Differential Diagnosis

• Single most likely diagnosis
  • Chemical Pregnancy: This is the most likely diagnosis given the confirmed ovulation, initial positive beta hCG that was very low (<2), and subsequent spotting. A chemical pregnancy occurs when a pregnancy is lost shortly after implantation, often before a woman even realizes she is pregnant. The low and transient hCG levels are consistent with this diagnosis.
• Other Likely diagnoses
  • Early Miscarriage: Similar to a chemical pregnancy, an early miscarriage could explain the low hCG levels followed by spotting. However, the distinction between a chemical pregnancy and an early miscarriage can sometimes be blurry and may depend on the gestational age at the time of the loss.
  • Pituitary hCG: Although less common, pituitary hCG can cause low levels of hCG to be detected, leading to a false-positive pregnancy test. However, this would not typically be associated with spotting in the context of a suspected pregnancy.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Ectopic Pregnancy: Although the hCG level was very low, an ectopic pregnancy must be considered, especially if there are any symptoms such as abdominal pain or if the spotting is heavy or accompanied by other concerning symptoms. Ectopic pregnancies can be life-threatening if not promptly diagnosed and treated.
• Rare diagnoses
  • Molar Pregnancy: A molar pregnancy could potentially present with low hCG levels initially, although typically, hCG levels in a molar pregnancy are abnormally high. The spotting could be consistent with this diagnosis, but given the context, it is less likely.
  • Heterotopic Pregnancy: This is a rare condition where there are simultaneous intrauterine and ectopic pregnancies. Given the confirmed ovulation and initial positive hCG, followed by low levels and spotting, this could be considered, especially in someone undergoing fertility treatments, but it is extremely rare in natural conceptions.