Sonography of Benign Conditions of the Anal Canal: An Update
Francesca Berton1,2,
Giada Gola1,3 and
Stephanie R. Wilson1,4
1 Department of Medical Imaging, Section of Ultrasound, Toronto General
Hospital, University of Toronto, Toronto, ON M5G 2N2, Canada.
2 Present address: Institute of Radiology, IRCCS S. Matteo Hospital, University
of Pavia, Pavia, Italy.
3 Present address: Serves di Radiologia, Ospedale Civile di Voghera, Voghera,
Pavia, Italy.
4 Present address: Department of Diagnostic Imaging, Foothills Medical Centre,
1403 29 St. NW, Calgary, AB T2N 2N9, Canada.
View larger version (34K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1 —Diagram of transvaginal sonography of anal canal performed
with biplane transducer with curved and linear array on transducer side. This
technique requires no angulation or elevation of examining hand for study of
anal canal and shows easily cross-sectional and long-axis views. Regardless of
transducer selection, crystal array must be directed at anal canal. (Courtesy
of Popovic G, Toronto, ON, Canada)
|
|
View larger version (16K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2A —Schematics of transperineal sonography. Long-axis (A)
and cross-sectional (B) views. Transducer is placed on perineum between
introitus and anal canal in women and between scrotum and anal canal in men.
(Courtesy of Popovic G, Toronto, ON, Canada)
|
|
View larger version (16K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2B —Schematics of transperineal sonography. Long-axis (A)
and cross-sectional (B) views. Transducer is placed on perineum between
introitus and anal canal in women and between scrotum and anal canal in men.
(Courtesy of Popovic G, Toronto, ON, Canada)
|
|
View larger version (133K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3A —Sonography of normal anal canal in three patients. A
and B are transanal scans obtained with biplane 9-MHz transducer,
C and D were obtained on curved transducer, and E and
F were obtained at anorectal junction with traditional end-fired
transvaginal probe. Axial image of healthy 20-year-old woman shows anterior
portion of anal canal. Internal anal sphincter (IS) is prominent hypoechoic
layer.
|
|
View larger version (109K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3B —Sonography of normal anal canal in three patients. A
and B are transanal scans obtained with biplane 9-MHz transducer,
C and D were obtained on curved transducer, and E and
F were obtained at anorectal junction with traditional end-fired
transvaginal probe. Long-axis view corresponding to A shows internal
sphincter (IS) in its entirety. Arrow marks anorectal junction, where thin
muscularis propria thickens and becomes more round-appearing internal anal
sphincter. There is no sphincter defect. Magnification on two crystal arrays
is never exactly same.
|
|
View larger version (165K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3C —Sonography of normal anal canal in three patients. A
and B are transanal scans obtained with biplane 9-MHz transducer,
C and D were obtained on curved transducer, and E and
F were obtained at anorectal junction with traditional end-fired
transvaginal probe. Axial image of healthy 40-year-old woman shows prominent
hypoechoic ring of internal anal sphincter (IS).
|
|
View larger version (140K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3D —Sonography of normal anal canal in three patients. A
and B are transanal scans obtained with biplane 9-MHz transducer,
C and D were obtained on curved transducer, and E and
F were obtained at anorectal junction with traditional end-fired
transvaginal probe. Rotating transducer by 90° from position in C
shows anal sphincter in longitudinal view. Anal verge is on right and
anorectal junction (arrow) on left of image. Internal anal sphincter
(IS) appears as two longitudinal substantial hypoechoic bands.
|
|
View larger version (138K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3E —Sonography of normal anal canal in three patients. A
and B are transanal scans obtained with biplane 9-MHz transducer,
C and D were obtained on curved transducer, and E and
F were obtained at anorectal junction with traditional end-fired
transvaginal probe. Axial image of lower rectum of healthy 56-year-old woman
shows prominence of submucosa as broad echogenic layer. Muscularis propria
(arrows) surrounds gut and is thin and hypoechoic.
