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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_1056_Библиотеки_им_академика_М_И_Перельмана.pdf
74 P. Garg
Table 2 Parks classification (Parks et al. 1976)
Grade Fistula description
I Intersphincteric Ia – Low
Ib – High extension in rectal wall without an additional high
opening in the rectum
Ic – High extension in rectal wall with an additional high opening in
the rectum
Id – No external opening in the perianal skin in the type Ib or Ic
Ie – High extension in pelvic cavity
If – Pelvic disease draining into the perianal skin through the
intersphincteric space
II Transsphincteric IIa – All fistulas below the puborectalis muscle
IIb – Fistula with a branch going
high in ischiorectal fossa (infralevator) or
high through levator muscle (translevator) but not opening into
the rectum
III Suprasphincteric Suprasphincteric fistula with or without a supralevator extension
IV Extrasphincteric IVa – Transsphincteric fistula with a branch going high through
Supralevator fistula could be present in grade I, II, or III
Translevator fistula could be present in grade II (IIb) or IV (IVa)
levator muscle (translevator) but opening into the rectum (type IIb
with an additional opening high in the rectum)
IVb – Extrasphincteric tract due to trauma
IVc – Extrasphincteric tract due to anorectal disease like Crohn’s
disease, ulcerative colitis, or carcinoma
IVd – Pelvic disease draining into the perianal skin after piercing
through the levator muscle
Table 3 Parks
classification: simple
version used commonly
Grade Fistula description
I Intersphincteric
II Transsphincteric
III Suprasphincteric
IV Extrasphincteric
4 Anal Fistula Classifications
Of all these classifications, the three most important ones (Parks, SJUH, and Garg)
will be discussed and compared in the following sections.
4.1 Parks Classification
In this classification, the fistula was divided in four distinct categories based on the
anatomical location of the fistulas (Parks et al. 1976). These were intersphincteric,
transsphincteric, suprasphincteric, and extrasphincteric fistulas. In the original
6 Classification of Anal Fistula and Abscess 75
version, each grade was divided into several subgrades (Table 2), but gradually, a
simpler version became more popular (Table 3). There were distinct advantages and
disadvantages of this classification:
4.1.1 Strong Points
1. First classification to be used widely.
2. Quite comprehensive.
3. Based on the clinical experience and data of 400 patients.
4. Excellent classification considering the fact that there was no MRI/TRUS available at that time.
5. It was proposed by surgeons.
4.1.2 Weak Points
1. The classification was too skewed because the first two grades contained more
than 90% of the fistulas while the last two grades included less than 10% of the
fistulas (Parks et al. 1976). In the series of Parks et al., this figure was 75% (grade
I + II) and 25% (grade III + IV), but the authors observed that these figures in a
general practice were 93% (grade I – 70% + II – 23%) and 7% (grade III –
5% + IV – 2%) (Parks et al. 1976). In the recently published data in 848 patients,
these figures were 98.4% in first two grades (grade I – 40.6% + II – 57.8%) and
1.6% in last two grades (grade III – 1.6% + IV – 0%) (Garg 2020).
2. This classificati on was primarily anatomical (based on the location of the fistulas)
and did not categorize fistulas on the basis of the increasing severity (Parks et al.
1976). It was incorrect to conclude that all transsphincteric fistulas were more
complex than intersphincteric fistulas. For example, a low linear 2 cm-long
transsphincteric fistula involving just 10% of external sphincter (grade IIa)
would be simpler and not more complex than a high intersphincteric supralevator
horseshoe fistula with high rectal opening (grade Ic). Therefore, the classification
did not grade fistulas on the increasing severity (complexity).
3. This classification did not provide any guidelines regarding the management of
the fistulas. The fundamental purpose of a classification is to guide the management. As fistula is a diverse disease, it becomes important that the classification
provides an insight regarding the management plan. Otherwise, the purpose of
proposing the classification stands defeated.
4. Though the classification was based on the experi ence of 400 patients, the
diagnosis of the fistulas was not validated/corroborated by MRI/TRUS as these
investigations were not available at that time (Parks et al. 1976). This could
perhaps be the reason why there were 25% (100/400) suprasphincteric or extrasphincteric fistulas in the cohort (Parks et al. 1976). This proportion of suprasphincteric and extrasphincteric fistulas seems to be on quite higher side. A recent
series in large number of patients in whom the findings were corroborated by MRI
and surgery, it was demonstrated that the suprasphincteric or extrasphincteric
fistulas were only 1.6% (14/848) (Garg 2020). Therefore, the suprasphincteric
or extrasphincteric fistulas either occurred more iatrogenically or were overdiagnosed in that era due to lack of availability of MRI/TRUS.
76 P. Garg
5. The status of supralevator fistulas was not clearly stated. As per Parks et al.,
supralevator extension could occur in any of the first three grades (I, II, or III)
(Parks et al. 1976).
