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The incidence and natural course of occult inguinal hernias
during TAPP repair
Repair is beneficial
Baukje van den Heuvel •Nikki Beudeker •
Joris van den Broek •Auke Bogte •
Boudewijn J. Dwars
Received: 18 February 2013 / Accepted: 30 April 2013 / Published online: 25 May 2013
!Springer Science+Business Media New York 2013
Abstract
Background One of the proposed advantages of laparo-
scopic inguinal hernia repair is complimentary inspection
of the contralateral side and possible detection of occult
hernias. Incidence of occult contralateral hernias is as high
as 50 %. The natural course of such occult defects is
unknown and therefore operative rationale is lacking. This
study was designed to analyze the incidence of occult
contralateral inguinal hernias and its natural course.
Methods A total of 1,681 patients were diagnosed pre-
operatively with unilateral inguinal hernia. None of these
patients had complaints of the contralateral side preoper-
atively. All patients underwent laparoscopic inguinal her-
nia transabdominal preperitoneal (TAPP) repair. Operative
details were analyzed retrospectively. Patients with occult
contralateral defects were identified and tracked. Patients
with an evident occult hernia received immediate repair.
Patients with a smaller beginning or incipient hernia were
followed.
Results In 218 (13 %) patients, an occult hernia was found
at the contralateral side during preoperative exploration. In
129 (8 %) patients, an occult true hernia was found. In 89
(5 %) patients, an occult incipient hernia was found. An
incipient hernia was defined as a beginning hernia. All
patients with an incipient hernia were followed. The mean
follow-up was 112 (range 16–218) months. Twenty-eight
(32 %) patients were lost to follow-up. In the 61 remaining
patients, 13 (21 %) occult incipient hernias became symp-
tomatic requiring repair. The mean time between primary
repair and development of a symptomatic hernia on the
contralateral side was 88 (range 24–210) months.
Conclusions This study shows that the incidence of
occult contralateral hernias is 13 % during TAPP repair of
unilateral diagnosed inguinal hernias. In 5 % of the cases,
the occult hernia consisted of a beginning hernia. Eventu-
ally, one of five will become symptomatic and require
repair. These outcomes support immediate repair of occult
defects, no matter its size.
Keywords Hernia !Endoscopy !Inguinal !Occult !
Repair
One of the many advantages of laparoscopic inguinal
hernia repair is routine visualization of the contralateral
myopectineal space. Simultaneous complimentary inspec-
tion of the myopectineal space during laparoscopic ingui-
nal hernia repair revealed occult contralateral inguinal
hernias, but also femoral, Spigelian, or obturator hernias
[1]. This phenomenon was new, but rather common. In
case of a unilateral inguinal hernia, a contralateral occult
hernia was found in 11–51 % of the patients [2–8].
Although it was promoted that immediate repair of an
occult detected hernia during laparoscopic repair was eas-
ily done within the same operational session, would avoid
reoperation, and minimize convalescence from work,
questions were raised about the clinical relevance of such
occult, asymptomatic inguinal hernias.
We therefore conducted a study to assess the incidence
of occult contralateral defects detected during laparoscopic
unilateral inguinal hernia repair. We distinguished between
B. van den Heuvel (&)!N. Beudeker !J. van den Broek !
B. J. Dwars
General Surgery, Slotervaartziekenhuis, Louwesweg 6,
1066 EC Amsterdam, The Netherlands
e-mail: baukjevdh@yahoo.com
A. Bogte
Gastroenterology and Hepatology, University Medical Center
Utrecht, Utrecht, The Netherlands
123
Surg Endosc (2013) 27:4142–4146
DOI 10.1007/s00464-013-3008-2
and Other Interventional Techniques
true occult inguinal hernias and beginning or incipient
hernias. We assessed the natural course of these incipient
hernias and evaluated whether these hernias become
symptomatic, requiring eventual repair.
