Objective: The purpose of this article is to investigate the prevalence, volume, and location of peritoneal fluid accumulation and to clarify the clinical significance of a small amount of peritoneal fluid accumulation in healthy men and postmenopausal women on pelvic MRI.
Materials and methods: Pelvic MRI was performed on 1017 healthy men and 310 healthy postmenopausal women. Two radiologists independently interpreted images and judged the presence or absence of fluid in the peritoneal cavity. For cases in which peritoneal fluid was detected, the volume and the location were recorded.
Results: Peritoneal fluid was identified in 39 of 1017 (3.8%) healthy men and 52 of 310 (16.8%) healthy postmenopausal women. Healthy postmenopausal women had a much higher prevalence than did healthy men (p < 0.0001). The mean (± SD) total volume of fluid accumulation was 3.0 ± 2.7 mL in healthy men and 2.3 ± 2.0 mL in postmenopausal women. The volume of total peritoneal fluid was less than 10 mL in all but one man, who had 10.3 mL of peritoneal fluid accumulation. Peritoneal fluid accumulation was located below the level of the S3 vertebra in all subjects.
Conclusion: A small amount of peritoneal fluid accumulation is occasionally observed in healthy men and postmenopausal women on pelvic MRI. Pelvic peritoneal fluid accumulation of less than 10 mL is not considered to be of clinical significance in men and postmenopausal women.