What Causes Ectopic Pregnancy?

Extrauterine pregnancy—commonly known as ectopic pregnancy—occurs when a fertilized egg implants and begins developing outside the uterine cavity, most frequently within a fallopian tube. This condition is a leading cause of maternal mortality in the first trimester and requires prompt diagnosis and intervention.

Several anatomical and physiological factors increase the risk of ectopic implantation. Prior pelvic inflammatory disease—often caused by *Chlamydia trachomatis* or *Neisseria gonorrhoeae*—can lead to tubal scarring, adhesions, and impaired ciliary function, disrupting normal ovum transport. Similarly, previous tubal surgery—including sterilization reversal or salpingostomy—alters tubal architecture and motility. Endometriosis may contribute through inflammation-induced tubal dysfunction and altered peritoneal environment.

Other established risk factors include a history of prior ectopic pregnancy, which confers a 10–15% recurrence risk; assisted reproductive technologies, particularly those involving embryo transfer into a compromised tubal environment; and use of intrauterine devices (IUDs) or progestin-only contraceptives, which—while highly effective at preventing intrauterine pregnancy—do not eliminate ovulation and may slightly elevate the relative risk of ectopic implantation should conception occur.

Less common but clinically significant contributors include congenital tubal anomalies, such as accessory ostia or diverticula, and conditions associated with abnormal tubal peristalsis—including smoking, which contains compounds that impair smooth muscle contractility and ciliary action in the fallopian tubes.

Early recognition hinges on clinical suspicion: patients may present with unilateral pelvic pain, vaginal bleeding, amenorrhea, or signs of hemodynamic instability in cases of rupture. Serum β-hCG trends combined with transvaginal ultrasonography remain the cornerstone of diagnosis. Management options range from expectant monitoring in stable, low-risk cases to medical therapy with methotrexate or surgical intervention—typically laparoscopic salpingectomy or salpingostomy—depending on clinical stability, lesion characteristics, and fertility preservation goals.