RC

Lower Gastrointestinal Problems – Comprehensive Study Notes

Diarrhea

  • Definition & temporal classification

    • Acute: \le 14\,\text{days}

    • Persistent: >14\,\text{days} but \le 30\,\text{days}

    • Chronic: >30\,\text{days}

  • Etiology & pathophysiology

    • Primary U.S. cause ➜ infectious organisms (esp. viruses)

    • Notable pathogens & presentations

    • Norovirus, rotavirus – watery stool

    • E.\,coli\,O157! :! H7 – hemorrhagic colitis, possible HUS

    • Giardia lamblia – protozoan; greasy, foul-smelling stool

    • Clostridium\,difficile (CDI) – antibiotic-associated colitis

    • Mechanisms of injury

    • Secretory: organisms ↑ secretion/↓ absorption in enterocytes; little/no inflammation

    • Inflammatory: organisms destroy mucosa, provoke colonic inflammation, generate toxins ➜ impaired absorption, exudation

  • Transmission pathways

    • Contaminated food/water

    • Fecal–oral contact, esp. in LTCFs, day-care

  • Host susceptibility

    • Elderly (↓ immunity, comorbidities)

    • ↓ Gastric acidity (PPIs, H2 blockers) ➜ ↑ survival of pathogens

    • Altered gut flora (broad-spectrum antibiotics)

    • Immunocompromised states; jejunal tube feedings

  • Non-infectious causes

    • Drugs: laxatives, Mg antacids, antibiotics, metformin, chemotherapy

    • Food intolerances: large sugar alcohol load, lactose, gluten, caffeine

    • Osmotic: rapid GI transit (tube feeds, gastrectomy)

    • Malabsorption: celiac disease, short-bowel syndrome

  • Clinical manifestations

    • Upper GI source: large-volume watery stool, crampy peri-umbilical pain, N/V, minimal fever

    • Lower GI source: small-volume, frequent, possibly bloody stool; fever

    • Severe cases: dehydration (\textit{fluid volume deficit}), hypokalemia, metabolic acidosis

    • CDI: fulminant colitis, toxic megacolon, perforation

  • Diagnostic studies

    • Stool culture (blood, mucus, WBCs, ova/parasites, C. diff toxin)

    • Blood culture if septic/immunocompromised

    • Labs: CBC, electrolytes, \text{BUN/Cr}, serum osmolality, pH

    • Specialized: fecal fat/protein, GI hormones for secretory diarrhea

  • Interprofessional management

    • Prevent transmission (contact precautions)

    • Replace fluids & electrolytes (oral rehydration or IV LR/NS)

    • Protect perianal skin (barrier creams, meticulous hygiene)

    • Antidiarrheals (if no infection suspected)

    • Coaters (bismuth), absorbents (kaolin-pectin), opiate analogs (loperamide, diphenoxylate), antisecretories (octreotide)

    • Contraindicated in IBD flare ➜ risk of toxic megacolon

  • CDIFF-specific care

    • HAI; spores survive \le 70\,\text{days} on surfaces

    • Strict contact isolation; soap-and-water handwash, 10 % bleach surface disinfection

    • First-line Rx: oral vancomycin 125\,\text{mg} q6h × 10 d OR fidaxomicin

    • Alternatives: metronidazole (mild), vanco + IV metro (severe/complicated)

    • Ileus ➜ vancomycin retention enema

    • Stop non-essential abx, laxatives, antidiarrheals

    • Recurrent CDI ➜ fecal microbiota transplantation (FMT) via colonoscopy, enema, or nasoenteric tube

    • Consider probiotic (\textit{Lactobacillus}) prophylaxis

  • Nursing priorities

    • Assume infectious until proven otherwise

    • Accurate I&O; daily weight; inspect skin

    • Teach hygiene, safe food handling, early HCP contact for blood/dehydration

Constipation

  • Definition & features

    • Symptom, not a disease

    • Difficult/infrequent BM, excessive straining, sensation of incomplete evacuation

    • Acute: <1\,\text{week}; Chronic: >3\,\text{months}

  • Risk factors

    • Low-fiber diet

    • Decreased physical activity

    • Ignoring urge to defecate ➜ rectal desensitization, stool desiccation

    • Emotional stress, anxiety, depression

    • Conditions slowing transit: DM, Parkinson’s, hypothyroid, spinal cord injury, scleroderma

    • Meds: opioids, anticholinergics, Ca/Al antacids, iron, antidepressants

    • Chronic stimulant laxative use ➜ cathartic colon (dilated, atonic)

