**4.** Adrenomedullin

Adrenomedullin is a peptide hormone belonging to calcitonin/calcitonin gene related peptide, and is thought be involved in endometrial angiogenesis. Liao et al found plasma and oviductal tissue adrenomedullin to be lower in EP and suggested that this decreases ciliary beating and muscle contraction leading to retained embryo and its implantation in the oviduct [99]. Similar findings were observed in nasal epithelium in patients of tEP by the same group [100]. Further studies are required to explore the possible role of serum adrenomedullin as a diagnostic marker for EP.

#### **5.** Activin B

Activins, dimeric proteins of transforming growth factor-beta (TGF-b), have recently been found in gonadal fluid with growth factor like actions [101]. It is produced by many organs including pituitary gland, gonads, placenta etc. It has been shown to promote decidualization of the endometrium during pregnancy [102]. Consequently low serum activin levels have been associated with ectopic pregnancy. Although recent studies have mainly focussed the role of serum activin A as a potential marker of ectopic pregnancy, limited literature is available regarding the role of activin B in-spite of the experimental evidence of differential effect of activin B on decidua. In our population, we observed that the concentration of activin B in maternal serum to be significantly lower in patients with tEP compared to those with normal IUP [Unpublished data]. Similar results were observed by Horne et al, who found decreased expression of activin B in endometrium along with decreased serum levels of activin B with normal levels of progesterone in 11 women with tEP [103]. Activin B is a new, though prom‐ ising marker for EP diagnostic triage.
