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Richter’s Hernia: Clinical Aspects and Management
141
Spiegelian hernias [Naylor, 1978; Montes and Deysine, 2003], lumbar hernias [Millard,
1959], as well as diaphragmatic defects [Kimmelstiel et al., 1987]
Iatrogenic Sites
Various surgical interventions involving the abdominal wall present the opportunity for
formation of defects that may lend themselves to the development of a hernia, including
Richter’s hernia.
The potential for a Richter’s hernia has been linked to the small size of a hernia defect.
However, though larger defects (particularly from standard laparotomy incisions) may be less
likely to develop a Richter’s hernia of the small intestine, their size may still only be enough
to allow partial herniation of a larger hollow viscus, such as the colon, with the potential for
incarceration and strangulation of a portion of the same [Kim et al., 2012].
With the increasing use of minimally-invasive surgery techniques, starting in the late
1980s, reports of hernias through laparoscopic port access sites became more frequent. Port
site hernias were considered to be rare complications by most reports in the early
development of laparoscopic surgery, but are now recognized complications of these
techniques. Larger size port sites (10 cm or greater) are generally implicated [Bourke, 1977;
Williams et al., 1995] although 5 mm port sites are not exempt [Fleming and Winter, 2008].
With the advent of single-port laparoscopic access techniques, the resulting larger defect may
potentially present increased risk for hernia development [Romanelli et al., 2010].
Tonuchi et al. [2004] reviewed 63 reports on port-site hernias, classifying them into three
types: an early onset type (involving dehiscence of the anterior and posterior fascial plane and
peritoneum), a late-onset type (involving dehiscence of the anterior and posterior fascial
plane, with peritoneum constituting the hernia sac), and a “special” type (dehiscence of the
entire abdominal wall with protrusion of intestine or omentum). The early-type is most
relevant for discussion in that it develops in the early stages after surgery, often presenting as
a small bowel obstruction. These are described as being predominantly Richter’s hernias, with
morbidly obese patients being particularly prone, despite adequate fascial closure, due to their
thick pre-peritoneum.
In addition to laparoscopic port sites, Richter’s hernias have resulted from abdominal
wall defects created at previous sites of peritoneal dialysis catheters [Martins et al., 2010],
percutaneous endoscopic gastrostomy (PEG) tubes [Kaplan and Delegge, 2006], at previous
colostomy sites, and even internally in association with adjustable gastric bands for morbid
obesity [Srikanth et al., 2005].
PATHOGENESIS
Richter’s hernias have been defined by most reports through the years as commonly
possessing the following features: a) involvement of the partial circumference of intestine, b)
a small hernia defect, large enough to allow the herniation and capture of a portion of an
intestinal loop but preventing the herniation of a complete loop of intestine, and c)
incarceration – a trapping of the partial circumference of intestine in the hernia defect.
Peter Bistolarides and Aziz M. Merchant
142
The definition of what constitutes a small versus a large defect is not clearly defined in
the literature. Potentially, a Richter’s hernia can occur through an orifice or defect of any size
and, more often than not, is not diagnosed until the time of surgery. Additionally, while small
intestine is the hollow viscus that is generally involved, partial circumference or even isolated
segments of other hollow viscus – particularly colon, but also stomach – can be involved
[Giokas and Karakousis, 1998; Kim et al., 2012]
To the Richter’s features described above, some authors have added the rigidity of the
edges of the hernia orifice, and the presence of strangulation of the involved segment of
bowel [Treves, 1887; Foltz, 1947; Kadirov et al., 1995; Montes and Deysine, 2003;
Skandalakis et al., 2006]. The presence of strangulation, while being a potential consequence
of a Richter’s hernia, is not necessary for its actual diagnosis. However, incarceration – the
irreducible trapping of a partial circumference or segment of bowel in the hernia defect –
appears to be necessary for the formation and possible clinical presentation of this condition.
Though no experimental model exists to study the actual mechanism of how a Richter’s
hernia develops, an explanation was proposed by Orr [1950], who noted that many patients
presented initially with a history suggestive of either transitory complete or partial small
bowel obstruction, which led him to the following hypothesis: an increase in intra-abdominal
pressure causes a loop of small intestine to engage in the hernial ring and enter the sac with
development of edema resulting in incarceration. He conjectured that subsequent propulsive
efforts of distended bowel proximal to the defect resulted in partial reduction of the hernia
content with re-establishment of lumen continuity, but leaving the anti-mesenteric segment
caught in the ring. The incarcerated segment is basically a “diverticulum” at the hernia site,
which can become distended and possibly ischemic.