Methods
In our series of 2,026 consecutive laparoscopic inguinal
hernia repairs, 1,681 (83 %) patients were diagnosed pre-
operatively with unilateral inguinal hernia. Presence of an
inguinal hernia was diagnosed by physical examination by
one expert surgeon. In case of a reducible swelling, pro-
voked during Valsalva maneuver, an inguinal hernia was
confirmed. None of the patients had complaints on the
contralateral side. The contralateral side was examined
routinely. In case of a reducible swelling provoked during
Valsalva manoeuvre, a bilateral inguinal hernia was diag-
nosed and the patient was excluded from analysis. All
unilateral inguinal hernias were repaired by a transab-
dominal preperitoneal (TAPP) repair. All repairs were done
or supervised by the same expert surgeon. During TAPP
repair, the contralateral side was inspected and presence
and details of occult defects were documented in the
operation report. A distinction was made between presence
of an evident inguinal hernia, a so-called true occult hernia,
and an incipient inguinal hernia. An incipient inguinal
hernia is a beginning or a looming inguinal hernia. A
discrete protrusion or bulging of the peritoneum is seen
during laparoscopic inspection but is considered to be too
small and shallow to be regarded as a hernia sac. There is
indeed a defect or hernia orifice in the abdominal wall, but
this defect is too small to facilitate any actual herniation of
intra-abdominal contents. In case of an evident occult
inguinal hernia at the contralateral side, an immediate
repair was done with a polypropylene mesh in a routine
matter, see ‘‘Technique.’’ In case of an incipient inguinal
hernia, no repair was performed. Patients with an incipient
inguinal hernia were not informed postoperatively about
the peroperative findings of the contralateral side. All of
the operation reports were analyzed retrospectively.
Operation reports with any remarks on the contralateral
side were identified. Data from the operation reports were
extracted, such as gender, age, type of hernia, side, and
type of occult or incipient hernia.
All patients who had an incipient inguinal hernia on the
contralateral side were contacted by phone and subse-
quently invited to the clinic. The main outcome was
development of a symptomatic inguinal hernia. Time from
primary inguinal hernia repair until development of an
actual symptomatic inguinal hernia on the contralateral site
was assessed in patients with an incipient inguinal hernia.
Approval was obtained by the local ethics committee.
Technique
Under general anesthesia, patients are positioned supine.
Pneumoperitoneum is established and an intra-abdominal
pressure of 12 mmHg is maintained throughout surgery. A
standard transabdominal approach is set up with three
trocars. Adhesions are dissected if present. The myopecti-
neal space is inspected bilaterally. Preperitoneal access is
gained by an incision of the peritoneum cranially to the
internal ring, starting laterally and ending at the obliterated
umbilical artery. The preperitoneal space is explored. The
hernia is dissected and care is taken not to damage the vas
deferens or the testicular vessels. When the hernia is dis-
sected completely, a mesh is introduced and positioned
with at least a three centimeter overlap of the mesh cov-
ering the defect. The mesh is only fixated on indication.
The peritoneal incision is closed with a running suture.
Removal of the trocars and closure of the skin is done in a
standard manner.
Results
In the Slotervaart Hospital in Amsterdam, The Nether-
lands, 1,681 patients were operated with a preoperative
diagnosed unilateral inguinal hernia (1993–2010). In 218
(13 %) patients, an occult defect was found at the contra-
lateral side during laparoscopic inspection. The majority of
patients were male (97 %) and the mean age was 58 (range
18–91) years.
In 129 (8 %) patients, a true occult inguinal hernia was
found at the contralateral side. None of the patients had
complaints of the contralateral side preoperatively. The
majority of these patients were male (96 %). The affected
side of the primary inguinal hernia was the right side in 72
(56 %) patients and the left side in 57 (44 %) patients. The
primary inguinal hernia was an indirect hernia in 68 (53 %)
patients, a direct hernia in 55 (43 %) patients, and a pan-
taloon hernia in 6 (5 %) patients. The secondary occult
inguinal hernia found peroperatively was an indirect hernia
in 52 (40 %) patients, a direct hernia in 65 (50 %) patients,
a pantaloon hernia in 6 (5 %) patients, and a femoral hernia
in 6 (5 %) patients. The correlation between the type of the
primary and the secondary occult hernia was analyzed
(Table 1).
