[Endoanal MR imaging: diagnostic assessment]

Diagnostic precision of endoanal MRI in the detection of anal sphincter pathology: a meta-analysis

OBJECTIVE

This study aims to evaluate the diagnostic precision of endoanal magnetic resonance imaging in identifying anal sphincter injury and/or atrophy when compared with either endoanal ultrasound or surgical diagnosis.

MATERIALS AND METHODS

Quantitative meta-analysis was performed on nine studies, comparing endoanal MRI with endoanal ultrasound or surgical diagnosis in 157 patients. Sensitivity, specificity, and diagnostic odds ratio were calculated for each study. Summary receiver operating characteristic curves (SROC) and subgroup analysis were undertaken.

RESULTS

The overall sensitivity and specificity of endoanal MRI for external sphincter injury was 0.78 (95%CI: 0.66-0.84) and 0.66 (95%CI: 0.51-0.79), respectively. For internal sphincter injury detection, this was 0.63 (95%CI: 0.50-0.74) and 0.71 (95%CI: 0.60-0.81), respectively. For detection of atrophy, this was 0.86 (95%CI: 0.71-0.95) and 0.82 (95%CI: 0.65-0.93), respectively. The area under the SROC curve and diagnostic odds ratio were 0.84 (SE = 0.07) and 6.14 (95%CI: 2.17-17.4) for external sphincter injury, 0.79 (SE = 0.07) and 4.60 (95%CI: 1.75-12.15) for internal sphincter injury, and 0.92 (SE = 0.08) and 21.49 (95%CI: 2.87-160.64) for sphincter atrophy.

CONCLUSION

Endoanal MRI was sensitive and specific for the detection of external sphincter injury and especially sphincter atrophy. It may be useful as an alternative to endoanal ultrasound in patients presenting with fecal incontinence, although further clinical studies are needed to identify its best application in clinical practice.

[Fecal incontinence]

Diagnosis and management of fecal incontinence requires exact understanding of the anatomic and pathophysiologic principles involved and demands a methodical, stepwise approach. Despite the potential appeal of surgical intervention, a considerable number of patients can be helped by comparatively simple, noninvasive measures. Initial treatment should be medical, including biofeedback in combination with a bowel management program. In the presence of a severely denervated pelvic floor, physiotherapeutic techniques rarely give rise to a satisfactory and long-lasting response. Obvious external sphincter defects and patients who failed medical management are treated surgically. Many injuries of the external sphincter can be treated by direct sphincter repair. If patients with intact external sphincters are unresponsive to medical measures, descending perineum and resultant idiopathic fecal incontinence will improve by radio-frequency delivery, sacral nerve stimulation, or postanal plication. Patients with complex neurologic disorders or extensive sphincter defects or who have undergone previous unsuccessful attempts at repair of the puborectalis itself should be considered for dynamic gracilis plastic or an artificial sphincter.