A Richter’s hernia may or may not be symptomatic. Any obstruction or distension distal
to the incarcerated segment may contribute to the clinical presentation of a Richter’s hernia
[Fluri et al., 2006]. Additionally, the fact that the segment of small intestine that is involved is
usually the anti-mesenteric border – the point at which the intestinal blood supply is at its
weakest – likely leads a Richter’s hernia to earlier strangulation and gangrene [Skandalakis et
al., 2006].
CLINICAL PRESENTATION
As with other types of hernia, the clinical presentation of a Richter’s hernia may range
from little to no symptoms or physical findings, to the presence of a palpable mass, to signs of
obstruction and strangulation with or without signs and symptoms of peritonitis or shock.
Therefore, diagnosis and treatment follow the same principles as for any type of hernia,
keeping in mind that the diagnosis of a Richter’s hernia is rarely made pre-operatively and
usually only at the time of definitive treatment. For diagnostic and treatment purposes, it is
useful to consider patients with a Richter’s hernia as presenting either acutely or chronically.
Richter’s Hernia: Clinical Aspects and Management
143
Acute Presentation
Gillespie et al. [1956] described three groups of patients with Richter’s hernia presenting
acutely: the “obstructive” group, manifesting signs and symptoms of intestinal obstruction
which could lead to serious sequelae if left untreated; the “post-necrotic” group, which results
from local strangulation resulting in necrosis and perforation, and eventual presentation as an
enterocutaneous fistula; and finally, what he described as the “dangerous” group, where
patients presenting acutely may have minimal abdominal signs, or the clinical picture of
obstruction is absent, and may suffer high morbidity and mortality due to resulting delay in
diagnosis. While this series was published in an era where many current imaging technologies
were not available, these patient groupings can still be considered relevant today. As in any
other type of hernia, pain or tenderness presenting acutely at a known hernia site is cause for
concern. Acute clinical presentation in a Richter’s hernia can range from unexplained mild
abdominal pain to full septic shock or peritonitis, and is often made difficult by the absence of
a detectable lump or mass at the site of the hernia.
Obstructive Presentation
In 1809, Scarpa produced experimental hernias, and by changing the circumference of the
hernia neck, he observed that when two-thirds or more of the bowel wall was constricted this
resulted in complete intestinal obstruction, while one-third or less resulted in partial
obstruction [Montes and Deysine, 2003]. Therefore, a Richter’s hernia may or may not
present acutely with intestinal obstruction. This is true even in the presence of strangulation
of the involved partial segment, where intestinal continuity may be maintained.
Signs and symptoms of obstruction - such as crampy abdominal pain, nausea, vomiting,
and abdominal distension - are dependent on the involved hollow viscus and on the duration
of obstruction. Although Richter’s hernia can present with incarceration and strangulation
without obstruction, progression to full obstruction may occur as local edema and/or necrosis
ensues.
Enterocutaneous Fistula and Abdominal Wall Inflammation
Localized perforation of a strangulated portion of a Richter’s hernia may be isolated well
enough from the peritoneal cavity by adhesion to prevent intra-peritoneal contamination. In
this case, the path of least resistance will be into the abdominal wall or the subcutaneous
tissue. Presentation of localized acute inflammation of the abdominal wall or skin – especially
at the location of a hernia site - should raise the concern for the presence of necrotic intestine.
The same concern should be considered when signs of inflammation or drainage present long-
term or recurrently at a laparoscopic port site or other abdominal incision; this should raise
the suspicion of a localized perforation of a Richter’s hernia [Agster and Christiansen, 1974;
Elakkary et al., 2005]
In one of the larger series of Richter’s hernias, Steinke and Zellweger [2000]
reported
that, in the course of almost one year, 80% of strangulated hernias turned out to ultimately be
Peter Bistolarides and Aziz M. Merchant
144
of a Richter’s type. Ninety percent of these had perforated on presentation, and more than half
had formed an enterocutaneous fistula. As expected from a partial circumferential hernia,
bowel obstruction occurred in only 11% of the patients in this study.
Chronic Presentation
In contrast to patients presenting with acute signs and symptoms of obstruction,
strangulation or perforation, patients may present with innocuous symptoms or equivocal
symptoms, especially coupled with the absence of physical findings. The occurrence of pain
without obstruction in the area of a palpable mass in the inguinal-femoral region, or pain at
the site of a previous operation or laparoscopic port insertion (with or without a mass), should
raise the possibility of a Richter’s hernia. Absence of any acute manifestation requiring
immediate attention, as described above, may provide the opportunity for further diagnostic
workup, particularly through imaging.
DIAGNOSIS
Historically, and with rare exception, most Richter’s hernias have been generally
diagnosed at the time of surgery. As there is no specific laboratory or imaging study that is
associated with the diagnosis of a Richter’s hernia, the selection of laboratory studies or
diagnostic imaging is determined by the patient’s presentation (acute or chronic) and by the
patient’s overall clinical status. While patients are generally adult, especially older adults, and
usually in the case of femoral hernias and other hernias occurring at natural anatomic orifices,
Richter’s can occur in children and infants as well. Shanbhogue and Miller [1986] reported a
series of neonates who presented with small intestinal obstruction, and each was found to
have a Richter’s hernia at the internal ring.