In 89 (5 %) patients, an incipient hernia was found. An
incipient inguinal hernia is a beginning or a looming
inguinal hernia. There is indeed a defect or hernia orifice in
the abdominal wall with peritoneal bulging, but this defect
is too small and the sac too shallow to facilitate any actual
herniation of intra-abdominal contents. None of the
patients had complaints of the contralateral side preoper-
atively. All but one patient was male. The affected side of
Surg Endosc (2013) 27:4142–4146 4143
123
the primary inguinal hernia was the right side in 38 (43 %)
patients and the left side in 51 (57 %) patients. The primary
inguinal hernia was an indirect hernia in 60 (67 %)
patients, a direct hernia in 26 (29 %) patients, a pantaloon
hernia in 2 (2 %) patients, and a femoral hernia in one
(1 %) patient. The incipient inguinal hernia found perop-
eratively was categorized as a beginning indirect hernia in
56 (63 %) patients, as a beginning direct hernia in 30
(34 %) patients, and as a beginning pantaloon hernia in 3
(3 %) patients. The correlation between the type of the
primary inguinal and the incipient inguinal hernia was
analyzed. In 75 (84 %) patients the type of primary hernia
matched the incipient hernia, in 5 (6 %) patients either the
primary or the incipient hernia was a pantaloon hernia, and
in 9 (10 %) patients the primary and incipient hernia
mismatched. There was no statistical difference between
the mismatch of primary and incipient inguinal hernia with
regards to type of hernia (Table 2).
All patients with an incipient inguinal hernia were fol-
lowed. The mean follow-up was 112 (range 16–218)
months. Twenty-eight (32 %) patients were lost to follow-
up, of which 18 patients died, 2 patients were not capable
of participating due to physical or mental disabilities, and 8
patients were untraceable, including emigration abroad. In
the group of the remaining 61 patients, 13 (21 %) patients
developed a symptomatic inguinal hernia on the contra-
lateral side. Their incipient inguinal hernia was in 8 (62 %)
patients an indirect hernia, in 4 (31 %) patients a direct
hernia, and in 1 (8 %) patient a pantaloon hernia. Twenty-
eight percent of the patients with an incipient direct or
pantaloon hernia developed a symptomatic inguinal hernia
and 19 % of the patients with an incipient indirect hernia
did. Eleven patients underwent surgical repair for the
symptomatic inguinal hernia, and two patients were still
awaiting surgical repair. The mean time between initial
operation of the primary inguinal hernia and development
of a symptomatic inguinal hernia on the contralateral side
was 88 (range 24–210) months. The remaining 48 patients
with an incipient hernia on the contralateral side had no
clinical signs (pain or bulge) of an inguinal hernia.
Discussion
In our large series of 1,681 unilateral TAPP repairs, we found
an incidence of occult contralateral hernias of 13 %. This
incidence is in accordance with rates reported by others in the
literature [3,4,6–8]. In our series, we have made the dis-
tinction between presence of an evident inguinal hernia, a so-
called true occult hernia, and an incipient inguinal hernia. An
incipient inguinal hernia is a beginning or a looming inguinal
hernia. There is indeed a defect or hernia orifice in the
abdominal wall, with peritoneal bulging, but this defect is too
small and too shallow to facilitate any actual herniation of
intra-abdominal contents. It was therefore assumed that such
an incipient hernia would not be clinical relevant and
accordingly no repair was undertaken and patients were
followed. In case of an evident inguinal hernia, an immediate
repair was undertaken with a mesh.
There are a few reports on the incidence of occult her-
nias found during exploration in inguinal hernia repair. The
main difficulty in interpreting or comparing these reports
are the variety of definitions of an occult inguinal hernia
and therefore also the clinical judgement or assessment, the
lack of routine contralateral exploration, the lack of details
concerning these occult defect, e.g. a direct or indirect
defect and the lack of follow-up. Used definitions reported
in studies vary from ‘‘presence of a peritoneal reflection
towards the internal ring during a preperitoneal dissection
in TEP repair’’ to ‘‘a hole, an open sinus tract, a peritoneal
dimpling or invagination on the region of inguinal hernias
or patent processus vaginalis’’ [8,9]. These descriptions
leave quite some liberty to the interpreter evaluating the
presence of an occult hernia. Without a well-described
definition, the entity of an occult hernia remains unclear.
