Reproductive · Year 2 · from Reproductive
Case 2: Ectopic Pregnancy
Clinical Image
Source: Wikipedia - Ectopic pregnancy - CC BY-SA 4.0
Case Presentation
A 28-year-old woman presents to the emergency department with 5 days of vaginal spotting and right lower quadrant pain. Her last menstrual period was 7 weeks ago. She has a history of pelvic inflammatory disease treated 3 years ago and uses an intrauterine device for contraception (which was removed 6 months ago when she and her partner decided to conceive). Vital signs are stable. Physical examination reveals right adnexal tenderness without peritoneal signs. Urine pregnancy test is positive. Serum beta-hCG is 2,400 mIU/mL. Transvaginal ultrasound shows no intrauterine gestational sac, a thickened endometrium, and a 2.5 cm adnexal mass with a yolk sac adjacent to the right ovary (tubal ring sign). No free fluid is seen in the pelvis. The diagnosis is unruptured ectopic pregnancy in the right fallopian tube. Given her hemodynamic stability, moderate beta-hCG level, and desire for future fertility, she is offered methotrexate treatment. She receives methotrexate 50 mg/m2 intramuscularly. Serial beta-hCG monitoring shows appropriate decline, and the ectopic pregnancy resolves without surgery.
Key Learning Points
- The fallopian tube ampulla is the most common site of ectopic pregnancy and the normal site of fertilization; tubal damage (from PID, prior ectopic, or surgery) is the major risk factor
- The discriminatory zone (beta-hCG level at which an intrauterine pregnancy should be visible on ultrasound, typically 1,500-2,000 mIU/mL) helps distinguish ectopic from early normal pregnancy
- Methotrexate is an option for hemodynamically stable patients with unruptured ectopic pregnancy and beta-hCG generally <5,000 mIU/mL
- Prior PID, particularly from Chlamydia, causes tubal damage that impairs oocyte transport and increases ectopic pregnancy risk