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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_1056_Библиотеки_им_академика_М_И_Перельмана.pdf
148 R. J. F. Felt-Bersma
Fig. 4 Hydrogen peroxide
) with a flexible cannula
(H
2O2
for introduction of the H
2O2
introduced into the external fistula opening using a flexible cannula (Fig. 4), illuminating the fistula tract. Figures 5, 6, 7, 8, 9, 10, 11, and 12 show different images of
fistulas and abscesses and the effect of adding hydrogen peroxide.
The advent of hydrogen peroxide as a contrast agent has significantl y improved
accuracy of EAUS. First described by Cheong et al. in 1993, subsequent studies
investigating this approach reported primary fistula classi fication accuracy rates up
to 95% (Poen et al. 1998b; Ratto et al. 2000; Navarro-Luna et al. 2004). Without
peroxide enhanced EAUS, fistula tracts appear as hypoechoic bands, and abscesses
as hypo- to anechoic regions, however, so do previous scarring, enlarged glands,
large blood vessels, or the anococcygeal ligament posterior in the distal anal canal.
After peroxide infusion, patent fistula tracks or abscesses will become hyperechoic
as a result of the formation of gas bubbles within the lumen. It is a safe, reliable, and
economic procedure for the assessment of perianal fistulas and can differentiate the
active fistula tract from previous scarring and surgery for fistulas.
4.5 Cryptoglandular Fistulas
Most first presentations of a cryptoglandular fistulas present as simple fistulas and
especially the recurrent fistulas are complex in up to 50% of cases (Sloots et al.
2001a). They investigated in 81 never operated (n ¼ 48) and recurrent (n ¼ 33)
patients with cryptoglandular fistulas. All patients were assessed by clinical examination and 3D-HPUS. All never operated fistulas were inter- or transsphincteric and
a secondary track was found in 5%. Recurrent fistulae were supra- or extrasphincteric in 15% and secondary tracts were present in 27%. Therefore, never
operated fistulae might not require any special preoperative workup as there is a
very small chance of fistula complexity. In contrast to a recurrent fistula where
10 Endoanal Ultrasound in the Diagnosis of Cryptoglandular Anal Fistulas and... 149
Fig. 5 Large abscess visible dorsally at the level of the PR muscle (a) and higher (b). Spontaneous
air is visible (arrow) (b). Adding H
(arrow) (c) and higher only the abscess (d). (e) shows the lateral few of the fistula tract to the
abscess. EAS ¼ external anal sphincter, IAS ¼ internal anal sphincter, A ¼ abscess, IO ¼ internal
opening
shows the internal opening and connection to the abscess
2O2
preoperative 3D-HPUS is advocated in order to deli neate the exact fistula pattern,
and avoid unnecessary iatrogenic anal sphincter damage.
A study of 115 patients with cryptoglandular fistula undergoing fistula surgery
investigated the diagnostic value of measuring the distance between external opening and anal orifice to evaluate its relation to fistula complexity. Mean distance in
simple fistula was 2.8 (SD 0.689) cm compared to 4.4 (SD 0.526) cm in complex
fistula. This difference was statistically significant. They also reported higher age
and prior operation to be related to fistula complexity (Becker et al. 2006).
It is important to establish the height of the internal opening, to decide upon
fistulotomy or a sphincter saving procedure to avoid fecal incontinence. The definition of high and low fistulas differs among surgeons (Vander Mijnsbrugge et al.
2019). To date, a height more than one third of the sphincter is considered high.
Murad-Regadas (2018) prospectively performed EUS preoperatively in patients
with anal fistulas and used the height of the internal opening as criteria to decide
upon fistulotomy (males <50% and females <40% sphincter involved) or a sphincter saving procedure (seton LIFT) and found similar outcome concerning minor
postoperative fecal incontinence (31%). Furthermore, the height of the internal
sphincter opening is related to fistula recurrence (Vander Mijnsbrugge et al. 2019).
Ratto et al. (2005) had showed that surgical treatment guided by EAUS led to
curative operation and preservation of fecal continence
.
However, other authors had
argued that the accuracy of preoperative EAUS had no influence on postoperative
150 R. J. F. Felt-Bersma
Fig. 6 An anterior fistula. (a) Hypoechogenic area is visible anterior. Adding H2O2illuminates the
fistula tract mid-sphincteric (b) and low sphincteric (c). (d) shows the lateral view
outcome in terms of failure rate and total number of surgeries (Weisman and Abba s
2008; Benjelloun et al. 2014). Thus, apart from EAUS accuracy, other factors may
influence postoperative clinical outcomes.
