Triphasic MRI of pelvic organ descent: sources of measurement error.

PURPOSE: To identify sources of error when measuring pelvic organ displacement during straining using triphasic dynamic magnetic resonance imaging (MRI). MATERIALS AND METHODS: Ten healthy nulliparous woman underwent triphasic dynamic 1.5 T pelvic MRI twice with 1 week between studies. The bladder was filled with 200 ml of a saline solution, the vagina and rectum were opacified with ultrasound gel. T2 weighted images in the sagittal plane were analysed twice by each of the two observers in a blinded fashion. Horizontal and vertical displacement of the bladder neck, bladder base, introitus vaginae, posterior fornix, cul-de sac, pouch of Douglas, anterior rectal wall, anorectal junction and change of the vaginal axis were measured eight times in each volunteer (two images, each read twice by two observers). Variance components were calculated for subject, observer, week, interactions of these three factors, and pure error. An overall standard error of measurement was calculated for a single observation by one observer on a film from one woman at one visit. RESULTS: For the majority of anatomical reference points, the range of displacements measured was wide and the overall measurement error was large. Intra-observer error and week-to-week variation within a subject were important sources of measurement error. CONCLUSION: Important sources of measurement error when using triphasic dynamic MRI to measure pelvic organ displacement during straining were identified. Recommendations to minimize those errors are made.

Rectal pressure response to a meal in patients with high spinal cord injury.

OBJECTIVES: To determine whether there is a postprandial increase of rectal pressure in patients with spinal cord injury (SCI) and to compare their rectal pressures with those of healthy volunteers. DESIGN: A before-after trial comparing SCI and control subjects. SETTING: Patients were recruited from the register of an SCI unit at a rehabilitation medicine department, and the study took place at the university hospital laboratory in Sweden. PARTICIPANTS: Ten patients with high traumatic SCI and 9 healthy volunteers. Eight patients had a lesion above level T5. INTERVENTION: Continuous anorectal manometry was performed. Rectal activity was calculated before and at regular time intervals after a 1000-cal test meal. MAIN OUTCOME MEASURE: Rectal activity measured as area under the pressure curve. RESULTS: There was a significant increase in rectal activity of 46% after 10 minutes in the patients but of 72% after 5 minutes in the volunteers. There was no difference in fasting rectal activity, but patients had a stronger mean rectal postprandial response during 60 minutes compared with volunteers. CONCLUSIONS: These results support the theory that the colonic response to food is preserved in patients with high SCI.