  • Clinical manifestations

    • Hard, dry, infrequent stool; straining

    • Abdominal distention, bloating, flatulence, rectal pressure

    • Hemorrhoids, anal fissures

    • Diverticulosis (elderly)

    • Obstipation/fecal impaction, perforation (rare)

  • Diagnostics

    • Thorough H&P; DRE, abdominal exam

    • Alarm signs >6 wk: hematochezia, anemia, wt loss, pain, FHx CRC/IBD

    • Imaging: plain ABD film, barium enema, colonoscopy, anorectal manometry, balloon expulsion, sitz-mark transit study

  • Management

    • ↑ dietary fiber (20–30 g/day), fruits/veg/whole grains; fluid \ge 2\,\text{L}/day

    • Regular exercise & defecation schedule

    • Laxatives (bulk-forming, osmotic, stool softeners, stimulants) – use judiciously

    • Enemas for acute impaction

    • Peripherally acting \mu-opioid receptor antagonists (methylnaltrexone) for OIC

    • Biofeedback for pelvic-floor dysfunction

    • Surgery (subtotal colectomy, ostomy) for refractory cases

  • Nursing care

    • Individualize plan; educate on diet, hydration, exercise

    • Encourage not ignoring urge; proper positioning; privacy

    • Discourage chronic laxative/enema abuse

Chronic Abdominal Pain

  • Qualities: dull, aching, diffuse, intermittent >3 mo

  • Common etiologies: IBS, chronic pancreatitis, chronic hepatitis, PID, adhesions, mesenteric ischemia

  • Work-up: comprehensive H&P, pain diary, labs, endoscopy, CT/MRI, laparoscopy

  • Therapy: treat cause; multidisciplinary pain management

Irritable Bowel Syndrome (IBS)

  • Functional disorder: recurrent abdominal pain + altered bowel habits without structural cause ≥3 mo

  • Rome IV diagnostic criteria

    • Abdominal pain on \ge 1\,\text{day/week} × 3 mo, with ≥2:

    1. Related to defecation

    2. Change in stool frequency

    3. Change in stool form

  • Subtypes

    • IBS-C (constipation-predominant)

    • IBS-D (diarrhea-predominant)

    • Mixed

    • Unsubtyped

  • Gender trends

    • Women 2–2.5× > men; more IBS-C, bloating, fatigue, depression

    • Men: more IBS-D, less likely to seek care

  • Triggers

    • Psychological stress, anxiety, depression

    • Post-infectious gut dysbiosis

    • Food sensitivities: gluten, FODMAPs (fructans, lactose, sorbitol, etc.)

  • Symptoms

    • GI: crampy pain, bloating, gas, mucus in stool, sense of incomplete evacuation

    • Non-GI: fatigue, HA, sleep disturbance

  • Management

    • Therapeutic alliance, reassurance

    • Cognitive-behavioral therapy, stress reduction

    • Diet: low-FODMAP, trial gluten-free, adequate fiber for IBS-C

    • Pharmacology

    • IBS-D: loperamide, bile-acid binders, eluxadoline, rifaximin, alosetron (\textbf{Drug Alert: ischemic colitis})

    • IBS-C: soluble fiber, osmotic laxatives, lubiprostone, linaclotide

    • Antispasmodics (dicyclomine), TCAs/SSRIs for pain modulation

Inflammatory Bowel Disease (IBD)

  • Chronic immune-mediated inflammation with remissions & exacerbations

  • Two primary phenotypes

    • Ulcerative colitis (UC): mucosal layer of colon/rectum

    • Crohn’s disease (CD): transmural, any part mouth→anus; terminal ileum common

  • Etiology

    • Genetic susceptibility (>200 genes, NOD2 variants)

    • Environment: diet high in refined sugar, fat, ω-6; smoking, stress, NSAIDs, antibiotics, OCPs

    • Microbiome dysregulation

    • Autoimmune dysregulation ➜ uncontrolled cytokine cascade (TNF-α, IL-12/23) → tissue destruction

  • Pathology

    • Crohn’s

    • Skip lesions, cobblestone mucosa, strictures, fistulas, abscesses

    • Transmural granulomatous inflammation

    • UC

    • Continuous lesion from rectum proximally

    • Only mucosa/submucosa; pseudopolyps; toxic megacolon risk

  • Clinical presentation

    • CD: diarrhea, crampy pain, weight loss, low-grade fever, fatigue, occasional rectal bleeding

