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Preoperative Imaging in Hernia S u r g e r y
Richard A. Pierce and Benjamin K. Poulose
3
Basics of Diagnostic Testing
In addition to a focused history and physical
exam, several imaging modalities are useful for
the detection and characterization of hernia
defects, and frequently, more than a single study
will be required. Ultrasound (US) has the advantages of being dynamic, in that the patient can be
positioned either upright or supine, and that
images can be obtained both while at rest and
while performing a Valsalva maneuver [ 3 ]. It also
avoids exposure to ionizing radiation, and can
potentially be performed in the surgeon’s offi ce.
However, ultrasound is very operator-dependent
and can be limited by patient body habitus.
Computed tomography (CT) is commonly used
in the identifi cation and characterization of ventral hernias, and somewhat less frequently in
identifying inguinal hernias. It is rapid, and most
surgeons are comfortable with interpreting the
images obtained. CT is limited, in that the patient
must be positioned either supine, or occasionally
prone, which may lead to spontaneous reduction
and lack of detection of small or easily reducible
hernias. Exposure to ionizing radiation may also
R. A. Pierce , M.D., Ph.D., F.A.C.S. (*)
B. K. Poulose , M.D., M.P.H., F.A.C.S.
Department of Surgery , Vanderbilt University
Medical Center ,
D-5203 Medical Center North, 1161 21st Avenue
South , Nashville , TN 37232 , USA
Richard.Pierce@Vanderbilt.Edu
e-mail:
be of concern in patients undergoing repeated
evaluations. Magnetic resonance imaging (MRI)
avoids the use of such radiation and gives excellent delineation of subtle tissue planes. Functional
MRI also has the advantage of being dynamic in
terms of allowing patients to perform a Valsalva
maneuver. Similarly to CT, however, the patient
must be either supine or prone, and the high cost
of this imaging modality is often restrictive.
Furthermore, most surgeons are generally not
comfortable with image interpretation. Although
not widely utilized in the United States, herniography can be benefi cial in the diagnosis of inguinal hernias. The images are usually easily
interpreted and the radiation exposure is signifi cantly less than that of CT. Unfortunately, the
procedure does carry with it the risks of visceral
puncture and potential reaction to the intraperitoneal dye injection [ 3 ].
The metrics of diagnostic testing are usually
described in terms of sensitivity, specifi city, and
predictive values (negative and positive).
Sensitivity and specifi city describe characteristics about the test itself. Given that the patient has
the disease, the probability the test is positive
describes sensitivity. Given that the patient does
not have the disease, the probability the test is
negative describes specifi city. Predictive values
refl ect real-world performance and take into consideration the prevalence of the disease. When a
test is positive, the probability that the patient
actually has the disease in question is the positive
predictive value (PPV). Conversely, when a test
Y.W. Novitsky (ed.), Hernia Surgery, DOI 10.1007/978-3-319-27470-6_3
23© Springer International Publishing Switzerland 2016
24
R.A. Pierce and B.K. Poulose
is negative, the probability that the patient does not
have the disease is the negative predictive value.
Inguinal Hernia
Patients who present with a complaint of groin
pain and an easily palpable bulge generally do
not present a diagnostic dilemma to surgeons.
The patient without a palpable bulge or impulse
with Valsalva presents a more challenging clinical scenario. In cases of inguinal strain, osteitis
pubis, athletic pubalgia, nerve entrapment, and
even femoroacetabular joint disorders, no defect
exists, and appropriate management will be different than a standard inguinal hernia repair.
However, small yet symptomatic hernias, and
even moderate-sized hernias in the obese can be
diffi cult to detect clinically. It is these “occult
hernias” that presented diagnostic challenges can
benefi t from the use of diagnostic imaging [ 4 ].
Ultrasound
Ultrasound is often considered the fi rst-line diagnostic test for the occult inguinal hernia. Although
quick, inexpensive, and noninvasive, US is subject to operator variability and may be limited by
an obese patient’s body habitus. A recent metaanalysis by Robinson et al. demonstrated US to
have a sensitivity of 96.6%, specifi city of 84.8%,
and a PPV of 92.6% [ 5 ]. However, these values
encompassed studies that included patients both
with and without palpable groin bulges, and the
authors note that both the sensitivity and PPV are
signifi cantly lower when only occult groin hernias were included [ 5 ]. In contrast, the specifi city
and negative predictive value were increased
when evaluating occult, as opposed to clinically
obvious, hernias. One such report from the
United Kingdom (UK) examined 52 patients
with a history suggestive of inguinal hernia, but
with a normal or inconclusive clinical exam.
