Anal perianal imaging part 1 ct mri anatomy dr ahmed esawy ANAL ,PERIANAL IMAGING (endovaginal ultrasound endoanal ultrasound perineal ultrasound MRI) FOR ANAL ,PERIANAL DISEASE3/ Image reconstruction and processing artifacts • ANAL ANATOMY • ANAL PERIANAL FISTULA • ANAL TEARS (OBSTETRIC) • FAECAL INCONTINENCE • OTHER DISEASES • NATOMY ANORECTAL ANATOMY : • Anal Sphincter: • internal sphincter • external sphincter • Puborectalis muscle and levator ani • Sub cutaneous perianal fistula • Sub mucous perianal fistula • Low anal perianal fistula • High anal perianal fistula • Pelvi rectal perianal fistula • Simple fistulography • Perianal fistulography • Endosonography Perianal fistula • A. A superficial fistula. • B. An intersphincteric fistula. • C. A transsphincteric fistula. • D. A suprasphincteric fistula. • E. An extrasphincteric fistula. •

1. Dr Ahmed Esawy

2. Dr Ahmed Esawy
ANAL PERIANAL IMAGING
Dr. Ahmed Esawy
MBBS M.Sc MD

3. Dr Ahmed Esawy
ANAL ,PERIANAL IMAGING
(endovaginal ultrasound
endoanal ultrasound
perineal ultrasound
MRI)
FOR ANAL ,PERIANAL
DISEASE

4. Dr Ahmed Esawy
HOME MASSEGE
• ANAL ANATOMY
• ANAL PERIANAL FISTULA
• ANAL TEARS (OBSTETRIC)
• FAECAL INCONTINENCE
• OTHER DISEASES

5. Dr Ahmed Esawy
NATOMY ANORECTAL ANATOMY :
Anal Sphincter:
internal sphincter
external sphincter
Puborectalis muscle and levator ani

6. Dr Ahmed Esawy
Anatomical canal :
- extends from perineal skin to dentate line
Surgical canal :
- extends from perineal skin to anorectal ring ( 1-1.5cm abov e dentate line )
- total length 4-5 cm

7. Dr Ahmed Esawy
ANATOMY OF THE ANAL CANAL
• The surgical anal canal extends from the anal verge distally to the anorectal
ring proximally.
• The anatomical anal canal extends from the anal verge distally to the dentate
line proximally.
• The dentate line is the junction of the ectoderm and endoderm in the anal
canal.
• The muscles of the anal canal can be regarded as forming a tube within a
funnel :
-The sides of the funnel are the levator ani muscles.
- The stem of the funnel is the external anal sphincter.
- The tube inside the stem of the funnel is the internal sphincter.

8. Dr Ahmed Esawy
The total length of the surgical anal canal is about 4-5 cm.
The anal sphincter is comprised of three layers:
1-Internal sphincter: continuance of the circular smooth muscle
of the rectum, involuntary and contracted during rest, relaxes at
defecation.
2-Intersphincteric space.
3-External sphincter: voluntary striated muscle, divided in three
layers that function as one unit.
These three layers are continuous cranially with the puborectal
muscle and levator ani

9. Dr Ahmed Esawy
Schematic representation of the anal canal with the probe in situ.
Level 1, puborectalis.
Level 2,deep (proximal) external anal sphincter (EAS).
Level 3, superficial (mid) EAS.
Level 4, subcutaneous (distal) EAS.

10. Dr Ahmed Esawy

11. Dr Ahmed Esawy

12. Dr Ahmed Esawy
THE INTERNAL ANAL SPHINCTER
• Is a thickened continuation of the circular muscle coat of the rectum.
• The internal anal sphincter is 2.5 cm long and 2.5 mm thick.

13. Dr Ahmed Esawy
THE EXTERNAL ANAL SPHINCTER
• It was Formerly subdivided into a deep, superficial and
subcutaneous portions but now is considered to be one
muscle.
• The external sphincter muscle is composed of voluntary
muscles.

14. Dr Ahmed Esawy
THE LEVATOR ANI MUSCLE
• The anatomy of the levator ani muscle is important as it
constitutes part of the sphincter mechanism of the anal canal.
• The levator ani is a broad, thin muscle, attached to the side of
the pelvis and united medially with its fellow to form the
greater part of the floor of the pelvic cavity.
• It consists of the following parts:
The Ilio coccygeus.
The pubococcygeus.
The puborectalis.

