Study guide
Lower Gastrointestinal Disorders: IBS, IBD, Diverticulitis & Colorectal Screening
AANPCB Adult-Gerontology Primary Care Nurse Practitioner A-GNP
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1 Exam Structure, APRN Foundations & Geriatric Assessment
A-GNP Exam Logistics, Blueprint & Scoring Structure APRN Scope of Practice, Consensus Model & Interprofessional Collaboration Comprehensive Health History & Subjective Assessment Across Adult Lifespan Comprehensive Physical Examination & Clinical Assessment Skills
2 Health Assessment, Diagnostic Reasoning & Clinical Procedures
Diagnostic Reasoning, Test Interpretation & Clinical Decision-Making Screening Guidelines & Evidence-Based Health Promotion (USPSTF) Comprehensive Geriatric Assessment (CGA), Frailty & Function In-Office Clinical Procedures, ECG Interpretation & Minor Surgical Skills
3 Cardiovascular & Peripheral Vascular Disorders
Essential Hypertension & Hypertensive Urgency/Emergency Management Coronary Artery Disease, Acute Coronary Syndromes & Post-MI Care Heart Failure (HFrEF & HFpEF) Diagnosis, Staging & 4-Pillar GDMT Arrhythmias (Atrial Fibrillation), Valvular Heart Disease & PAD
4 Respiratory, HEENT & Dermatological Disorders
Asthma Management across the Adult Lifespan (GINA Guidelines) Chronic Obstructive Pulmonary Disease (COPD) Staging & Management (GOLD Guidelines) Community-Acquired Pneumonia & Lower Respiratory Tract Infections Common HEENT Disorders: Otitis, Sinusitis, Pharyngitis, Glaucoma & Macular Degeneration
5 Endocrine, Metabolic & Renal/Genitourinary Disorders
Type 2 Diabetes Mellitus Management Thyroid Disorders: Hypothyroidism, Hyperthyroidism & Subclinical Disease Chronic Kidney Disease (CKD) Staging & Diabetic/Hypertensive Nephropathy Genitourinary Disorders: BPH, Urinary Incontinence, UTIs & Prostatitis
6 Gastrointestinal, Hematologic & Immunologic Disorders
Upper Gastrointestinal Disorders: Dyspepsia, GERD, PUD & H. pylori Lower Gastrointestinal Disorders: IBS, IBD, Diverticulitis & Colorectal Screening Liver, Biliary & Pancreatic Disorders: NAFLD/MASLD, Cirrhosis & Cholecystitis Hematologic & Immunologic Disorders: Anemias, Anticoagulation & Immunizations
7 Neurological, Cognitive & Psychiatric Disorders
Cognitive Assessment: Delirium, Dementia & Mild Cognitive Impairment Neurological Disorders: Stroke, TIA, Parkinson's Disease & Headache Syndromes Major Depressive Disorder & Anxiety Disorders in Adults & Older Adults Sleep Disorders, Insomnia & Restless Legs Syndrome
8 Geriatric Syndromes, Polypharmacy & Deprescribing
The Beers Criteria & STOPP/START Criteria for Potentially Inappropriate Medication Use Polypharmacy Management, Pharmacokinetics/Pharmacodynamics in Aging & Deprescribing Protocols Fall Risk Assessment (CDC STEADI), Gait/Balance & Mobility Impairments Pressure Injury Prevention/Staging, Urinary/Fecal Incontinence & Frailty Assessment
9 APRN Professional Practice, Ethics, Quality & Healthcare Policy
Musculoskeletal Disorders: Osteoarthritis, Osteoporosis, Gout & Back Pain Dermatological Disorders: Lesions, Skin Cancers, Infections & Rash Evaluation Palliative Care, Advance Care Planning, Pain Management & End-of-Life APRN Professional Practice, Quality Improvement, Ethics & Healthcare Policy
Lower Gastrointestinal Disorders: IBS, IBD, Diverticulitis & Colorectal Screening
Key Takeaways Explain This Topic AI
Irritable Bowel Syndrome (IBS) is diagnosed using Rome IV criteria: recurrent abdominal pain at least 1 day per week over the last 3 months associated with 2 or more defecation or stool features.