When correlated with surgical fi ndings, US
showed a sensitivity of only 33%, and a specifi city of 100% [ 6 ]. Thus, we advocate that, if an
occult hernia is detected by US, then the diagno-
sis is confi rmed, but if no hernia is seen, the surgeon should consider other imaging modalities
before ruling out a true defect.
Computed Tomography
Despite its extremely widespread use in the
United States and Europe, there are relatively few
studies evaluating the use of CT in the diagnosis
of occult inguinal hernias [ 7 – 9 ]. A systematic
review and meta-analysis by Robinson and colleagues describe the overall sensitivity of CT as
being approximately 80%, and the specifi city
being approximately 65% [ 4 ]. This was actually
found to be inferior to both ultrasound and herniography in the same analysis. Additionally, CT
performed after intraperitoneal injection of contrast did not give any signifi cant improvement in
the sensitivity or specifi city versus standard herniography [ 5 ]. Nevertheless, despite its higher
cost, CT has the distinct advantage of evaluating
the entire abdomen, and thus may help identify
other sources of pain such as soft tissue and/or
skeletal abnormalities that might not be seen with
US or herniography. CT is also useful in evaluation of the multiply recurrent inguinal hernia
to assess potential involvement of adjacent
structures and displaced mesh prostheses.
Similarly, CT can be very helpful in delineating
inguinal defects that do not contain a true hernia
sac, but contain only herniated preperitoneal fat
that can be a cause of signifi cant pain if incarcerated (Fig. 3.1 ).
Thus, while US is the preferred fi rst-line
evaluation for the occult inguinal hernia, it is reasonable to proceed next to CT of the pelvis in the
setting of a compelling history for inguinal hernia but a negative clinical exam and negative or
equivocal ultrasound study.
Magnetic Resonance Imaging
Similarly to CT, there are few reports describing
MRI in the diagnosis of occult inguinal hernias.
Although noninvasive and safe, the modality is
expensive and may be uncomfortable for patients
3 Preoperative Imaging in Hernia Surgery
25
with claustrophobia. Surgeons are typically not as
comfortable with image interpretation as they are
with those obtained by CT. In a study by Leander
et al., MRI following herniography did not appear
to be superior to herniography alone with respect
to hernia detection. In the setting of a normal herniogram, however, MRI was able to identify other
potential sources of groin pain in a limited number
of patients [ 10 ]. A recent report by Miller et al.
actually showed MRI (sensitivity = 91%) to be
superior to both US (sensitivity = 33%) and CT
(sensitivity = 54%) in the diagnosis of occult
inguinal hernias [ 11 ] (Fig. 3.2 ). All patients
underwent an operation, used as the gold standard reference, and the authors state that MRI
correctly identifi ed an occult hernia in 10 out of
Fig. 3.1 Axial CT image of bilateral fat-containing inguinal hernias ( arrows ) without obvious hernia sac protru-
sion. Original image
11 cases where the hernia was not detected by
CT. The single patient with a false positive MRI
actually had a surgically correctable fascial tear
of the external oblique but no true hernia [ 11 ].
Thus, although not a fi rst- or second-line study,
MRI can play a valuable role in patients with signifi cant groin pain but an otherwise negative
workup. In fact, MRI is likely the preferred
modality in this setting, as it can not only rule out
an occult hernia, but also elucidate other causes
of groin pain such as osteitis pubis, femoral acetabular impingement (FAI) syndrome, and subtle
abnormalities of the musculoskeletal attachments
in the pelvis [ 3 ].
Herniography
First described in 1967 in Canada, herniography
is a technique that uses intraperitoneal injection
of radiopaque contrast followed by plain abdominal X-rays in the upright position to detect occult
inguinal hernias (Fig. 3.3 ).
Although somewhat more commonly utilized
in Scandinavia and the UK, it does not appear to
have been widely adopted in the United States
[ 4 ]. Nevertheless, herniography has been shown
to be highly sensitive and specifi c in several
reports [ 12 , 13 ]. A recent systematic review out
of the UK showed herniography to be superior to
both CT and US, with a sensitivity of 91% and
Fig. 3.2 MRI appearance of a small, fat-containing right inguinal hernia ( arrows ). ( a ) Axial, and ( b ) Coronal views.
