DO LOW-RISK PRENATAL PATIENTS REALLY NEED A SCREENING GLUCOSE CHALLENGE TEST

BACKGROUND. It is common practice to routinely screen pregnant women f or gestational diabetes. The screening technique typically used is the 1-hour 50-g oral glucose tolerance test (OGTT), with a subsequent 3-h our 100-g OGTT for women whose 1-hour test was positive. This process can be both time-consuming and inconvenient for patients. Additionally , its sensitivity and specificity are estimated to be 70% and 87% resp ectively, and data about the effect of screening and treatment on low- risk pregnancy outcomes are limited. The objective of this study was t o reassess the value of routine screening of all pregnant patients wit h a 1-hour glucose challenge test. METHODS. At a university-based fami ly practice center with a predominantly low-risk population, a retrosp ective analysis was performed of all patients (n=595) who received pre natal care and gave birth between January 1988 and December 1993. Amon g women in whom gestational diabetes was diagnosed on the basis of glu cose tolerance testing, we identified those with risk factors for the disease, and examined whether a selective screening program based on r isk factors alone would have resulted in correct diagnoses of gestatio nal diabetes. RESULTS. Of the 595 patients, 544 (91.4%) were screened with a 1-hour 50-g OGTT. This initial screening test was positive in 7 6 women (12.8%). Of these, 58 (76.3%) then had a 3-hour 100-g OGTT, an d 13 received a diagnosis of gestational diabetes. Nine of these 13 wo men had risk factors for gestational diabetes. We determined that less than 1% of prenatal patients without risk factors for gestational dia betes were ultimately found to have gestational diabetes. CONCLUSIONS. Screening with a 1-hour 50-g OGTT only those women who have identifia ble risk factors for gestational diabetes is a reasonable approach to identifying the disease in a low-risk population. All pregnant women s hould have a thorough history taken to determine whether they have ris k factors for gestational diabetes.