Patients presenting with signs or symptoms of acute obstruction, strangulation or
perforation will usually undergo those appropriate laboratory and diagnostic studies that focus
on obtaining a rapid diagnosis of the patient’s problem, and assisting in resuscitating and
preparing the patient for definitive surgical treatment.
Patients presenting in an ambulatory setting, with a chronic or recurrent problem (usually
pain), afford the opportunity for obtaining imaging studies to try and delineate a cause for
their pain, especially in the absence of clinical findings. Various diagnostic imaging
techniques may be employed to establish a diagnosis, although the likelihood remains that
they may not yield any useful information.
Where clinical evaluation (with or without diagnostic imaging) has failed to establish a
diagnosis, operative exploration of a port site may be required. While this can be done in an
open fashion directly at the port site, diagnostic laparoscopy is a useful and preferred
modality both for diagnosis of a Richter’s hernia, and its simultaneous treatment.
Richter’s Hernia: Clinical Aspects and Management
145
Role of Diagnostic Imaging
Modern diagnostic imaging techniques – in particular, ultrasound and computed
tomography (CT) scanning - may provide information to help establish a diagnosis (or at
least, support the clinical suspicion) of a Richter’s and help guide treatment in selected
patients who present with recurrent or non-specific symptoms, such as localized pain or
obstructive symptoms, or to determine the nature of a palpable mass.
Ultrasound of a suspected mass, especially in the femoral region, has been used in
selected cases where there is uncertainty as to whether the mass contains bowel. One report
observed the presence of a “double-doughnut” sign in a femoral hernia as indicative of the
presence of a complete loop of entrapped small intestine, while a “single doughnut” was
described as a finding characteristic of the partial circumference involvement in a Richter’s
hernia [Middlebrook and Eftekhari, 1992]. Ultrasonographic evidence of continuity between
the Richter’s hernia, and the afferent and efferent limbs associated with it, has also been
described [Hiller et al., 1994].
Figure 1. CT scan of the abdomen showing an incarcerated Richter’s hernia of the transverse colon.
CT scanning has demonstrated usefulness in the diagnosis of Richter’s hernia. Figure 1
shows an incarcerated Richter’s hernia of the transverse colon (operative findings shown in
Figure 2), clearly demonstrating the partial circumference involvement. An example of a
femoral Richter’s hernia demonstrating its partial circumferential nature on a CT scan is
shown in Figures 3 and 4. CT finds its greatest use in the acute situation of intestinal
obstruction, especially in the absence of an external mass or lump (Figure 5). The “single
doughnut” sign of an incarcerated segment of bowel on a CT scan may be indicative of a
Richter’s hernia, as has been described for ultrasound (Figure 6).
Peter Bistolarides and Aziz M. Merchant
146
Figure 2. Operative findings in the patient in Figure 1, showing ischemic partial circumference of
transverse colon.
Figure 3. CT scan showing the “single doughnut” sign consistent with the partial circumference
involvement of small intestine in a right femoral Richter’s hernia.
Richter’s Hernia: Clinical Aspects and Management
147
Figure 4. Coronal CT of the patient in Figure 3, showing continuity between the Richter’s hernia, and
the afferent and efferent loop.
Figure 5. CT scan of a Richter’s hernia of the left obturator foramen, showing almost complete
obstruction of proximal small bowel.
Peter Bistolarides and Aziz M. Merchant
148
Figure 6. Transverse section of the patient in Figure 5, showing the “single doughnut” sign consistent
with a partial circumference incarceration of small intestine.
A CT scan of the abdomen in the non-acute situation may provide clues as to the etiology
of recurrent abdominal wall pain or discomfort in a patient with previous surgery, and is
useful in investigating for Spiegelian, lumbar and other intra-parietal hernias, in addition to
hernias occurring at port-site insertion points [Naylor, 1978; Middlebrook and Eftekhari,
1992; Archer et al., 1994]. These types of hernias are often difficult to detect or define
clinically. [Fisichella, 2007]. A loop of small or large intestine seen adjacent to the
approximate location of a port site on a CT scan may be a clue to the possibility of a Richter’s
hernia [Archer et al., 1994].
Plain abdominal films – while they may show intestinal obstruction – are likewise not
reliable in the pre-operative diagnosis of Richter’s and indeed the absence of radiological
signs of obstruction can be misleading. The role or efficacy of magnetic resonance imaging
(MRI) in the pre-operative diagnosis of Richter’s hernia has not been established, although it
could potentially be used in patients in whom CT may be contraindicated, such as pregnant
patients, or patients in whom contrast may present a problem (such as chronic renal disease
and allergies).