From Leander (2000), with permission
26
R.A. Pierce and B.K. Poulose
Fig. 3.4 Axial CT image of a small left femoral hernia
( arrow ). Modifi ed from Burkhardt (2011), with
Fig. 3.3 Right inguinal hernia as seen on herniogram.
From Alam (2005), with permission
permission
preservation of the inguinal canal and its contents
specifi city of 83% [ 4 ]. Despite these excellent
results, this invasive procedure carries with it the
risk of injection site hematoma, visceral puncture, and vasovagal reaction to the intraperitoneal
dye, which may explain its lack of widespread
use in the United States [ 13 ].
[ 15 ]. In one retrospective study, CT correctly
identifi ed 74 out of 75 hernias (47 inguinal and
28 femoral) which were later confi rmed at surgery [ 14 ]. In the setting of an acute abdomen with
bowel obstruction, CT should be the fi rst mode of
imaging in order to evaluate for all possible
sources of obstruction, even if a femoral hernia is
the suspected culprit (Fig. 3.4 ).
Femoral and Obturator Hernias
Despite being the most frequently encountered pelvic fl oor hernias, obturator hernias are
Although only about 1/10 the incidence of inguinal hernias, femoral hernias are more prone to
strangulation (20% vs. 3% at 3 months after diagnosis) [ 14 , 15 ]. Thus, accurate diagnosis and
prompt surgical correction are extremely important to prevent bowel ischemia and necrosis in an
incarcerated femoral hernia. Clinical presentation is generally a mildly painful, nonreducible
groin bulge below the inguinal ligament, however, differentiation of a femoral from an inguinal hernia on physical exam is not entirely
reliable, regardless of the examining surgeon’s
experience [ 14 ]. Similarly to inguinal hernias,
ultrasound should be the initial imaging study if
there is ambiguity, with reported sensitivities and
specifi cities of approximately 100% in two separate studies [ 16 , 17 ]. As ultrasound does carry the
variable of being operator-dependent, any equivocal study should be followed by a CT in order to
confi rm or rule out the diagnosis. On careful
inspection, CT images will often display a subtle
indentation of the ipsilateral femoral vein with
even less common than femoral hernias, with an
incidence of 0.05–1.4% of all hernias [ 18 , 19 ].
However, rapid and accurate diagnosis is again
critical, as mortality can be as high as 70% when
obturator hernias become acutely incarcerated
[ 19 ]. Obturator hernias most commonly present
as unexplained intestinal obstruction in an
elderly, emaciated female patient without prior
abdominal operations. Small bowel obstruction
is the presenting complaint in nearly 90% of
cases, with variable physical fi ndings seen in the
“classic triad” of obturator hernia (obturator neuralgia, Howship-Romberg sign, Hannington-Kiff
sign). A palpable groin mass is a very uncommon
fi nding [ 18 , 19 ]. Ultrasound can occasionally be
useful in the diagnosis, as it can display the level
of bowel obstruction and distention. However, it
can also be fraught with inaccuracy due to the
relative depth of the obturator foramen within the
pelvis. Therefore, CT is considered the initial
imaging modality of choice, and several studies
have shown a near 100% accuracy in diagnosing
3 Preoperative Imaging in Hernia Surgery
27
obturator hernia [ 19 ]. Again, CT has the added
advantage of assessing the entire abdomen and
pelvis, and can thus rule out other possible
sources of obstruction, especially when oral contrast is used (Fig. 3.5 ).
Ventral Hernia
Similar to the occult groin hernia, detection of
smaller, yet symptomatic ventral and incisional
hernias can often be challenging, especially in
the obese patient. In contrast, incisional and
recurrent hernias of the ventral abdominal wall
often have the propensity to be highly complex,
Fig. 3.5 Axial CT image of a left obturator hernia
( arrow ). Modifi ed from Petrie (2011), with permission
involving signifi cant adhesions to both omentum
and abdominal viscera, abdominal muscle atrophy, and even loss of abdominal wall domain in
the setting of a very large defect. Consequently,
thorough evaluation and treatment of the ventral
hernia can require both rapid and inexpensive
modalities for detecting small defects, as well as
high-resolution studies capable of predicting
repair complexity in large recurrent defects.
