall

Relative or orthostatic change can precede resting hypotension.

Pulse pressure (mmHg)

May narrow

Reduced stroke volume can narrow pulse pressure as depletion worsens.

Temperature (°C)

Variable

Fever supports infection; hypothermia may occur in severe illness.

Front-load in the triage report

  • Small-volume leakage with constipation history can mimic diarrhea.
  • Duration/frequency.
  • Blood or melena?
Red flags

Findings that should escalate concern

  • Blood, severe pain, peritonism, shock, recent antibiotics, immune compromise, or profound weakness raises concern for complicated disease.
  • Colitis, GI bleed, or sepsis: Blood, fever, severe pain, immune compromise, or poor perfusion.
Related EMS presentations

Continue the clinical pathway

GIAbdominal painGeneral MedicalNausea / vomitingInfectiousFever / suspected infection / sepsisGIGI bleedGIConstipation / fecal impaction
References

Clinical and academic sources

Curated clinical guidance and peer-reviewed evidence supporting this presentation. Current BCEHS guidance, medical direction, and local policy remain authoritative for practice.

BCEHS Handbook — specific CPGs

  1. E05: Abdominal PainBC Emergency Health Services Handbook

    Official BCEHS clinical practice guidance for abdominal pain.

Supporting clinical and academic evidence

  1. Appropriateness Criteria: Acute Nonlocalized Abdominal PainAmerican College of Radiology

    Evidence-based diagnostic context for acute nonlocalized abdominal pain.

  2. CEDIS Presenting Complaint List updateCanadian Association of Emergency Physicians

    Presenting-complaint terminology and categorization context. It does not establish a prehospital “top 100” ranking.

  3. 2017 IDSA Clinical Practice Guidelines for Infectious DiarrheaClinical Infectious Diseases · 2017

    Assessment of dehydration, severe infection, exposure risk, and complications of acute diarrhea.