Comprehensive Overview of Gastrointestinal Conditions
1. Abdominal Pain (Chronic)
Pathophysiology: Chronic GI pain arises from visceral hypersensitivity, altered gut motility, central nervous system amplification of pain signals, and psychological factors that lower pain thresholds 1.
Signs & Symptoms:
- Persistent or recurrent abdominal pain >3 months
- Pain may be diffuse or localized
- Often worsens with stress or eating
- May be associated with altered bowel habits
Diagnostics:
- Rule out structural causes: CBC, CRP, imaging (ultrasound/CT)
- Consider colonoscopy if alarm features present
- Assess for visceral vs. centrally mediated pain patterns
Treatment:
- Medications: Neuromodulators are first-line for centrally mediated pain—tricyclic antidepressants (amitriptyline 10-50mg nightly) or SNRIs (duloxetine 30-60mg daily) 1
- Avoid opioids completely for chronic GI pain in DGBI 1
- Lifestyle: Stress management, regular exercise
- Procedures: Psychological therapies (CBT, gut-directed hypnotherapy) should be introduced early 1
2. Acid Reflux / GERD / Heartburn
Pathophysiology: Retrograde movement of gastric acid into the esophagus due to lower esophageal sphincter dysfunction, delayed gastric emptying, or hiatal hernia 2.
Signs & Symptoms:
- Heartburn (retrosternal burning)
- Regurgitation of acid/food
- Dysphagia, chronic cough, hoarseness (atypical)
- Worse after meals, lying down
Diagnostics:
- Clinical diagnosis based on typical symptoms
- Upper endoscopy if alarm features (dysphagia, weight loss, anemia) or refractory symptoms
- Ambulatory pH monitoring for atypical cases
- High-resolution manometry before surgical intervention
Treatment:
- Medications: Proton pump inhibitors (omeprazole 20-40mg daily, lansoprazole 30mg daily) are first-line 2
- Alginates for breakthrough symptoms
- Baclofen for refractory reflux
- Lifestyle: Elevate head of bed, avoid late meals, weight loss, avoid trigger foods (caffeine, alcohol, fatty foods)
- Procedures: Fundoplication or endoscopic interventions for refractory cases 2
3. Barrett's Esophagus
Pathophysiology: Metaplastic change of esophageal squamous epithelium to columnar epithelium with goblet cells, secondary to chronic GERD exposure—precancerous condition.
Signs & Symptoms:
- Often asymptomatic
- May have chronic GERD symptoms
Diagnostics:
- Upper endoscopy with systematic biopsies
- Surveillance intervals based on dysplasia grade
Treatment:
- Medications: High-dose PPI therapy (twice daily dosing)
- Lifestyle: Same as GERD management
- Procedures: Endoscopic ablation (radiofrequency ablation) for dysplasia; endoscopic mucosal resection for visible lesions
4. Blood in Stool / Rectal Bleeding / GI Bleeding
Pathophysiology: Varies by source—upper GI (peptic ulcer, varices, Mallory-Weiss tear) vs. lower GI (hemorrhoids, diverticulosis, IBD, polyps, cancer).
Signs & Symptoms:
- Upper GI: Melena (black tarry stools), hematemesis, coffee-ground emesis
- Lower GI: Hematochezia (bright red blood), maroon stools
- Anemia symptoms: fatigue, pallor, tachycardia
Diagnostics:
- Hemodynamic assessment first
- CBC, coagulation studies, type and cross
- Upper endoscopy for suspected upper source
- Colonoscopy for lower GI bleeding
- CT angiography or tagged RBC scan for active bleeding
Treatment:
- Acute: IV resuscitation, blood transfusion if needed
- Medications: PPIs for upper GI bleeding (IV bolus then infusion); octreotide for variceal bleeding
- Procedures: Endoscopic hemostasis (clips, cautery, band ligation); interventional radiology embolization; surgery for refractory cases
5. Celiac Disease
Pathophysiology: Autoimmune enteropathy triggered by gluten (gliadin) ingestion in genetically susceptible individuals (HLA-DQ2/DQ8), causing villous atrophy and malabsorption.