Ultrasound
For detecting ventral abdominal hernias, US again
has the advantage of being inexpensive, dynamic,
and noninvasive. In the past, however, its utility has
been limited by lack of standardize technique and
operator variability, resulting in a sensitivity of only
71% [ 20 ]. Recently, Beck et al. have described a
straightforward, standardized, and surgeon performed approach to using US and the detection of
midline and lateral abdominal hernia defects [ 21 ].
Termed Dynamic Abdominal Sonography for
Hernia (DASH), the technique uses a 12-MHz linear ultrasound probe in fi ve sequential cranial-tocaudal passes of the ventral abdominal wall to
detect even small fascial defects (Fig. 3.6 ).
Fig. 3.6 Dynamic Abdominal Sonography for Hernia
(DASH) schematic ( left panel ) and representative ultra-
sound images from the ( a ) midline epigastrium, ( b ) umbi-
licus, ( c ) midline below the arcuate line, ( d , f ) left and
right linea semilunaris, ( e , g ) left and right oblique muscu-
lature ( right panel ). From Beck (2013), with permission
28
R.A. Pierce and B.K. Poulose
DASH has resulted in a highly sensitive (98%)
and specifi c (88%) method for hernia detection,
even exceeding that of CT, costing signifi cantly
less and avoiding a dedicated trip to the radiology
suite [ 21 ]. Ultrasound evaluation can still be lim-
ited in the severely obese with a very thick layer
of subcutaneous fat obscuring the fi ne detail of
the underlying abdominal wall. Additionally,
comprehensive evaluation of large defects by
ultrasound can be challenging due to small probe
size and the inability to perform three-dimensional reconstruction of the hernia sac. Both of
these limitations can potentially be overcome by
the use of an Automated Breast Volume Scanner
(ABVS) as described in the recent report from
Diao et al. [ 22 ]. At our institution, we typically
rely on the use of DASH to assess for small primary defects or recurrences in patients presenting with new pain or bulge. We then standardly
proceed to CT scanning for larger or more complex defects requiring further delineation of anatomic detail.
Computed Tomography
Due to its rapid image acquisition, demonstration of fi ne morphologic detail, 3-D reconstructability, and reproducibility, CT is generally the
most popular imaging modality for the evaluation of known ventral abdominal hernias [ 3 ].
Although a non-contrasted study is suffi cient in
most situations, IV contrast should be used if
there is a suspicion of infection or malignancy
and the patient has satisfactory renal function.
Perhaps most important is the ability to use CT
imaging to preoperatively predict the surgeons
ability to close a given hernia defect in an
abdominal wall reconstruction scenario. Several
algorithms are currently being developed for this
purpose, such as the one described by Allen and
colleagues. Their protocol allows for highly
accurate length and volume calculations of the
critical abdominal wall structures and compartments from otherwise standard axial and sagittal
CT images [ 23 ] (Fig. 3.7 ).
Fig. 3.7 Axial CT images showing abdominal wall segmentation and labeling. Top panel : ( a ) rectus abdominis/
pyramidalis musculature, ( b ) oblique musculature, ( c )
psoas muscles, ( d ) linea alba, ( e ) linea semilunaris, ( f )
umbilicus, ( g ) xiphoid process, ( h ) anterior superior iliac
spines, ( i ) pubic symphysis. Bottom panel : ( a ) outer
abdominal wall, ( b ) inner abdominal wall, ( c ) posterior
abdominal cavity. From Allen (2013), with permission
3 Preoperative Imaging in Hernia Surgery
29
In a recent report, Franklin et al. retrospectively analyzed CT images from patients who
underwent abdominal wall reconstruction with
component separation over a 5-year period.
Signifi cant differences were seen with regard to
transverse defect size, defect area, and the percentage of the total abdominal wall occupied by
the defect in patients in whom fascial reapproximation was achieved as opposed to those two
required a bridged repair [ 24 ]. Having such
knowledge preoperatively can signifi cantly infl uence surgical decision making in terms of an
open versus laparoscopic approach, the type of
mesh prosthetic used, and ultimately the placement of prosthetics. This is especially applicable
in the setting of a recurrent hernia and a planned
reoperation for abdominal wall reconstruction.
Thus, it is commonplace to obtain preoperative
CT scans on patients with large, complex, or
recurrent defects. This allows for optimal operative planning and it maximizes the surgeon’s
chances of achieving fascial closure in these
challenging patients.