15. Dr Ahmed Esawy

16. Dr Ahmed Esawy
SURGICAL ANATOMY
Line diagram shows coronal-view of the anal canal
and perianal region.

17. Dr Ahmed Esawy
Diagrams of anal sphincters. Coronal (A) and axial (B) views show the IAS and
EAS and the other anal canal anatomic structures.
A indicates anal canal; and R, rectum.

18. Dr Ahmed Esawy
• Diagram shows the normal anatomy of the Anorecal region
in the coronal plane a = anal canal, IRF = ischiorectal
fossa, R = rectum (Quoted from John et al., 1999).

19. Dr Ahmed Esawy
The total length of the surgical anal canal is about 4-5 cm.
The anal sphincter is comprised of three layers:
1-Internal sphincter: continuance of the circular smooth muscle of the rectum,
involuntary and contracted during rest, relaxes at defecation.
2-Intersphincteric space.
3-External sphincter: voluntary striated muscle, divided in three layers that function as
one unit.
These three layers are continuous cranially with the puborectal muscle and levator ani

20. Dr Ahmed Esawy
The puborectal muscle is contracted at rest and accounts for the 80? angulation of
the anorectal junction. It relaxes during defecation.

21. Dr Ahmed Esawy
ENDOANAL ULTRASOUND (EUS)
• It is a simple technique that analyzes anatomy in real time.
• Peroxide-enhanced EUS was found to be a useful technique
for detection of the presence, number, types and internal
course of perianal fistulas.

22. Dr Ahmed Esawy
ANATOMY AT US
Four anatomical layers could be demonstrated on EUS:
• The Plastic Cone: produces an inner, well defined ring of high
reflectivity.
• The Submucosa : is moderately reflective.
• The Internal sphincter: a well-defined, circular, hypoechoic band.
• The External sphincter: seen as a circular ring with low or
intermediate echogenicity.
• The Intersphincteric space: round hyperechoic ring between the
hypoechoic internal & external sphincter.

23. Dr Ahmed Esawy
• The Puborectalis muscle is identified as a hypoechoic U-
shaped band at the level of the anorectal flexure.
• The appearance of the anal canal at ultrasound is dependent on
the height of the axial level being imaged.
• The lower end of the canal is identified by the loss of the
circumferential hypoechoic ring of the internal sphincter.
• The upper end of the canal is identified by the hypoechoic
horseshoe sling of the levator ani muscle posteriorly.

24. Dr Ahmed Esawy
The normal 2-D anal sphincter complex

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• At the anal verge, the internal anal sphincter is typically
seen as an incomplete ring (arrows) that partially
encircles the canal.

26. Dr Ahmed Esawy
• The internal sphincter is seen as a continuous
hypoechoic ring (large arrows) that surrounds the
submucosal space (small arrows).

27. Dr Ahmed Esawy
• At the cranial end, the external sphincter muscle
becomes hypoechoic (arrow) and gives rise to the
levator ani sling above this level (arrows ).

28. Dr Ahmed Esawy
Normal appearance of the anal canal at US. Axial images of the anal canal show the normal anatomy from
the most caudal aspect of the anal verge (a) extending up to the level of the levator ani muscle (d). (a) At
the anal verge, the internal anal sphincter is typically seen as an incomplete ring (arrows) that partially
encircles the canal.

29. Dr Ahmed Esawy
Once the transducer is in the anal canal, the internal sphincter is seen as a continuous
hypoechoic ring (large arrows) that surrounds the submucosal space (small arrows). The
external anal sphincter appears as a less well-defined hyperechoic band immediately
outside the internal sphincter .

30. Dr Ahmed Esawy
At the cranial end of the anal canal, the external sphincter muscle becomes more
hypoechoic (arrow in c).

31. Dr Ahmed Esawy
The echogenicity of the internal anal sphincter increases
with age, with the replacement of smooth muscle by the
connective tissues. (Nielsen et al., 2001).
The thickness of the internal anal sphincter is measured
at the 3 O‟clock or 9 O‟clock position where the muscle
is symmetrical. The muscle thickness is age dependant,
increasing in thickness whilst become less distinct with
age. (Rottenberg & Williams, 2003 ).
In the adult; The measured thicknesses of the Internal
anal sphincter range from (0.5–3.7 mm), while for
External anal sphincter range from ( 5.8–9.8 mm).These
measurement is less in neonate: the internal anal
sphincter range from (0.8-1.9 mm), while external anal
sphincter range from (1.2-2.3 mm). ( Nielsen et al.,
2001).