Crohn's Disease causes transmural inflammation, skip lesions from mouth to anus, and non-caseating granulomas, whereas Ulcerative Colitis is limited to mucosal continuous rectal and colonic inflammation.
Fecal calprotectin and lactoferrin are biomarker assays used to differentiate organic inflammatory bowel disease (IBD) from functional gut disorders like IBS.
Abdominal/pelvic CT with contrast is the imaging study of choice for acute diverticulitis; colonoscopy is strictly contraindicated during an acute flare due to perforation risk.
USPSTF guidelines recommend colorectal cancer screening for average-risk adults aged 45 to 75 years using colonoscopy every 10 years, annual FIT, or FIT-fecal DNA every 3 years.
Last updated: July 2026
- Lower Gastrointestinal Disorders: IBS, IBD, Diverticulitis & Colorectal Screening
- Irritable Bowel Syndrome (IBS)
Irritable Bowel Syndrome (IBS) is a functional gastrointestinal disorder characterized by chronic abdominal pain and altered bowel habits in the absence of structural, metabolic, or infectious abnormalities. Pathophysiology involves visceral hypersensitivity, altered intestinal motility, brain-gut axis dysregulation, low-grade immune activation, and intestinal dysbiosis.
Rome IV Diagnostic Criteria
According to Rome IV criteria , IBS is diagnosed when patients experience recurrent abdominal pain, on average at least 1 day per week in the last 3 months , with symptom onset at least 6 months prior, associated with 2 or more of the following:
Related to defecation (pain relieved or exacerbated by bowel movements).
Associated with a change in stool frequency .
Associated with a change in stool form (appearance) (e.g., Bristol Stool Form Scale Types 1-2 vs Types 6-7).
Subtypes based on predominant stool consistency:
IBS-C (Constipation predominant): >25% hard/lumpy stools (Bristol 1-2).
IBS-D (Diarrhea predominant): >25% loose/watery stools (Bristol 6-7).
IBS-M (Mixed habits): >25% hard AND >25% loose stools.
IBS-U (Unclassified).
Diagnostic evaluation must confirm the absence of red flags : Age >= 50 years, nocturnal diarrhea, hematochezia, unintentional weight loss, fever, or family history of colorectal cancer, IBD, or celiac disease.
Evidence-Based Management
Non-Pharmacologic : Low-FODMAP diet restricting fermentable oligosaccharides, disaccharides, monosaccharides, and polyols implemented in a 3-phase approach (elimination for 2-6 weeks, reintroduction, and personalization); soluble fiber ( psyllium ) supplementation.
IBS-C Pharmacotherapy : Osmotic laxatives (polyethylene glycol [PEG]); Guanylate Cyclase-C agonists ( linaclotide , plecanatide which stimulate cGMP to increase intestinal fluid secretion); Chloride channel activators ( lubiprostone ).
IBS-D Pharmacotherapy : Opioid agonists ( loperamide ); Eluxadoline (mu-opioid agonist); Non-absorbable antibiotic rifaximin (550 mg TID for 14 days); 5-HT3 antagonists ( alosetron ).
Visceral Hypersensitivity & Cramping : Antispasmodics ( dicyclomine , hyoscyamine ) PRN before meals; low-dose Tricyclic Antidepressants ( TCAs like desipramine) to modulate central pain pathways.
Inflammatory Bowel Disease (IBD): Crohn's vs. Ulcerative Colitis
IBD includes Crohn's Disease (CD) and Ulcerative Colitis (UC) , chronic idiopathic autoimmune inflammatory disorders of the gastrointestinal tract.
