What is causing my Hcg levels to be in the 90's and nothing is showing on ultrasound?

HCG levels in the 90s with no visible pregnancy on ultrasound could indicate a few possibilities, including a very early pregnancy that is not yet detectable, a biochemical pregnancy where the embryo did not develop, or an ectopic pregnancy. It's essential to consult with a healthcare provider for further evaluation, as they may recommend repeat HCG testing or additional imaging to determine the cause.