Researchers at University of Pennsylvania School of Medicine in the US have developed a blood test to diagnose ectopic pregnancy, a complication where the foetus implants itself outside the womb.

The test checks for four blood biomarkers to deliver one of three results: a confirmed ectopic pregnancy, a confirmed normal pregnancy or no confirmed result.

In a trial in involving 200 women, half of whom had an ectopic pregnancy and half had a normally developing pregnancy, the test was able to give a confirmed result in 42% of cases.

Of these, the test was able to distinguish between ectopic and normal pregnancies with 99% accuracy.