Clinical and Histopathologic Comparison
Feature Crohn's Disease Ulcerative Colitis
Location Any segment from mouth to anus (ileocolonic most common) Restricted to colon and rectum ; continuous from rectum proximally
- Inflammation Depth Transmural (full thickness through mucosa to serosa) Mucosal and submucosal only
- Pattern Skip lesions interspersed with normal tissue Continuous mucosal involvement
- Histology Non-caseating granulomas , cobblestoning Crypt abscesses , pseudopolyps
Presentation Crampy RLQ pain, diarrhea, weight loss, fever Relapsing bloody diarrhea with mucus , tenesmus, LLQ pain
Complications Strictures, fistulas, perianal abscesses, vitamin malabsorption Toxic megacolon (>6 cm distension + toxicity), severe anemia, PSC
Extraintestinal Manifestations & Biomarkers
Extraintestinal features include enteropathic arthritis, erythema nodosum, pyoderma gangrenosum, uveitis, and Primary Sclerosing Cholangitis (PSC, overwhelmingly associated with UC).
Fecal Calprotectin and Fecal Lactoferrin are non-invasive neutrophil biomarkers excreted in stool during active inflammation that reliably distinguish organic IBD from functional IBS.
Medical Therapy & Surgical Considerations
5-ASAs : Oral/topical mesalamine is first-line for mild-to-moderate UC induction and maintenance.
Corticosteroids : Oral budesonide or prednisone for acute flare induction , not long-term maintenance.
Immunomodulators & Biologics : Azathioprine, methotrexate, anti-TNF agents ( infliximab , adalimumab ), anti-integrins ( vedolizumab ), IL-12/23 inhibitors ( ustekinumab ), and oral JAK inhibitors ( tofacitinib ).
Surgical Nuance : Total proctocolectomy is curative for Ulcerative Colitis, whereas bowel resection in Crohn's Disease is non-curative due to high risk of postoperative recurrence.
Diverticular Disease & Acute Diverticulitis
Diverticulosis involves mucosal outpouchings herniating through the colonic muscular layer, predominantly in the sigmoid colon .
Presentation, Imaging & Management
Acute diverticulitis occurs when microperforation triggers focal pericolic inflammation, presenting with constant LLQ abdominal pain , fever, leukocytosis, and altered bowel habits.
Imaging Modality of Choice : Abdominal/pelvic CT with IV and oral contrast , showing colonic wall thickening (>4 mm) and pericolic fat stranding.
CONTRAINDICATION : Colonoscopy is strictly contraindicated during acute diverticulitis due to high colonic perforation risk. Colonoscopy should be delayed 6 to 8 weeks post-resolution to exclude underlying malignancy.
Outpatient Management : Mild uncomplicated cases in reliable patients are treated with oral broad-spectrum antibiotics for 7-10 days: Ciprofloxacin (500 mg BID) + Metronidazole (500 mg TID), OR Amoxicillin-clavulanate (875/125 mg BID). Clear liquid diet initially, advancing as tolerated.
Post-Resolution : Transition to a high-fiber diet (25-35 g daily). Restricting nuts, seeds, or popcorn is no longer recommended .
Colorectal Cancer (CRC) Screening Guidelines
USPSTF (2021/2026) screening recommendations for average-risk adults:
Ages 45 to 75 Years : Screening is strongly recommended ( Grade A/B ) starting at age 45 .
Ages 76 to 85 Years : Screening decisions should be individualized (Grade C) based on health status and life expectancy.
Age > 85 Years : Discontinue screening.
Screening Options & Intervals
Colonoscopy : Every 10 years (Gold standard).
Stool DNA-FIT (Cologuard) : Every 3 years (combines NDRG4/BMP3 gene hypermethylation with stool hemoglobin).
Annual FIT or annual gFOBT : Every 1 year .
CT Colonography : Every 5 years . Note : Any positive non-colonoscopy screening test requires follow-up diagnostic colonoscopy .
High-Risk Screening
Individuals with a first-degree relative diagnosed with CRC before age 60 should initiate colonoscopy at age 40 or 10 years earlier than the youngest affected relative , repeated every 5 years .