Ah. Sultan et al., ANAL ENDOSONOGRAPHY FOR IDENTIFYING EXTERNAL SPHINCTER DEFECTS CONFIRMED HISTOLOGICALLY, British Journal of Surgery, 81(3), 1994, pp. 463-465
Defects of the external anal sphincter have traditionally been diagnos
ed by palpation, anal manometry and electromyography (EMG), but anal e
ndosonography enables clear imaging of both the internal and external
sphincter muscles. A study was performed to validate the interpretatio
n of ultrasonographic images of external sphincter defects using histo
logy as a 'gold standard'. In addition the accuracy of clinical examin
ation, manometry, EMG mapping and anal endosonography in the diagnosis
of sphincter defects were compared prospectively. Twelve consecutive
patients with faecal incontinence (11 women, one man; mean age 46 (ran
ge 30-64) years) who required sphincter repair underwent clinical asse
ssment, anal manometry, concentric-needle EMG mapping and anal endoson
ography before surgery. The endosonographer was unaware of the history
or results of physiological tests and the surgeon performing the repa
ir was blind to the ultrasonographic findings. At operation most or al
l of the suspected defect was excised and examined histologically. The
pathologist was unaware of the endosonographic or operative findings
at the time of reporting. Combined operative and histological examinat
ion identified an external sphincter defect in nine of the 12 patients
. Anal endosonography correctly identified all nine defects and the th
ree normal sphincters. The accuracy of clinical examination was 50 per
cent and that of both EMG and anal manometry 75 per cent. In addition
, anal endosonography identified a defect of the internal anal sphinct
er in eight patients. External sphincter defects identified by endoson
ography have not been previously verified histologically. Precise sphi
ncter assessment is mandatory for the correct management of faecal inc
ontinence. Anal endosonography is more accurate than clinical and conv
entional physiological methods and also provides information on the in
ternal sphincter.