Suspicion of ectopic pregnancy is abnormal bleeding or severe abdominal pain during pregnancy. Beta HCG levels need to be evaluated for this purpose of diagnosis.
The serum quantitative HCG is then repeated serially (typically every two days) to assess whether the increase in concentration is consistent with an abnormal pregnancy. In some cases, the diagnosis of ectopic pregnancy can be made after a single measurement of HCG in combination with transvaginal ultrasound, if the HCG is above the discriminatory zone and transvaginal ultrasound shows no evidence of an intrauterine pregnancy and the presence of findings that suggest an ectopic pregnancy.
With regards to a Last Menstrual Period an amenorrhea of >4 weeks preceded the current vaginal bleeding may be a suspect case too detect such issues early.