Signs & Symptoms:
- Chronic diarrhea, steatorrhea
- Abdominal bloating, pain
- Weight loss, failure to thrive (children)
- Iron-deficiency anemia, osteoporosis
- Dermatitis herpetiformis
Diagnostics:
- Serology: Tissue transglutaminase IgA (tTG-IgA) with total IgA level 3
- Upper endoscopy with duodenal biopsies showing villous atrophy
- HLA typing if diagnosis uncertain
Treatment:
- Strict lifelong gluten-free diet (no wheat, barley, rye)
- Nutritional supplementation (iron, calcium, vitamin D, B12)
- Dietitian consultation mandatory
- Monitor for compliance and symptom resolution
6. Cirrhosis and Liver Disease
Pathophysiology: End-stage liver fibrosis from chronic injury (alcohol, viral hepatitis, NAFLD, autoimmune) leading to portal hypertension and hepatic dysfunction.
Signs & Symptoms:
- Jaundice, ascites, peripheral edema
- Spider angiomata, palmar erythema
- Hepatic encephalopathy (confusion, asterixis)
- Variceal bleeding, splenomegaly
Diagnostics:
- Liver function tests, albumin, INR
- Imaging: Ultrasound with Doppler, CT/MRI
- Upper endoscopy for varices
- Liver biopsy or elastography for staging
Treatment:
- Medications: Diuretics for ascites (spironolactone + furosemide); lactulose/rifaximin for encephalopathy; beta-blockers for variceal prophylaxis
- Lifestyle: Alcohol abstinence, sodium restriction
- Procedures: Paracentesis, TIPS for refractory ascites/bleeding; liver transplantation evaluation
7. Colon Cancer
Pathophysiology: Malignant transformation of colonic epithelium, typically from adenomatous polyps (adenoma-carcinoma sequence).
Signs & Symptoms:
- Change in bowel habits
- Rectal bleeding, iron-deficiency anemia
- Abdominal pain, obstruction
- Weight loss, fatigue
Diagnostics:
- Colonoscopy with biopsy (gold standard)
- CT chest/abdomen/pelvis for staging
- CEA tumor marker
Treatment:
- Surgery: Surgical resection (hemicolectomy) is primary treatment
- Medications: Adjuvant chemotherapy (FOLFOX) for stage III/high-risk stage II
- Procedures: Neoadjuvant chemoradiation for rectal cancer; palliative stenting for obstruction
8. Constipation
Pathophysiology: Slow colonic transit, pelvic floor dysfunction, or inadequate fiber/fluid intake leading to infrequent, difficult bowel movements.
Signs & Symptoms:
- <3 bowel movements per week
- Hard, lumpy stools
- Straining, incomplete evacuation
- Abdominal discomfort
Diagnostics:
- Clinical diagnosis
- Rule out secondary causes: thyroid function, calcium, medications
- Colonoscopy if alarm features or age >45
- Anorectal manometry/defecography for refractory cases
Treatment:
- Medications: Osmotic laxatives (polyethylene glycol) first-line 4; stimulant laxatives (senna) as needed; secretagogues (linaclotide, plecanatide) for refractory cases 4
- Lifestyle: Increase fiber (25-30g/day), adequate hydration, regular exercise 3
- Procedures: Biofeedback for pelvic floor dysfunction
9. Crohn's Disease
Pathophysiology: Chronic transmural inflammatory bowel disease affecting any part of GI tract (mouth to anus), characterized by skip lesions, granulomas, and complications (strictures, fistulae).
Signs & Symptoms:
- Chronic diarrhea (often non-bloody)
- Abdominal pain (right lower quadrant)
- Weight loss, fever
- Perianal disease (fistulae, abscesses)
- Extraintestinal manifestations (arthritis, uveitis)
Diagnostics:
- Ileocolonoscopy with biopsies showing skip lesions, granulomas 5
- MR enterography or intestinal ultrasound for small bowel evaluation 5
- Fecal calprotectin elevated
- CBC (anemia), CRP elevated
Treatment:
- Mild-moderate ileocolonic disease: Budesonide 9mg daily or corticosteroids (prednisolone 40mg, taper over 8 weeks) 6
- Moderate-severe: Azathioprine 1.5-2.5mg/kg/day or mercaptopurine 0.75-1.5mg/kg/day as steroid-sparing agents 6
- Severe/refractory: Infliximab 5mg/kg at 0,2,6 weeks then every 8 weeks 6
- Perianal fistulae: Metronidazole 400mg TDS + ciprofloxacin 500mg BD first-line 6; infliximab for refractory cases 6
- Lifestyle: Smoking cessation is critical 6
- Procedures: Surgery for failed medical therapy or limited disease 6; seton drainage for fistulae 6
10. Diverticulosis and Diverticulitis
Pathophysiology: Diverticulosis = outpouchings of colonic mucosa through muscular wall. Diverticulitis = inflammation/infection of diverticula.