    • UC: bloody diarrhea; stool frequency correlates w/ severity

    • Mild <4/d; Moderate ≤10/d; Severe 10–20/d ± fever, anemia, tachycardia

    • Pain, weight loss, fatigue

  • Complications

    • Local: hemorrhage, strictures, perforation, abscess, fistula, CDI, toxic megacolon

    • Systemic: ↑ risk CRC (esp. >8 yr disease), cholangiocarcinoma, malabsorption, osteoporosis, spondyloarthropathies, PSC, erythema nodosum, uveitis

  • Diagnostics

    • CBC (anemia, leukocytosis), BMP (lytes), albumin, ESR/CRP, stool ova/parasites & cultures

    • Imaging: double-contrast BE, small-bowel follow-through, CT/MRI enterography, US

    • Endoscopy: colonoscopy w/ biopsies; capsule endoscopy for CD

  • Therapeutic goals

    • Rest bowel, control inflammation, fight infection, correct malnutrition, alleviate stress, symptom relief, QOL improvement

  • Pharmacologic therapy (step-up vs step-down)

    • 5! -! ASA agents: sulfasalazine, mesalamine (PO/PR) – 1st line UC

    • Corticosteroids: prednisone, budesonide, IV methyl-pred for flares (short-term)

    • Immunomodulators: azathioprine, 6-MP, methotrexate (maintenance)

    • Biologics

    • Anti-TNF: infliximab (IV), adalimumab, certolizumab, golimumab

    • Integrin antagonists: natalizumab, vedolizumab

    • Risks: infection (TB, HBV), malignancy; no live vaccines

    • JAK inhibitor (tofacitinib) for moderate-severe UC

  • Surgical options

    • UC: curative

    • Total proctocolectomy + IPAA (J- or S-pouch)

    • Total proctocolectomy + permanent ileostomy

    • CD: surgery for complications; resection w/ anastomosis, strictureplasty; risk short-bowel syndrome

  • Nutrition

    • Individualized; high-cal/high-protein during remission

    • Acute flare: enteral elemental formulas; may need TPN

    • Supplements: folate (sulfasalazine), Ca/Vit D (steroids), B12 (ileal disease), Fe, Zn, Mg, trace elements

    • Food diary to identify triggers (dairy, high-fat, cold foods, high-fiber in strictures)

  • Nursing care

    • Monitor hemodynamics, pain, stool output, weight, labs

    • I&O, daily wt, assess for bleeding, infection, skin integrity

    • Pre-/post-op ostomy teaching

    • Coping strategies; CCFA resources

  • Gerontologic considerations

    • Second incidence peak ~60 yr; left-sided UC common

    • Atypical sx; polypharmacy ↑ adverse effects

    • ↑ infection, malignancy risk; ambulatory limitations

Diverticular Disease

  • Definitions

    • Diverticula: saccular mucosal outpouchings in colon wall, most sigmoid

    • Diverticulosis: presence of multiple diverticula without inflammation

    • Diverticulitis: inflammation of a diverticulum

  • Etiology

    • Weak points where vasa recta penetrate circular muscle

    • ↑ intraluminal pressure from constipation/straining

    • Low-fiber diet, obesity, inactivity, smoking, excess ETOH, NSAIDs, genetics

  • Clinical manifestations

    • Diverticulosis: often asymptomatic; possible LLQ pain, bloating, flatulence, change bowel habit; hematochezia

    • Diverticulitis: acute LLQ pain, fever, leukocytosis, ↓/absent BS, N/V; elderly may be afebrile

  • Complications: perforation, abscess, fistula, peritonitis, hemorrhage

  • Diagnostics

    • CT Abd w/ oral contrast (preferred)

    • Sigmoidoscopy/colonoscopy once inflammation resolved

    • Labs: CBC, UA, blood cultures, FOBT; XR to r/o free air

  • Management

    • Prevention: high-fiber, ↓ fat/red meat, weight control, exercise

    • Acute mild: bowel rest (clear liquids), oral abx, analgesia

    • Severe/septic/comorbid: NPO, NG suction, IV fluids, broad-spectrum IV abx, monitor for abscess/peritonitis

    • Recurrent/complicated: elective sigmoid resection ± temporary colostomy

  • Education: 2 L fluids/day, avoid straining, lifting, tight belts

Malabsorption Syndromes

  • General: defective absorption of fat, CHO, protein, vitamins, minerals, water

  • Hallmarks: weight loss, diarrhea, steatorrhea (bulky, pale, foul, oil-ring stool)

  • Common causes

    • Lactose intolerance (most prevalent)

