Which test is used to diagnose whether a woman is pregnant?

The urine or blood hCG test is utilized to diagnose pregnancy due to its ability to specifically detect the presence of human chorionic gonadotropin (hCG), a hormone produced shortly after a fertilized egg attaches to the uterine lining. In early pregnancy, hCG is released into the bloodstream and can be measured in both blood and urine samples, making these tests highly effective for confirming pregnancy.

These tests can provide reliable results even before a missed menstrual period in some cases, particularly the blood test, which can detect lower levels of hCG compared to urine tests. The hCG test is considered the most sensitive and widely used method for confirming pregnancy, allowing for early diagnosis and monitoring of the pregnancy.

Other tests and methods mentioned, such as X-rays and ultrasound scans, are not primarily used for confirming a pregnancy. X-rays can pose risks to the developing fetus and are generally avoided during pregnancy. Ultrasound is used to visualize the fetus and confirm the viability of a pregnancy but is not typically the first-line test for diagnosing pregnancy. A pelvic exam can assess various reproductive health issues but does not provide a specific diagnosis of pregnancy. Thus, the urine or blood hCG test is the most appropriate and accurate choice for determining whether a woman is pregnant.