Signs & Symptoms:
- Diverticulosis: Usually asymptomatic; may have painless rectal bleeding
- Diverticulitis: Left lower quadrant pain, fever, leukocytosis, change in bowel habits
Diagnostics:
- CT abdomen/pelvis with IV contrast (gold standard for diverticulitis)
- Colonoscopy after acute episode resolves (6-8 weeks)
Treatment:
- Uncomplicated diverticulitis: Outpatient oral antibiotics (ciprofloxacin + metronidazole or amoxicillin-clavulanate) 7-10 days; clear liquid diet initially
- Complicated (abscess, perforation): IV antibiotics, NPO; CT-guided drainage for abscess >3cm
- Lifestyle: High-fiber diet after resolution
- Procedures: Elective sigmoid colectomy for recurrent episodes or complications
11. Dysphagia (Difficulty Swallowing)
Pathophysiology: Oropharyngeal (neuromuscular) vs. esophageal (mechanical obstruction, motility disorder).
Signs & Symptoms:
- Difficulty initiating swallow (oropharyngeal) vs. food sticking sensation (esophageal)
- Odynophagia (painful swallowing)
- Regurgitation, weight loss
Diagnostics:
- Upper endoscopy to rule out stricture, mass, eosinophilic esophagitis
- Barium swallow for structural assessment
- High-resolution manometry for motility disorders
Treatment:
- Medications: PPIs for reflux-related strictures; topical steroids for eosinophilic esophagitis
- Procedures: Endoscopic dilation for strictures; botulinum toxin or myotomy for achalasia
- Lifestyle: Dietary modifications (soft foods, small bites)
12. Eosinophilic Esophagitis
Pathophysiology: Chronic immune-mediated esophageal inflammation driven by food antigens, characterized by eosinophilic infiltration (≥15 eosinophils/HPF).
Signs & Symptoms:
- Dysphagia, food impaction
- Chest pain
- Reflux-like symptoms unresponsive to PPIs
Diagnostics:
- Upper endoscopy showing rings, furrows, white exudates
- Esophageal biopsies (≥15 eosinophils/HPF)
Treatment:
- Medications: Topical corticosteroids (swallowed fluticasone 880-1760mcg BID or budesonide slurry 1mg BID); PPIs may help subset
- Dietary: Six-food elimination diet or targeted elimination based on testing
- Procedures: Dilation for strictures (cautiously—higher perforation risk)
13. Fecal Incontinence
Pathophysiology: Loss of voluntary control of defecation due to sphincter damage, neuropathy, or severe diarrhea.
Signs & Symptoms:
- Involuntary passage of stool
- Urgency, inability to defer defecation
- Soiling
Diagnostics:
- Anorectal manometry
- Endoanal ultrasound for sphincter defects
- Colonoscopy to rule out inflammatory causes
Treatment:
- Medications: Loperamide to thicken stool; fiber supplementation
- Lifestyle: Bowel retraining, scheduled toileting
- Procedures: Biofeedback therapy; sacral nerve stimulation; sphincteroplasty for anatomic defects
14. Food Allergies
Pathophysiology: IgE-mediated (immediate hypersensitivity) or non-IgE-mediated immune responses to food proteins.
Signs & Symptoms:
- IgE-mediated: Urticaria, angioedema, anaphylaxis within minutes-hours
- Non-IgE: Delayed GI symptoms (vomiting, diarrhea, eosinophilic disorders)
Diagnostics:
- Skin prick testing or serum-specific IgE
- Oral food challenge (gold standard)
- Elimination diet trial
Treatment:
- Strict avoidance of trigger foods
- Medications: Epinephrine auto-injector for IgE-mediated reactions; antihistamines for mild reactions
- Lifestyle: Read food labels; dietitian consultation
15. Gallstones
Pathophysiology: Precipitation of cholesterol or bilirubin in bile, forming stones in gallbladder; risk factors include obesity, rapid weight loss, female sex, pregnancy.
Signs & Symptoms:
- Biliary colic: Right upper quadrant pain radiating to back/shoulder, postprandial, lasting 30min-6hrs
- Nausea, vomiting
- Complications: cholecystitis (fever, Murphy's sign), choledocholithiasis (jaundice), pancreatitis
Diagnostics:
- Right upper quadrant ultrasound (first-line)
- HIDA scan for cholecystitis
- MRCP or ERCP for bile duct stones
Treatment:
- Asymptomatic: Observation
- Symptomatic: Laparoscopic cholecystectomy (definitive)
- Medications: Ursodeoxycholic acid for small cholesterol stones (limited role)
- Procedures: ERCP with sphincterotomy for choledocholithiasis
16. H. pylori Infection
Pathophysiology: Gram-negative bacteria colonizing gastric mucosa, causing chronic gastritis, peptic ulcers, and increasing gastric cancer risk.