Percutaneous aspiration or biopsy of a palpable mass in a known or potential hernia site
should be approached with caution, and preferably avoided, if the possibility of a Richter’s
hernia is even considered. CT scan or other imaging may occasionally present images
mimicking other conditions, such as an abscess or fluid collection, and judicious use of
invasive diagnostic techniques is called for [Baker et al., 1988].
It is vital to remember that there is no definitive imaging modality for Richter’s hernia,
and that the absence of radiological findings – just like the absence of obstructive signs - may
be misleading.
Richter’s Hernia: Clinical Aspects and Management
149
TREATMENT AND PREVENTION
The principles of treatment in a patient with a Richter’s hernia follow the same principles
as for any hernia, and are dependent on the patient’s presentation. In an acute presentation,
this includes a) resuscitation of the patient as required, followed by b) definitive surgical
repair of the offending defect or orifice. It is important to remember that no attempt should be
made to manually reduce an incarcerated or suspected strangulated mass, especially if painful.
An incarcerated or strangulated Richter’s hernia warrants emergency surgery. At surgery,
after reduction of the incarcerated segment of intestine, observation of the segment is often
performed to assess viability and try and preserve intestine (Figures 7 and 8). Obviously
necrotic bowel, or bowel in which there is uncertainty over perfusion and viability, should be
resected. A larger viscus, such as colon, may be amenable to resection of a localized segment
of the intestinal circumference [Naylor, 1978]. Definitive repair of the hernia orifice, with or
without resection of intestine, is performed according to accepted hernia repair principles.
Repair of the hernia orifice often requires insertion of mesh, but the decision is made by the
surgeon intra-operatively based on hernia size, presence of contamination or need for bowel
resection, and other patient factors dictating whether a mesh is required and whether artificial
prosthetic or biological mesh is used.
Figure 7. Operative findings of the patient in Figures 5 and 6, showing incarcerated small intestine in
the obturator foramen.
Definitive surgical treatment of a Richter’s hernia is amenable to a laparoscopic
approach, and this approach may be used for diagnostic purposes as well – although it is
important to adhere to principles of laparoscopic surgery and recognize a need to convert to
an open procedure if, based on the surgical experience, conditions are not ideal for
completion of the laparoscopic approach.
Due to the widespread use of laparoscopic surgery and the potential of leaving behind
small, rigid hernia defects at port insertion sites, various techniques have been proposed that,
while not guaranteeing complete prevention, may potentially reduce the risk of formation of
Richter’s hernia.
Peter Bistolarides and Aziz M. Merchant
150
Figure 8. After reduction, necrotic partial circumference segment of small intestine characteristic of a
Richter’s hernia.
The practice employed by most surgeons is to routinely close standard 10 and 12 mm (or
larger) laparoscopic port sites. Various other preventive techniques have been tried or
proposed on an empiric basis. Besides the use of smaller laparoscopic trocars, other
maneuvers proposed to decrease the risk of port-site hernia formation include use of non-
bladed (optical) trocars – especially above the arcuate line - and the “tangential” insertion of
trocars [Boughey et al., 2003; Tonouchi et al., 2004], which theoretically “staggers” the
opening made through successive layers of the abdominal wall. Naturally, none of these
maneuvers guarantee complete prevention of Richter’s hernias.
As increased intra-abdominal pressure from gas insufflation, forcing intestinal loops up to
port sites, has been identified by some reports as a possible contributing factor to
development of port-site hernias [Kiibolma and Makinen, 1988; Hass and Schrager, 1993]
desufflation of the abdomen prior to removal of access ports, “shaking” of the abdomen
during desufflation, and conducting desufflation through the epigastric port site (supposedly
due to the presence of the liver preventing bowel herniation) have all been suggested.
The size or body habitus of the patient should be taken into consideration. Closure of port
sites in a morbidly obese patient remains a challenge due to the technical difficulty of
exposure and visualization of the fascia. Additionally, the thickened pre-peritoneal space –
preventing proper closure of the peritoneum – is suggested as an increased risk factor for the
formation of a Richter’s hernia, even if fascial closure is achieved [Matthews et al., 2001;
Tonouchi et al., 2004]. This also presents a challenge in diagnosing Richter’s hernia in this
group of patients.
While cases of hernias occurring in 5 mm sites have been reported [Van Deusen et al.,
2002; Fleming and Winter, 2008], these are rare, and routine closure of these is not generally
performed. However, it may be reasonable to consider doing this in pediatric patients, where
port sites are accessible and the potential for hernia greater due to the relative ratio of
intestinal diameter to port site diameter which may allow herniation through smaller port sites
[Waldhausen, 1996], or even in adult patients who are thinner.