What Every Radiologist Should Know: First Trimester (2025)-R3-COB04-2025

Video Transcription

Video Summary

The session reviews key first‑trimester imaging concepts, emphasizing standardized ultrasound terminology and how wording affects patient management.

Dr. Suchi Rogers summarizes the Society of Radiologists in Ultrasound (SRU) multispecialty lexicon for early pregnancy. A gestational sac with a yolk sac is a <strong>definite</strong> intrauterine pregnancy (IUP); without a yolk sac it is <strong>probable</strong>. The updated definition of <strong>pregnancy of unknown location (PUL)</strong> is a positive pregnancy test with <strong>no probable or definite</strong> intrauterine or ectopic pregnancy on transvaginal ultrasound. The confusing term “pseudosac” should be avoided; use <strong>intracavitary fluid collection</strong> instead. For <strong>early pregnancy loss (EPL)</strong>, “failure” is discouraged due to patient impact. The SRU keeps the 2013 diagnostic criteria but recommends using “EPL” with modifiers (concerning for, diagnostic, in progress, incomplete, completed).

Maitreyi Patel reviews ectopic pregnancy pitfalls and pearls. Definitive ectopic diagnosis requires yolk sac/embryo outside the uterus; an <strong>adnexal ring</strong> is also strongly supportive. Avoid informal terms (“donut/blob”). Distinguish ectopic from corpus luteum by <strong>echogenic ring</strong> (ectopic) rather than relying on “ring of fire.” Cine clips and “slide sign” help, especially with hemoperitoneum. Interstitial ectopic is best recognized by <strong>lack of surrounding/clawing endometrium</strong> and uterine bulge; differentiate from <strong>eccentric IUP</strong> where endometrium surrounds the sac. Cervical and C‑section scar ectopics require prompt recognition, focusing on placental location relative to the scar.

Dr. Lina Pota discusses post‑pregnancy bleeding. Secondary hemorrhage (up to 12 weeks) most commonly reflects <strong>retained products of conception (RPOC)</strong> and/or <strong>enhanced myometrial vascularity (EMV)</strong> from delayed placental bed involution. Endometrial thickness <10 mm has high negative predictive value, but interpretation must integrate vascularity and symptoms. True congenital uterine AVM is extremely rare and often overdiagnosed; most cases warrant watchful waiting, with embolization reserved for extreme vascular abnormalities or focal lesions (AVF/pseudoaneurysm).

Dr. Chris Fung covers adnexal masses in early pregnancy: common, usually benign, and ~70% resolve. He advocates applying <strong>O-RADS</strong> risk stratification with pregnancy‑appropriate follow-up. A key pitfall is <strong>decidualized endometrioma</strong>, which can mimic malignancy but typically regresses on surveillance. Symptomatic torsion or high-suspicion malignancy requires urgent surgical evaluation.

Keywords

first-trimester ultrasound

SRU lexicon

intrauterine pregnancy (IUP) criteria

pregnancy of unknown location (PUL)

early pregnancy loss (EPL) terminology

ectopic pregnancy diagnosis

adnexal ring sign

interstitial ectopic vs eccentric IUP

retained products of conception (RPOC)

O-RADS in pregnancy