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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_627_Библиотеки_им_академика_М_И_Перельмана
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FIGURE 11-1 Goodsall rule.
Understanding of the anatomy of the postanal space and appreciation of
horseshoe abscess extensions due to the communication within the
supralevator, ischioanal, and intersphincteric compartments are essential
when dealing with complex anorectal sepsis (Fig. 11-2).
FIGURE 11-2 Sites of anorectal abscesses.
Sterile Instruments/Equipment
Equipment used for anorectal cases includes:
Set of fiberoptic-lighted Hill-Ferguson retractors: small, medium, and
large
This is used for all perianal cases placed in lithotomy position.
Set of fiberoptic-lighted Fansler retractors: small, medium, and large
This is selectively used for perianal cases placed in prone (Kraske)
position.
Set of Lockhart-Mummery fistula probes
Set of curettes
Vessel loops (to be used as seton)
Monopolar electrocautery
We routinely use 40 cut with 60 coagulation settings
A selection of Pezzer (ie, mushroom) drains
A selection of Penrose drains
Hydrogen peroxide
Technique
Positioning
The default position to perform an examination of the perineum and
drainage of anorectal sepsis is in lithotomy with buttocks overhanging the
edge of the operating table.
Prone jackknife position may be used for selected cases, although this is
typically of most benefit for addressing anorectal fistulas with an anterior
internal opening.
Examination under Anesthesia
Following appropriate positioning, the examination is commenced by
close inspection of the perineum.
This may reveal undrained sepsis, previous scars, and external
openings.
The clinician then proceeds to a digital rectal examination and an
anoscopy. Our preferred retractor is a fiberoptic-lighted Hill-Ferguson
with lubricant applied only to its convex surface.
Some surgeons prefer to do an anoscopy prior to digital rectal
examination. A “bead of pus” from an anal crypt at the site of the dentate
line may be the only sign of an internal opening.
Sepsis in the deep postanal space may present without a visible abscess, or
an identifiable internal opening. Posterior fullness on digital rectal
examination may alert an astute examiner. A presacral tumor should be
remembered as a differential in such a scenario. Ultrasound or MRI
imaging and not aspiration is required in this setting.
PEARLS AND PITFALLS
Be mindful of Crohn disease, pilonidal cyst, and hidradenitis
suppurativa as etiologies that may be mascarading as benign external
openings of an anal fistula. Furthermore, an internal opening not located
at the dentate line should warrant suspicion for Crohn disease,
iatrogenic injury, or malignancy. Management of these conditions is
described in the appropriate chapters of this textbook.
Specific Considerations in the Management of Anorectal
Abscess
Role of Antibiotics
We do not routinely give postoperative antibiotics, but consider treatment
in patients who are immunocompromised, diabetic, or have associated
cellulitis.
Optimal drainage should typically preclude the need for antibiotics in the
absence of above.
In persistent cellulitis, consider the potential for undrained sepsis or
another process.
Identification of a Fistula at the Time of Abscess
Drainage
We do not probe the abscess cavity to identify a possible fistula in an
index anorectal abscess, as we feel that the rate of iatrogenic fistula tract
formation is underreported.
However, if, during anoscopy, there is purulent discharge into the anal
canal from a crypt, one can assume a patent fistula tract is present, and we
will then attempt to control the tract with a seton.
For recurrent abscesses, a careful probe may also aid in identification of a
fistula, though we stress outmost caution.
Perianal and Ischioanal (Also Known as Ischiorectal)
Abscess
Draining an acute abscess or cavity is essential. Principles include
minimizing the distance from incision to the anal verge (with view of
shorter fistulas being less challenging to manage).
Superficial cavities can be drained with a cruciate (with excision of
corners) or elliptical incision.
Aspiration of abscess with a medium- to large-bore needle may confirm
the presence of an abscess in a patient with erythema, but without
fluctuance.
A culture of enteric organisms from the abscess cavity, as compared to a
growth of cutaneous organisms, can aid in delineating the origin of the
pathology that precipitated the abscess.