Table 1 Type of primary hernia and contralateral hernia
Primary hernia N(%) Occult hernia N(%)
Indirect 68 (53) Indirect 42 (62)
Direct 17 (25)
Pantaloon 4 (6)
Femoral 5 (7)
Direct 55 (43) Direct 44 (80)
Indirect 9 (13)
Pantaloon 1 (2)
Femoral 1 (2)
Pantaloon 6 (5) Pantaloon 1 (17)
Indirect 1 (17)
Direct 4 (67)
Total 129 (100)
Table 2 Type of primary hernia and contralateral incipient hernia
Primary hernia N(%) Incipient hernia N(%)
Indirect 60 (67) Indirect 53 (88)
Direct 5 (8)
Pantaloon 2 (3)
Direct 26 (29) Direct 22 (85)
Indirect 3 (12)
Pantaloon 1 (4)
Pantaloon 2 (2) Direct 2
Femoral 1 (1) Direct 1
Total 89 (100)
4144 Surg Endosc (2013) 27:4142–4146
123
Bochkarev et al. [8] found 22 % occult contralateral
defects in 100 patients undergoing laparoscopic TEP
repair. All occult defects were indirect hernias, in which
one was accompanied by a direct defect as well. Crawford
et al. [5] discovered in 37 (51 %) of 73 patients with a
unilateral inguinal hernia an occult contralateral defect
during laparoscopic exploration. The majority of the occult
defects involved direct inguinal hernias. Koehler [4] found
9 (13 %) occult contralateral hernias in 69 patients during
transabdominal inspection, followed by a TEP repair.
These nine hernias were comprised of five direct, two
indirect, and two pantaloon hernias.
TAPP repair allows easy evaluation of a potential occult
defect on the contralateral side without any additional
dissection, whereas TEP repair requires additional dissec-
tion for evaluating the contralateral side. Some suggest that
an occult hernia might be falsely assessed during TEP
repair due to an artefact of the preperitoneal dissection
itself. The peritoneum is sometimes adherent to the internal
ring, possibly mimicking an occult defect. The incidence of
occult lesions during TEP repair might therefore be over-
stated [5,8].
Some experts suggest that occult hernias should not be
mistaken by a patent processus vaginalis (PPV). In our series,
we found 8 % true occult hernias and 5 % incipient hernias.
We have assumed that a true occult hernia will not be mis-
taken by a PPV, but an incipient hernia might. Van Veen et al.
[10] analyzed the presence of a PPV during transperitoneal
laparoscopic surgery for other indications than hernia repair.
In 15 % of 337 patients, a PPV was found. A PPV was
defined as a protrusion of peritoneum at the side of the
internal ring [11]. The group of patients with a PPV was
compared to a control group of patients with an obliterated
PPV. During follow-up of more than 5 years, 12 % of the
patients with a PPV developed an inguinal hernia versus 3 %
in the obliterated group. The authors concluded that a PPV is
a common phenomenon during laparoscopy and a risk factor
in developing an inguinal hernia.
Based on the definitions given in the literature for an
occult hernia and a PPV, no distinction between the two
entities can be made [8,11]. A PPV can be mistaken for an
indirect occult inguinal hernia or vice versa. In our series,
19 % of the patients with an incipient indirect hernia
developed a symptomatic hernia over 11 years. Compared
with the outcome of van Veen et al., in which 12 % of the
patients with a PPV developed a symptomatic hernia over
5 years, these outcomes are much alike. These results
suggest that the natural course of a PPV and indirect
incipient hernia are alike and that both entities can be
regarded as one and the same as distinction is clinically
irrelevant.