|
|
View larger version (144K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3F —Sonography of normal anal canal in three patients. A
and B are transanal scans obtained with biplane 9-MHz transducer,
C and D were obtained on curved transducer, and E and
F were obtained at anorectal junction with traditional end-fired
transvaginal probe. At anorectal junction of same patient as in E, thin
muscularis propria thickens and becomes more roundappearing internal anal
sphincter (IS). External anal sphincter (arrowheads) appears at this
level as echogenic, rather poorly marginated sling-like structure around
posterior aspect of anal canal. There is no sphincter defect.
|
|
View larger version (138K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4B —Classic sphincter defect from obstetric trauma in 28-year-old
woman. Sagittal transperineal image shows that defect is full-length given
that no internal anal sphincter can be seen anteriorly. Residual internal anal
sphincter (IS) is normal posteriorly and appears as dominant linear hypoechoic
band.
|
|
View larger version (154K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 5A —Anal sphincter defects shown in four patients. Axial
transperineal image in 27-year-old woman with prior obstetric trauma shows
defect in hypoechoic ring of internal anal sphincter from 10- to 1-o'clock
positions. Smaller hypoechoic defect is seen in echogenic tissue of external
anal sphincter from 11- to 12-o'clock positions. This very clear defect in
both sphincters suggests that surgical repair would be potentially
possible.
|
|
View larger version (147K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 5B —Anal sphincter defects shown in four patients. Axial
transvaginal image obtained with probe in 22-year-old woman with fecal
incontinence after severe previous injury from boat propeller shows unusual
disruption of anal sphincters. There are two defects: one anteriorly in
external anal sphincter, showing hypoechoic defect from 12- to 2-o'clock
positions, and second full-thickness defect of internal anal sphincter and
external anal sphincter from about 6- to 9-o'clock positions. These multifocal
defects suggest difficulty for surgical repair.
|
|
View larger version (159K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 5C —Anal sphincter defects shown in four patients. Axial
transperineal image in 30-year-old woman with previous obstetric trauma and
large episiotomy shows extensive anterior disruption with full-thickness
sphincter disruption from 8- to 4-o'clock positions. Multiple echogenic
bubbles of air are noted in secondary anovaginal fistula.
|
|
View larger version (168K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 5D —Anal sphincter defects shown in four patients. Axial linear
transperineal image obtained in 34-year-old woman with first-degree tear after
obstetric delivery shows anovaginal air-containing fistula as echogenic
air-containing tract running directly anterior from anal canal to vagina.
There is large anterior full-thickness defect in anal sphincter from 10- to
2-o'clock positions.
|
|
View larger version (63K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 6 —Diagram shows different types of fistulous tracts as
classified according to Parks et al.
[23]: On left of image,
cephalad line represents extrasphincteric tract running in suprasphincteric
plane before descending to perineum. Middle line shows transsphincteric tract,
and caudal line shows short extrasphincteric tract running directly from anal
canal to external opening on perianal skin. On right of image are two
intersphincteric tracts: Cephalad tract ascends in intersphincteric plane
before running suprasphincteric to descend in extrasphincteric plane. More
caudal tract on right descends in intersphincteric plane to skin. (Adapted
with permission from Parks AG, Gordon PH, Hardcastle JD. A classification of
fistula-in-ano. Br J Surg 1976; 63:1–12
[23]. Permission granted by
John Wiley & Sons Ltd. on behalf of BJSS Ltd.)
|
|
View larger version (163K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 7A —Spontaneous perianal inflammatory disease in two patients.
Axial transperineal image in 32-year-old man shows internal opening at
6-o'clock position posteriorly (arrowhead). Transsphincteric
hypoechoic tract runs through sphincter and then shows extension to both right
and left (arrows). Tract could be followed to external opening on
right buttock (not shown).
|
|
View larger version (151K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 7B —Spontaneous perianal inflammatory disease in two patients.
