This is an update of a Cochrane Review first published in 2001. Hernias are protrusions
of all or part of an organ through the body wall that normally contains it. Groin
hernias include inguinal (96%) and femoral (4%) hernias, and are often symptomatic
with discomfort. They are extremely common, with an estimated lifetime risk in men
of 27%. Occasionally they may present as emergencies with complications such as bowel
incarceration, obstruction and strangulation. The definitive treatment of all hernias
is surgical repair, inguinal hernia repair being one of the most common surgical procedures
performed. Mesh (hernioplasty) and the traditional non‐mesh repairs (herniorrhaphy)
are commonly used, with an increasing preference towards mesh repairs in high‐income
countries. To evaluate the benefits and harms of different inguinal and femoral hernia
repair techniques in adults, specifically comparing closure with mesh versus without
mesh. Outcomes include hernia recurrence, complications (including neurovascular or
visceral injury, haematoma, seroma, testicular injury, infection, postoperative pain),
mortality, duration of operation, postoperative hospital stay and time to return to
activities of daily living. We searched the following databases on 9 May 2018: Cochrane
Colorectal Cancer Group Specialized Register, Cochrane Central Register of Controlled
Trials (Issue 1), Ovid MEDLINE (from 1950), Ovid Embase (from 1974) and Web of Science
(from 1900). Furthermore, we checked the WHO International Clinical Trials Registry
Platform (ICTRP) and ClinicalTrials.gov for trials. We applied no language or publication
restrictions. We also searched the reference lists of included trials and review articles.
We included randomised controlled trials of mesh compared to non‐mesh inguinal or
femoral hernia repairs in adults over the age of 18 years. We used standard methodological
procedures expected by Cochrane. Where available, we collected information on adverse
effects. We presented dichotomous data as risk ratios, and where possible we calculated
the number needed to treat for an additional beneficial outcome (NNTB). We presented
continuous data as mean difference. Analysis of missing data was based on intention‐to‐treat
principles, and we assessed heterogeneity using an evaluation of clinical and methodological
diversity, Chi 2 test and I 2 statistic. We used GRADE to assess the quality of
evidence for each outcome. We included 25 studies (6293 participants) in this review.
All included studies specified inguinal hernias, and two studies reported that femoral
hernias were included. Mesh repair probably reduces the risk of hernia recurrence
compared to non‐mesh repair (21 studies, 5575 participants; RR 0.46, 95% CI 0.26 to
0.80, I 2 = 44%, moderate‐quality evidence). In absolute numbers, one hernia recurrence
was prevented for every 46 mesh repairs compared with non‐mesh repairs. Twenty‐four
studies (6293 participants) assessed a wide range of complications with varying follow‐up
times. Neurovascular and visceral injuries were more common in non‐mesh repair groups
(RR 0.61, 95% CI 0.49 to 0.76, I 2 = 0%, NNTB = 22, high‐quality evidence). Wound
infection was found slightly more commonly in the mesh group (20 studies, 4540 participants;
RR 1.29, 95% CI 0.89 to 1.86, I 2 = 0%, NNTB = 200, low‐quality evidence). Mesh repair
reduced the risk of haematoma compared to non‐mesh repair (15 studies, 3773 participants;
RR 0.88, 95% CI 0.68 to 1.13, I 2 = 0%, NNTB = 143, low‐quality evidence). Seromas
probably occur more frequently with mesh repair than with non‐mesh repair (14 studies,
2640 participants; RR 1.63, 95% CI 1.03 to 2.59, I 2 = 0%, NNTB = 72, moderate‐quality
evidence), as does wound swelling (two studies, 388 participants; RR 4.56, 95% CI
1.02 to 20.48, I 2 = 33%, NNTB = 72, moderate‐quality evidence). The comparative
effect on wound dehiscence is uncertain due to wide confidence intervals (two studies,
329 participants; RR 0.55, 95% CI 0.12 to 2.48, I 2 = 37% NNTB = 77, low‐quality
evidence). Testicular complications showed nearly equivocal results; they probably
occurred slightly more often in the mesh group however the confidence interval around
the effect was wide (14 studies, 3741 participants; RR 1.06, 95% CI 0.63 to 1.76,
I 2 = 0%, NNTB = 2000, low‐quality evidence). Mesh reduced the risk of postoperative
urinary retention compared to non‐mesh (eight studies, 1539 participants; RR 0.53,
95% CI 0.38 to 0.73, I 2 = 56%, NNTB = 16, moderate‐quality evidence). Postoperative
and chronic pain could not be compared due to variations in measurement methods and
follow‐up time (low‐quality evidence). No deaths occurred during the follow‐up periods
