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Pathophysiology andDiagnostics ofVentral andIncisional Hernias
269
24
. Fig.24.3 CT scan shows rectus diastasis
. Fig.24.4 CT scan shows incarcerated large umbilical
hernia
measured easily (. Figs.24.3, 24.4, and 24.5). By
using computed tomography, clinically and sonographically undiscovered hernias can be diagnosed. Likewise possible further pathological
ndings can be eliminated. In most cases, pseudorelapses can be detected by means of CT investigation. With large hernias, an approximate
measurement of the ratio between the volume of
the hernia’s contents and the abdominal cavity is
possible (. Fig. 24.6). is is particularly indispensable in terms of hernias with loss of domain,
in order to make a decision about the necessary
preoperative preparation of the patient. Also with
traumatic hernias, we undertake a CT investigation so that accompanying injuries can be
excluded.
. Fig.24.5 CT scan shows incarcerated small umbilical
hernia
. Fig.24.6 Incarcerated incisional hernia with large
defect and big hernia content
MRI scans are performed very rarely in con-
nection with ventral hernia.
24.2 Part II
24.2.1 Scientic Evidence
Preoperative diagnostics are essential to decide
for which technique of hernia repair to opt. We
must know as exact as possible how big the defect
is, how many defects there are, how big the hernia
sac is, and what are the hernia sac contents.
Dynamic abdominal sonography is a useful
tool for the accurate characterization of incisional hernia. Especially for obese patients and
24
270
R. Schrittwieser
. Fig.24.7 Incisional hernia: CT shows precisely the
thickness of the abdominal wall and the size of the defect
and gives information about the hernia content
in patients with large hernias, it demonstrated its
accuracy [1]. It oers the advantages of real-time
imaging and no ionizing radiation.
With regard to preoperative CT investigation, there are isolated studies, which in some
cases provide important additional new information. Killeen et al. [2] carried out CT examinations of patients with blunt abdominal trauma
and traumatic hernias. 9 of the 14 patients were
found to have accompanying injuries, although
only 1 patient displayed clinical indications of
a hernia. Computed tomography can therefore
supply valuable information about accompanying injuries, about potential hematomas, and also
about the general condition of the hernia. But CT
scans also provide important information about
the clinically relevant parameters of the hernia
(. Figs.24.6, 24.7, 24.8, and 24.9). Protocols were
developed to predict the need for a bridging mesh
or if fascial closure can be reached [3].
Likewise a CT investigation can be helpful
with rare hernias. Skrekas etal. [4] reported the
case of a patient with swelling in the le lumbar
region, which computed tomography showed
as being a Grynfeltt hernia. Gough et al. [5]
described an incarcerated spigelian hernia as the
cause of abdominal pain.
In connection with obese patients, there
are references in literature indicating that new
information can be obtained through computed
. Fig.24.8 CT shows a hernia umbilicalis with a
concomitant rectus diastasis
. Fig.24.9 Trocar hernia: CT shows severe small bowel
ileus because of a strangulated hernia
tomography. us, Rose et al. [6] reported that
with three patients it was not possible to clinically
diagnose a ventral hernia. However, by undertaking CT investigations, ventral hernias were discovered to be the cause of the complaint.
In relation to undertaking an MRI investigation within the context of preoperative diagnosis,
there is at present insucient data in order to be
able to give any recommendations, although there
is literature that indicates that a cine MRI can be
helpful to detect intraperitoneal adhesions [7].
Pathophysiology andDiagnostics ofVentral andIncisional Hernias
271
24
References
1. Baucom RB, Beck WC, Phillips SE, Holzman MD, Sharp
KW, Nealon WH, et al. Comparative evaluation of
dynamic abdominal sonography for hernia and computed tomography for characterization of incisional
hernia. JAMA Surg. 2014;149(6):591–6. https://doi.
org/10.1001/jamasurg.2014.36.
2. Killeen KL, Girard S, De Meo JH, Shanmuganathan K,
Mirvis SE.Using CT to diagnose traumatic lumbar hernia. AJR Am J Roentgenol. 2000;174(5):1413–5.
3. Xu Z, Asman AJ, Baucom RB, Abramson RG, Poulose
BK, Landman BA. Quantitative CT imaging of ventral
hernias: preliminary validation of an anatomical labeling protocol. PLoS One. 2015;10(10):e0141671. https://
doi.org/10.1371/journal.pone.0141671. eCollection
2015.