Regarding functional outcome, EAUS had a role in quantifying the length of
muscle to be transected during surgery and identifying occult anal sphincter defect
(Emile et al. 2017) which guides the safer operative option and minimize the rate of FI
(Ratto et al. 2005; Murad-Regadas et al. 2010). Ding et al. (2015) had confirmed the
favorable impact of 3D-EAUS on operative outcomes, mainly on continence function.
In their study, anorectal manometry (ARM) had been used. There was a significant
decrease in anal sphincter resting pressure after operation in all subjects with complex
FiA. However, only subjects without preoperative EAUS had significant decrease in
squeeze pressure. Change in FISS after operation is a common consequence of fistula
surgery (Roig et al. 2009). Tantiphlachiva et al. (2019) found significant worsening of
FISS in patients where no EUS was performed preoperatively.
10 Endoanal Ultrasound in the Diagnosis of Cryptoglandular Anal Fistulas and... 151
Fig. 7 Recurrent high perianal fistula at the left. (a) Above the level of the PR muscle. (b)
Mid-sphincteric, where an anterior defect of the IS and a defect of the ES is visible (arrow) due
to previous surgery and (c) distal in the anus. There is no obvious sign of a fistula tract. Adding
shows at exactly the same levels, respectively, (d, e, f) the large fistula tract as a hyperechoic
H
2O2
tract left dorsal
Fig. 8 Posterior fistula. (a) Hypoechogenic area is visible (arrow). Adding H2O2illuminates the
tract (b), and (c) lateral view illustrates the fistula tract
Furthermore, missing an extension of a fistula tract can lead to a recurrence (Poen
et al. 1998b).
Referrals to tertiary centers have an extreme high percentage of complex
fistulas up to 90%, documented by EUS, which tempers the success percentage
of techniques originally described as very effective (Vander Mijnsbrugge
et al. 2019).
152 R. J. F. Felt-Bersma
Fig. 9 Rectovaginal fistula. (a) Rectal image and (b) vaginal image. The fistula is only visible as a
hypo echogenic structure indistinguishable from a defect. After adding H
becomes clearly visible in both rectal transversal (c), sagittal (d), and vaginal (e) image
the fistula tract
2O2
4.6 Crohn’s Fistulas
Anorectal involvement of Crohn’s disease (CD) is common, affecting around 40% of
patients. Perianal CD, including fistulae, abscesses, or fissures, may precede the
development of the intestinal disease, to be present at diagnosis or to appear during
the clinical course (Eglinton et al. 2012).
Fistulas in Crohn’s disease are generally complex and can extend very high
(Sloots et al. 2001b). A study in 41 patients assessing fistula classification using
3D-HPUS showed that only 22% of fistulae were single intersphincteric or transsphincteric tracts. Single suprasphincteric or extrasphincteric tracts were present in
12%, rectovaginal and anovaginal fistulae were present in 32%, and secondary tracts
were seen in 34% of the patients. In this cohort, 78% of the patients had a complex
fistula. Three-dimensional HPUS is highly accurate for delineating the anatomy of
complex perianal fistula and for determining the site of the internal fistula opening.
However, not all Crohn fistulae are complex; especially on first presentation, it can
be difficult to differentiate CD from cryptoglandular fistulae.
Distinct differences in anorectal ultrasound features in patients with CD have been
described (Blom et al. 2011;Zawadzkietal.2012;Zbaretal.2013;Luglioetal.
2018). Four criteria are used to distinguish Crohn’s fistulas from cryptoglandular
fistulas: 1. CUFS, 2. presence of a double tract, 3. maximum width of the fistulous
tract (>4 mm), and 4. presence of hyperechoic material in the abscess or tract. Luglio
10 Endoanal Ultrasound in the Diagnosis of Cryptoglandular Anal Fistulas and... 153
Fig. 10 High perianal fistula. (a) Level of puborectal muscle, (b) mid-sphincteric level. A
hypoechogenic area is visible anterolateral right (arrow) in the external anal sphincter (EAS) and
the internal anal sphincter (IAS) is disrupted. After hydrogen peroxide injection, the internal
opening becomes (arrow) visible (c) and the fistula tract is visible up to very high (d). (e) Frontal
view of the high fistula tract
Fig. 11 Two external openings at 5 and 10’clock. H2O2was added. (a) Level mid-sphincteric at
3 cm and (b) level distal at 1 cm from the anal verge
et al. (2018) described the interobserver agreement as good for all features and were
more frequent in patients with Crohn’sdisease(p< 0.0001), especially the combina-
tion of a width > 4 mm in conjunction with double duct sign or CUFF (Crohn’s
ultrasound fistula sign) was found to be specific (1.00).
