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152 The ASCRS Manual of Colon and Rectal Surgery
• Defects of the internal anal sphincter are represented by the
lack of segment of the hypoechoic band of internal sphincter
muscle. There is usually associated contralateral thickening of
the hypoechoic internal anal sphincter.
• With complete sphincter disruption, EAUS demonstrates the
ends of the internal and external anal sphincter widely separated and bridged with intervening scar tissue of variable echogenicity (Fig. 7.14 ).
• An examining digit used to measure the perineal body distance in the mid anal canal can accentuate an anterior sphincter
defect, helping to identify a sphincter injury ( Fig. 7.15 ).
• EAUS provides an objective means to evaluate the anal sphincter mechanism in patients with postoperative fecal incontinence
after anorectal surgery such as hemorrhoidectomy, fi stulotomy,
lateral internal sphincterotomy, or sphincteroplasty.
• The identifi cation of localized sphincter defects is important in
the evaluation of the incontinent patient, because these defects
may be amenable to surgical repair.
Fig. 7.14. This image depicts a complete anterior sphincter disruption in a
female patient. The hypoechoic internal anal sphincter can be seen completely
disrupted in its anterior location (A arrows ). Similarly, the hyperechoic external
anal sphincter is completely disrupted anteriorly (B arrows ) .
7. Endoluminal Ultrasound 153
Fig. 7.15. This image demonstrates the measurement of the anterior perineal
body in this patient with an anterior sphincter disruption. The curvilinear hyperechoic structure (A) is the examiner’s fi nger in the vagina. This technique can
often accentuate the defect (B) seen in the internal anal sphincter and the external
anal sphincter, and documents the decreased thickness of the anterior sphincter
and perineal body.
• Anorectal manometry and pudendal nerve terminal motor
latency testing are complementary but do not defi nitively correlate with a surgically correctable defect.
• EAUS remains the defi nitive test that can identify a surgically correctable defect in a symptomatic patient with fecal incontinence.
Evaluation of Perianal Sepsis and Fistula-in-Ano
• Occasionally, an abscess is strongly suspected on clinical grounds
but is not readily identifi ed on physical examination. In these situations, an EAUS may be useful in the evaluation of perianal or
perirectal abscesses. EAUS can be helpful to localize an obscure
abscess to plan the appropriate surgical intervention.
• Often, clinical examination of perianal or perirectal abscesses
is quite painful and examination under anesthesia is required.
Because the ultrasound equipment is portable, the EAUS
154 The ASCRS Manual of Colon and Rectal Surgery
examination can be performed in the operating room while the
patient is anesthetized.
• Abscesses appear as hypoechoic areas often surrounded by a
hyperechoic border.
• In patients with perianal Crohn’s disease, EAUS may be useful
in distinguishing discrete abscesses that require surgical drainage from infl ammation that requires medical treatment.
• The use of EAUS has also been evaluated in patients with ileoanal
pouch anastomosis and can be helpful in demonstrating pouch
pathology including infl ammation, abscesses, and fi stulas.
• Use of EAUS can be helpful in identifi cation of fi stulous
communications in patients with complex and recurrent fi stula-in-ano. Fistula tracts are generally hypoechoic defects
that can be followed to identify direction and extent. The anatomic details of the fi stula tract can be delineated in relation
to the anal sphincter. The EAUS examination should include
the anal canal and distal rectum to search for the presence
of high blind tracts. Hydrogen peroxide has been used to
enhance the imaging of complex fi stula. Hydrogen peroxide causes a release of oxygen, accentuating the fi stula and
appears as a brightly hyperechoic image on the ultrasound
image. The technique increases the identifi cation of the internal opening to greater than 90%. An example of a fi stula-inano with hydrogen peroxide enhancement is demonstrated in
Fig. 7.16 .
Anal Canal Neoplasms
• Endoanal ultrasonography images the normal anal canal and
associated pathologies quite well. EAUS can have an important role in the evaluation of benign and malignant anal canal
neoplasms.
• Benign neoplasms such lipomas and leiomyomas can be demonstrated along with their relationship to adjacent anal canal
structures. Lesions within the anal canal appear as hypoechoic
areas. Tissue diagnosis may be obtained with ultrasounddirected needle biopsies when desired.
• Anal canal malignancies evaluated by EAUS include leiomyosarcomas, malignant melanomas, anal canal adenocarcinomas,
and squamous cell carcinomas.