4. Skrekas G, Stafyla VK, Papalois VE.A Grynfeltt hernia:
report of a case. Hernia. 2005;9(2):188–91. Epub 2004
Sep 10.
5. Gough VM, Vella M. Timely computed tomography
scan diagnoses spigelian hernia: a case study. Ann R
Engl Coll Surg. 2009;91(8):W9–10. https://doi.org/10.1
308/147870809X450629.
6. Rose M, Eliakim R, Bar-Ziv Y, Vromen A, Rachmilewitz
D. Abdominal wall hernias. The value of computed
tomography diagnosis in the obese patient. J Clin Gastroenterol. 1994;19(2):94–6.
7. Mussak T, Fischer T, Ladurner R, Gangkofer A, Bensler S,
Hallfeldt KK, etal. Cinemagnetic resonance imaging vs
high-resolution ultrasonography for detection of
adhesions after laparoscopic and open incisional hernia repair: a matched pair pilot analysis. Surg Endosc.
2005;19(12):1538–43.
Classication ofVentral
andIncisional Hernias
UlrichA.Dietz andJulianeBingener-Casey
25.1 Introduction – 274
25.2 Chevrel andRath (2000) – 275
25.3 Consensus Classication of
Korenkov etal. (2001) – 276
25.4 Würzburg Classication (2007) – 277
25.5 EHS Classication (2009) – 279
273
25
25.6 Conclusions andProspects – 279
References – 281
© Springer-Verlag GmbH Germany, part of Springer Nature 2018
R. Bittner et al. (eds.), Laparo-endoscopic Hernia Surgery,
https://doi.org/10.1007/978-3-662-55493-7_25
274
U. A. Dietz and J. Bingener-Casey
25
25.1 Introduction
Classications are an expression of the need for
structure and organization within complex realities. e manner in which complex phenomena are
classied is fundamental to how they are understood and dealt with [1]. It is therefore necessary
that classication systems are subjected to validation. e rst step in this process can be the retrospective evaluation of the data that were collected
and the second step prospective conrmation of
the validation. A classication system is accepted
as useful if it can generate veriable hypotheses.
In the validation process, a classication is tested
for its utility in answering specic questions, a test
that can have one of three results: the system is veried (its methodology conrmed), it is falsied (its
methodology refuted), or the test is inconclusive
(neither conrmed nor refuted). Validation of a
classication conrms that it has met the requirements for its intended use. Any classication,
however, is valid only so long as it can withstand
or adapt to continued critical testing based on continuous renement of the knowledge on which it is
based. Unlike truth, provisional validation is based
on a large body of basic data [2]. Every type of classication thus relies on empirical validation. e
goal is to create an evidentiary foundation upon
which to build as knowledge increases [3].
Surgical data sets can be very heterogeneous:
values, entities, terminologies, conventions, ontologies, and algorithms are only a few of the facets.
Such data sets can only be organized by taking into
account factors that extend far beyond the eld of
surgery. Philosophy contributes in providing epistemological methodologies and the consequences
arising from them. Computer science and statistics
facilitate the systematic collection and evaluation
of information– especially large bodies of data.
But what instruments are available for validating
systems of classication? e following discussion
of the methodology of validation of incisional hernia classications will explore the signicance of
taxonomy and the choice of validation criteria.
Classication of any entity requires from the
outset general acceptance and clarity regarding the
terms applied. A nomenclature attempts to anchor
the meaning of words within a system and incorporates for this purpose in terms of natural language in an analyzable data set [1]. is requires an
unambiguous and unique taxonomy of both terms
and abbreviations. In the context of international
communications, in particular, the use of natural
language is of vital importance; at the start a widely
recognized language and/or nomenclature must
be worked out [1]. In medicine this consists in
large part of Latin roots and the English language
(Anglicization of communication). It is precisely
in the English-speaking world that the use of natural language is widespread in surgery. A precise,
simple, practical, everyday relevant terminology
is essential. Confusion and misunderstanding are
especially likely in the use of eponyms and abbreviations. It can be assumed that in international
publications, denitions and terminologies will be
used fortuitously, imprecisely, and injudiciously;
this should be prevented by all means.