Signs & Symptoms:
- Often asymptomatic
- Dyspepsia, epigastric pain
- Peptic ulcer symptoms
Diagnostics:
- Non-invasive: Urea breath test, stool antigen test
- Invasive: Endoscopy with biopsy (rapid urease test, histology, culture)
Treatment:
- Triple therapy: PPI (omeprazole 20mg BID) + clarithromycin 500mg BID + amoxicillin 1g BID for 14 days
- Quadruple therapy: PPI + bismuth + tetracycline + metronidazole for 14 days (if clarithromycin resistance)
- Confirm eradication: Urea breath test or stool antigen ≥4 weeks after treatment
17. Hemorrhoids
Pathophysiology: Swollen vascular cushions in anal canal due to increased intra-abdominal pressure (straining, pregnancy, chronic constipation).
Signs & Symptoms:
- Painless bright red rectal bleeding
- Prolapse, itching, discomfort
- Thrombosed external hemorrhoids cause severe pain
Diagnostics:
- Clinical examination, anoscopy
- Colonoscopy if >45 years or alarm features
Treatment:
- Medications: Topical anesthetics/steroids for symptom relief; stool softeners
- Lifestyle: High-fiber diet, adequate hydration, avoid straining
- Procedures: Rubber band ligation for internal hemorrhoids; hemorrhoidectomy for severe/refractory cases; thrombectomy for thrombosed external hemorrhoids
18. Irritable Bowel Syndrome (IBS)
Pathophysiology: Disorder of gut-brain interaction involving visceral hypersensitivity, altered motility, gut microbiota changes, low-grade inflammation, and psychosocial factors 3.
Signs & Symptoms:
- Recurrent abdominal pain ≥1 day/week for ≥3 months
- Associated with defecation and/or change in stool frequency/form
- Subtypes: IBS-D (diarrhea), IBS-C (constipation), IBS-M (mixed)
Diagnostics:
- Positive clinical diagnosis based on Rome V criteria 3
- Screening tests: CBC, CRP/ESR, coeliac serology, fecal calprotectin (<45 years with diarrhea) 3
- No colonoscopy unless alarm features or atypical features suggesting microscopic colitis 3
Treatment:
- First-line lifestyle: Regular exercise (strong recommendation) 3
- First-line dietary: Standard dietary advice; soluble fiber (ispaghula 3-4g/day, gradually increase) 3
- Second-line dietary: Low FODMAP diet (dietitian-supervised, 10+ weeks) 3, 4, 3
- IBS-D medications: Loperamide first-line; rifaximin or eluxadoline second-line 4
- IBS-C medications: Osmotic laxatives (polyethylene glycol) first-line; secretagogues (linaclotide, plecanatide) second-line 4
- Pain: Antispasmodics (hyoscine) or peppermint oil; neuromodulators (amitriptyline 10-30mg nightly) for refractory pain 3, 4
- Psychological therapies: CBT, gut-directed hypnotherapy (4-12 sessions) 3, 4, 3
19. Jaundice
Pathophysiology: Elevated bilirubin causing yellow discoloration of skin/sclera. Classified as pre-hepatic (hemolysis), hepatic (liver dysfunction), or post-hepatic (biliary obstruction).
Signs & Symptoms:
- Yellow skin and sclera
- Dark urine (conjugated hyperbilirubinemia)
- Pale stools (biliary obstruction)
- Pruritus
Diagnostics:
- Liver function tests, bilirubin fractionation
- Right upper quadrant ultrasound
- MRCP or ERCP for biliary obstruction
- Liver biopsy if hepatic cause unclear
Treatment:
- Treat underlying cause: Hemolysis management, hepatitis treatment, biliary decompression
- Procedures: ERCP with stenting for malignant obstruction; cholecystectomy for gallstone disease
20. Pancreatic Cysts
Pathophysiology: Fluid-filled lesions in pancreas—pseudocysts (post-pancreatitis) vs. cystic neoplasms (mucinous cystadenoma, IPMN).
