A Prospective Study on the Reliability of First-Trimester Ultrasound in Identifying the Gestational Sac Implantation Site

Objectives: Normal and abnormal implantation of the gestational sac may affect obstetrical outcomes. We sought to evaluate whether ultrasound can correctly identify the first-trimester gestational sac implantation wall compared to diagnostic hysteroscopy. Methods: Consecutive women diagnosed with first-trimester pregnancy loss who opted for surgical termination of pregnancy were prospectively recruited to the study. Pre-operatively, an ultrasound scan was performed to assess for the gestational sac implantation wall. Subsequently, the surgical procedure of diagnostic hysteroscopy combined with suction and curettage was performed. The sonographers were blinded to the hysteroscopy results. The gestational sac implantation wall was determined and compared between the two modalities. Results: Twenty-three women were included in the study. The median gestational age 9 (range: 6 to 13) weeks, and the median crown-rump length was 7 (range 6-9) mm. In one case, the implantation site was determined only by the U.S. In the remaining, the U.S. and hysteroscopy gestational sac location were identical (21/22, 95%). Thus, the correlation between the sonographic and hysteroscopy findings was 0.96. Conclusion: Ultrasound is a reliable method for the detection of the early gestational sac implantation site.