In order to avoid sources of error in classications, the terminology must ensure the most objective possible statements regarding the entities they
are classifying. Terminology must always remain
distinct from concepts because concepts change
over time with the natural increase in knowledge.
Terminologies and denitions must be comprised
of recognized terms free of bias. Terminology
can be dened as follows: “Standardized terms
and their synonyms which record patient ndings, circumstances, events, and interventions
with sucient details to support clinical care,
decision support, outcomes research, and quality
improvement; and can be eciently mapped to
broader classications for administrative, regulatory, oversight, and scal requirements” [4]. A
clear terminology makes the comparison of data
from multiple patients possible, a key to improving patient care [4]. Consider the virtual scenario:
data from a patient is entered into a data bank,
and a request is made to see whether the system
already contains data from a similar case. If a similar case is found, information of the prior patient’s
outcome should be made available and what can
be predicted regarding the present patient based
on this “model patient” [1, 4, 5]. e signicance
of unambiguous terminologies for the sharing of
medical knowledge nds its strongest expression
in the Unied Medical Language System (UMLS).
How complex can a data set be and still be of
use in clinical routine? e complexity of medical
knowledge is best conveyed by breaking it down
into smaller units. How this can be done is explained
in the theory of granular partitions [6]. Granularity
is the way in which something can be tted into a
Classication ofVentral andIncisional Hernias
275
25
larger context and determines the perspective from
which knowledge or data are viewed. e higher
the level of granularity (as in an organigram), the
more general is its subject matter (simpler, more
intelligible, more supercial); the lower the granulation level, the ner are its details distinguished
from entities at an immediately higher level (clearer,
more focused, ner grained). us, dierent granulation levels are created. e ndings on patients
with, e.g., incisional hernias are apportioned to different levels of granulation, which allows the data
to be viewed and used from dierent perspectives.
A classication of incisional hernias must therefore
apply terminologically unambiguous criteria and
a level of granulation that balances a minimum of
information (for meaningful clinical utility) and a
maximum of predictive value.
Four classications described in the literature
attempt to summarize these essential points [7–10].
25.2 Chevrel andRath (2000)
e 2000 classication of Chevrel and Rath
represents the rst attempt to classify incisional
hernias [7]. It applies three criteria: the site of
the incisional hernia, its width, and the type of
occurrence (. Fig. 25.1). e site of the hernia
is divided into two groups: medial (“M”) and
lateral (“L”); each group is further divided into
subgroups. Because the authors chose the site of
the hernia in relation to the midline rather than
morphology, clinically relevant aspects are disregarded. Medial hernias are classied in their
relation to the umbilicus, which is not always of
clinical relevance. Supraumbilical hernias (M1),
for example, can vary greatly depending on the
nature of the sternocostal angle, whereas subumbilical hernias (M4) are of particular concern
if they are suprapubic (lack of posterior rectus
sheath). Chevrel and Rath dene the size of the
hernial opening by width (“W”) subdivided
in 5 cm increments (W1 to W4), thus registering but a single aspect of the size and rendering impossible by this subgrouping subsequent
defragmentation of the data. Because morphology and width are coded applying an arbitrary
principle, the data set reects an interpretive bias.
In their original paper, the authors oer a validation, but they limit it to a denition of the patient
population without epidemiological or prognostic relevance [7].
. Fig.25.1 Chevrel and
Rath (2000) classication
[of incisional hernias]. The
morphology (site) is
divided into medial and
lateral and the hernial
opening measured only as
width. This sets limiting
values for future subgroup
analyses with a variance of
5cm. Already in 2000,
Chevrel and Rath pointed
out the importance of
recurrence status
Chevral and Rath (2000)
Site:
Medial incisional hernias are coded as M, with 4 subgroups:
M1 - supraumbilical incisional hernias
M2 - juxtaumbilical incisional hernias
M3 - subumbilical incisional hernias
M4 - xipho-public incisional hernias
Lateral incisional hernias are coded as L, with 4 subgroups:
L1 - subcostal incisional hernias
L2 - transverse incisional hernias
L3 - iliac incisional hernias
L4 - lumber incisional hernias.
