INFANT OF DIABETIC MOTHER WORKUP

Lab Studies (infant of diabetic mother):
• Complete blood cell count
o Polycythemia, commonly defined as a central hematocrit higher than 65% or hemoglobin concentration higher than 20 g/dL, is a potential concern.
o Maternal-fetal hyperglycemia is a strong stimulus for fetal erythropoietin production and subsequent increase in fetal hemoglobin concentration secondary to chronic in utero hypoxia, which can be associated with the infant of a diabetic mother. Fetal hyperviscosity, intravascular sludging, regional ischemia, and hypoxemia are all potential complications. Thrombocytopenia may occur because of impaired thrombopoiesis due to "crowding-out" of thrombocytes by the excess of erythroid precursors in the bone marrow.

• Glucose concentration (serum or whole-blood)
o Seizures, coma, and long-term brain damage may occur if neonatal hypoglycemia is unrecognized and untreated.
o Most centers recognize levels lower than 20-40 mg/dL within the first 24 hours after birth as abnormal, but the precise level remains controversial. A policy to screen IDMs for hypoglycemia should be in place in every hospital. A recent suggestion of operational thresholds was proposed by Cornblath et al. Their suggestion in an infant with compromised metabolic adaptation (ie, IDMs) should include blood glucose measurements (1) as soon as possible after birth, (2) within 2-3 hours after birth and before feeding, and (3) at any time abnormal clinical signs are observed.

• Magnesium concentration (serum)
o Hypomagnesemia is related to younger maternal age, severity of maternal diabetes, and prematurity. Neonatal magnesium levels are also related to maternal serum magnesium, neonatal calcium and phosphorus levels, and neonatal parathyroid function.
o The clinical significance of low magnesium levels in these infants remains controversial and uncertain.

• Calcium concentration (serum, ionized or total levels):
Low serum calcium levels in IDMs are common. They are speculated to be caused by a functional hypoparathyroidism; however, their clinical relevance remains uncertain and controversial.

• Bilirubin level (serum, total and unconjugated): Hyperbilirubinemia is notably more common than in the general population of neonates. Causative factors include prematurity, hepatic enzyme immaturity, polycythemia with hyperviscosity and "sludging," and reduced red blood cell half-life.

• Arterial blood gas:
Assessing oxygenation and ventilation is essential in infants with clinical evidence of respiratory distress. Although noninvasive methods (eg, transcutaneous oxygen and carbon dioxide electrodes, oximeters) have gained wide acceptance at many centers, comparison of results with those from arterial blood is intermittently required.

Imaging Studies (infant of diabetic mother):
• Chest radiograph
o Clinical evidences of cardiopulmonary distress require a detailed evaluation, which always should include a chest radiograph.
o Adequacy of lung expansion, evidences of focal or diffuse atelectasis, presence of interstitial fluid, signs of free air in pleural or interstitial spaces, as well as findings of pneumonia should be looked for carefully. The possibility of pulmonary malformations also should be considered. In the macrosomic infant with a history of shoulder dystocia, examination of the clavicles may be indicated.
o Cardiac size, shape, and great vessel/outflow tract should be examined carefully.

• Cardiac echocardiogram
o A thickened myocardium and significant septal hypertrophy may be present in as many as 1 in 3 IDMs. Evidence of hypercontractile, thickened myocardium, often with septal hypertrophy disproportionate to the size of the ventricular free walls, may be noted on examination. Myocardial contractility also should be evaluated because the myocardium is overstretched and poorly contractile with congenital cardiomyopathies. Evidence of anatomical malformation must be searched for carefully because cardiac malformations are significantly more common in IDMs, including a VSD and a TGA.

• Abdominal, pelvic, or lower extremity radiographs
o When caudal dysplasia is present, anatomic details must be evaluated. Orthopedic anomalies may include fusion of the legs, hypoplastic femur, defects of the tibia and the fibula,flexion contractures of the knee and hip,or clubfoot.Sacral agenesis also is describe
o Lower extremity congenital malformations require radiographic evaluation to determine the exact skeletal defect or defects present.

• Barium enema
o Infants with feeding intolerance, abdominal distention, nonbilious emesis, or poor passage of meconium may require a barium enema. Congenital anomalies of the gastrointestinal tract are more common in IDMs. These infants may have "small left colon syndrome," also known as "lazy colon."
o Clinical features of the small left colon syndrome may mimic those of Hirschsprung disease and distal tapering of the colon is a radiologic feature of both disorders. The 2 disorders can be distinguished using a biopsy because normal ganglionic cells are present in lazy colon and absent in Hirschsprung disease.

Procedures (infant of diabetic mother):
• Nasal or endotracheal continuous positive airway pressure, endotracheal intubation, and mechanical ventilation
o Nasal continuous positive airway pressure (NCPAP) or endotracheal intubation with CPAP and/or intermittent mandatory or synchronized positive pressure ventilation (IMV, SIMV) may be employed for management of severe respiratory distress.
o Common criteria for such interventions include inspired oxygen requirements (FiO2) of 60-100% to maintain arterial PO2 of 50-80 mm Hg, arterial PCO2 levels higher than 60-80 mm Hg or rising 10 or more mm Hg/h, and apnea. The specific criteria for using these modes of assisted ventilation may vary considerably among neonatologists or across institutions.

• Indwelling vascular lines (peripheral, umbilical, or central)
o Noninvasive blood gas monitoring using transcutaneous electrodes (PaO2 and PaCO2) and oximeters (O2% saturation) has greatly reduced the need for invasive indwelling catheters. However, indwelling lines often are needed early in the course of cardiorespiratory disease. In some instances, the need for continuous arterial blood pressure monitoring may warrant placement of a peripheral or umbilical arterial line. Once again, use of these invasive methods varies.
o Placement of an umbilical venous or a central venous catheter often is employed when the infant requires hyperosmolar intravenous fluids or when peripheral access is limited or exhausted.

Histologic Findings: The pancreas has larger and more numerous islets. Sections from neonatal myocardium show cellular hyperplasia and hypertrophy.