Screening Tests

Screening Tests Due at 27 Weeks Gestation

You will have your testing done in our office.  They may be scheduled at one of the following times:

  • Regular monthly OB visit: When our office assistant instructs you when the appropriate time of screening is due you may have this testing done at your regular monthly visit.  You will be in our office for at least one hour, so please schedule this visit prior to 2:30 P.M. to insure that adequate time is allotted for these tests.
  • Lab only appointment: If it is more convenient or your regular OB visit does not occur during this time period you may schedule a lab only appointment.  During this visit, you will not see your physician; our lab personnel will administer the testing.

Hematocrit –  This blood test evaluates for the possibility of anemia.  Certain levels of anemia are not uncommon during pregnancy.  Your physician may recommend adding an iron supplement along with your prenatal vitamins if this count is low.  

HIV –  During the 3rd trimester an additional screening test is required by law.

Antibody Screen – If your blood type is Rh Negative (and your spouse is Rh Positive) you will be screened to evaluate for the possibility of Rh incompatibility.  The Rhogam injection that protects against this will be given the same day the blood work is drawn.

Modified Glucose Testing –  This blood test screens for the possibility of gestational diabetes.  

  • It is not necessary to be fasting for this test to be performed.  Any food/drinks that are ingested prior to testing should be low in sugar, carbohydrates are okay.
  • You will be at the laboratory for at least one hour.  You will be given a controlled amount of glucose to drink.  This should be consumed within a 5-minute period.  One hour after beginning the glucose drink, your blood specimen will be collected.  During this hour, it is best for you to sit quietly because excessive movement may cause the blood sugar to elevate.
  • Our office should receive these results within one week.  If the blood sugar level is 140 or greater, you will be instructed to have further testing done.  A full glucose tolerance test would then be necessary. 

Full Glucose Tolerance Test – This is the definitive test that will evaluate for Gestational Diabetes (GDM).  You will be in our office for at least 3 hours.  You should sit quietly for the duration of the test because excessive movement may cause blood sugar to elevate.

  1. Schedule a lab only, morning appointment. 
  2. Follow 2000 calorie diabetic diet for 3 days prior to test.
  3. Do not eat or drink anything (except water) after Midnight the night prior to testing.  You must be fasting to begin this test.
  4. Upon admission to the lab, a fasting blood sugar will be checked.  You will then be given a measured amount of glucose to drink.  This drink should be consumed within a 5-minute time span.  From the time you began drinking the glucose, your blood sugar will be checked at 1 hour, 2 hours and 3-hour intervals.
  5. Call our office within one week if one of our nurses has not already contacted you for these results.

Gestational Diabetes 2,000 Calorie Diet/Meal Planning Guide