Ectopic pregnancy prediction in women with a pregnancy of unknown location: data beyond 48 h are necessary.
Zee J, Sammel MD, Chung K, Takacs P, Bourne T, Barnhart KT. Ectopic pregnancy prediction in women with a pregnancy of unknown location: data beyond 48 h are necessary. Hum Reprod. 2014 Mar; 29(3):441-7.