32. Dr Ahmed Esawy
Transverse endoanal US image shows (a) normal sphincter complex. ES =
external sphincter, IS = internal sphincter

33. Dr Ahmed Esawy
Transverse endorectal US image shows M: mucosa SM: sub mucosa MP:
muscularis propria SS: sub serosa

34. Dr Ahmed Esawy
Transverse endoanal US scan of the anal sphincter complex shows the internal
sphincter muscle as a homogeneous hypoechoic circular band (curved arrows). 2-4 mm
The external sphincter (straight arrows) is shown with mixed echogenicity. Note that the
borders of the external sphincter are more difficult to define at endoanal US.
Between the internal and external sphincters, the intersphincteric space (arrowheads) is
depicted as a hyperechoic band. Within this band, the hypoechoic longitudinal muscle
can be identified

35. Dr Ahmed Esawy
Normal endoanal sonographic appearances of
anal sphincters at 3 different levels. A, Upper
anal canal level, identified by the horseshoe
sling of the puborectalis muscle posteriorly
(arrows) and loss of the EAS in the midline
anteriorly. The IAS is also shown by arrowheads.
B, Middle canal level, identified by the
completion of the EAS ring anteriorly (black
arrows) and maximum IAS thickness (white
arrows). C, Lower canal level, defined as that
immediately caudal to the termination of the IAS
and comprising the subcutaneous the EAS
(arrows). The anococcygeal ligament is also
shown posteriorly (arrowheads).
C

36. Dr Ahmed Esawy
Normal appearance of the anal canal at US: Axial images of the anal canal show the
normal anatomy of anal canal from the most caudal aspect of the anal verge at (a)
extending up to the level of the levator ani muscle at (d): (a) At the anal verge, the
internal anal sphincter is typically seen as an incomplete ring (arrows) that partially
encircles the canal. (b) Once the transducer is in the anal canal, the internal sphincter is
seen as a continuous hypoechoic ring (large arrows) that surrounds the submucosal
space (small arrows). The external anal sphincter appears as a less well-defined
hyperechoic band immediately outside the internal sphincter

37. Dr Ahmed Esawy
(c, d) At the cranial end of the anal canal, the external sphincter muscle
becomes more hypoechoic (arrow in c) and gives rise to the levator ani sling
above this level (arrows in d)

38. Dr Ahmed Esawy
Sphincter Muscle Thickness Measured at Endoanal Sonography, Endoanal MRI,
and Phased Array MRI

39. Dr Ahmed Esawy
Endovaginal sonography performed at the level of the bladder neck: the
intramural portion of the urethra (yellow arrow), the anal canal (red arrow) and the
pubovisceral muscle (short black arrow) are depicted.

40. Dr Ahmed Esawy
transanal scans obtained with biplane 9-MHz transducer
A, Axial image of healthy 20-year-old woman shows anterior portion of anal canal.
Internal anal sphincter (IS) is prominent hypoechoic layer. B, 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.

41. Dr Ahmed Esawy
curved transducer
A, Axial image of healthy 40-year-old woman shows prominent hypoechoic ring
of internal anal sphincter (IS). B, Rotating transducer by 90° from position in A
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.

42. Dr Ahmed Esawy
anorectal junction with traditional end-fired transvaginal probe
A, 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. B, At anorectal junction of same patient as in A, 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.

43. Dr Ahmed Esawy

44. Dr Ahmed Esawy
FUNCTION OF ANAL SPHINCTER AND
PUBORECTALIS
• Puborectalis: control continence over
solid stool
• Internal sphincter: control of liquid
faeces
• External sphincter provide internal
sphincter in times of sudden need, such
as raised intra abdominal presures
• Anal cushion : the amount of blood
flowing through its arteriovenous
channels provide control over flatus

45. Dr Ahmed Esawy
(a) Endoanal scan demonstrating the „„U‟‟-shaped puborectalis muscle, which
attaches to the pubic rami anteriorly. (b) Endoanal scan demonstrating the internal
anal sphincter (white arrow) and the external anal sphincter (black arrow). (c)
Three dimensional endoanal ultrasound demonstrating the circumference/width as
well as length of the anal sphincter defect.

