USMLE STEP 1 GASTROINTESTINAL Questions and Answers with Complete Solutions 2024

USMLE STEP 1 GASTROINTESTINAL Questions and Answers with Complete Solutions 2024 Foregut - ANSPharynx to duodenum Midgut - ANSDuodenum to proximal 2/3 of transverse colon Hindgut - ANSDistal 1/3 of transverse colon to anal canal above pectinate line Abnormal Rostral Fold Closure - ANSDevelopmental defect of anterior abdominal wall that leads to STERNAL DEFECTS Abnormal Lateral Fold Closure - ANSDevelopmental defect of anterior abdominal wall that leads to OMPHALOCELE, GASTROSCHISIS Abnormal Caudal Fold Closure - ANSDevelopmental defect of anterior abdominal wall that leads to BLADDER EXSTROPHY Duodenal atresia - ANSFailure to recanalize [Trisomy 21] Jejunal, Ileal, Colonic atresia - ANSDue to vascular accident [Apple Peel Atresia] Midgut development - ANS1. 6th week = Midgut herniates through umbilical ring 2. 10th week = Returns to abdominal cavity + ROTATES around SUPERIOR MESENTERIC ARTERY [SMA] Malrotation of midgut leads to - ANSOmphalocele, intestinal atresia or stenosis, Volvulus Gastroschisis - ANSExtrusion of abdominal contents through abdominal folds, not covered by peritoneum Omphalocele - ANSPersistence of herniation of abdominal contents into umbilical cord, sealed by peritoneum Esophageal atresia with distal tracheoesophageal fistula - ANS1. Esophageal atresia [EA] with distal tracheoesophageal fistula [TEF] = MOST COMMON [85%] Clinical Manifestations: 1. Drooling 2. Choking 3. Vomiting w/ first feeding TEF Allows air into stomach [Visible on CXR] CYANOSIS SECONDA