I think miscarried at four weeks pregnant but my blood test showed no hcg in system days later. Is it still possible that was pregnant?

A negative blood test for human chorionic gonadotropin (hCG) several days after a suspected miscarriage at four weeks of pregnancy can indicate that you were not pregnant or that the pregnancy loss occurred so early that hCG levels were not detectable in your blood.

In early pregnancy, hCG levels rise rapidly and can be detected in the blood as early as 10-14 days after ovulation. However, if the pregnancy loss occurs very early, before significant hCG production, the levels may not have reached a detectable level in your blood by the time of the test.

It's important to note that pregnancy tests, including blood tests, have a certain sensitivity level. If hCG levels are very low, they may not be detected by the test, leading to a false-negative result. Additionally, some factors can affect hCG levels, including the timing of the test, medication interference, or ectopic pregnancy.

To confirm the pregnancy loss and ensure accurate information, it's advisable to consult your doctor or healthcare provider. They may recommend additional tests, such as a repeat blood test or an ultrasound, to determine if you were indeed pregnant and to assess your current health status.