Snapshot A 2-day-old neonate is noted in the well-baby nursery to have some abdominal distention. He had one episode of bilious vomiting. He is feeding well and does not seem altered. However, his mom is concerned that he has not passed any stool yet. Abdominal radiography shows distended loops of bowel. A barium enema shows a dilated colon with a funnel-shaped transition zone. Pediatric surgery is consulted for biopsy and surgical correction. Introduction Congenital megacolon functional (vs mechanical) intestinal obstruction Pathogenesis absence of ganglion cells/enteric nervous plexus in intestine lack of nerves causes constant contraction failure of neural crest cell migration 99% localized in rectum Genetics associated with mutations in RET gene Associated conditions risk ↑ with Down syndrome risk ↑ with Chagas disease acquired disease as a result of amastigote destruction of ganglion cells Presentation Symptoms bilious vomiting failure to pass meconium in first 48 hours of life chronic constipation large bowel obstruction Physical exam abdominal distention extremely tight anal sphincter no stool in rectal vault Evaluation Gold standard diagnosis rectal suction biopsy lack of ganglionic cells in submucosa Imaging abdominal radiography distended bowel loops lack of air in rectum Differential Diagnosis Imperforate anus Functional constipation Intussusception Duodenal atresia Meconium ileus Treatment Supportive care Surgical resection Prognosis, Prevention, and Complications Prognosis very good overall mortality < 1% normal quality of life in most patients Complications ↑ risk of enterocolitis rupture
QUESTIONS 1 of 4 1 2 3 4 Previous Next Lab Values Blood Hematologic Cerebrospinal Sweat, Urine, and BMI Blood, Plasma, Serum Reference Range ALT 8-20 U/L Amylase, serum 25-125 U/L AST 8-20 U/L Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL Calcium, serum (Ca2+) 8.4-10.2 mg/dL Cholesterol, serum Rec: < 200 mg/dL Cortisol, serum 0800 h: 5-23 μg/dL //1600 h: 3-15 μg/dL 2000 h: ≤ 50% of 0800 h Creatine kinase, serum Male: 25-90 U/LFemale: 10-70 U/L Creatinine, serum 0.6-1.2 mg/dL Electrolytes, serum Sodium (Na+) 136-145 mEq/L Chloride (Cl-) 95-105 mEq/L Potassium (K+) 3.5-5.0 mEq/L Bicarbonate (HCO3-) 22-28 mEq/L Magnesium (Mg2+) 1.5-2.0 mEq/L Estriol, total, serum (in pregnancy) 24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL 28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL Ferritin, serum Male: 15-200 ng/mLFemale: 12-150 ng/mL Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL Female: premenopause: 4-30 mIU/mL midcycle peak: 10-90 mIU/mL postmenopause: 40-250 pH 7.35-7.45 PCO2 33-45 mmHg PO2 75-105 mmHg Glucose, serum Fasting: 70-110 mg/dL2-h postprandial:<120 mg/dL Growth hormone - arginine stimulation Fasting: <5 ng/mLProvocative stimuli: > 7ng/mL Immunoglobulins, serum IgA 76-390 mg/dL IgE 0-380 IU/mL IgG 650-1500 mg/dL IgM 40-345 mg/dL Iron 50-170 μg/dL Lactate dehydrogenase, serum 45-90 U/L Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL Female: follicular phase: 5-30 mIU/mL midcycle: 75-150 mIU/mL postmenopause 30-200 mIU/mL Osmolality, serum 275-295 mOsmol/kd H2O Parathyroid hormone, serume, N-terminal 230-630 pg/mL Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L Phosphorus (inorganic), serum 3.0-4.5 mg/dL Prolactin, serum (hPRL) < 20 ng/mL Proteins, serum Total (recumbent) 6.0-7.8 g/dL Albumin 3.5-5.5 g/dL Globulin 2.3-3.5 g/dL Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h Thyroxine (T4), serum 5-12 μg/dL Triglycerides, serum 35-160 mg/dL Triiodothyronine (T3), serum (RIA) 115-190 ng/dL Triiodothyronine (T3) resin uptake 25%-35% Urea nitrogen, serum 7-18 mg/dL Uric acid, serum 3.0-8.2 mg/dL Hematologic Reference Range Bleeding time 2-7 minutes Erythrocyte count Male: 4.3-5.9 