Evaluation of incidental pelvic fluid in relation to physiological changes in healthy pubescent children using pelvic magnetic resonance imaging

Abstract

Background: Peritoneal free fluid (PFF) can indicate an underlying disease process; however, detection of minimal PFF in healthy children is not uncommon. Objective: To assess the significance of incidental PFF within healthy children by MRI and its relation to physiological changes during puberty. Methods: This prospective study was performed on 32 healthy volunteers (20 males) between the ages of 8 to 13 years, with consecutive follow-ups every 8–10 months for an average of 3 years. BMIz score, pubertal status, C-reactive protein and sex hormone concentrations assessed prior to MRI studies. A total of 120 pelvic MRI studies (61 males) were reviewed, and the quantity of PFF was measured. Linear mixed model accounting for within-patient correlations was used for statistical analysis. Results: The mean ± standard deviation volume of PFF was 4.7 ± 5.65 mL in females and 1.9 ± 3.11 mL in males with a maximum volume of 25 mL and 17 mL, respectively. The prevalence of PFF was significantly higher in females (91%) compared to males (67%) (P = 0.0035). In 15% of the females and 3% of the males the fluid was greater than 10 mL. The mean volume of PFF in 4th stage was higher and significantly different with the first stage of puberty (P = 0.01). Conclusion: Among healthy pubescent children, the prevalence of PFF is significantly higher in females. The volume of PFF may reach volumes greater than 10 mL during normal puberty, especially in 4th stage, and can be assumed normal in the absence of active disease.