Width (preoperative measurement) is classified by 5 cm increments:
W1 - < 5cm
W2 - 5 to 10 cm
W3 - 10 to 15 cm
W4 - > 15 cm
Recurrence is defined by its number:
No recurrence:
First recurrence:
Second recurrence:
Rfirst
R1
R2, etc.
276
U. A. Dietz and J. Bingener-Casey
25
25.3 Consensus Classication of
Korenkov etal. (2001)
A second incisional hernia classication system is that of Korenkov et al., whose criteria
were worked out by an international panel of
experts [8]. As with Chevrel and Rath, the recommended criteria are “site,” “size,” and “recurrence” (. Fig.25.2) [7, 8]. e category “site” is
subdivided into vertical, transversal, oblique, and
combined. is morphological approach takes
into account anatomical features that are highly
important for hernia repair. e “size” of the hernial opening is categorized according to length
or width into three subcategories, large, medium,
and small. Here too, Korenkov’s denition “length
or width” is inadequate from the clinical point of
view because in the planning of a Ramirez operation, for example, it is important to note whether
it is the length or the width that is “large.” A new
. Fig.25.2 Classication
criteria of Korenkov etal.
(2001). Categorization of
the morphology notes the
orientation of the incision,
and thus groups under
vertical hernias morphologically are very diverse
types of hernia, such as
midline and paramedian
hernias. The categorization
of hernial opening size is
done similar to Chevrel and
Rath but with only three
subcategories. The criterion
“symptomatic” can be
useful for “watchful
waiting,” and it need not
however be part of a
classication
Korenkov et al. (2001)
According to localisation:
Vertical
1
1.1
Midline above or below umbilicus
Midline including umbilicus right or left
1.2
Paramedian right or left
1.3
Transversal
2
Above or below umbilicus right or left
2.1
Crossed midline or not
2.2
Oblique
3
Above or below umbilicus right or left
3.1
4
Combined (midline + oblique; midline + parastomal; etc)
According to size:
Small (<5 cm in width or length)
1
Medium (5–10 cm in width or length)
2
Large (> 10 cm in width or length)
3
According to recurrence:
Primary incisional hernia
1
Recurrence of an incisional hernia (1,2,3, etc. with type of hernioplasty:
2
adaptation, Mayo-duplication, prosthetic implantation, autodermal etc.)
criterion is used regarding the hernial opening
(“reducible” or “not reducible”) and clinical presentation (“symptomatic” or “asymptomatic”).
e Korenkov classication does not include risk
factors [8].
e classications of Chevrel and Korenkov
were rarely used. is may be due to their imprecise taxonomy of morphological ndings and the
categorization into interpretative subgroups, both
deviations from natural language and early obstacles to granularity. Both classication systems
oer little room for the addition of lower granulation levels to accommodate advances in medical knowledge. An entirely dierent approach
is taken by the Ventral Hernia Working Group,
which recommends a hernia grading system
based on risk factors for a tailored approach and
for mesh selection (biological or synthetic). is
instrument, however, does not represent a true
incisional hernia classication [11].
According to the situation at the hernia gate:
Reducible with or without obstruction
1
Irreducible with or without obstruction
2
According to symptoms:
Asymptomatic
1
Symptomatic
2
Classication ofVentral andIncisional Hernias
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25
25.4 Würzburg Classication (2007)
e Würzburg Incisional Hernia Classication
does not only allow an easily comprehensible
classication of hernia ndings but the preoperative assessment of risks for use in surgical planning [9]. It encompasses three granularity levels:
(1) pathophysiologically dierent “ventral” and
“incisional” hernias; (2) the criteria “occurrence,”
“morphology,” “size,” and “risk factors”; and (3)
a more precise breakdown of the criteria of levels (1) and (2). e pathophysiological category
(pv=primary ventral or pi=primary incisional)
is present as “occurrence” in the incisional hernias, with the addition if applicable of the number
of recurrences (e.g., r1, r2, etc.). e morphology involves the clinical-anatomic description
of what the examiner sees in the patient (natural
language) applying accepted anatomical terms
(median, median-subcostal, umbilical, suprapubic, transversal, subcostal, and/or lumbal), with
the optional designation as “not classiable”
(n.c.). ese terms can be inserted into the classication scheme using their respective unambiguous abbreviations with no interpretive loss.
