1. Are gestational age and endometrial thickness alternatives for serum human chorionic gonadotropin as criteria for the diagnosis of ectopic pregnancy? 
Ben W.J Mol, M.D., Ph.D., Petra J Hajenius, M.D., Ph.D., Simone Engelsbel, M.D., Willem M Ankum, M.D., Ph.D., Fulco van der Veen, M.D., Ph.D., Douwe J Hemrika, M.D., Ph.D., Patrick M.M Bossuyt, Ph.D. 
Fertility and Sterility 
Volume 72, Issue 4, Pages (October 1999)
DOI: /S (99)

2. FIGURE 1
Receiver operating characteristic curves demonstrating the performance of serum hCG concentration (——), gestational age (•••••), and endometrial stripe thickness in the diagnosis of ectopic pregnancy. For endometrial stripe thickness, there are two curves, one for all patients with inconclusive ultrasonographic findings (—–—), and one for patients with inconclusive ultrasonographic findings and serum hCG concentrations of <1,500 IU/L (—--—). The line y = x represents a test without any discriminative performance (-----).
Mol. Gestational age and endometrial thickness. Fertil Steril 1999.
Fertility and Sterility  , DOI: ( /S (99) )