Thank you for your question. I think your question relates to diagnosing pregnancy and its location accurately.
If your urine pregnancy test is positive a transvaginal ultrasound examination should detect an intrauterine pregnancy at 5 weeks from the last period. If nothing is visible in the uterus, it may be too early or the pregnancy may be outside the uterus, most commonly in a tube. This is called an ectopic pregnancy. The diagnosis is made based on symptoms, clinical examination, pregnancy test, transvaginal ultrasound and a blood test which assesses the level of pregnancy hormone in the mothers blood. There are several aspects to the diagnosis so a high index of suspicion is required on the part of the clinician. Any lady who has a positive pregnancy test needs to have ectopic pregnancy ruled out. This is because such a pregnancy can rupture and cause unpredictable bleeding inside the tummy. So it is important to see a gynaecologist when the pregnancy test is positive and have an ultrasound examination that confirms the pregnancy is inside the uterus.