Magnetic Resonance Imaging
Given the high degree of accuracy with which
CT is able to characterize most ventral hernia
defects, the use of MRI for this purpose is signifi cantly limited. Although it does avoid radiation
exposure of CT, additional cost of MRI is not
typically justifi ed to use as a routine imaging
modality [ 3 ]. The one advantage that MRI can
have over CT in the setting of recurrent hernia is
an enhanced ability to visualize prosthetic mesh
and its potential for dynamic assessment of the
abdominal wall and visceral motion when using
functional “cine” MRI. Namely, images can be
obtained with the patient both at rest and during
performance of a Valsalva maneuver. The motion
of the abdominal viscera relative to that of the
abdominal wall (“visceral slide”) can then be
ascertained and used to predict the degree of
adhesion formation in a postoperative patient
[ 25 ]. In May 2009 report by Kirchhoff et al.,
functional cine MRI was used to locate and quantify intra-abdominal adhesions in 43 patients who
had undergone prior ventral hernia repair by
either an open or laparoscopic approach. Twentyfi ve patients subsequently underwent reoperation, and after quantifying adhesions
intraoperatively, the accuracy of MRI for predicting these adhesions was found to be approximately 86% [ 26 ]. The routine use of MRI for
ventral hernia evaluation is not currently advocated outside the setting of a clinical trial.
However, the imaging modality does show prominence for adhesion identifi cation and could
infl uence surgical decision making in patients
without a detectable recurrence, but with signifi cant abdominal pain after prior ventral hernia
repair with mesh placement.
Conclusion
In terms of inguinal hernia detection, the initial use
of US, possibly followed by CT, represents a sensitive and cost-effective progression for the evaluation of the patient with a clinical history suggestive
of a hernia, but without evidence of a hernia on
exam. Herniography is not widely utilized, but it
does represent a sensitive and specifi c test in the
hands of an experienced radiologist. MRI may be
used to further evaluate other causes of groin pain in
a patient with a negative US or CT study.
For ventral hernias, the use of DASH in the
clinic is highly sensitive and specifi c if the diagnosis of a new or recurrent defect is in doubt.
While MRI may be used in a research setting at
this time, it should not supplant the use of CT. The
use of CT is recommended in patients with large,
recurrent, or complex ventral hernias in order to
optimize preoperative planning and maximize
the chance of obtaining abdominal wall defect
closure.
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Preoperative Preparation of the Patient Undergoing Incisional Hernia Repair: Optimizing Chances for Success
Robert G. Martindale and Clifford W. Deveney
4
Introduction
The recurrence rate following a seemingly successful incisional hernia repair is reported to be
between 10 and 60%. Although the majority of
recurrences occur within 2 years of repair, these
hernias can recur for up to 20 or 30 years following the index procedure [ 1 ]. Repairs of recurrent
hernias have an even higher recurrence rate [ 1 ].
Although some causes of hernia recurrence are
related to surgical technique, several patient factors contribute profoundly to hernia recurrence
by delaying wound healing, or actually causing
necrosis or absorption of connective tissue. It is
also well-reported that perioperative surgical site
occurrence (SSO), defi ned as infection, seroma,
wound ischemia, and dehiscence increases the
risk of recurrent hernia by at least threefold, if not
more [ 2 ].
Because the success of hernia repair is often
measured by the absence of recurrence, the focus
of preoperative optimization aims at eliminating
factors that inhibit wound healing. Welldocumented factors of adverse effects on wound
healing include smoking, obesity, hyperglycemia, nutritional defi ciencies, and infection.
R. G. Martindale (*) • C. W. Deveney
Department of Surgery , Oregon Health and Science
University ,
3181 SW Sam Jackson Park Road, L223A , Portland ,
OR 97239 , USA
martindr@ohsu.edu; deveneyc@ohsu.edu
e-mail:
Modifi able factors should be addressed and
corrected before elective repair, if possible. By
correcting, eliminating, or reducing them if they
are abnormal, one optimizes a patient’s chance of
undergoing successful hernia repair without
recurrence, post-op infectious complications, or
delayed wound healing [ 3 ].
Smoking
There are numerous studies that have documented the deleterious effects of smoking on
wound healing and the role cessation has in the
prevention of wound infections [ 4 , 5 ]. Cigarette
smoke contains myriad of compounds, such as
nicotine, carbon monoxide, hydrogen cyanide,
nitrogen oxides, nitrosamines, aldehydes, and
polyaromatic hydrocarbons, all or some of which
affect every aspect of wound healing. The adverse
effects of smoking are well-summarized in two
recent reviews [ 6 , 7 ].
