Ruptured ectopic — hemorrhagic emergency: Free pelvic/abdominal fluid + positive β-hCG = ruptured ectopic until proven otherwise. Do NOT delay for MRI. Hemodynamically unstable patient goes directly to OR. Hemodynamically stable: US to confirm. Hemoperitoneum extending to Morrison's pouch or paracolic gutters = large hemorrhage.
Heterotopic pregnancy: Simultaneous intrauterine and ectopic pregnancy. Rare in general population (1:30,000) but significantly increased with ART (1:100–500). Presence of an intrauterine pregnancy does NOT exclude a co-existing ectopic. Always evaluate adnexa even when IUP is confirmed in ART patients.
Ultrasound Findings
| Finding | Description |
|---|---|
| Empty uterus with β-hCG >1500–2000 mIU/mL | Discriminatory zone: β-hCG above which IUP should be visible on TVUS (1500–2000 mIU/mL for TVUS; 6500 mIU/mL for transabdominal). Empty uterus above discriminatory zone = ectopic or failed IUP. Note: heterotopic can have IUP + ectopic simultaneously. |
| Ring of fire sign | Trophoblastic "ring of fire" Doppler signal around ectopic sac; echogenic ring on B-mode ("bagel sign"); distinct from the ovary (surrounded by ovarian parenchyma = corpus luteum cyst); TVUS most sensitive |
| Tubal ring sign / extrauterine gestational sac | Round or oval adnexal structure separate from ovary; may contain yolk sac or embryo (definitive diagnosis); Doppler: "ring of fire" around ectopic sac (trophoblastic flow) |
| Free pelvic fluid (hemorrhage) | Non-dependent echogenic free fluid in cul-de-sac, Morrison's pouch, paracolic gutters; complex/echogenic = hemoperitoneum; simple free fluid less specific; volume correlates with degree of hemorrhage |
| Interstitial ectopic | Gestational sac within myometrium at cornual region; interstitial line sign (echogenic line connecting ectopic sac to endometrium); thin myometrial rim <5 mm; presents later (8–12 weeks) with greater hemorrhage risk than tubal ectopic; 2–4% of ectopics; high mortality |
Reporting Checklist
- β-hCG level vs discriminatory zone (>1500–2000 mIU/mL should demonstrate IUP)
- Uterine findings: IUP present / empty uterus / pseudogestational sac
- Adnexal ring sign: location (tubal / interstitial / ovarian / cervical)
- Gestational sac contents: yolk sac / embryo (CRL in mm if visible)
- Cardiac activity: present / absent
- Free pelvic fluid: location / amount / echogenicity (hemorrhagic = ruptured)
- Myometrial rim thickness if interstitial (<5mm = high rupture risk)
- Heterotopic pregnancy consideration if ART patient
References
Barnhart KT. Ectopic pregnancy. N Engl J Med. 2009;361(4):379–87.
Radiopaedia — Ectopic pregnancy