Signs & Symptoms:
- Often asymptomatic (incidental finding)
- Abdominal pain, early satiety if large
- Complications: infection, rupture, malignant transformation
Diagnostics:
- CT or MRI pancreas protocol
- Endoscopic ultrasound with FNA for cyst fluid analysis (CEA, amylase, cytology)
Treatment:
- Pseudocysts: Observation if asymptomatic; drainage if symptomatic/infected
- Mucinous cysts: Surgical resection due to malignant potential
- Serous cystadenomas: Observation (benign)
- Surveillance: MRI for cysts with low malignant potential
21. Pancreatitis (Acute and Chronic)
Pathophysiology:
- Acute: Premature activation of pancreatic enzymes causing autodigestion (gallstones, alcohol most common)
- Chronic: Progressive fibrosis from recurrent injury (alcohol, genetic, autoimmune)
Signs & Symptoms:
- Acute: Severe epigastric pain radiating to back, nausea, vomiting, fever
- Chronic: Recurrent pain, steatorrhea, diabetes mellitus
Diagnostics:
- Acute: Lipase >3× upper limit normal; CT abdomen for complications
- Chronic: CT/MRI showing calcifications, ductal changes; fecal elastase for exocrine insufficiency
Treatment:
- Acute: NPO, IV fluids (aggressive resuscitation), analgesia; ERCP if biliary obstruction
- Chronic medications: Pancreatic enzyme replacement (25,000-40,000 units lipase with meals) 7; fat-soluble vitamins; pain management with neuromodulators (avoid opioids)
- Lifestyle: Alcohol abstinence, low-fat diet
- Procedures: Endoscopic or surgical drainage for pseudocysts; celiac plexus block for pain
22. Peptic Ulcer Disease
Pathophysiology: Mucosal breaks in stomach/duodenum from imbalance between acid/pepsin and mucosal defense (H. pylori, NSAIDs main causes).
Signs & Symptoms:
- Epigastric pain (burning, gnawing)
- Gastric ulcer: Pain worsens with eating
- Duodenal ulcer: Pain improves with eating, worse 2-3 hours postprandial
- Complications: bleeding, perforation, obstruction
Diagnostics:
- Upper endoscopy with biopsy (rule out malignancy in gastric ulcers)
- H. pylori testing (biopsy, urea breath test, stool antigen)
Treatment:
- H. pylori positive: Eradication therapy (see H. pylori section)
- H. pylori negative: PPI (omeprazole 20-40mg daily) for 4-8 weeks
- NSAID-related: Stop NSAID if possible; PPI therapy; switch to COX-2 selective if NSAID needed
- Lifestyle: Avoid NSAIDs, alcohol, smoking
- Procedures: Endoscopic hemostasis for bleeding; surgery for perforation
23. Ulcerative Colitis
Pathophysiology: Chronic inflammatory bowel disease limited to colon, characterized by continuous mucosal inflammation starting from rectum, extending proximally.
Signs & Symptoms:
- Bloody diarrhea
- Urgency, tenesmus
- Abdominal cramping
- Extraintestinal manifestations (arthritis, primary sclerosing cholangitis)
Diagnostics:
- Colonoscopy with biopsies showing continuous inflammation, crypt abscesses 5
- Fecal calprotectin elevated
- CBC (anemia), CRP elevated
Treatment:
- Mild-moderate distal colitis: Topical mesalazine (suppository 1g daily for proctitis; enema 1-2g daily for left-sided) + oral mesalazine 2.4-4.8g daily 8
- Moderate-severe or extensive: Oral corticosteroids (prednisolone 40mg, taper over 8 weeks)
- Severe/hospitalized: IV hydrocortisone 400mg/day or methylprednisolone 60mg/day 6; consider IV ciclosporin or infliximab for steroid-refractory disease 8
- Maintenance: Oral mesalazine; azathioprine/mercaptopurine for steroid-dependent disease 8
- Refractory proctitis: Consider topical tacrolimus or infliximab 8
- Lifestyle: Smoking cessation (protective in UC but still harmful overall)
- Procedures: Colectomy with ileal pouch-anal anastomosis for refractory disease or dysplasia 6
Key Clinical Pitfalls:
- IBS: Do not perform colonoscopy routinely—make positive diagnosis based on symptoms and negative screening tests 3
- Chronic pain: Never use opioids for DGBI-related pain 1
- IBD: Smoking cessation is the most important factor in maintaining Crohn's remission 6
- GERD: Atypical symptoms require careful evaluation to exclude cardiac, pulmonary, or other causes 2
- Constipation in IBS: Laxatives have limited evidence specifically for IBS-C; secretagogues are preferred second-line 4