Investigations of diabetes during pregnancy

Investigations play a major role during pregnancy. Types of investigations are laboratory investigations, imaging studies and other investigations. Type of the investigation required is determined by the trimester of the pregnancy.
Goals of investigations are;
1. To ensure the maternal wellbeing.
2. To ensure the fetal wellbeing.
Lab Studies
First trimester (in addition to normal prenatal laboratory tests)
1. Hemoglobin A1C
2. Blood urea nitrogen and creatinine
3. Thyrotropin
4. Free thyroxine
5. Twenty-four–hour urine collection for protein and creatinine
6. Blood sugar levels from a capillary device 4-7 times daily

Second trimester

1. Repeat 24-hour urine studies in women with elevated creatinine value in first trimester or 24-hour protein or creatinine clearance less than 100 mL/min
2. Repeat HbA1C
3. Blood sugar levels from capillary device 4-7 times daily in all women with diabetes
If preeclampsia is suggested

1. Repeat 24-hour urine studies
2. Blood urea nitrogen and creatinine
3. Liver function tests
4. Uric acid
5. CBC count with platelets
6. Assessment of fetal well-being with nonstress test, amniotic fluid index, fetal growth, and Doppler examination of the umbilical cord and middle cerebral artery

Imaging Studies
First trimester
1. Ultrasonogram (crown-rump length) for dating and viability

Second trimester

2. Detailed anatomy ultrasonogram at 18-20 weeks' gestation
3. Fetal echocardiogram if HbA1C value was elevated in first trimester
Third trimester

1. Growth ultrasonogram to assess fetal size every 4-6 weeks from 26-36 weeks' gestation in women with overt preexisting diabetes
2. Growth ultrasonogram for fetal size at least once at 36-37 weeks' gestation for women with GDM (Consider performing this study more frequently if macrosomia is suggested.)
Other Tests
• First trimester - Ophthalmologic evaluation
Procedures
• Third trimester - Amniocentesis for fetal lung profile if delivery is contemplated prior to 39 weeks' gestation