Taxonomically, the terms are dened and meet the
abovementioned requirements for nomenclature;
no conicts of semantic comprehension arise. e
size of the hernial opening is measured in length
and width, which allows calculation of the elliptic
area of the hernia orice. e last criterion is the
number of relevant risk factors (. Fig.25.3) [9].
A good example of a successful taxonomy
with abbreviations is the TNM classication [14].
In analogy to the TNM classication, the graphic
representation of the Würzburg Classication is
not given as a table but as a hernia formula. is
can be easily included in any medical report. e
data in our own classication are not divided into
categories, which enables adaptation of individual
criteria with variation in cutos– in the sense of
regroupings– to be made in light of future developments with no loss of data [14].
Heuristic criteria are of central importance
in the validation process. Useful solutions must
be found applying limited knowledge and an
acceptable expenditure of time. Ideal for this purpose are simple data sets which provide a good
overview of the case at hand [15]. Validation of
the Würzburg Incisional Hernia Classication
conrmed that (a) the contents of the data collection are available in clinical routine, (b) individual
errors did not endanger the entire data set, and
(c) the collected data delivered epidemiological and prognostic clues that can be applied in a
treatment algorithm. In-house validation of the
Würzburg Classication was done in 2012 using
a cohort of 330 patients. In multivariate analysis,
“occurrence” (on the rst granularity level) was an
independent predictor for the occurrence of postoperative complications: “ventral hernias” had
fewer complications than “primary incisional hernias,” while these in turn had fewer complications
than “recurrent incisional hernias” (OR 2.04; 95%
CI 1.09–3.84). In our cohort, morphology was
a not a signicant factor; this however was confounded by the fact that morphology as a criterion
was already preoperatively part of the decisionmaking process regarding the surgical procedure.
e “width” of the hernia opening can also serve
as a predictor of the occurrence of postoperative
complications in multivariate analysis (OR 1.98;
95% CI 1.19–3.29; <5cm vs. >5cm). e “length”
of the hernial opening is an independent predictor
of recurrence during follow-up (HR 2.05; 95% CI
1.25–3.37; <5cm vs.>5 cm). Comorbidities also
have an inuence on the incidence of recurrences
(HR 2.25; 95% CI 1.28–9.92) [12, 16].
ese classication criteria can be of great
practical value in routine clinical practice. e
morphology is regarded by some authors as important for planning surgical strategy. Conze (2005)
and Losano (2007) point out the peculiarities of
subxiphoidal incisional hernias, in the Würzburg
system denoted as “Mm+sc” (median+subcostal) [17, 18]. Varnell (2008) describes the special
characteristics of the suprapubic incisional hernias and underscores the importance of this morphological subgroup [19]. ese examples show
that the grouping of these hernias exclusively as
“median hernias” does not do justice to the surgical exigencies. e phenotype of the patient must
sometimes also be considered, being especially
relevant to surgery on subxiphoidal hernias with
a narrow subcostal angle [9]. Also of clinical relevance is the complex of comorbidities, termed
risk factors. In an overview paper, Höer (2002)
retrospectively investigated the cause of incisional
hernias in 2,983 patients who had undergone
laparotomy and emphasized the signicance of
25
278
U. A. Dietz and J. Bingener-Casey
Dietz et al. (2007)
Median (Linea alba) Lateral
Median (m) Umbilical (u) Suprapubic (sp)Median+Subcostal
(m+sc)
Subcostal (sc) Transversal (t) Lumbal (1) Paramedian (pm)
Occurrence M = morphology S = size (cm) RF = risk factors
p (primary)
r (recurrent)
. Fig.25.3 Würzburg Classication according to Dietz
etal. (2007) [9]. This classication notes the dierence
between ventral and incisional (v/i); in morphology (M), it
takes into account phenotypical criteria that can inuence
the choice of OP technique (e.g., “m+sc”), calculates
u (umbilical)
sp (suprapubic)
sc (subcostal)
t (transversal)
I (lumbal)
pm (paramedian)
nc (other)
v/i M... S...X... RF...
(+
→
+++)
a x bm (median)
hernial opening size as length × width (S), and registers
risk factors of possible prognostic relevance (RF). Every
risk factor is qualied by a “+,” up to a maximum of “+++.”