154 R. J. F. Felt-Bersma
Fig. 12 Spontaneous air in
fistula tract. No H
given here
2O2
was
The CUFS was first described by Zawadzki et al. (2012) as a homogeneous
moderately hyperechoic abscess of fistula tract, delineated by a thin hypoechoic rim
and surrounded by a hyperechogenic area. The biological and histological bases of
this sign are not fully understood, probably being related to the fact that the CD
fistulas are more likely to create a deeper and cavitating inflammatory process, with
some debris inside. They state that the sign had a very high specificity (0.98) and
moderate sensitivity (0.69) for perianal CD. It has also been investigated by Zbar
et al. (2013), who found similar specificity (0.97) but lower sensitivity (0.43). Luglio
et al. (2018) found relatively high specificity (0.86), although it was lower than those
reported so far, and moderate sensitivity (0.70), similar to that originally reported.
The presence of debris (hyperechoic secretions) in the fistulous tract or abscess as a
sign peculiar of perianal CD was first proposed by Blom et al. (2011) and later
investigated by Zbar et al. (2013), who found poorer sensitivity (0.03). Luglia (2018)
confirmed that this sign is often absent in patients with perianal CD (sensitivity ¼ 0.52) but seldom present in patients without perianal CD, as evidenced by
the specificity (0.80). The presence of a fistul ous tract bifurcation or a double tract
was found to be a specific sign of perianal CD, being very rare in cryptoglandular
fistulas (specificity ¼ 0.98). However, it often lacks in CD fistulas as well (sensitivity ¼ 0.59). A wider fistulous tract has been correlated with perianal CD by Blom
et al. (2011). In particular, a tract width >3 mm in cross-sectional reconstruction was
suggested to aid in distinguishing CD related to cryptoglandular fistulas; however,
the diagnostic accuracy of this parameter was not evaluated. Luglio et al. (2018)
using ROC analysis found great accuracy (area under the ROC curve ¼ 0.92) in
using the maximum width of the fistula. In addition, a cutoff value of 4 mm was
found to maximize both the sensitivity and specificity (0.813 and 0.97). They
concluded that a fistula tract width 4 mm is very likely CD related.
10 Endoanal Ultrasound in the Diagnosis of Cryptoglandular Anal Fistulas and... 155
Although it is good to be alert for these features, all these patients had established
Crohn’s disease. The message should be that in patients with complex, bizarre, and
or recurrent fistulas the diagno sis of Crohn’s disease should be considered and
further tests like laboratory tests, colonoscopy, and imaging of the small bowel
may be necessary and warranted, since the treatment of fistulas is Crohn’s disease
differs from cryptoglandular fistulas. Except for the acute abscess, the treatment of
fistulas in CD is primary medical with immunomodulation and biologicals.
The ECCO guidelines for evaluating perianal fistulas in CD state the MRI is
considered the initial procedure for the assessment of perianal fistulizing CD and
consider EUA a good alternative when rectal stenosis is excluded (Van Assche et al.
2010). However, once detected, EUS is a good means of follow-up in experienced
hands. The criticism on EUS that high fistulas cannot be seen with EUS and
therefore will be missed is not true. Only when in doubt about the extent of the
fistula or when the delineation of the abscess is not clear especially in high situated
abscesses (out of reach) or with dorsal extension (poor visibility due to the shadow of
the coccygeal bone) it is obvious an MRI needs to be performed. The performing
EUS specialist should be aware of this and results are excellent in experienced
hands.
Several studies evaluated treatment with EUS in patients with perianal fistulas
in CD.
Bodegraven et al. (2002) documented fistula tracts at baseline and after three
infusions of infliximab (5 mg/kg) in eight patients with CD. Vaginal or perineal
fistulas did not clinically respond to therapy, whereas patients with perianal fistulas
improved considerably. Yet in all patients’ fistulous remainders could still be demonstrated 4 weeks after the last infliximab infusion. Similar results were found in
later studies.
5 Comparison with Other Diagnostic Modalities
5.1 Comparison with Surgery
Generally, surgery is considered the golden standard when comparing other the
findings of EUS and MRI, although both are well-established techniques for
assessing fistulas. The use of surgery as a gold standard has been questioned. A
EUS study (Poen et al. 1998b) demonstrated two secondary tracts with HPUS that
were not found during surgery, these patients developed a recurrent fistula,
suggesting that these branches were actually present at the time of HPUS. In a
follow-up study with 37 patients body coil MRI was shown to make better predictions regarding patient outcome than surgical findings (Spencer et al. 1998).