One of the principle effects of smoking is
decreased tissue oxygenation. Low oxygen tension leads to tissue ischemia and necrosis in marginally perfused tissue, and is reversed within an
hour of smoke inhalation. There are many other
additional detrimental effects on the infl ammatory and reparative processes of wound healing
that predispose a patient to complications such as
infection, dehiscence, and recurrent hernia.
Several clinical studies have demonstrated a
maximal response to smoking cessation 3–4
Y.W. Novitsky (ed.), Hernia Surgery, DOI 10.1007/978-3-319-27470-6_4
31© Springer International Publishing Switzerland 2016
32
R.G. Martindale and C.W. Deveney
weeks post-operatively [ 8 , 9 ]. After 4 weeks, the
infl ammatory components of wound healing normalize, but the proliferative phase of wound
healing is still blunted. Nicotine attenuates the
infl ammatory phase of wound healing, but
enhances the proliferative phase. In clinical trials, the effects of nicotine replacement therapy
used in aiding smoking cessation do not seem to
have detrimental signifi cance [ 10 ].
With the abundance of information regarding
the negative effects of smoking on wound healing, we require that all patients who will be
undergoing elective herniorrhaphy cease smoking for at least 1 month before surgery. It is currently unclear whether or not nicotine patches
alter wound healing or have adverse infl uence on
post-operative physiology; as such, the use of
nicotine patches as an aid to stop smoking is
allowed. If the patient wears the patch, however,
the physician will be unable to confi rm abstinence from smoking with serum or urine nicotine
levels. At our institution, we therefore reserve its
use for those patients who seem most reliable,
and have cohabitants that can corroborate their
abstinence from smoking. It is also important to
advise the patient that it will be necessary to
abstain from smoking for at least 1 month following surgery, though permanent cessation is preferable because smoking will affect tissue healing,
even after 1 month.
patients with a BMI ≥ 50. In our prospective data-
base (2300 patients), the recurrence rate following
hernia repair in those patients with a BMI ≥ 50
approaches 100%. It takes months for a patient to
lose signifi cant weight, even following a bariatric
operation. If the surgeon has the luxury to delay
(e.g., in the case of minimally or non-symptomatic
reducible hernia), he or she should do so until the
patient has lost a considerable amount of weight.
Unfortunately, for those hernias which are symptomatic or incarcerated, the surgeon does not have
this advantage.
Although it would be ideal for obese patients
to lose weight perioperatively, in the majority of
cases they do not. In the morbidly obese patient
with an epigastric hernia who is to undergo a
laparoscopic bariatric procedure , the hernia may
or may not be repaired at the time of that procedure. If the bariatric procedure is an open one, it
may be necessary to repair the hernia to safely
close the abdomen. If the bariatric procedure can
be done laparoscopically, the hernia may also be
repaired laparoscopically [ 11 ]. If the hernia is
symptomatic, or presents a threat of strangulation, the priority would be to repair the hernia and
perform the bariatric procedure only if it can be
done safely [ 12 ].
Glucose Control
Obesity
Smoking cessation, glycemic control, and nutritional and metabolic support can all be achieved
over a relatively short time (1–5 weeks), but obesity is a much weightier problem and unfortunately takes months to resolve in the best setting. It
is probably the greatest concomitant factor infl uencing the development of incisional hernias and
their recurrence. The effect of obesity on hernia
formation is particularly pertinent in this era,
where obesity rates have been increasing by epidemic proportions worldwide. With increasing
weight, the probability of recurrence also increases
almost exponentially. Presently, literature supports
not performing routine elective hernia repairs in
It has been established that post-operative hyperglycemia is associated with an increase in surgical site infections (SSI). In a study of patients
undergoing surgery in the Veterans
Administration hospitals, an increased rate of SSI
was seen in patients with HbA1c > 7%. The
authors of this article recommended that, when
possible, glycemic control should be used until
the HbA1C is 7% or lower [ 13 ]. In another study,
it was found that the rate of SSI increased in
increments of 30% when the glucose level
increased by 40 mg/dL, over a normal level of
110 mg/dL [ 14 , 15 ]. The control of post-op glu-
cose levels in the prevention of SSI seems to be
most critical in the fi rst 24 hours, because
hyperglycemia impairs the ability of neutrophils
to kill any bacteria in a wound.