FCPS TOACS · Infant of Diabetic Mother (IDM)

❓ Q1. Identify the condition and describe the key clinical features shown in the image. (2 marks)

✅ Model Answer: • Condition: Infant of a diabetic mother (IDM) with macrosomia.
• Key features: Plethoric (ruddy) complexion, puffy facies, extremely large body habitus, abundant vernix caseosa, hypertrichosis, large birth weight (>6000 g).
• Associated with maternal hyperglycemia during pregnancy.

❓ Q2. Explain the pathophysiology of macrosomia in an IDM. (2 marks)

✅ Model Answer: • Maternal hyperglycemia → fetal hyperglycemia.
• Fetal hyperglycemia → fetal hyperinsulinemia (pancreatic β-cell hyperplasia).
• Hyperinsulinemia → anabolic effects: increased fat deposition, glycogen synthesis, and protein synthesis.
• Results in excessive fetal growth (macrosomia), especially in the trunk and shoulders.

❓ Q3. What is the most common metabolic complication in IDMs? How would you screen for it? (2 marks)

✅ Model Answer: • Most common: Hypoglycemia (incidence 25-50%).
• Pathophysiology: Fetal hyperinsulinemia persists after birth → increased glucose utilization, suppressed glycogenolysis.
• Screening: Check blood glucose within 30-60 minutes of life, then before each feed for first 24-48 hours.
• Thresholds: <40 mg/dL in first 4 hours; <45 mg/dL after 4 hours.
• Treatment: Early feeding (breast milk/formula). If symptomatic or <40 mg/dL, IV 10% dextrose 2 mL/kg bolus, then continuous infusion.

❓ Q4. The infant has a weak left arm in the "waiter's tip" position. What is the diagnosis? Which nerve roots are involved? (2 marks)

✅ Model Answer: • Diagnosis: Erb-Duchenne paralysis (Erb palsy).
• Nerve roots involved: C5 and C6 (sometimes C7).
• Clinical findings: Arm held in adduction, internal rotation, elbow extended, forearm pronated, wrist flexed (“waiter's tip”).
• Cause: Shoulder dystocia → excessive lateral traction on the head and neck.
• Management: Physiotherapy, passive range-of-motion exercises. Most recover spontaneously within 3-6 months.

❓ Q5. What cardiac complication is unique to IDMs? How is it managed? (2 marks)

✅ Model Answer: • Condition: Hypertrophic cardiomyopathy (asymmetric septal hypertrophy) – also called HOCM/IHSS.
• Pathophysiology: Fetal hyperinsulinemia → myocardial hypertrophy, especially interventricular septum → LVOT obstruction.
• Diagnosis: Echocardiogram shows thickened septum, systolic anterior motion (SAM) of mitral valve.
• Management (critical): Avoid inotropic agents (dopamine, dobutamine) – they worsen obstruction.
• Use beta-blockers (propranolol 1-2 mg/kg/day) to reduce heart rate and increase filling time.
• Avoid dehydration and diuretics (reduce preload → worsen obstruction).
• Most resolve spontaneously by 6-12 months.

❓ Q6. What is the incidence of polycythemia in IDMs? When would you perform a partial exchange transfusion? (2 marks)

✅ Model Answer: • Incidence: 15-30% in IDMs.
• Pathophysiology: Fetal hyperinsulinemia → increased oxygen consumption → chronic hypoxia → increased erythropoietin → excessive RBC production.
• Definition: Central venous hematocrit >65%.
• Partial exchange transfusion (PET) indications: Symptomatic hyperviscosity (respiratory distress, neurologic, feeding issues) AND Hct >65%; OR asymptomatic with Hct >70%.
• Procedure: Remove 5-10 mL/kg of blood, replace with normal saline. Target Hct 50-55%.

❓ Q7. Why are IDMs at increased risk of hyperbilirubinemia? (1 mark)

✅ Model Answer: • Polycythemia → increased RBC breakdown.
• Increased enterohepatic circulation (delayed meconium).
• Birth trauma (cephalohematoma, bruising).
• Functional immaturity of liver (prematurity common).
• Management: Early feeding, phototherapy per AAP guidelines.

❓ Q8. What electrolyte abnormalities are common in IDMs? When do they present? (2 marks)

✅ Model Answer: • Hypocalcemia (serum calcium <7 mg/dL) – presents at 24-72 hours. Mechanism: hypomagnesemia → impaired PTH secretion/action.
• Hypomagnesemia (magnesium <1.5 mg/dL).
• Treatment of symptomatic hypocalcemia: IV calcium gluconate 10% (1-2 mL/kg = 100-200 mg/kg) slowly over 30-60 minutes with cardiac monitoring. Check magnesium; if low, give IV magnesium sulfate 25-50 mg/kg over 30 minutes.

