Small Intestine Pathology

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Congenital Anomalies - Quirks & Twists

⭐ Meckel's diverticulum, the most common GI congenital anomaly, typically presents with painless rectal bleeding in children due to ectopic gastric mucosa.

  • Meckel's Diverticulum: True diverticulum (all gut layers).
    • 📌 Rule of 2s: 2% population, 2 feet from ileocecal valve, 2 inches long, 2% symptomatic, 2 common ectopic tissues (gastric, pancreatic).
    • Complications: Bleeding (commonest), intussusception (lead point), diverticulitis, volvulus, perforation.
  • Malrotation & Volvulus:
    • Abnormal midgut rotation; Ladd's bands may cause duodenal obstruction.
    • Midgut volvulus: Neonatal bilious emesis. Surgical emergency!
  • Intestinal Atresia/Stenosis:
    • Duodenal: "Double bubble" sign on X-ray; strong association with Trisomy 21.
    • Jejunoileal: Caused by in-utero vascular accidents (e.g., SMA branch occlusion). "Apple peel" or "Christmas tree" deformity.

Double bubble sign in duodenal atresia

Inflammatory Conditions - Battles & Bugs

  • Crohn's Disease (CD)
    • Skip lesions, cobblestone mucosa, string sign (barium)
    • Complications: fistulas, strictures, abscesses
    • ASCA positive
    • EIMs: arthritis, uveitis, erythema nodosum

    ⭐ Crohn's disease is characterized by transmural inflammation, non-caseating granulomas, and can affect any part of the GIT from mouth to anus, most commonly the terminal ileum.

  • Intestinal Tuberculosis (TB)
    • Ileocecal commonest; transverse ulcers
    • Caseating granulomas
    • Complications: strictures, obstruction, perforation
    • Ileocecal tuberculosis: ulcers, stricture, pseudopolyps
  • Typhoid (Enteric) Fever
    • Salmonella typhi; Peyer's patch hypertrophy (terminal ileum)
    • Longitudinal ulcers
    • Complications: perforation, hemorrhage (2nd-3rd week)
  • Other Infections
    • Yersiniosis: mimics appendicitis, terminal ileitis
    • Whipple's Disease: T. whipplei; PAS+ macrophages, malabsorption, steatorrhea

Obstruction & Vascular Issues - Blockades & Bummers

  • Small Bowel Obstruction (SBO)
    • Etiology: Adhesions (most common), hernias, tumors. 📌 "ABC": Adhesions, Bulges (hernias), Cancer.
    • Clinical (4 cardinal signs): Colicky pain, vomiting (bilious→faeculent), distension, obstipation.
    • Diagnosis: X-ray (dilated loops >3cm, air-fluid levels). CT confirms, shows cause/complications.
    • Management: NPO, IV fluids, NG tube. Surgery for strangulation, closed-loop, or no resolution.

    ⭐ Adhesions from previous surgery are the leading cause of small bowel obstruction in adults, while hernias are the second most common.

  • Acute Mesenteric Ischemia (AMI)
    • Types: Arterial (embolus/thrombus), venous, NOMI.
    • Classic: Severe pain "out of proportion" to exam. ↑Lactate, metabolic acidosis.
    • Diagnosis: CT Angiography (CTA) is key.
    • Treatment: Urgent surgery (revascularization/resection of non-viable bowel). High mortality. Small bowel obstruction: Laparoscopy and CT

Small Bowel Neoplasms & SBS - Tumors & Takeouts

  • Neoplasms: Often vague symptoms (pain, bleeding, obstruction).
    • Benign: Adenoma, Leiomyoma, Lipoma.
    • Malignant: AdenoCa (MC, duod/jej), Carcinoid (ileum), Lymphoma (ileum, celiac assoc.), GIST (c-KIT+).

    ⭐ Carcinoid tumors are the most common endocrine tumors of the GI tract, often arising in the ileum and appendix; hepatic metastases are required for carcinoid syndrome.

    • Carcinoid Syndrome (if liver mets): Flushing, diarrhea, bronchospasm. Dx: ↑ 5-HIAA.
  • Short Bowel Syndrome (SBS):
    • Malabsorption if < 200 cm SB remaining.
    • Etiology: Crohn's, volvulus, ischemia, massive resection.
    • Complications: Malnutrition, dehydration, electrolyte imbalance, gallstones, oxalate renal stones.
    • Mgmt: Diet (high calorie/protein, low fat), TPN, octreotide.

High‑Yield Points - ⚡ Biggest Takeaways

  • Meckel's diverticulum: Rule of 2s, most common congenital GI anomaly, ectopic gastric mucosa.
  • Crohn's disease: Transmural inflammation, skip lesions, cobblestoning, non-caseating granulomas.
  • Intussusception: Commonest cause of infant intestinal obstruction, currant jelly stool, target sign (USG).
  • Small Bowel Obstruction (SBO): Adhesions (post-op) are leading cause in adults; hernias second.
  • Carcinoid tumors: Most common in appendix; carcinoid syndrome with liver metastasis (flushing, diarrhea).
  • Celiac disease: Gluten sensitivity causing villous atrophy; anti-TTG antibodies positive_._

Practice Questions: Small Intestine Pathology

Test your understanding with these related questions

A pregnant female had meconium-stained liquor and underwent emergency LSCS. A few days later, her condition deteriorated, and an ultrasound showed edematous bowels. What is the most likely cause of her condition?

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Flashcards: Small Intestine Pathology

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The diagnosis of acute appendicitis needs neutrophilic infiltration of the _____ layer

TAP TO REVEAL ANSWER

The diagnosis of acute appendicitis needs neutrophilic infiltration of the _____ layer

muscularis propria

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