million/mm3Female: 3.5-5.5 million mm3 Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/hFemale: 0-20 mm/h Hematocrit Male: 41%-53%Female: 36%-46% Hemoglobin A1c ≤ 6 % Hemoglobin, blood Male: 13.5-17.5 g/dLFemale: 12.0-16.0 g/dL Hemoglobin, plasma 1-4 mg/dL Leukocyte count and differential Leukocyte count 4,500-11,000/mm3 Segmented neutrophils 54%-62% Bands 3%-5% Eosinophils 1%-3% Basophils 0%-0.75% Lymphocytes 25%-33% Monocytes 3%-7% Mean corpuscular hemoglobin 25.4-34.6 pg/cell Mean corpuscular hemoglobin concentration 31%-36% Hb/cell Mean corpuscular volume 80-100 μm3 Partial thromboplastin time (activated) 25-40 seconds Platelet count 150,000-400,000/mm3 Prothrombin time 11-15 seconds Reticulocyte count 0.5%-1.5% of red cells Thrombin time < 2 seconds deviation from control Volume Plasma Male: 25-43 mL/kgFemale: 28-45 mL/kg Red cell Male: 20-36 mL/kgFemale: 19-31 mL/kg Cerebrospinal Fluid Reference Range Cell count 0-5/mm3 Chloride 118-132 mEq/L Gamma globulin 3%-12% total proteins Glucose 40-70 mg/dL Pressure 70-180 mm H2O Proteins, total < 40 mg/dL Sweat Reference Range Chloride 0-35 mmol/L Urine Calcium 100-300 mg/24 h Chloride Varies with intake Creatinine clearance Male: 97-137 mL/minFemale: 88-128 mL/min Estriol, total (in pregnancy) 30 wks 6-18 mg/24 h 35 wks 9-28 mg/24 h 40 wks 13-42 mg/24 h 17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 hFemale: 2.0-8.0 mg/24 h 17-Ketosteroids, total Male: 8-20 mg/24 hFemale: 6-15 mg/24 h Osmolality 50-1400 mOsmol/kg H2O Oxalate 8-40 μg/mL Potassium Varies with diet Proteins, total < 150 mg/24 h Sodium Varies with diet Uric acid Varies with diet Body Mass Index (BMI) Adult: 19-25 kg/m2 Calculator ( ) xy AC 7 8 9 ÷ 4 5 6 × 1 2 3 - 0 . = + Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (M1.GI.62) You are examining a 2-day-old male infant with abdominal distension and bilious vomiting. His mother informs you that he has not yet had a bowel movement. On exam, you note a release of stool with digital disimpaction. An abdominal radiograph is shown in Figure A. What is the most likely cause of his condition? Review Topic QID: 106448 FIGURES: A 1 Maternal diabetes mellitus 2% (3/138) 2 Mutation of the CFTR gene 4% (5/138) 3 Failure of canalization of the duodenal lumen 17% (24/138) 4 Hypertrophy of the muscularis externa of the pyloric sphincter 5% (7/138) 5 Failure of neural crest cell migration 71% (98/138) M1 Select Answer to see Preferred Response PREFERRED RESPONSE 5 (M1.GI.103) Two days following the home birth of her son, a mother brings the infant to the pediatric emergency room because of bilious vomiting. He is unable to pass meconium and his abdomen is distended. Endoscopic biopsy of the proximal colon demonstrates an absence of Meissner’s and Auerbach’s plexi in the bowel wall. Which of the following is the most likely diagnosis? Review Topic QID: 101160 1 Hirschsprung’s disease 96% (98/102) 2 Ileocecal intussusception 1% (1/102) 3 Meckel’s diverticulum 1% (1/102) 4 Juvenile polyposis syndrome 1% (1/102) 5 Volvulus of the sigmoid colon 0% (0/102) M1 Select Answer to see Preferred Response PREFERRED RESPONSE 1 (M1.GI.8) A 5-day-old male is brought to your office by his mother. The infant is experiencing bilious vomiting, abdominal distension, and overall failure to thrive. A contrast enema shows a transition point at the transverse colon between dilated ascending colon and non-distended distal portion of the colon. Which of the following is the most likely etiology of this patient's disease? Review Topic QID: 101902 1 Muscle hypertrophy 0% (0/17) 2 Mechanical bowel obstruction 12% (2/17) 3 CFTR gene mutation 0% (0/17) 4 Meiotic nondisjunction 0% (0/17) 5 Failure of neural crest cell migration 88% (15/17) M1 Select Answer to see Preferred Response PREFERRED RESPONSE 5