Citation, DOI and article data
The fetal pole is the first direct imaging manifestation of the fetus and is seen as a thickening on the margin of the yolk sac during early pregnancy. It is often used synonymously with the term "embryo".
The fetal pole is usually identified at ~6.5 weeks with transabdominal ultrasound imaging and at ~6 weeks 2 with transvaginal ultrasound imaging, although it may not be seen until ~9 weeks in some cases.
- a fetal pole should be seen when MSD ≥16 mm on TVS (by RCOG criteria), or MSD ≥25 mm on TAS
- pregnancy failure is not diagnosed until a fetal pole is not seen when MSD ≥25 mm on TVS
When the fetal pole measures ≥7 mm, a fetal heartbeat should be detected.
- 1. Hung N. Winn (Editor), John C. Hobbins (Editor). Clinical Maternal-Fetal Medicine. (2000) ISBN: 1850707987
- 2. F. Bahlmann (Contributor), R. Bollmann (Contributor), R. Chaoui (Contributor). Ultrasound in Obstetrics and GynecologyDiagnostic Ultrasound in Obstetrics: Obstetrics. (2005) ISBN: 1588901475
- 3. Jain K, Hamper U, Sanders R. Comparison of Transvaginal and Transabdominal Sonography in the Detection of Early Pregnancy and Its Complications. AJR Am J Roentgenol. 1988;151(6):1139-43. doi:10.2214/ajr.151.6.1139