❓ Q9. Which congenital anomaly is pathognomonic for IDM? Name two other common anomalies. (2 marks)

✅ Model Answer: • Pathognomonic: Caudal regression syndrome (sacral agenesis) – absence of sacrum and lower vertebrae.
• Other common anomalies:
- Cardiac: Transposition of great arteries, VSD, ASD, coarctation.
- Neural tube defects: Spina bifida, anencephaly.
- Renal: Renal agenesis, hydronephrosis.
- Gastrointestinal: Duodenal atresia, anorectal malformations.

❓ Q10. What is small left colon syndrome? How is it diagnosed and managed? (2 marks)

✅ Model Answer: • Definition: Functional obstruction of the left colon due to immaturity of the enteric nervous system, strongly associated with maternal diabetes.
• Presentation: Delayed passage of meconium (>48 hours), abdominal distension, bilious vomiting.
• Diagnosis: Contrast enema shows narrow left colon from splenic flexure to rectum, with a transition zone.
• Management: Conservative – rectal irrigations, NG decompression. Most resolve spontaneously. Biopsy if no improvement (to exclude Hirschsprung).

❓ Q11. What is renal vein thrombosis? Why are IDMs at risk? (2 marks)

✅ Model Answer: • Renal vein thrombosis: Thrombotic occlusion of the renal vein, often due to hyperviscosity.
• Risk in IDMs: Polycythemia → hyperviscosity → sluggish blood flow → thrombosis.
• Presentation: Unilateral flank mass, hematuria, thrombocytopenia, hypertension, AKI.
• Diagnosis: Renal Doppler ultrasound.
• Management: Supportive – hydration, partial exchange transfusion for polycythemia. Avoid anticoagulation unless extension into IVC.

❓ Q12. Outline your immediate management plan for this IDM in the first hour of life. (2 marks)

✅ Model Answer: • 1. Airway and breathing: Assess respiratory distress. Oxygen, CPAP, or intubation as needed. Chest X-ray.
• 2. Hypoglycemia prevention: Check blood glucose within 30 minutes. Early feeding (breast milk or formula). IV dextrose if unable to feed.
• 3. Assess birth trauma: Neurologic exam for Erb palsy. X-ray for clavicular fracture.
• 4. Polycythemia screen: Central hematocrit at 2-4 hours.
• 5. Echocardiogram: To rule out hypertrophic cardiomyopathy and CHD.
• 6. Electrolytes: Calcium, magnesium at 24 hours.
• 7. Bilirubin: Start monitoring at 24 hours.
• 8. Monitor for small left colon syndrome (delayed meconium).

❓ Q13. What are the long-term risks for this infant? How would you counsel the parents? (2 marks)

✅ Model Answer: • Long-term risks: Childhood obesity, type 2 diabetes mellitus, metabolic syndrome, hypertension, cardiovascular disease.
• Counseling: Promote breastfeeding, healthy diet, physical activity. Regular pediatric follow-up for growth, BP, and developmental screening. Monitor for symptoms of diabetes. For future pregnancies, emphasize tight glycemic control preconception.

❓ Q14. How can macrosomia be prevented in future pregnancies? (1 mark)

✅ Model Answer: • Preconception glycemic control (HbA1c <6.5%).
• Strict maternal glucose monitoring (fasting <95 mg/dL, postprandial <120-140 mg/dL).
• Appropriate insulin/oral hypoglycemics.
• Consider Cesarean section if estimated fetal weight >4500 g to prevent shoulder dystocia.

❓ Q15. The mother is anxious and asks why her baby is so large. How will you counsel her? (2 marks)

✅ Model Answer: • "Your baby is large because your blood sugar was high during pregnancy, causing him to make extra insulin – a growth hormone. This is not your fault; managing diabetes in pregnancy is very difficult."
• "The most important thing now is to prevent low blood sugar. We will check his sugar frequently and feed him early. Most of these complications are temporary."
• "His arm weakness (Erb palsy) is from the difficult delivery. Most babies recover fully with gentle exercises."
• "We will also check his heart, blood counts, and calcium levels. We are here to help both of you. Breastfeeding is strongly encouraged."
• "For future pregnancies, tight glucose control before and during pregnancy can greatly reduce these risks."

FCPS MCPS IMM MD Paediatrics TOACS