• Squamous cell or epidermoid carcinoma of the anal canal are
the most common anal canal malignancy. EAUS can be used in
7. Endoluminal Ultrasound 155
Fig. 7.16. This image depicts a fi stula-in-ano that has been enhanced by the
introduction of hydrogen peroxide. The hyperechoic features posteriorly represent the hydrogen peroxide within the fi stula tract ( short arrows ). There is an
obvious hypoechoic defect in the internal anal sphincter in the midline posteriorly (A), representing the internal fi stula opening. The hypoechoic horseshoe
tract can be seen extending toward the patient’s left.
the initial evaluation to stage the lesion as well as in follow-up
for patients with squamous cell carcinoma of the anal canal.
• Because squamous cell carcinomas of the anus are primarily
treated nonoperatively with combined chemoradiation therapy,
it is desirable to have an accurate method of staging to assess
response to multimodality therapy.
• Although clinical (digital) examination is important in the
assessment of squamous cell carcinoma of the anus, EAUS is
more precise in accurately measuring the actual size and circumferential involvement of the lesion. EAUS staging (uTNM)
of anal cancers corresponds to the TNM [UICC (International
Union Against Cancer)] staging (Table 7.3 ).
• The extent of sphincter involvement can be determined and
other staging systems stage these lesions based on depth of
invasion. One such staging system is depicted in Table 7.4 ).
Three-Dimensional Ultrasound
• Three-dimensional ultrasound allows for multiplanar imaging
of both the rectum and the anal canal.
156 The ASCRS Manual of Colon and Rectal Surgery
Table 7.3. Ultrasound staging classifi cation (uTNM) for anal canal cancer.
Primary tumor (T)
Tx Primary tumor cannot be assessed
T0 No evidence of primary tumor
Tis Carcinoma in situ
T1 Tumor 2 cm or less in greatest dimension
T2 Tumor more than 2 cm but no more than 5 cm in greatest
dimension
T3 Tumor more than 5 cm in greatest dimension
T4 Tumor of any size that invades an adjacent organ(s), e.g., vagina,
urethra, bladder (involvement of the sphincter muscle(s) alone is
not classifi ed as T4)
Regional lymph nodes (N)
Nx Regional lymph nodes cannot be assessed
N0 No regional lymph node metastasis
N1 Metastasis in perirectal lymph node(s)
N2 Metastasis in unilateral internal iliac and/or inguinal lymph
node(s)
N3 Metastasis in perirectal and inguinal lymph nodes and/or
bilateral internal iliac and/or inguinal lymph nodes
Distant metastasis
Mx Distant metastasis cannot be assessed
M0 No distant metastasis
M1
Distant metastasis
Table 7.4. Ultrasound staging classifi cation by depth of invasion
(uTNM) for anal canal cancer.
uT1 Tumor confi ned to the submucosa
uT2a Tumor invades only the internal anal sphincter
uT2b Tumor penetrates into the external anal sphincter
uT3 Tumor invades through the sphincter complex
and into the perianal tissues
uT4
Tumor invades adjacent structures
• Three-dimensional ultrasound can be used to assess anal fi stulous tracts, to evaluate anal sphincter injury, as well as to stage
both rectal and anal tumors.
• Comparison of standard two-dimensional ultrasound with 3DERUS and endorectal MRI and reported an accuracy for depth
of wall invasion by rectal cancer of 84, 88, and 91, respectively.
7. Endoluminal Ultrasound 157
• The accuracy of 3D-ERUS for predicting lymph node status
was 84.8% compared with 66.7% for conventional ERUS.
• Three-dimensional EAUS has also been applied to benign
anal disorders such as anal sphincter injury and anal fi stula
assessment.
8 . Preoperative Management:
Risk Assessment, Medical Evaluation,
and Bowel Preparation
A. Perioperative Risk Assessment Scoring Systems
• Risks related to surgery are a function of many factors. Patientrelated factors include the underlying disease processes and
the patient’s physical ability to tolerate the physiologic stress
related to the surgical procedure. Increasing amounts of data
now show that risk is also affected by the volume of a procedure performed at the medical institution, but perhaps most
importantly by the experience, training, and volume of surgery
performed by the individual surgeon.
• Scoring systems assess the patients’ risk for morbidity and
mortality as a result of anesthesia and surgery. These systems
generally use data acquired during pre-hospital and in-hospital
care, and some supplement this with components measuring
operative severity.
• Some classifi cation systems are designed to allow comparison
of results between institutions and surgeons, whereas others
are designed to distinguish patients who subsequently will
have postoperative adverse events from those who will not.
• A primary aim of a scoring system is the evaluation of therapeutic benefi t, i.e., the ratio of the relative harm and the relative
benefi t that are likely to follow a specifi c operation for a specifi c illness, whether in a specifi c patient, institution, or health
system. Parameters that are useful in this evaluation include
the natural history of the disease process, and the urgency of a
specifi c procedure.
