What is the cause of intermittent sharp abdominal pain, nausea, and headache that occur after eating and at night after laying down in a patient?

Differential Diagnosis: Gastroesophageal Reflux Disease (GERD) with Possible Functional Dyspepsia Overlap

The most likely diagnosis is gastroesophageal reflux disease (GERD), given the classic presentation of sharp epigastric pain and nausea that worsens after eating and when lying down at night, with headache as a common associated non-gastrointestinal symptom. 1

Clinical Reasoning

Primary Diagnosis: GERD

• Sharp abdominal pain after eating that worsens when lying down at night is pathognomonic for GERD, as the supine position allows gastric acid to reflux into the esophagus 1, 2
• The burning sensation starting in the epigastrium that may radiate upward differentiates GERD from functional dyspepsia 1
• Approximately one-third of patients with functional dyspepsia have coexisting GERD symptoms, and clinicians tend to favor a GERD diagnosis when both are present 1

Associated Symptoms

• Headache is a recognized non-gastrointestinal symptom that occurs in functional gastrointestinal disorders and does not exclude GERD 1
• Nausea commonly accompanies GERD and functional dyspepsia, with 42-87% overlap between these conditions 1

Critical Red Flags to Exclude (Require Immediate Evaluation)

• Age >50 years at symptom onset 1, 3
• Documented weight loss or short symptom duration 1, 3
• Nocturnal symptoms that wake the patient from sleep (your patient has symptoms after lying down, but clarify if they wake from sleep) 1, 3
• Rectal bleeding or anemia 1, 3
• Persistent vomiting suggesting obstruction 4
• Family history of gastroesophageal malignancy 1

Diagnostic Approach

Initial Assessment

• If age ≥55 years with new-onset dyspepsia, perform upper endoscopy to exclude malignancy before initiating empirical therapy 1
• If age <55 years without alarm features, proceed with non-invasive testing 1
• Test for H. pylori using breath or stool testing before initiating symptomatic therapy, as positive results require antibiotic treatment 1, 5
• Consider full blood count if age ≥55 years 1
• Consider coeliac serology only if IBS-type symptoms (abdominal pain related to defecation) are present 1

Distinguishing GERD from Other Conditions

• Unlike IBS, abdominal pain in GERD/functional dyspepsia is unrelated to defecation 1
• Duodenal ulcer pain occurs several hours after eating (often at night) and improves with food, whereas gastric ulcer pain occurs immediately after eating and worsens with food 2
• Biliary colic presents as epigastric pain <1 year duration with specific characteristics warranting abdominal ultrasound 1
• Gastroparesis presents with severe persistent vomiting and early satiety, not intermittent symptoms 1, 4

Management Algorithm

Step 1: Empirical PPI Trial (If No Alarm Features)

• Initiate omeprazole 20 mg once daily before meals for 4-8 weeks as first-line therapy for GERD 1, 6
• This approach is appropriate if H. pylori testing is negative or after successful eradication 1, 5
• Common adverse reactions include headache (7%), abdominal pain (5%), nausea (4%), and diarrhea (4%) 6

Step 2: Lifestyle Modifications

• Avoid lying down within 2-3 hours after eating 1
• Elevate head of bed for nighttime symptoms 1
• Avoid trigger foods (fatty foods, caffeine, alcohol) 1
• Maintain adequate hydration (1.5-2 L daily) to prevent dehydration-related GERD worsening 5

Step 3: Reassessment at 4-8 Weeks

• If symptoms persist despite PPI therapy and negative H. pylori, consider functional dyspepsia overlap and refer to gastroenterology for possible endoscopy 1
• If symptoms resolve, continue PPI at lowest effective dose 1
• Do not perform repetitive testing once functional diagnosis is established 7

Common Pitfalls to Avoid

• Do not assume functional dyspepsia without first excluding organic causes with appropriate testing based on age and alarm features 4
• Do not delay endoscopy in patients >55 years with new-onset symptoms, as this is the threshold for malignancy risk 1
• Do not overlook H. pylori testing, as treatment failure without eradication leads to persistent symptoms 1, 5
• Do not misdiagnose IBS when pain is unrelated to defecation—this presentation lacks the cardinal IBS feature of pain associated with bowel movements 1
• Do not attribute all symptoms to GERD if severe vomiting develops, as this may indicate gastroparesis or obstruction requiring imaging 1, 4