1. Acute and chronic presentation of ectopic pregnancy may be two clinical entities 
Kurt T Barnhart, M.D., M.S.C.E., Paolo Rinaudo, M.D., Ph.D., Amy Hummel, B.S., Joseph Pena, M.D., Mary D Sammel, Sc.D., Jesse Chittams, M.S. 
Fertility and Sterility 
Volume 80, Issue 6, Pages (December 2003)
DOI: /j.fertnstert

2. FIGURE 1
Two hypothetical distinct natural histories of an ectopic pregnancy (not shown to scale). (A) Patient has a β-hCG concentration that increases well above the discriminatory zone and is often diagnosed with the aid of ultrasound. (B) Patient has a β-hCG concentration that may start to decline before reaching the discriminatory zone, and is often diagnosed without direct visualization on ultrasound using serial β-hCG values.
Barnhart. Acute and chronic ectopic pregnancy. Fertil Steril 2003.
Fertility and Sterility  , DOI: ( /j.fertnstert )