Open-magnet MR defaecography compared with evacuation proctography in the diagnosis and management of patients with rectal intussusception.

OBJECTIVE: The aim of this study was to determine whether open-magnet magnetic resonance (MR) defaecography could provide more useful clinical information than evacuation proctography (EP) alone in the evaluation of a cohort of patients with full-thickness rectal intussusception and could assist in decisions concerning management.
METHODS: Ten patients (4 male; median age 43, range 30-65) with symptomatic circumferential rectal intussusception diagnosed on EP, underwent open-magnet MR defaecography. Pathologies visible with each technique were recorded and 12 parameters of anorectal configuration and morphology measured and compared.
RESULTS: There was discordance in the diagnosis of rectal intussusception in three cases. In another two patients, MR defaecography demonstrated mucosal descent only. Measurements of anorectal configuration and morphology were similar between techniques; only rectal size and lateral dimensions of the rectocoele were significantly different, being smaller on MR defaecography than EP. Two patients were shown on MR defaecography to have significant bladder descent and two female patients had significant vaginal descent.
CONCLUSION: EP remains the first line investigation for the diagnosis of rectal intussusception, but may not distinguish mucosal from full-thickness descent. MR defaecography further complements EP by giving information on movements of the whole pelvic floor, 30% of the patients studied having associated abnormal anterior and/or middle pelvic organ descent. If surgery is planned for patients with rectal intussusception, MR defaecography provides useful information regarding the presence and degree of anterior pelvic compartment descent that may need to be addressed if a good functional outcome is to be achieved.