In ectopic pregnancy, implantation occurs outside of the uterus. The most common site is the fallopian tube, but other possible sites include the pelvic or abdominal cavity, uterine cornu, cervix, or ovary.
Risk factors include previous ectopic pregnancy, history of abdominal or tubal surgery, infertility, pelvic inflammatory disease (PID), intrauterine device (IUD) use, and in-utero diethylstilbestrol (DES) exposure.
The most common clinical presentation of ectopic pregnancy is a period of amenorrhea followed by abdominal pain and/or abnormal vaginal bleeding. Symptoms may also be absent until rupture occurs, causing syncope, hemorrhagic shock, or shoulder pain secondary to hemoperitoneum. Physical examination may reveal cervical motion tenderness and an adnexal mass.
Diagnosis of ectopic pregnancy is by measurement of serum β-hCG levels and ultrasonography. Transvaginal ultrasound (TVUS) should detect a gestational sac in the uterus when the serum β-hCG is above a certain level called the discriminatory zone. This level is usually 1500 or 2000 IU/L, depending on the institution. Absence of an intrauterine gestational sac with a β-hCG greater than 2000 IU/L is highly suggestive of an ectopic pregnancy. Serial measurements of the serum β-hCG demonstrate a failure to double every 48 hours. Treatment is with methotrexate (MTX) therapy or surgical resection.