PURPOSE: To demonstrate the normal involution process of the post-partum pelvis with serial magnetic resonance (MR) imaging. MATERIALS AND METHODS: MR imaging was performed in 14 women after uncomplicated vaginal delivery. Six women underwent serial MR examinations at less than 30 hours and at 1 week, 2 weeks, 6 weeks, and 6 months after delivery; eight women were examined only within 30 hours of delivery. The dimensions and signal intensity of the uterus and cervix and the appearance of other pelvic structures were evaluated. RESULTS: The mean length of the uterine corpus was 13.8 cm within 30 hours of delivery and 5.0 cm at 6 months. The mean length of the cervix was 5.6 cm within 30 hours of delivery and 2.9 cm at 6 months. The junctional zone was not visible before 2 weeks; however, it was visible in all cases at 6 months. The outer cervical stroma had high signal intensity less than 30 hours after delivery and intermediate signal intensity thereafter. The inner cervical stroma was visible as a low-signal-intensity stripe on all images. CONCLUSION: Knowledge of the normal MR appearance of the involuting postpartum pelvis provides a baseline for interpretation of MR images obtained during this period.
PURPOSE: To demonstrate the normal involution process of the post-partum pelvis with serial magnetic resonance (MR) imaging. MATERIALS AND METHODS: MR imaging was performed in 14 women after uncomplicated vaginal delivery. Six women underwent serial MR examinations at less than 30 hours and at 1 week, 2 weeks, 6 weeks, and 6 months after delivery; eight women were examined only within 30 hours of delivery. The dimensions and signal intensity of the uterus and cervix and the appearance of other pelvic structures were evaluated. RESULTS: The mean length of the uterine corpus was 13.8 cm within 30 hours of delivery and 5.0 cm at 6 months. The mean length of the cervix was 5.6 cm within 30 hours of delivery and 2.9 cm at 6 months. The junctional zone was not visible before 2 weeks; however, it was visible in all cases at 6 months. The outer cervical stroma had high signal intensity less than 30 hours after delivery and intermediate signal intensity thereafter. The inner cervical stroma was visible as a low-signal-intensity stripe on all images. CONCLUSION: Knowledge of the normal MR appearance of the involuting postpartum pelvis provides a baseline for interpretation of MR images obtained during this period.