46. Dr Ahmed Esawy
Endoanal ultrasound of middle anal canal
demonstrating IAS ,EAS in healthy
asymptomatic female

47. Dr Ahmed Esawy

48. Dr Ahmed Esawy

49. Dr Ahmed Esawy
Normal perianal anatomy of 47-year-old
female volunteer imaged with CT
CT (A-C) of inner internal sphincter (+),
outer external sphincter (white dovetail
arrows), levator ani muscle (B, thick
arrows), and fat-containing ischioanal
fossa (*).

50. Dr Ahmed Esawy
Normal perianal anatomy of 45-year-old male
volunteer imaged with CT anal sphincter complex
is seen as two concentric rings. Inner internal
sphincter (+), outer external sphincter (white or
black dovetail arrows), levator ani muscle (thick
arrows), fat containing ischioanal fossa (*).

51. Dr Ahmed Esawy
MRI ANAL & PERIANAL REGION

52. Dr Ahmed Esawy
Line diagram shows the normal
anatomy of the perianal region in the
axial plane
The puborectal muscle has
its origin on both sides of the
pubic symphysis, forming a
'sling' around the
anorectum.

53. Dr Ahmed Esawy
• On axial and coronal MR
images , the different
layers of anal sphincter
and the surrounding
structures can be
displayed perfectly

54. Dr Ahmed Esawy
Drawing illustrates the anal clock, which is the surgeon's view of the perianal region when the patient is
in the lithotomy position. The anterior perineum (p) is at the 12 o'clock position, and the natal cleft (n) is at
the 6 o'clock position; 3 o'clock refers to the left lateral aspect, and 9 o'clock, the right lateral aspect of the
anal canal. This schema exactly corresponds to the orientation of axial MR images of the perianal region.

55. Dr Ahmed Esawy
Normal perianal anatomy. axialT1-weighted (a)
and coronalT2-weighted (b) MR images show the normal
anatomy of the perianal region. a = anal canal, es =
external sphincter, iaf = ischioanal fossa, irf = ischiorectal
fossa, R = rectum, straight arrow in a = the levator plate.

56. Dr Ahmed Esawy
AxialCoronal

57. Dr Ahmed Esawy
Normal perianal anatomy of 47-year-
old female volunteer imaged with MR
imaging.
Anal sphincter complex is seen as two
concentric rings. MR imaging: inner (+)
internal sphincter and outer external
sphincter (white dovetail arrows) appear
relatively hypointense on all T2-weighted
images without fat suppression (A-C).
Levator ani muscle (B, thick arrows)
forms superior boundary of fat-
containing ischioanal fossa (*) on either
side of anal canal.

58. Dr Ahmed Esawy
Normal perianal anatomy of 45-year-old
male volunteer imaged with MR
imaging.
MR imaging (T2-weighted without fat
suppression images; A-C)
anal sphincter complex is seen as two
concentric rings. Inner internal sphincter
(+), outer external sphincter (white or black
dovetail arrows), levator ani muscle (thick
arrows), fat containing ischioanal fossa (*).

59. Dr Ahmed Esawy
Transperineal
Ultrasound

60. Dr Ahmed Esawy
The female pelvic floor from below.

61. Dr Ahmed Esawy
2D Transperineal
Functional Imaging
• Enterocele, Rectocele,
Cystocele,Mesh, Slings.
The patient position and the probe position
during transperineal scanning

62. Dr Ahmed Esawy
Describes the sample steps for performing transperineal 2D imaging using any
abdominal probe
transperineal imaging
Identify the suitable transducer
Identify the probe orientation
Press the button on the side of the probe to activate the probe
Set the depth at 6.7 cm
Set the resolution at 1/32 Hz
Place the transducer on the perineal area and obtain sagittal view of the bladder,
vagina, and the rectum (including the midsagittal view of pubic symphysis)
Adjust the gain
Ask the subject to cough or bear down to visualize the movement of anterior,
apical, and posterior compartments
Ask the subject to “squeeze vaginal muscles or perform Kegels” to visualize the
movement of the levator plate
Transperineal US

63. Dr Ahmed Esawy
This view demonstrates Incorrect positioning as the starting 2D field of view should
include pubic symphysis anteriorly and the anorectal angle posteriorly. The field of view
as demonstrated does not contain the pubic symphysis, and as such the distance from
the edge of the pubic symphysis to the edge of the levator plate that creates the
anorectal angle cannot be obtained. Depending on the patient‟s body habitus and pelvic
floor laxity, the field of view may need to be made larger

