**5. Use of multiple biomarkers in ectopic pregnancy**

As maintenance of a viable pregnancy requires an interplay of multiple factors, no single marker has been used successfully as a biomarker for EP. It seems prudent, therefore, to combine these markers and use them in the multiple marker setting. Rausch et al demonstrated that a four-marker test including Progesterone, VEGF, Inhibin A, and Activin A could predict EP with 100% accuracy in those with an hCG<1500 mIU/mL [28]. Further studies are necessary to fully assess the discriminatory capacity of such a test. Similarly, Feng et al found a combi‐ nation of Δβ-hCG, Progesterone and Oestradiol to be helpful in distinguishing EPs and normal IUPs, facilitating earlier diagnosis and the timely implementation of medical treatment to prevent tubal rupture [132].

Soriano et al found that the combination of inflammatory cytokines IL-6, IL-8, and TNF-alpha was able to predict EP with specificity of 100%, but sensitivity of 52.9% [115].

Another group in Switzerland developed a multiple marker test, the "triple marker analysis" [VEGF/(PAPP-A X P)] had a sensitivity of 97.7% with a specificity of 92.4% in diagnosing EP [38].

In another study, investigators studied serum levels of 17β-estradiol (E2), progesterone (P4), testosterone (T), beta-human chorionic gonadotropin (β-hCG), vascular endothelial growth factor-A (VEGF-A), placental growth factor (PIGF), and a distintegrin and metalloprotease protein 12 (ADAM12) in different patient groups with no definite results [133].
