Final answer:
An intrauterine pregnancy can be detected in the US at around 5 to 6 weeks gestation using an ultrasound or transvaginal ultrasound.
Step-by-step explanation:
In the United States, an intrauterine pregnancy can be identified as early as five to six weeks gestation. An ultrasound, also known as a transvaginal ultrasound, is commonly used for this purpose. It employs sound waves to produce an image of the developing embryo. Since the developing embryo is still quite little at this point, an ultrasound of the abdomen may not show it. On the other hand, when the transvaginal ultrasound probe is inserted directly into the vagina, it can produce a sharper image. This makes the gestational sac and occasionally the baby heartbeat visible to medical professionals. It's important to note that the timing of when an intrauterine pregnancy can be detected may vary depending on several factors, such as the equipment used and the experience of the healthcare provider.