Routine obstetric screening for all patients should include a Pap smear, urinalysis and urine culture, complete blood count, blood type, Rh factor and direct Coombs' test. Patients should also be screened for syphilis, rubella, gonorrhea and diabetes. For patients at high risk for certain conditions, additional studies of value include obstetric ultrasound, amniocentesis, serum alpha-fetoprotein level and screening for sickle cell anemia, herpes, hepatitis B, Chlamydia and human immunodeficiency virus.