D.E. Beck et al. (eds.), The ASCRS Manual of Colon and Rectal Surgery, 159
DOI: 10.1007/978-0-387-73440-8_8, © Springer Science + Business Media, LLC 2009
160 The ASCRS Manual of Colon and Rectal Surgery
Table 8. 1. Perioperative scoring systems (references in text).
Physiologic scores Preoperative scores
APACHE (I and II) ASA grading
E-PASS Goldman cardiac risk index
ISS/TRISS Hospital prognostic index
POSSUM Prognostic nutritional index
P-POSSUM Pulmonary complication risk
SAPS
Sepsis score
Sickness score
Therapeutic intervention score
• Age may have an infl uence on operative risk, as many elderly
patients require concurrent management of multiple organ
degenerative diseases. Elderly patients often tolerate operations well but tolerate complications poorly, hence prediction
of the potential morbidity of an operation is particularly important in this group of patients.
• Scoring systems also provide a useful means of comparing
outcomes from different institutions and patient groups by correcting for different comorbidities.
• Various scoring systems have been developed in an effort to quantify the risk of a patient from disease or intervention, and systems
can be classifi ed as preoperative or physiologic (Table 8.1 ).
Risk Assessment for Complications from Specifi c
Organ Systems
Cardiac Risk
Goldman Cardiac Risk
• The Goldman risk model is probably the best-accepted model for
pure determination of cardiac risk for surgery. Point scores are
assigned to each of nine clinical factors and patients are divided
into four risk classes based on the total point score (Table 8.2 ).
• This is an important score because it reminds clinicians of the
major cardiac risk factors in noncardiac surgery. Although the
system is easy to use and utilizes relative weighting of risk
factors, it was designed in the 1970s, and has not been updated
for modern practice in anesthesia, medicine, or surgery.
8. Preoperative Management 161
Table 8. 2. Goldman cardiac risk index.
Cardiac risk event Points
Myocardial infarction within 6 months 10
Age >70 years 5
S3 gallop or jugular venous distension 11
Important aortic valve stenosis 3
Rhythm other than sinus, or sinus
rhythm and atrial premature
contractions on last preoperative
electrocardiogram
More than fi ve premature ventricular
contractions per minute anytime
before surgery
Poor general medical status 3
Intraperitoneal, intrathoracic, or aortic
operation
Emergency operation
Class Points Life-threatening
complication
risk (%)
I 0–5 0.7 0.2
II 6–12 5 2
III1 3–25 11 2
IV 26 22 56
7
7
3
4
Cardiac death
risk (%)
Respiratory Risk
Pulmonary Complication Risk
• Findings on respiratory examination, chest X-ray, Goldman’s
cardiac risk index, and the Charlson comorbidity index have
been used for predicting respiratory complications.
Risk Assessment for Postoperative Morbidity
and Mortality
American Society of Anesthesiologists Classifi cation
• The American Society of Anesthesiologists (ASA) classifi cation system (Table 8.3 ) was initially developed to alert anesthesiologists to preexisting diseases. Because of the ease of use,
162 The ASCRS Manual of Colon and Rectal Surgery
Table 8. 3. ASA classifi cation scheme.
I Normal healthy patient
II Mild systemic disease
III Severe, noncapacitating systemic disease
IV Incapacitating systemic disease, threatening life
V Moribund, not expected to survive 24 h
E Emergency
and the fact that no tests are required, it has also been used to
estimate operative risk.
• ASA class directly correlates with perioperative mortality
and morbidity and also correlates signifi cantly with perioperative variables such as intraoperative blood loss, duration
of postoperative ventilation, and duration of intensive care
unit (ICU) stay.
• Disadvantages to using the ASA score are that the score awarded
depends on the subjective clinical judgment of the attending
anesthesiologist, and that the small numbers of groups available means there can be little meaningful comparison between
different surgeons or institutions.
Prognostic Nutritional Index
• The prognostic nutritional index (PNI) was devised to predict
complication risk based on mortality, and correlates with postoperative sepsis and death.
• The PNI uses four factors, namely, serum albumin level, serum
transferrin level, triceps skinfold thickness, and cutaneous
delayed-type hypersensitivity.
• Serum albumin level, serum transferrin level, and delayed
hypersensitivity were the only accurate predictors of postoperative morbidity and mortality.
• In addition to predicting postoperative morbidity and mortality, PNI can be used for predicting patients who might need
nutritional support in the perioperative period.
APACHE (Acute Physiology and Chronic Health Evaluation) Scoring
Systems
• This score was initially designed primarily for patients in the
ICU but has been used for the assessment of patients with severe
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