One other small study of Thumbe and Evans [3]
explored the natural course of 21 patients with an occult
contralateral defect. These occult defects included 5 direct,
14 indirect, and 2 pantaloon defects. During follow-up of
8 months, six patients (29 %) developed a clinically
demonstrable hernia, including two direct, three indirect,
and one pantaloon hernia. One could assume that over time
more occult hernias will become symptomatic and require
repair. These results advocate the clinical relevance of
repairing a contralateral occult inguinal hernia when
encountered during laparoscopic exploration.
In our study, we have made a distinction between occult
and incipient occult inguinal hernias. The difference
between the two entities is based on the size of the hernia
orifice and sac and the possibility of herniation of intra-
abdominal structures, which is an arbitrary interpretation of
the surgeon. As long as no clear descriptions are defined for
incipient and occult hernias, and patent processus vagi-
nalis, uniform comparisons and interpretation of results
will be limited for future researchers. A distinction could
be made based on size of hernia orifice and depth of the
hernia sac. We believe that a hernia orifice with a diameter
of less than 3 cm and depth of the hernia sac of no more
than 2 cm will not allow any herniation. We apply these
cutoff points in our hernia practice nowadays for defining
an incipient hernia.
A limitation of our study is the subjectivity of one hernia
expert. One hernia expert clinically assessed all patients
and diagnosed the presence of a unilateral hernia and
absence of a contralateral hernia. Did this large amount of
218 patients truly miss any clinical signs of a contralateral
hernia? Because only one hernia expert assessed these
patients, this is hard to verify. As long as an inguinal hernia
is a clinical diagnosis, and not a radiological one, this
problem will remain for future researchers.
At last, our study had a retrospective design. Almost one
third of the patients with an incipient hernia were loss to
follow-up during a period of more than 11 years, resulting
in some omission of data. A prospective setup would
diminish the amount of loss to follow-up, especially in such
a long period of time.
The strength of our study is its size and length of follow-
up. Our series is the largest on occult contralateral hernias,
including 1,681 unilateral TAPP repairs. All patients with
incipient hernias were followed for more than 11 years, the
longest follow-up reported so far.
In our series, we have found an incidence of 8 % of true
occult contralateral hernias. Repairing a contralateral
occult hernia in the same session will prolong the operation
time with 7–25 min [1,6,8,12–14]. However, a second
operation is prevented, resulting in minimizing convales-
cence and without differences is morbidity [3,5–8,13,14].
In 5 % of the patients, an incipient inguinal hernia was
present. Key questions to evaluate its clinical relevance are
what the benefits of immediate repair are and do they
Surg Endosc (2013) 27:4142–4146 4145
123
outweigh the disadvantages. Our series show that 21 % of
the incipient hernias will become symptomatic. The num-
ber needed to treat is 5, implying that five patients require
repair of their incipient hernia to prevent one to become
symptomatic. The additional repair will prolong operation
time and will increase operation costs by one additional
mesh and some additional time. However, immediate
repair will prevent a second operation in one in five,
including preoperative assessment by a surgeon and anes-
thesiologist, actual operating time, operation costs, hospital
admittance, postoperative follow-up, work convalescence,
and has no increase in morbidity compared with unilateral
repair [13,14]. Although the cost-benefit analysis will vary
for different health care systems in different countries, in
most cases the cost-benefit analysis will support preventive
repair [3].
Conclusions
An occult contralateral hernia is a common phenomenon
encountered during laparoscopic repair of a unilateral
inguinal hernia. In our series, we have found an incidence
of occult contralateral hernias of 13 % (8 % true hernias
and 5 % incipient hernias). The natural course of a small
beginning or looming hernia has never been analyzed in
such large series. Twenty-one percent of all incipient her-
nias will become symptomatic and will require repair.
Immediate repair of occult contralateral hernias is easily
done in the same operation session and is supported by our
results, no matter its size or type.
Disclosures Baukje van den Heuvel, Nikki Beudeker, Joris van den
Broek, Auke Bogte, and Boudewijn Dwars have no conflicts of
interest or financial ties to disclose.
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