    • IBD, celiac disease, tropical sprue, cystic fibrosis

    • Short-bowel syndrome, pancreatic insufficiency, bile-acid deficiency

  • Diagnostic tests

    • Stool fat (\textit{Sudan III}), fecal elastase

    • D-xylose absorption, lactose tolerance/H2 breath

    • Serology: anti-tTG IgA for celiac

    • Imaging: small-bowel follow-through, CT, capsule endoscopy

    • Labs: CBC, PT (Vit K), vit A, carotene, lytes, Ca, cholesterol

Celiac Disease
  • Autoimmune enteropathy triggered by gluten (prolamines) in genetically predisposed (HLA-DQ2/DQ8)

  • Associated autoimmune disorders: RA, T1DM, thyroiditis

  • Manifestations

    • Classic: foul diarrhea, abdominal pain, flatulence, distention, malnutrition

    • Atypical: osteoporosis, fertility issues, neuropathy, dermatitis herpetiformis

    • Laboratory: Fe-def anemia, ↓ folate, B12

  • Diagnosis:

    • Serology (anti-tTG, EMA) while on gluten diet

    • Upper endoscopy + duodenal biopsy (villous atrophy)

    • Genetic HLA typing (supportive)

  • Management

    • Strict gluten-free diet (no wheat, barley, rye)

    • Dietician referral; monitor Ca/Vit D, Fe, B12

    • Resources: CSA, CDF

Lactase Deficiency
  • Absent/low lactase enzyme ➜ unabsorbed lactose fermented in colon

  • Populations: Asians, Africans, premature infants, Congenital rare

  • Symptoms within 30 min of dairy: bloating, cramps, flatulence, diarrhea

  • Diagnosis: lactose tolerance test, H2 breath test, genetic testing

  • Treatment: lactase enzyme (Lactaid), lactose-free diet, Ca & Vit D supplementation

Short-Bowel Syndrome (SBS)
  • <25–30 % functional small intestine

  • Causes: massive resections (Crohn’s, volvulus), congenital atresia, necrotizing enterocolitis

  • Manifestations: chronic diarrhea, malnutrition, wt loss, dehydration, steatorrhea, lyte deficits (Mg, Zn)

  • Care

    • Fluid/lyte replacement, antidiarrheals (loperamide), acid suppression

    • Nutritional support: TPN initial, transition to enteral; high-complex CHO, low-fat; MCT oil

    • GLP-2 analog (teduglutide) to enhance adaptation

    • Intestinal transplant for refractory failure

Gastrointestinal Stromal Tumor (GIST)

  • Rare mesenchymal tumor from interstitial cells of Cajal; KIT or PDGFRA mutation

  • Early nonspecific: early satiety, bloating, N/V, altered BM

  • Late: GI bleed, obstruction

  • Diagnosis: EUS-guided biopsy, CT/MRI

  • Treatment: surgical resection; imatinib (tyrosine-kinase inhibitor) for unresectable/metastatic

Hemorrhoids

  • Varicose dilatation of hemorrhoidal veins

    • Internal (above dentate line)

    • External (below dentate line)

  • Risk factors: pregnancy, constipation/straining, diarrhea, heavy lifting, prolonged sitting/standing, obesity, ascites

  • Clinical

    • Internal: painless bright-red bleeding, mucus, prolapse causing dull ache

    • External: bluish mass, pruritus, burning, edema; thrombosis → severe pain

  • Diagnosis: inspection, DRE; anoscopy/sigmoidoscopy for internal

  • Management

    • Conservative: high-fiber diet, ↑ fluids, stool softeners, topical anesthetics/astringents, sitz baths

    • Office procedures: rubber-band ligation, infrared coagulation, sclerotherapy, laser

    • Surgical hemorrhoidectomy for large prolapse or thrombosis

  • Post-op nursing: pain control (opioids, NSAIDs, topical), packing care, encourage fiber/fluids, avoid straining, watch for urinary retention, bleeding

Anal Disorders

Anal Fissure
  • Linear ulcer in anoderm from trauma (hard stool, vaginal delivery) or IBD/STD

  • Severe burning pain with BM, bright-red bleeding

  • Therapy: fiber, fluids, stool softeners, topical nitroglycerin/diltiazem, botulinum inj; lateral internal sphincterotomy if chronic

Anal Fistula
  • Abnormal tract from anal canal to perianal skin/vagina; often post-abscess or Crohn’s

  • Purulent/bloody drainage, pruritus

  • Treatment: fistulotomy; complex tracts may need LIFT procedure, advancement flap, fibrin glue/plug