Ectopic Pregnancy and PUL

Quick Answer: Ectopic = pregnancy outside uterus; look for adnexal mass separate from ovary, tubal ring, free fluid. PUL = positive hCG, no IUP or ectopic seen—serial hCG/US. Rupture = hemoperitoneum + instability. Know discriminatory zone concepts.

Epidemiology and Risk

Ectopic complicates ~1–2% pregnancies. Risk factors: prior ectopic, tubal surgery, PID, IUD (still can be IUP), ART, smoking. Sonographers must perform complete TV evaluation including adnexa and cul-de-sac when β-hCG positive.

Ultrasound Findings

Definite Ectopic

Extrauterine gestational sac with yolk sac/embryo/cardiac activity outside uterus—rare but diagnostic.

Probable Ectopic

Pseudosac

Intrauterine fluid without decidual signs—not proof of IUP.

PUL (Pregnancy of Unknown Location)

Definition: positive pregnancy test, no IUP, no definite ectopic on US. Management per M6M/RCOG-style algorithms:

1. Correlate β-hCG and progesterone
2. Repeat US in 48 hours to 7 days
3. Expect 66% rise in 48h if viable IUP (not exact rule for all)

Discriminatory Zone Concept

β-hCG level above which IUP should be visible on TVUS—often cited ~1500–2000 mIU/mL (institution varies). Below zone with PUL: caution against diagnosing ectopic without serial testing.

Worked Scenario

β-hCG 800, no IUP, normal adnexa → PUL, not ectopic diagnosis. β-hCG 2500, no IUP, complex right adnexal mass + free fluid → ectopic likely, urgent OB consult.

Ruptured Ectopic

• Free fluid in Morrison pouch and cul-de-sac (blood)
• Maternal tachycardia, pain, hemodynamic compromise clinically
• Sonographer action: immediate physician notification, do not delay for complete biometry

Interstitial / Cornual Ectopic

Implants in myometrial segment of tube—closer to uterine cavity, vascular, dangerous rupture. Look for eccentric high fundal sac surrounded by myometrium <5 mm or interstitial line sign.

Cervical and Cesarean Scar Ectopic

Rare; cervical ectopic shows hourglass cervix with closed internal os; scar ectopic in niche after C-section—know existence for registry image banks.

Heterotopic Pregnancy

Intrauterine + extrauterine—risk increased with ART. Never ignore adnexa because IUP seen.

Corpus Luteum vs. Ectopic Differentiation

Management Overview (For Exam)

Sonographers don't prescribe—but registry asks next best step recognition.

Exam Traps

• Diagnosing ectopic with empty uterus alone at low hCG (PUL).
• Calling corpus luteum cyst ectopic without separate gestational sac ring.
• Missing free fluid on fast sagittal sweep through cul-de-sac.
• Ignoring heterotopic because IUP was documented first.

Ectopic items reward systematic TV habit: uterus, endometrium, both adnexa, cul-de-sac, both iliac fossae for free fluid.

Serum Biomarker Correlation Table

Progesterone <5 ng/mL supports non-viable pregnancy but does not distinguish ectopic from failed IUP alone.

Ovarian Pregnancy and Rare Sites

Ovarian ectopic implants within ovarian stroma—gestational sac within ovary, not separate ring. Cervical ectopic shows gestational sac in cervix with closed internal os and hourglass shape; bleeding risk high. Cesarean scar ectopic lies in lower uterine segment niche—vascular on Doppler, different from cervical canal pregnancy. Each site changes surgical urgency on registry management questions.

Methotrexate Eligibility (Recognition Only)

Stable patient, unruptured, mass <3.5–4 cm, no cardiac activity, β-hCG below institutional ceiling, no contraindications—may qualify for medical management. Cardiac activity in extrauterine pregnancy generally excludes methotrexate on exam vignettes. Sonographer role remains complete imaging and urgent communication, not prescribing.

Free Fluid Grading

Trace cul-de-sac fluid can be physiologic in early pregnancy. Moderate to large echogenic free fluid with pain suggests hemoperitoneum. Extend scan to Morrison pouch (hepato-renal space) when rupture suspected—fluid accumulates superiorly in supine patient.

Stepwise TV Algorithm for Suspected Ectopic

Perform in order: (1) sagittal uterus for decidual reaction and sac; (2) transverse uterus for fundal/cornual eccentricity; (3) both adnexa in transverse; (4) longitudinal adnexal sweeps; (5) cul-de-sac fluid; (6) Morrison pouch if pain or hemodynamic concern. Skipping adnexa when "early" IUP not seen is the most common clinical and registry error.

Live Ectopic and Cardiac Activity

Extrauterine embryo with cardiac activity usually mandates surgical management rather than methotrexate on exam vignettes. Document exact location (tubal, interstitial, ovarian) when visible. Interstitial pregnancies rupture with catastrophic hemorrhage—myometrial mantle <5 mm around sac is danger sign.

Expectant Management Imaging

Declining β-hCG with resolving adnexal mass may support expectant management of ectopic under physician protocol. Sonographer documents mass size, free fluid, and cardiac activity at each visit—rising fluid or new cardiac activity changes pathway.