The Würzburg Classication underwent in-house
validation on a series of 330 patients [12, 13]
Obesity (BMI >25)
Male gender
Nicotine abuse
Wound contamination
Age > 45 years
Disease
2nd laparot. < 1 month
Emergency procedure
Postop. Complicaitons
...
Classication ofVentral andIncisional Hernias
279
25
the endogenous risk factors [20]. Klinge (2001)
pointed out the importance of collagen [21] and
Sorensen (2005) of smoking [22]. Jenkins (2010)
thought COPD was an independent factor that
exacerbated the complexity of laparoscopic hernia surgery, while the higher the BMI and ASA
status, the longer the time needed to create the
pneumoperitoneum [23]. Similarly, Klinge (2008)
postulated that incisional hernia patients required
an individual assessment for surgical planning, a
requirement that cannot be met in the context of
randomized controlled studies [24]. Our in- house
validation process showed that risk factors play a
hitherto underestimated and highly signicant
role that should be included in patient counseling,
surgical decision-making, and the formulation of
new avenues of research; for these reasons they
must be incorporated into a classication. In the
future, surgical planning may also take the risk
prole into account of, with patients in one risk
group receiving treatment by surgical technique
A and patients in another risk group by surgical
technique B.is could mean, for example, that
young patients with fewer comorbidities and a
larger median hernia would be treated with sublay
or retromuscular mesh implantation (morphological reconstruction of the linea alba, although major
surgical trauma with good wound healing prerogatives), whereas patients with a high-risk prole for
wound healing disturbance (obesity, advanced age,
nicotine, diabetes, steroid medication, hernia orice <8cm) would receive a laparoscopic intraperitoneal mesh (IPOM) as a means of symptomatic
treatment [13, 25, 26]. Detailed specication of
the risk factors in the incisional hernia classication will soon require one or more ner granularity levels. Among other things, chronic diseases
must be assessed with regard to their clinical activity. Studies are already planned to investigate this
matter, including the European Incisional Hernia
Registry of the European Hernia Society (visit the
EuraHS website at 7 www.eurahs.eu). It is also
conceivable that dierent combinations of these
risk factors could have not only an aggravating but
also a protective eect on the postoperative results.
25.5 EHS Classication (2009)
e European Hernia Society (EHS) has put forth
a further classication approach [10]. It is based
on previous systems and is summarized in the
form of a table. e EHS Classication is oriented
intraoperatively with regard to denitions and–
unlike the Würzburg Classication– is designed
to be a tool for description of the hernia site alone,
with no claim to predicting surgical planning or
assessing surgical risk. e morphology is divided
into medial and lateral regions, each having four
subregions. e medial area (or linea alba) is
divided into the regions M1 to M5 and the lateral area in the regions L1 to L4 (each designated
with R=right or L= le). Hernia orice size is
denoted as length and width (in cm); in the classication summary table, it is placed into one of
three width categories (W1 to W3) (. Fig.25.4)
[10]. e EHS Classication is recommended by
a panel of experts as the standard for the classication of ventral and incisional hernias. Due
to its high acceptance, it should make possible
for the rst time the standardized collection and
evaluation of data across national borders [10].
e EHS Classication still has no validation
data; they are expected soon however as part of
the European Registry of Ventral and Incisional
Hernias (EuraHS) from the EHS, the so-called
EuraHS Project “Class of 2013.”
25.6 Conclusions andProspects
e classication criteria discussed above are
highly signicant for estimation of surgical risk,
for patient counseling (prognosis for recurrence
and complications), and for planning of surgical
strategy (
the classication criteria is especially useful for
patient counseling and surgical planning; if risk
factors are included, they assist in estimating the
risk. Data collected intraoperatively regarding the
exact size of the hernial opening facilitate subsequent comparison of data. e corresponding
author for the present chapter therefore uses the
Würzburg Classication for patient counseling,
risk assessment, and selection of surgical procedure [9] and the EHS Classication for documentation of intraoperative ndings in EuraHS [10].
e two classications are not mutually exclusive
but rather compliment each other (the Würzburg
Classication for OP planning, the EHS for standardized data collection for future data comparison). e use of both classications is a natural
constituent of patient care and does not require
any signicant time and eort for documentation.
. Fig.25.5). Preoperative assessment of