64. Dr Ahmed Esawy
This view demonstrates CORRECT positioning as the starting 2D field of view
includes the pubic symphysis (S) anteriorly and the levator plate (LP) posteriorly.
Also noted are the bladder (B), uterus (U), vagina (V), and anorectum (R)
2D Transperineal

65. Dr Ahmed Esawy
Perineal ultrasound
Axial images of the levator hiatus at rest (a), during contraction (b) and during
valsalva
manoeuvre (c). A) anal opening; U) urethra; V) vagina

66. Dr Ahmed Esawy
The appearance of the puborectalis muscle in a rendered volume in the axial
plane, using translabial 3D ultrasound with speckle reduction imaging.
The two arrows indicate the gap between urethra and puborectalis insertion
that can conveniently be palpated to determine muscle integrity

67. Dr Ahmed Esawy
(a) Transperineal scan demonstrating the puborectalis muscle. (b) Transperineal
scan demonstrating the internal anal sphincter (white arrow) and the external anal
sphincter (black arrow). Note that the external anal sphincter is circumferential at a
more distal level to the puborectalis.

68. Dr Ahmed Esawy
Transperineal US show intact EAS ,IAS,
with muscular atrophy in 75 y old female with
fecal incontinence

69. Dr Ahmed Esawy
Transperineal US demonstrating
anal fistula

70. Dr Ahmed Esawy

71. Dr Ahmed Esawy
2D/3D Endovaginal

72. Dr Ahmed Esawy
The view of the left side of the anterior compartment:
( a ) histologic section, ( b ) drawing of the anterior
compartment structures, and ( c ) the left sagittal view
of the 3D EVUS cube with the structures marked.
BL bladder,
CU compressor urethra,
LCM longitudinal and circular layer,
P pubic bone, PCF pubocervical fascia,
SUG striated urogenital sphincter, TP trigonal plate,
TR trigonal ring, U urethra, UT uterus, V vagina,
VT vesical trigone
2D/3D Endovaginal
Anterior
Compartment Imaging

73. Dr Ahmed Esawy
The view of the left side of the posterior
compartment: ( a ) histologic section, ( b )
drawing of the posterior compartment structures,
and ( c ) the left sagittal
view of the 3D EVUS volume with the structures
marked. EAS - m external anal sphincter main
section,EAS - n external anal sphincter notch,
EAS - sq external
anal sphincter subcutaneous section, IAS
internal anal sphincter, IAS - L internal anal
sphincter length, IAS – T internal anal sphincter
thickness, R rectum, RS rectovaginal
septum, STP superfi cial transverse perinei, V
vagina.
2D/3D Endovaginal
posterior
Compartment Imaging

74. Dr Ahmed Esawy
view of the perineal area upon anal entry.
The external anal sphincter (EAS), internal anal sphincter (IAS), probe in the
anorectum (T), anal mucosa (AM),rectovaginal fascia (RVF), vaginal epithelium
(VE),urethra (U), and the vagina are marked (V)

75. Dr Ahmed Esawy
2D vaginal ultrasound visualising the anal mucosa, IAS (IS), EAS and the
ano-rectal junction. The vaginal transducer is placed in the posterior
vaginal fourchette.
A coronal section from the mid canal level (left) and a sagittal section
(right) where also rectum (R) visualise

76. Dr Ahmed Esawy
3D vaginal ultrasound acquisitions seen in a transverse section (right) and in a
sagittal section (left). VT: vaginal transducer. TPS: transversus perinei superficialis.
CTP: centrum tendineum perinei. M: Anal mucosa. IAS: internal anal sphincter.
EAS: external anal sphincter. PBR: puborectalis.

77. Dr Ahmed Esawy
(a) Endovaginal scan demonstrating the puborectalis muscle (white arrow). (b)
Endovaginal scan demonstrating the internal anal sphincter (white arrow) and the
external anal sphincter (black arrow).

