A woman has a strongly positive urine pregnancy test but no pregnancy is seen on ultrasound and she has very high hCG. Which single point about the pregnancy test as a 'probable' sign is most relevant?

Answer: E. A positive test can occur in trophoblastic disease (molar pregnancy, choriocarcinoma)

The pregnancy test as a probable sign

A positive pregnancy test detects hCG, but it is classed as a probable sign because hCG can be raised in conditions other than a normal intrauterine pregnancy.

Causes of a positive test beyond normal pregnancy

• Hydatidiform mole and choriocarcinoma (trophoblastic disease), often with very high hCG.
• Ectopic pregnancy.
• Occasionally false-positive results.

This scenario

• Very high hCG with no intrauterine pregnancy on ultrasound raises suspicion of molar pregnancy or other trophoblastic disease (and ectopic must be excluded).
• This is why a positive test alone is not a positive (diagnostic) sign of a normal pregnancy; ultrasound visualisation of the fetus is needed.