Journal of Ultrasound in Medicine, Vol 13, Issue 4 281-284, Copyright © 1994 by American Institute of Ultrasound in Medicine
High-resolution endoluminal sonography of the anal sphincter complex
A. A. Alexander, L. S. Miller, J. B. Liu, R. I. Feld and B. B. Goldberg
Department of Radiology, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania.
The ability of a high-frequency miniature ultrasonographic transducer to
image the anatomy of the anal sphincter complex was investigated in 20
normal subjects. A 9 Fr catheter containing a 12.5 MHz transducer was
inserted into the anal canal. Cross-sectional ultrasonographic images of
the canal were acquired as the catheter was advanced through the canal into
the distal rectum. Three analog images were digitally stored on a computer
system, and measurements of the anal sphincters were made from an eight
octant grid by two independent investigators. In all 20 subjects the
hypoechoic mucosa, hyperechoic submucosa, and hypoechoic internal anal
sphincter (IAS) were identified. The first band of the external anal
sphincter (EAS) was imaged in 12 of 20 subjects. The mean width of the IAS
was 3.5 +/- 0.5 mm (range, 2.6-4.3 mm). The mean width of the first band of
the EAS was 2.3 +/- 0.5 mm (range, 1.6-3.2 mm). High-resolution sonography
of the anal canal allows detailed evaluation of anatomic structures that
cannot be achieved by conventional imaging technology.