Another study (Gustafsson et al. 2001) with 22 patients found that in two patients
who did not heal after surgery EUS showed an extension and/or abscess, which was
not identified at the time of operation. For body coil MRI the corresponding figure
was three. In the same study no internal opening was found during surgery in three
patients.
156 R. J. F. Felt-Bersma
A prospective study of retrospective data (Kołodziejczak et al. 2017) determined
the accuracy of 3D-EUS with intraoperative findings (golden standard). The overall
accuracy of 3D-EAUS was 91% for fistula type (271/299 fistulas: 97% transsphincteric, 100% intersphincteric, 57% suprasphincteric, 0% extrasphincteric) and
92% for fistula height (275/299 fistulas: 80% high and 100% low) and concluded to a
very good agreement with surgery in the assessment of fistula type (proportion of
agreement 0.88, κ ¼ 0.89) and height (proportion of agreement 0.90, κ ¼ 0.91).
A recent retrospective study (Almeida et al. 2019) compared EUS with EUA and
they found a correct prediction of the primary tract with EUS in only 71%. The
authors recognized that probing the fistula and inflating the exter nal opening would
have improved the outcome.
5.2 Comparison with MRI
In the guidelines of many medical and surgical societies both EAUS and MRI are
mentioned. Some consider MRI first choice, especially in CD. Although MRI as first
choice is often advocated, many (private) practices use EAUS due to accessibility and
low costs. The American guidelines make no definite recommendation. The German
guideline mentions both techniques as equally acceptable, the Italian consensus
statement accepts EAUS as a first choice but recognizes MRI for complex higher
fistulas, and the Dutch guideline prefer MRI and only promotes EAUS in experienced
hands. The guideline of the European Society of Coloproctology is expected in 2022
and due to possibilities and accessibilities in the different countries will probably not
make a hard choice and consider MRI in cases where EAUS imaging remains
inconclusive. This is the general trend in the literature, apart from purists. Figures 13
and 14 show the imaging of both EAUS and MRI in patients with perianal fistula.
Siddiqui et al. (2012) performed a meta-analysis comparing MRI with EU for the
assessment of cryptoglandular and CD anal fistula and found a similar sensitivity
(0.87 (95% confidence interval (CI) 0.63–0.96); 0.87 (95% CI 0.07–0.95)
groups. The specificity was higher for MRI (0.69 vs. 0.43), although it was poor
overall for both imaging modalities, whereas EU showed better detection of the
internal opening. However, many studies were excluded, the four remaining were
older studies (1999–2003), had few patients, and no hydrogen peroxide was used.
West et al. (2004) performed a prospective study comparing 3D EAUS with endocoil
MRI and found also good agreement for both modalities. Alabiso et al. (2016)
compared 3D-EUS (without H
) with MRI in 51 patients with CD. There was
2O2
no difference in detecting transsphincteric fistulas. 3D-EAUS was preferable to MRI
in the detection of intersphincteric fistulas; conversely, in the evaluation of suprasphincteric and extrasphincteric fistulas the MRI was preferable to 3D-EAUS.
Brillantino et al. (2019) performed a prospective study in 124 patients comparing
unenhanced and H
enhanced 3D-EAUS, MRI, and surgical findings. Perfect
2O2
agreement between 3D-EAUS and surgery in the anal fistulas’ severity grading was
found (K ¼ 1). The fistulas were classified as simple in 68/126 (53.9%) and complex
in 58/126 (46.03%) cases. In both simple and complex anal fistulas, 3D-EAUS did not
) in both
2
10 Endoanal Ultrasound in the Diagnosis of Cryptoglandular Anal Fistulas and... 157
Fig. 13 Comparison of EAUS and MRI (with anal probe) in perianal fistulas. Dorsal fistula.
Transversal view in (a) EAUS and (b) MRI. Sagittal image in (a) EAUS and (d) MRI and frontal
image in EAUS (e) and MRI (f). EAS ¼ external anal sphincter, IAS ¼ internal anal sphincter,
F ¼ fistula tract
Fig. 14 Comparison of EAUS with H2O2and MRI (with anal probe) in perianal fistulas. Left
lateral fistula. Transversal view in (a) EAUS and (b) MRI. Sagittal image in (a) EAUS and (d) MRI
and frontal image in EAUS (e) and MRI (f). EAS ¼ external anal sphincter, IAS ¼ internal anal
sphincter, F ¼ fistula tract