6. One full category having four different subtypes was assigned to the extra sphincteric fistulas. However, with frequent usage of MRI/TRUS, it has been
shown that the extrasphincteric fistulas do not exist or are extremely rare (Garg
2017, 2018). This is so because it is extremely difficult for an abscess/fistula to
pierce through the strong levator plate especially when a lot of soft tissue for
expansion is available in the ischiorectal fossa (Fig. 13) (Garg 2017b, 2018c).
This shall be discussed in detail in the subsequent section.
7. The subset of translevator fistulas (fistulas which were crossing the levator
muscles) which were opening into the rectum high-up were categorized as
extrasphincteric fistulas (grade IVa) (Parks et al. 1976). On the other hand,
another subset of translevator fistulas which were reaching the pararectal tissues
but were not opening into the rectum were categorized as grade 2 with transsphincteric fistula (grade IIb) (Parks et al. 1976).
8. There was no category for anterior fistula in a female or patients with
comorbidities like anal fistulas with Crohn’s disease, previous irradiation, weak-
ened sphincter due to previous operations, etc. (Parks et al. 1976).
9. The strength of this classification was its comprehensiveness, but this was not
fully utilized. The original version (Table 2) was perhaps cumbersome to be used
and hence got replaced by the simpler version (Table 3). Though the latter got
used extensively, a lot of relevant information and utility was lost.
5 St James’s University Hospital MR Imaging Classification
This was the first classification based on MRI (Morris et al. 2000). In this classification, the fistulas were divided in five categories (Table 4). The first two grades were
intersphincteric (I – linear; II – associated with abscess or multiple tracts). These were
categorized as simple fistulas with negligible recurrence rates. The next three grades
(III–V) were categorized as complex fistulas in which further surgery was generally
required. These were grades III–V. Grade III was a linear transsphincteric fistula, grade
Table 4 St James
University Hospital
classification
Grade Fistula description
I Intersphincteric – linear
II Intersphincteric – multiple tracts or associated abscess
III Transsphincteric – linear
IV Transsphincteric – multiple tracts or associated abscess
V Supralevator or translevator/extrasphincteric
Suprasphincteric fistulas was categorized along transsphincteric fistu-
las as grade IV
6 Classification of Anal Fistula and Abscess 77
IV was a transsphinctericfistula associated with abscess or multiple tracts,and grade V
was a supralevator or a translevator (extrasphincteric) fistula (Table 4) (Morris et al.
2000). The significant difference from the Parks classification was that suprasphincteric
fistulas were categorized along with transsphincteric fistulas as grade IV and supra-
levator fistulas were categorized along with extrasphincteric fistula as grade V (Morris
et al. 2000). There were distinct strong and weak points of this classification.
5.1 Strong Points
1. First classification which was MRI based.
2. Widely used.
3. Unlike Parks classification, all supralevator and translevator fistulas were categorized in the highest grade (grade V). This was perhaps the strongest point of
this classification.
5.2 Weak Points
1. There was nothing much different from Parks classification. As the classification was
a minor modification of “simple version” of Parks classification (Tables 3 and 4), the
two distinct shortcomings of Parks classification persisted in this classification as
well. Like Parks, SJUH classification also did not correlate with the disease severity
and nor it gave any help to operating surgeons regarding the disease management
(Morris et al. 2000). The only guideline it gave was “Grades I and II were associated
with a satisfactory outcome (i.e., no further surgery needed), whereas grades III–V
were associated with unsatisfactory outcome (i.e., further surgery needed). More
complex surgery may be required in these (grades III–V) that may threaten continence or may require fecal diversion (colostomy) to allow healing” (Morris et al.
2000). The latest data of the decade clearly show that this is not true (Garg 2017c,
2018b, c). The success rate is quite high (>90%) in low transsphincteric fistulas
(SJUH grade III or IV) which can be safely dealt with fistulotomy (Garg 2018b).
Fecal diversion is now very rarely required while managing anal fistula.
2. The first two grades of Parks classification were each further divided into two
more grades. However, suprasphincteric fistulas were categorized along with
transsphincteric fistulas (Morris et al. 2000). This was a weak point as the
management and prognosis of suprasphincteric fistulas is as difficult as supralevator fistulas.
3. This classification was not validated by any patient data (Morris et al. 2000).
4. Despite utilizing the classic advantage provided by MRI and added knowledge of
quarter of a century, this classification failed to improve over Parks classification.
That was perhaps the reason that though this classification became widely used
but it failed to replace Parks classifi
and Parks) have been used in the last two decades.
cation. Therefore, both classifications (SJUH
78 P. Garg
5. Patient with comorbidities like anal fistulas with Crohn’s disease, previous
irradiation, weakened sphincter due to previous operations, etc. and anterior
fistula in females were not included in the classification.
6. This classification was proposed primarily by the radiologists and was perhaps
intended to be a radiological classification as suggested by the name too –“St
James’s University Hospital MR Imaging Classification” (Morris et al. 2000).
