Résumé : Objective: To describe a new grading method for stomach position (SP) in fetuses with left-sided congenital diaphragmatic hernia (L-CDH) using ultrasound and to correlate SP to liver position and to liver-to-thoracic cavity volume ratio (LiTR) using magnetic resonance imaging. Methods: SP were graded at the level of the 4-chamber view as following: grade 1-to-4 for stomach not visualised, visualised anteriorly at the apex of the heart, stomach showing abdominal structures anteriorly and stomach with its larger part posterior to the level of the atrial-ventricular heart valves, respectively. The LiTR was calculated and correlated to SP using the Mann-Whitney U test. Results: Seventy-four fetuses were included. Median LiTR for grade 1 SP was 0% and was not different from median LiTR for grade 2 SP (0%, p=NS). Median LiTR for grade 3 SP was 14.9% and was significantly higher than for grade 2 SP (p<0.001). Similarly, median LiTR for grade 4 SP was 20.7% and was significantly higher than for grade 3 SP (p<0.05). When SP was grade 1 or 2, liver was intra-abdominal in 21 (84%) out of 25 fetuses while it was always intrathoracic for SP 3 or 4. Conclusion: In L-CDH, SP as described represents a simple indirect measurement of intrathoracic position and quantification of liver.