## Anatomical Sites of Ectopic Pregnancy **Key Point:** The ampulla is the most common site of ectopic pregnancy, accounting for approximately 70% of all tubal pregnancies. ### Frequency Distribution by Site | Site | Frequency | Clinical Features | |------|-----------|------------------| | Ampulla (widest segment) | 70% | Rupture occurs later; allows larger gestational sac | | Isthmus (narrow segment) | 12% | Rupture occurs earlier due to limited space | | Fimbriae | 11% | May result in tubal abortion | | Interstitial | 2–3% | Rupture occurs late; massive hemorrhage | | Cervical/Abdominal/Ovarian | <2% | Rare; variable presentations | **High-Yield:** The ampulla's larger diameter allows the pregnancy to implant and grow longer before rupture occurs, whereas the isthmus ruptures earlier because of its narrow lumen and thick muscular wall. **Clinical Pearl:** Interstitial (cornual) pregnancies, though rare, are clinically significant because they can reach 12–16 weeks before rupture, leading to catastrophic hemorrhage and maternal mortality if not recognized early.
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