6 Garg Classification
This classification was proposed in 2017 to fill the vacuum in the classification of
anal fistulas as none of the existing classifications were able to grade the disease on
its severity or to guide the management of anal fistulas (Garg 2017a). The initially
published version of this classification was quite detailed and looked a bit confusing
for general surgeons (Garg 2017a). However, its simplified version was subsequently published and has been used extensively (Garg 2018a, 2019b, 2020). This
classification was validated by a data of 440 patients, operated for anal fistula, and
MRI was done for all patients (Garg 2017). Thus, this was the largest series of fistula
patients utilized for proposing a classification and was also the first to be validated by
a fully MRI-based series (Garg 2017a).
Theprimarygradinginthisclassification was done on the basis of the involve-
ment of the external sphincter (Table 5)(Garg2017a). The fistulas involving less
than one-third of the external sphincter were classified as low fistulas (grades I and
II) irrespective of whether they were intersphincteric or transsphincteric (Garg
2017a, 2018a). Grade I are linear low fistulas (intersphincteric or transsphincteric)
whereas grade II are low fistula with associated abscess, multiple tracts, or horseshoe tracts (intersphincteric or transsphincteric). These fistulas are “simple”
Table 5 Garg classification
Grade Fistula description
I LOW – single tract (intersphincteric or transsphincteric)
II LOW – multiple tracts or associated abscess or horseshoe tract (intersphincteric or
III HIGH – single tract (intersphincteric or transsphincteric) or
IV HIGH – multiple tracts or associated abscess or horseshoe tract (intersphincteric or
V Suprasphincteric or
LOW – involves <1/3 of external sphincter; HIGH – involves >1/3 of external sphincter
a
Associated comorbidities: already damaged/weakened sphincter, post-radiotherapy, Crohn’s
disease
transsphincteric)
Anterior fistula in a female or
Associated comorbidities
transsphincteric)
Supralevator or
Extrasphincteric
a
6 Classification of Anal Fistula and Abscess 79
fistulas; therefore, fistulotomy can be carried out in these fistulas safely without
any risk to the continence (Garg 2017a). Once properly classified, these fistulas can
be conveniently managed even by less experienced surgeons with fistulotomy
(Garg 2017a, 2018a).
On the other hand, the fistulas involving more than one-third of the external
sphincter are categorized as high fistulas (grades III–V) (Table 5) (Garg 2017a,
2018a, 2020). Grade III are high linear transsphincteric fistulas, anterior fistulas in
females, or fistulas associated with preexisting comorbidities like Crohn’s disease,
previous irradiation, weakened sphincter due to previous operations, etc. Grade IV
are high transsphincteric fistulas with associated abscess, multiple tracts, or horseshoe tracts. Grade V are suprasphincteric, supralevator, or extrasphincteric fistula
(Garg 2017a, 2018a, 2020). These are the “complex” fistulas as fistulotomy should
not be attempted in these fistulas as that would carry a high risk of incontinence
(Garg 2017a, 2018a, 2020). A sphincter-saving procedure should be performed in
these fistulas (Garg 2017a, 2018a, 2020). These “complex” fistulas are better
referred to an experienced colorectal surgeon (Garg 2018).
Fistulotomy i s the one of the oldest, easiest (easy to learn a nd reproduce), and
is the most commonly done procedure for anal fistulas across the glo be.
Therefore, fistulotomy has been kept as a benchmark while defining manage ment
with this classi
minds of surgeons while performing fistulotomy. Therefore, Garg classification
clearly demarcates the patients which can be safely managed by fistulotomy
from the ones in which fistulotomy should not be attempted at all (Garg
2018a, 2020).
fication. However, the risk of incontinence is prominent in the
6.1 Grade I: LOW – Single Tract (Intersphincteric
or Transsphincteric)
See Figs. 1 and 2.
6.2 Grade II: LOW – Multiple Tracts or Associated Abscess
or Horseshoe Tract (Intersphincteric or Transsphincteric)
See Figs. 3, 4, and 5.
6.3 Grade III: HIGH – Single Tract (Intersphincteric or
Transsphincteric) or Associated Comorbidities (Anterior
Fistula in a Female or Already Damaged/Weakened
Sphincter, Post-Radiotherapy, Crohn’s Disease)
See Figs. 6 and 7.
80 P. Garg
Fig. 1 Grade I fistulas – schematic diagram
Fig. 2 Grade I fistulas – a posterior intersphincteric fistula in a 45-year-old male
6 Classification of Anal Fistula and Abscess 81
Fig. 3 Grade II fistulas – schematic diagram
Fig. 4 Grade II fistulas – a low transsphincteric fistula with an associated abscess in a 33-year-
old male
82 P. Garg
Fig. 5 Grade II fistulas – a low transsphincteric fistula with multiple branches in a 30-year-old male
Fig. 6 Grade III fistula – schematic diagram of an anterior fistula in a female
6.4 Grade IV: HIGH – Multiple Tracts or Associated Abscess
or Horseshoe Tract (Intersphincteric or Transsphincteric)
See Figs. 8 and 9.
6 Classification of Anal Fistula and Abscess 83
Fig. 7 Grade III fistulas – an anterior transsphincteric fistula with an associated abscess in a
45-year-old female
Fig. 8 Grade IV fistulas – schematic diagram