17.5 Gastrointestinal & Dermatologic Conditions

Gastrointestinal Conditions: GERD & Irritable Bowel Syndrome

Gastroesophageal Reflux Disease (GERD)

GERD is characterized by retrograde flow of gastric contents into the esophagus causing troublesome symptoms or mucosal damage. The core pathophysiology involves transient lower esophageal sphincter (LES) relaxations.

• Symptoms: Heartburn (retrosternal burning pain, pyrosis), acid regurgitation, dysphagia, water brash, globus sensation, and extra-esophageal manifestations (chronic cough, asthma exacerbations, hoarseness, dental enamel erosion).
• Lifestyle Interventions: Elevate head of bed by 6 to 8 inches; avoid eating within 2 to 3 hours of reclining; achieve weight reduction; eliminate dietary triggers (chocolate, peppermint, high-fat foods, citrus, tomatoes, caffeine, alcohol); cease tobacco smoking.
• Stepwise Pharmacotherapy: Antacids (calcium carbonate) for immediate prn relief; Histamine-2 Receptor Antagonists (H2RAs; Famotidine 20 mg PO daily or BID) for mild/intermittent symptoms; Proton Pump Inhibitors (PPIs; Omeprazole 20 mg daily, Pantoprazole 40 mg daily) taken 30 to 60 minutes prior to the first meal of the day for moderate-to-severe symptoms or erosive esophagitis.
• Alarm Symptoms ("Red Flags") Mandating Prompt Gastroenterology Referral & EGD:
  • New-onset dysphagia (difficulty swallowing) or odynophagia (painful swallowing).
  • Unexplained weight loss, persistent vomiting, or gastrointestinal bleeding (hematemesis, melena, occult blood).
  • Unexplained iron deficiency anemia or new symptom onset in individuals aged >50–55 years.

Irritable Bowel Syndrome (IBS)

IBS is a chronic functional disorder of the gut-brain interaction characterized by visceral hypersensitivity, altered gastrointestinal motility, and intestinal dysbiosis.

• Rome IV Diagnostic Criteria: Recurrent abdominal pain on average at least 1 day per week in the last 3 months, associated with two or more of the following features:
  1. Related to defecation (pain relieved or aggravated by bowel movements).
  2. Associated with a change in stool frequency (increased or decreased stools).
  3. Associated with a change in stool form / appearance (Bristol Stool Form Scale). (Criteria fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis.)
• Bristol Stool Form Scale Subtyping:
  • IBS-C (Constipation-predominant): >25% bowel movements Bristol types 1–2 (hard, lumpy); <25% types 6–7.
  • IBS-D (Diarrhea-predominant): >25% bowel movements Bristol types 6–7 (mushy, liquid); <25% types 1–2.
  • IBS-M (Mixed bowel habits): >25% types 1–2 AND >25% types 6–7.
  • IBS-U (Unclassified): Insufficient stool abnormality to meet above criteria.
• Alarm Features Ruling Out Simple IBS: Nocturnal diarrhea awakening patient from sleep, rectal bleeding, unintended weight loss, fever, onset after age 50, or family history of inflammatory bowel disease (IBD) or colorectal cancer.
• Midwifery Management: Comprehensive dietary trial of a low-FODMAP diet (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) with dietitian support; soluble fiber supplementation (psyllium husk; avoid insoluble bran which worsens bloating); antispasmodics (hyoscyamine, dicyclomine); osmotic laxatives (polyethylene glycol) for IBS-C; loperamide for IBS-D; low-dose tricyclic antidepressants or SSRIs for visceral pain modulation.