78. Dr Ahmed Esawy
The perineal body (1) is hypoechogenic.
The perineal membrane (2) is anchored in the
perineal body and stretches towards the central
point (4), and is relatively hypoechogenic.
The hyperechogenic puboperineal muscles (3)
are positioned anterior to the external anal
sphincter (5).
The hypoechogenic central point (4) is located
dorsal to the vaginal introitus, gathering fibers
from the perineal membrane,
the superficial vaginal muscles, Colles‟ fascia and
the external anal sphincter.
Between the external (5) and the internal (7) anal
sphincters is the thin hyperechogenic conjoined
longitudinal muscle (6), which is interrupted by the
perineal body immediately cranial to the external
sphincter.
The rectovaginal septum (8) is seen cranial to the
perineal membrane. Inside the anal canal,
the rectal columns (9) fill the lumen of the anal
canal.
Transvaginal sagittal midline ultrasound image of the anal canal and the perineum
during pregnancy.

79. Dr Ahmed Esawy
Transvaginal sagittal midline ultrasound
image of the perineum, rectovaginal
septum and anal canal immediately after
delivery in a woman with a first-degree
perineal tear with all
perineal structures preserved. Marked
edema is seen in the perineal membrane
(2), rectovaginal septum (8) and perineal
body (1).
The fibers in the external anal sphincter
(5) are intact, but it has a different
appearance from that seen before
delivery.
3,puboperineal muscle;
4, central point;
6, conjoined longitudinal muscle;
7, internal anal sphincter;
9, rectal columns.

80. Dr Ahmed Esawy
Transvaginal semicircular transverse ultrasound image of the perineal body and
anal canal during pregnancy. The perineal membrane (2) and the puboperineal
muscle (3) meet in the midline in the perineal body (1).
5, external anal sphincter;
7, internal anal sphincter

81. Dr Ahmed Esawy
Transvaginal sagittal midline ultrasound image of the anal canal immediately after
delivery in a woman with a fourth-degree perineal tear. All structures in the perineum
including the rectovaginal septum are torn, and are missing from the image. The
following structures can be identified dorsal to the anal canal: external anal sphincter
(5), conjoined longitudinal muscle (6),internal anal sphincter (7) and puborectal
muscle (PR). Anterior to the anal canal, the cranial part of the internal anal sphincter
(7) remains intact.
9, rectal columns.

82. Dr Ahmed Esawy
4D/3D SONOGRAPHIC DESCRIPTION
OF THE SQUEEZE MECHANISM IN THE
ANAL SPHINCTER

83. Dr Ahmed Esawy
The anal squeeze mechanism in the external anal sphincter (EAS) has been
described as two (alternative three) slings with different insertions that when
contracting, pull different segments of the anal canal in anterior or posterior
directions thus closing the anal canal .
The function in the internal anal sphincter (IAS) is to maintain the resting
pressure in the anal canal and to relax, thus enabling rectal sensations and
evacuation.
The third component of the anal sphincter - the conjoined longitudinal muscle
(LM) - has not been discussed in relation to continence.
The aim of the present study was to describe the movements in the anal
sphincter during voluntary squeeze in healthy nulliparous women using a new
ultrasonographic technique.

84. Dr Ahmed Esawy
A ) At rest, the midsagittal external anal sphincter (EAS) (1) almost parallels the
perineum (5). The longitudinal muscle (LM) (2) is hypoechogeneic and the internal
anal sphincter (IAS) (3) is hyperechogeneic on transanal sonography.
B). During a contraction, the EAS (1) is elongated in a cranial direction. The IAS (3)
and the LM (2) are stretched and the walls of the IAS get thinner.

85. Dr Ahmed Esawy
C) At rest in a transverse projection the EAS (1) and the IAS (3) are hyperechogeneic
and the LM is hypoechogeneic.
D). During a squeeze the walls of the IAS (3) are compressed, while the thickness of the
LM (2) increases or remains unchanged. The EAS (1) compress the anal canal.
Vagina (5).

86. Dr Ahmed Esawy
During a squeeze of the anal sphincter complex, the EAS contracts by a
diameter reduction and by an elongation in cranial direction. The LM
moves in cranial direction along the anal canal and the walls of IAS are
compressed. Thus, the present study did not confirm the old sling theory
on anal continence

87. Dr Ahmed Esawy
translabial ultrasound of the anal sphincter using the VCI-static technique in a
patient with a IAS and EAS defect

88. Dr Ahmed Esawy

89. Dr Ahmed Esawy
Anatomic relationships in the perianal region

90. Dr Ahmed Esawy
Parts of levator ani muscles as seen from the pelvic aspect

91. Dr Ahmed Esawy