Leading cause of maternal death in first trimester and overall third leading cause of maternal death
Occur in 2% of all<unk> es and as high as 6-16% in those presenting to the ED<unk>  in patient with prior tubal ligation or IUD in place is<unk>  until proven otherwise (25-50% are<unk> 
Even if an IUP is visualized, there is a small risk of heterotopic<unk> 
General Population = 1 per 4000
IVF Population = 1 per 100
General Population = 1 per 4000
IVF Population = 1 per 100
Risk factors absent in almost half of patients
Most common location is the ampulla of the fallopian tube
Very rare with delayed diagnoses due to decreased accuracy of US
As high as 10% with reproductive IVF
Typically presents after 8 wks, with rupture possibly occurring as early as 5 wks
Implantation in myometrium in proximal part of fallopian tube, commonly misdiagnosed on ultrasound as intrauterine<unk> 
65% diagnosis on ultrasound and laparascopy is gold standard
US characteristics:
Empty uterus
Gestational sac separate from endometrium
Gestational sac > 1 cm from lateral aspect of uterine cavity
< 5 mm mantle surrounding the sac
Empty uterus
Gestational sac separate from endometrium
Gestational sac > 1 cm from lateral aspect of uterine cavity
< 5 mm mantle surrounding the sac
Ectopic pregnancy
Ovarian torsion
Subchorionic hematoma
Tubo-ovarian abscess
First Trimester Abortion
Ovarian cyst
Complete Abortion
Endometriosis