Abdomen, Pelvis, and Perineun

Nausea and Vomiting

Determining the Cause

Clinical Presentation

a. History: Sudden Onset

Sudden onset nausea typically indicates something acute or rapidly evolving.
Conditions that present suddenly may be more serious or life-threatening, requiring immediate evaluation.

Differential Diagnosis

Cause	Typical Associated Features
Gastroenteritis	Vomiting, diarrhea, cramps, fever (often viral or foodborne)
Food poisoning	Onset within hours of ingestion; may have diarrhea, vomiting
Vestibular disorders	Sudden vertigo, imbalance, nystagmus (e.g., vestibular neuritis)
Migraine	Nausea with headache, photophobia, aura
Acute myocardial infarction	Especially in older adults; nausea with chest discomfort
Acute pancreatitis	Severe epigastric pain radiating to the back + vomiting
Appendicitis or peritonitis	Sudden abdominal pain + nausea, guarding, rebound tenderness
Increased intracranial pressure	Headache, vomiting, changes in consciousness (e.g., from a hemorrhage)
Medication or toxin ingestion	Antidepressants, alcohol, overdoses, or chemotherapy agents
Pregnancy (esp. hyperemesis)	Nausea may feel sudden, especially early in pregnancy

Next Pivotal Assessment	Findings
Further History

Determining the cause of sudden-onset nausea involves a systematic approach, considering time course, associated symptoms, and patient history. Here's a clinical framework to guide you:

🔍 STEP 1: Characterize the Nausea

Onset: Sudden vs. gradual
Duration: Hours, days
Frequency: Constant, episodic
Associated vomiting? Yes/No

🧭 STEP 2: Look for Red Flags (Urgent Causes)

Ask or check for:

Severe headache → ↑ ICP, migraine, subarachnoid hemorrhage
Chest pain → MI
Abdominal pain → Surgical abdomen (e.g. appendicitis, pancreatitis)
Fever + stiff neck → Meningitis
Altered mental status → Toxin, metabolic cause, CNS

🧠 STEP 3: Use a Symptom-Based Differential

🩺 1. Gastrointestinal Causes

Gastroenteritis (viral or bacterial): diarrhea, fever, cramps
Food poisoning: sudden onset after eating, others affected
Bowel obstruction: pain, distention, no bowel movement
Appendicitis, pancreatitis: localized pain

🧠 2. Central Nervous System Causes

Migraine: history of migraines, photophobia, aura
Increased intracranial pressure: headache worse in the morning or lying down
Vestibular dysfunction (e.g. labyrinthitis, BPPV): vertigo + nausea

❤️ 3. Cardiovascular Causes

Myocardial infarction (especially in elderly or diabetics): nausea, diaphoresis, chest discomfort
Hypotension: postural nausea

🩸 4. Metabolic / Endocrine Causes

Diabetic ketoacidosis (DKA): fruity breath, polyuria, fatigue
Uremia: known kidney disease, anorexia
Hypercalcemia: “bones, stones, groans, moans”

💊 5. Medications / Toxins

New medications (opioids, antibiotics, chemotherapy)
Alcohol, cannabis, toxins
Withdrawal (e.g. opioids, nicotine)

🤰 6. Pregnancy

In women of childbearing age → rule out pregnancy (even if unlikely)

🧪 STEP 4: Initial Workup (if needed)

Vitals: BP, pulse, fever
Glucose, electrolytes, renal function
Pregnancy test
Imaging: Head CT (neuro signs), abdominal CT/US (pain)

🧠 Decision Tree (Simplified)

Is it life-threatening?    └── Yes → Headache, chest pain, altered sensorium → ER    Localized symptoms?    └── GI symptoms (pain, diarrhea) → Gastroenteritis, appendicitis, etc.    └── Neuro symptoms (vertigo, headache) → Migraine, vestibular, CNS lesion    └── Metabolic context (diabetes, CKD) → DKA, uremia, etc.    Pregnant female?    └── Check β-hCG → Consider morning sickness, ectopic pregnancy    Medications/toxins?    └── Recent drug use, changes → Drug-induced nausea

Would you like a printable version of this as a decision tree diagram?

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🧠 Clinical Example

A patient who says, “I suddenly felt nauseated after lunch” might be evaluated for:
- Foodborne illness
- Gastric irritation
- Pancreatitis or gallbladder disease
A patient who wakes up suddenly nauseated and dizzy might have:
- Vestibular dysfunction
- Elevated intracranial pressure
- Alcohol or medication withdrawal

🚨 When Sudden Nausea Is a Red Flag

If sudden nausea is accompanied by chest pain, neurologic symptoms (confusion, slurred speech, vertigo), or severe abdominal pain, it may be a sign of:

Heart attack
Stroke
Peritonitis
Acute poisoning

Immediate evaluation is necessary in such cases.

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🧭 Decision Tree: Sudden-Onset Nausea

                         ┌──────────────┐                           │Sudden Nausea?│                           └──────┬───────┘                                  │                 ┌────────────────────────────────┐                 ↓                                ↓      ⚠️ Has associated chest pain?       🧠 Has headache, confusion,           or sweating?                         vision changes, vertigo?                 ↓                                ↓           ┌────Yes────┐                    ┌──────Yes──────┐           ↓           ↓                    ↓               ↓    Suspect Acute     No             Suspect CNS Cause   No     Coronary Syndrome                 (Stroke, ↑ICP,     ↓       (ER refer)                     vestibular issue)   ↓                                                      ┌────────────┐                                                      │Is there     │                                                      │abdominal    │                                                      │pain/tenderness?│                                                      └──────┬───────┘                                                             ↓                                          ┌───────────────Yes───────────────┐                                          ↓                                 ↓                       🔥Localized RUQ or LUQ pain?             Diffuse/severe pain?                                ↓                                          ↓            ┌────Yes────┐                     ┌────Yes────┐         ┌────Yes────┐            ↓           ↓                     ↓           ↓         ↓           ↓    Suspect gallbladder   No         Suspect pancreatitis  No   Suspect peritonitis,      or liver issue                     (↑amylase/lipase)        appendicitis, etc.                                                                   (Needs imaging/ER)                                                                                    ↓                  📆 Any recent meal within past 6–8 hrs?                            ↓                  ┌────Yes────┐                  ↓           ↓      Suspect foodborne illness     No       (gastroenteritis, toxin)     ↓                                   🧪 Review medications,                                      pregnancy test,                                      bloodwork for                                      metabolic causes

📝 Notes:

Always consider pregnancy in reproductive-age women.
Elderly may present atypically (e.g., nausea only in MI).
Use labs and imaging if symptoms persist or worsen.