Deep cavities are drained with the aid of a mushroom-type drain. We
rarely utilize wound packing in this treatment algorithm (Fig. 11-3).
Our preferred drain is a “Pezzer” catheter, with two extra openings
being cut prior to insertion. We find that “Malecot” catheters are more
likely to get dislodged.
FIGURE 11-3 Mushroom drain into ischioanal abscess. Seton positioned through
transsphincteric fistula tract.
Typically, drains are left for 7-10 days and removed during a
postoperative visit in the office.
PEARLS AND PITFALLS
Use of a fine needle may prove ineffective where purulent fluid is most
often quite viscous.
Submucosal Abscess
Drain into the rectum using diathermy.
Intersphincteric Abscess
These abscesses are infrequent. Patients typically report perianal pain and
may develop fevers.
This abscess is drained in combination with an internal sphincterotomy.
Supralevator Abscess
A supralevator abscess may be due to an intersphincteric abscess tracking
cranially (ie, cryptoglandular origin) or a pelvic abscess (ie, diverticulitis)
tracking caudally.
Differentiating the origin is essential, as source control dictates subsequent
management. One way to think about this from the perianal source, is
picturing the origin of a fistula via Park’s classification (Fig. 11-4).
An abscess of cryptoglandular origin may be treated with a
combination of sphincterotomy and mushroom-type drainage.
FIGURE 11-4 Park classification of anorectal fistulas. A. Intersphincteric (type I).
B. Transsphincteric (type II). C. Suprasphincteric (type III). D. Extrasphincteric (type
IV).
An abscess with a pelvic origin may require transabdominal drainage.
In severe cases, source control may only be obtained with the aid of a
temporary ostomy.
Deep Anterior or Posterior Anal Space and Horseshoe
Abscess
These are infrequent, yet very complex clinical situations.
The most common of these anal space infections is an abscess in the deep
postanal space. This is a potential space bordered by the levator ani
muscles, anococcygeal ligament, external sphincter, and sacrum, which
communicates with the ischioanal fossae (Fig. 11-5).
FIGURE 11-5 Sagittal view of posterior cavities.
CT imaging preoperatively in these cases is helpful in making the
diagnosis and establishing the extent of disease (Figs. 11-6 and 11-7).
FIGURE 11-6 Axial computed tomography imaging of horseshoe abscess. Arrows
indicate the abscess.
FIGURE 11-7 Sagittal computed tomography of horseshoe abscess demonstrating
extension into deep postanal space. Note the abscess in respect to coccyx. Arrows
indicate the abscess.
The causative anorectal pathology is typically an internal opening at the
posterior midline with an associated deep postanal abscess and
anterolateral extensions on either side of the anus.
Posterior superficial and anterior horseshoe fistulas can occur, but are very
infrequent. The principles of management of all horseshoe fistulas involve
drainage of sepsis using counterincisions (Fig. 11-8).
FIGURE 11-8 Horseshoe fistula with seton in place.
Technique
Position the patient in lithotomy, as the source of this anorectal abscess is
typically a posterior midline internal opening at the dentate line.
If external openings are seen over the anterolateral extensions, enlarge
and define the trajectory of the tracts using Lockhart-Mummery fistula
probes. Typically, these extensions will communicate posteriorly from
both sides.
Create a skin incision along the midline, just posterior to the sphincter
complex. One must traverse the anococcygeal ligament in the posterior
midline to enter and adequately drain the deep postanal space. A long
hypodermic needle on a syringe for aspiration can aid in identifying the
posterior cavity prior to making your incision.
Horseshoe fistulas have external openings. In horseshoe abscesses, no
anterolateral openings exist. Pass a Kelly clamp from your posterior
incision through the deep postanal space into the ischioanal fossa
laterally. Counterincisions over the anterolateral extension are now
made at the tip of the Kelly clamp. A silk tie is used to control the
tracts. This is performed unilaterally in a hemi-horseshoe or bilaterally
in a classic horseshoe (Figs. 11-9 and 11-10).
FIGURE 11-9 Kelly clamp inserted into deep postanal space into ischioanal fossa.
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