Probability of Ectopic Pregnancy

Ectopic pregnancy, where a fertilized egg implants outside the uterus (most commonly in a fallopian tube), occurs in approximately 1-2% of all pregnancies in the United States. It is a life-threatening condition and remains a leading cause of first-trimester maternal death.

Risk factors include previous ectopic pregnancy (recurrence risk of 10-25%), pelvic inflammatory disease (PID), prior fallopian tube surgery, endometriosis, use of an IUD (if pregnancy occurs with an IUD in place), smoking, history of infertility, and assisted reproductive technology (especially IVF). Women over 35 also have a somewhat higher risk.

Symptoms include abdominal pain (usually on one side), vaginal bleeding, dizziness, and shoulder pain (if internal bleeding irritates the diaphragm). Early detection through transvaginal ultrasound and blood hCG monitoring is critical. Treatment depends on the clinical situation: methotrexate (a medication that stops cell growth) can treat early, unruptured ectopic pregnancies, while surgical intervention (usually laparoscopic salpingostomy or salpingectomy) is necessary for ruptured ectopics or cases not suitable for medical management.