Transperineal sagittal image obtained with linear probe placed on skin
immediately lateral to anal canal in 50-year-old man who presented with
perianal pain and no external opening shows anal canal (AC) in median view as
hypoechoic band. Air-containing abscess (A) communicates with anal canal at
its mid point posteriorly. There was no tract to skin.
|
|
View larger version (129K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 8 —Sonogram shows contribution of 3D volume acquisition to
assessment of transsphincteric fistula in 44-year-old woman with no history of
inflammatory bowel disease. Three-dimensional volume was achieved in
transverse plane (not shown). Coronal reconstruction image shows entire course
of fistulous tract (arrows), which ascends inside of sphincter before
crossing through sphincter to descend outside of sphincter to perineum.
|
|
View larger version (156K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 9 —Thickening of rectal wall shown in 29-year-old woman with
symptomatic Crohn's disease. Axial transvaginal image shows thick rectal wall
in cross section. Outer mixed echogenic layer of soft tissue surrounds entire
rectum.
|
|
View larger version (172K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 10A —Complex and extensive perianal abscesses in 35-year-old woman
with known Crohn's disease. Transvaginal axial image of anal canal shows large
internal opening (arrow) at 6-o'clock position posteriorly.
Transsphincteric tract runs to bilobed horseshoe abscess with components to
right and left of anal canal.
|
|
View larger version (159K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 10B —Complex and extensive perianal abscesses in 35-year-old woman
with known Crohn's disease. Obtained at slightly different location, image
shows additional deep, lobulated fluid-containing abscess on left side.
|
|
View larger version (149K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 11A —Adenocarcinoma complicating chronic fistula in 61-year-old
man with Crohn's disease. Transperineal low axial image shows anal canal in
cross section. Posterior to canal, well-defined and solidappearing mass
(arrows) is seen.
|
|
View larger version (109K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 11B —Adenocarcinoma complicating chronic fistula in 61-year-old
man with Crohn's disease. Transanal transverse color Doppler sonogram confirms
solid and vascular mass totally engulfs the seton, which shows here as
echogenic focus with shadowing (arrow). Tumor arises from mucosa, and
complete destruction of wall layers is shown.
|
|
View larger version (150K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 12A —Biopsy-proven chronic inflammatory mass in symptomatic
47-year-old man with rectal pain, unchanged over 3-year interval. No evidence
of cancer or Crohn's disease was seen either clinically or on biopsy.
Endorectal axial sonogram shows heterogeneous hypoechoic mass mimicking rectal
cancer. Wall layers are destroyed.
|
|
View larger version (109K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 12B —Biopsy-proven chronic inflammatory mass in symptomatic
47-year-old man with rectal pain, unchanged over 3-year interval. No evidence
of cancer or Crohn's disease was seen either clinically or on biopsy. Addition
of color Doppler sonogram shows mild hypervascularity of mass.
|
|
View larger version (137K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 13A —Pouchitis and anastomotic inflammatory mass in 48-year-old
woman with total colectomy for ulcerative colitis and ileoanal anastomosis.
Transvaginal image of pouch (P) shows that it is thick walled, distended with
liquid stool, and surrounded by excessive echogenic inflammatory fat (F).
|
|
View larger version (155K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 13B —Pouchitis and anastomotic inflammatory mass in 48-year-old
woman with total colectomy for ulcerative colitis and ileoanal anastomosis.
Axial image taken with transvaginal probe shows region of ileoanal
anastomosis. There is hypoechoic masslike area within thickened anterior
wall.
|
|
View larger version (110K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 13C —Pouchitis and anastomotic inflammatory mass in 48-year-old
woman with total colectomy for ulcerative colitis and ileoanal anastomosis.
Addition of color Doppler sonogram shows profuse hypervascularity in this
inflammatory mass. This patient responded to conservative management.
Pouchogram (not shown) obtained 1 month later did not show leak and follow-up
sonogram (not shown) showed normal appearance.
|
|
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
Copyright © 2007 by the American Roentgen Ray Society.
