Intussusception: - Invagination (telescoping) of one segment of bowel into an adjacent segment - Most common in infants 3–12 months; boys > girls; often at ileocecal junction - Classic presentation: - Episodic severe crampy abdominal pain — child draws up knees, cries intensely, then is quiet between episodes - Currant jelly stool (blood + mucus) — late sign; indicates ischemia - Sausage-shaped abdominal mass in right upper quadrant - Vomiting - Diagnosis: ultrasound (target sign/donut sign) - Treatment: Air or saline enema reduction (therapeutic and diagnostic) — first-line; surgery if enema fails or perforation present Meckel Diverticulum: - Remnant of the omphalomesenteric duct — most common GI congenital anomaly - Rule of 2s: - 2% of population - 2 inches long - 2 feet from the ileocecal valve - Presents within first 2 years of life - 2 types of ectopic tissue (gastric and pancreatic) - Symptoms: painless rectal bleeding (most common — ectopic gastric tissue produces acid → ulceration), intussusception, obstruction, diverticulitis-like pain - Diagnosis: Meckel scan (technetium-99m pertechnetate — detects ectopic gastric mucosa) - Treatment: surgical resection **Intestinal...