Dermatologic Conditions: Dermatitis, Acne & Herpes Zoster

Contact Dermatitis: Irritant vs. Allergic

• Irritant Contact Dermatitis (ICD): Non-immunologic, localized inflammatory reaction resulting from direct physical or chemical damage to the epidermal barrier (soaps, detergents, alcohol hand sanitizers, wet work). Clinically manifests as dry, chapped, erythematous, cracked skin with prominent burning and stinging sensations rather than itching.
• Allergic Contact Dermatitis (ACD): Type IV delayed-type hypersensitivity reaction occurring 24 to 72 hours after cutaneous re-exposure to a sensitized allergen (poison ivy/urushiol, nickel, neomycin, fragrances, rubber additives). Clinically manifests as intense pruritus, erythema, edema, and grouped papules, vesicles, and bullae arranged in sharp, linear, or geometric configurations corresponding to contact points. Diagnosed definitively via epicutaneous patch testing.
• Management: Identification and strict avoidance of causal agent; skin barrier restoration with ceramide emollients. Topical corticosteroids: apply medium-to-high potency (Triamcinolone acetonide 0.1%, Clobetasol propionate 0.05%) for body/extremities. Use only low-potency corticosteroids (Hydrocortisone 1% or 2.5%) on the face, groin, axillae, and intertriginous areas to prevent cutaneous atrophy, striae, and telangiectasias. For severe, extensive ACD (>20% body surface area or facial involvement), prescribe an oral prednisone taper over 14 to 21 days (avoid short 6-day Medrol dose packs which trigger severe rebound dermatitis).

Acne Vulgaris & Teratogenic Hazards

• Pathophysiology: Follicular hyperkeratinization, sebum overproduction (androgen-driven), Cutibacterium acnes proliferation, and inflammatory cytokine release.
• Stepwise Topical & Systemic Therapy:
  • Mild comedonal/inflammatory: Topical retinoid (Adapalene 0.1%, Tretinoin) plus topical Benzoyl Peroxide (BPO).
  • Moderate papulopustular: Topical retinoid + BPO + topical antibiotic (Clindamycin 1% combined with BPO to prevent resistance); add oral antibiotic (Doxycycline 50–100 mg BID, limited to a 3- to 4-month course).
  • Hormonal therapy in women: Combined oral contraceptives (COCs) or Spironolactone (50–200 mg daily; requires concurrent reliable contraception due to feminization risk in male fetuses).
  • Severe recalcitrant nodulocystic: Oral Isotretinoin (13-cis-retinoic acid).
• Isotretinoin Teratogenicity & The iPLEDGE REMS Program:
  • Isotretinoin is a catastrophic teratogen causing major craniofacial, cardiac, thymic, and central nervous system anomalies in up to 30% to 50% of exposed fetuses, along with severe cognitive deficits in surviving children.
  • iPLEDGE Requirements for Reproductive-Potential Patients: Mandatory registration in the federal iPLEDGE REMS registry; two negative CLIA-certified pregnancy tests obtained prior to initiating therapy; agreement to use two complementary forms of effective contraception (or practice absolute abstinence) starting 1 month prior to therapy, continuously throughout therapy, and for 1 full month following treatment cessation; monthly negative pregnancy tests confirmed in the portal prior to receiving a strictly capped 30-day medication supply with zero refills.

Herpes Zoster (Shingles)

• Etiology: Reactivation of latent Varicella-Zoster Virus (VZV) sequestered in dorsal root or cranial nerve sensory ganglia.
• Presentation: Dermatomal prodromal burning pain, paresthesias, and hyperesthesia lasting 2 to 3 days, followed by the eruption of unilateral, grouped, erythematous papules that rapidly evolve into clear vesicles distributed along a single dermatome (does not cross midline). Most common in thoracic and lumbar dermatomes.
• Complications:
  • Postherpetic Neuralgia (PHN): Severe, debilitating neuropathic pain persisting for >90 days after rash resolution.
  • Herpes Zoster Ophthalmicus (HZO): Involves the ophthalmic division (V1) of the trigeminal nerve. The presence of vesicles on the tip or side of the nose (Hutchinson sign) indicates nasociliary branch involvement and carries a high risk of corneal ulceration, uveitis, and permanent blindness; requires immediate emergency ophthalmology consultation.
• Antiviral Pharmacotherapy: Must be initiated within 72 hours of rash onset to accelerate healing, blunt acute neuralgia, and reduce PHN incidence:
  • Valacyclovir: 1,000 mg PO TID for 7 days (preferred due to superior bioavailability and dosing convenience).
  • Famciclovir: 500 mg PO TID for 7 days.
  • Acyclovir: 800 mg PO 5 times daily for 7 days.
• Prevention: Recombinant zoster vaccine (Shingrix), a 2-dose intramuscular series (at 0 and 2–6 months) for immunocompetent adults aged ≥50 years and immunocompromised adults aged ≥19 years (>90% efficacy in preventing shingles and PHN).