reported in the seven studies (2546 participants) reporting this outcome (high‐quality
evidence). The average operating time was longer for non‐mesh repairs by a mean of
4 minutes 22 seconds, despite wide variation across the studies regarding size and
direction of effect, thus this result is uncertain (20 studies, 4148 participants;
95% CI ‐6.85 to ‐1.60, I 2 = 97%, very low‐quality evidence). Hospital stay may be
shorter with mesh repair, by 0.6 days (12 studies, 2966 participants; 95% CI ‐0.86
to ‐0.34, I 2 = 98%, low‐quality evidence), and participants undergoing mesh repairs
may return to normal activities of daily living a mean of 2.87 days sooner than those
with non‐mesh repair (10 studies, 3183 participants; 95% CI ‐4.42 to ‐1.32, I 2 =
96%, low‐quality evidence), although the results of both these outcomes are also limited
by wide variation in the size and direction of effect across the studies. Mesh and
non‐mesh repairs are effective surgical approaches in treating hernias, each demonstrating
benefits in different areas. Compared to non‐mesh repairs, mesh repairs probably reduce
the rate of hernia recurrence, and reduce visceral or neurovascular injuries, making
mesh repair a common repair approach. Mesh repairs may result in a reduced length
of hospital stay and time to return to activities of daily living, but these results
are uncertain due to variation in the results of the studies. Non‐mesh repair is less
likely to cause seroma formation and has been favoured in low‐income countries due
to low cost and reduced availability of mesh materials. Risk of bias in the included
studies was low to moderate and generally handled well by study authors, with attention
to details of allocation, blinding, attrition and reporting. Review question This
review assessed the difference in outcomes between surgical hernia repair with and
without mesh. Background Hernias are out‐pouchings of an organ through the body wall
that normally contains it; in this review, we refer to the bowel or its surrounding
fatty tissues protruding through the abdominal wall in the groin region. This is a
very common medical problem, affecting 27 out of every 100 men. These hernias can
cause significant discomfort, and can occasionally become so tightly stuck that the
blood supply can be cut off (strangulation), requiring emergency surgery. The curative
treatment of hernias is surgical repair, which can be closed with sutured techniques
(non‐mesh repair) or with a fine mesh to promote tissue growth to strengthen the previously
weak area (mesh repair). Mesh repair is becoming increasingly popular in many countries,
particularly in conjunction with laparoscopic (key‐hole) surgery. Search date We searched
a number of databases for studies; this search was last updated on 9 May 2018. Study
characteristics In this update of a review originally published in 2001, we included
a total of 25 studies (with a total of 6293 people) undertaken in a number of different
countries. A variety of outcomes were assessed, including return of the hernia after
initial repair (hernia recurrence), a variety of complications including pain, duration
of surgery, hospital stay and time before going back to normal activities. Key results
One hernia recurrence is prevented for every 46 mesh repairs performed rather than
non‐mesh repairs. Compared to non‐mesh repairs, mesh repairs are more likely to develop
collections of fluid next to the surgical wound, but are less likely to result in
difficulty urinating following the operation, or injury to nerves, blood vessels or
other organs. Postoperative pain could not be clearly compared between studies due
to differences in measurement methods and time frames, but overall the studies appeared
to indicate that participants who had mesh repairs had less pain. The length of the
surgical operation was slightly shorter for mesh repairs. Participants who had a mesh
repair were more likely to have a shorter hospital stay and had a shorter average
recovery time before returning to their normal activities. Quality of the evidence
The studies included in this review used good‐quality methods, considered potential
factors which could affect the results, and addressed their proposed outcomes clearly.
In our assessment of the quality of evidence, we marked down some outcomes to 'moderate'
quality, particularly due to variability within results. Conclusions Overall, hernia
repairs with and without mesh both proved effective in the treatment of hernias, although
mesh repairs demonstrated fewer hernia recurrences, a shorter operation time and faster
return to normal activities. Non‐mesh repairs are still widely used, often due to
the cost and poor availability of the mesh product itself.