Evidence-Based Hernia Treatment in Adults

Background: Inguinal hernia repair is the most common general surgical procedure in industrialized countries, with a frequency of about 200 operations per 100 000 persons per year. Suture- and mesh-based techniques can be used, and the procedure can be either open or minimally invasive.

Method: This review is based on a selective search of the literature, with interpretation of the published findings according to the principles of evidence-based medicine.

Results: Inguinal hernia is diagnosed by physical examination. Surgery is not necessarily indicated for a primary, asymptomatic inguinal hernia in a male patient, but all inguinal hernias in women should be operated on. For hernias in women, and for all bilateral hernias, a laparoscopic or endoscopic procedure is preferable to an open procedure. Primary unilateral hernias in men can be treated either by open surgery or by laparoscopy/endoscopy. Patients treated by laparoscopy/endoscopy develop chronic pain less often than those treated by open surgery. A mesh-based repair is generally recommended; this seems reasonable in view of the pathogenesis of the condition, which involves an abnormality of the extracellular matrix.

Conclusion: The choice of procedure has been addressed by international guidelines based on high-level evidence. Surgeons should deviate from their recommendations only in exceptional cases and for special reasons. Guideline conformity implies that hernia surgeons must master both open and endoscopic/laparoscopic techniques.

Inguinal hernia repair is the most common operation in visceral and general surgery. It has therefore been the subject of many clinical trials, meta-analyses, and systematic reviews. These, in turn, provide the basis for the existing international guidelines, which were formulated with the application of the Oxford criteria. The recommendations contained in them are based on high-level evidence and should therefore be followed in essentially all cases, with rare, individually justified exceptions.

Learning goals

This article is intended to acquaint the reader with the modern treatment of inguinal hernia, and in particular with:

• the indications for treatment,
• the indications for each of the available treatment methods (tailored approach), and
• the significance of chronic postoperative pain and its prevention.

Epidemiology

The lifetime risk of developing an inguinal hernia is 3% for women and 27% for men (e1). The incidence rises with age and is eight times higher in persons with a positive family history.

The following risk factors have been described (1):

• chronic obstructive pulmonary disease,
• cigarette smoking,
• low body-mass index,
• and collagen diseases.

Indirect, direct, and femoral hernias are anatomically distinct from one another and arise at different frequencies. Indirect hernias are twice as common as direct ones; femoral hernias account for only 5% of all inguinal hernias. Inguinal hernias are more often on the right side than the left (e2).

Clinical features and diagnostic evaluation

A reducible protrusion in the inguinal region is definitive evidence of an inguinal hernia and needs no further diagnostic evaluation beyond physical examination. This consists of inspection followed by palpation of the patient’s groin in the standing and the supine positions, including digital exploration of the inguinal canal. An inguinal hernia can be distinguished from a scrotal hernia with an accompanying hydrocele by palpation, with the aid of diaphanoscopy if necessary, before further studies such as ultrasonography are performed. In contrast, non-reducible inguinal masses always need further diagnostic evaluation, even if they are asymptomatic. A meta-analysis confirmed the utility of ultrasonography for this purpose, with 96.6% sensitivity, 84.8% specificity, and a positive predictive value of 92.6% (1). In a study of 36 patients with occult hernias, magnetic resonance imaging was found to be superior to both ultrasonography and computerized tomography (e3). Remarkably, herniography is still mentioned in a current systematic review as the most sensitive diagnostic modality of all (2). Dynamic sonography is a good compromise with regard to expense, diagnostic value, and availability, although this can only be stated as a grade C recommendation because of the suboptimal quality of the underlying studies.

In a recent study, a standardized questionnaire was used to evaluate symptoms in 231 patients with a documented inguinal hernia, and in a control group of 231 persons chosen at random (3). 69% had discomfort in the hernia itself and 66% in the groin, while 50% complained of increased peristalsis, without any difference between right-sided, left-sided, or bilateral hernias. Only 7% had no symptoms. The hernia patients complained significantly more than the control subjects did of pain in the groin and in the genital area, pain on urination/altered urinary function, increased peristalsis, and tenesmus. The latter two symptoms were mainly a feature of left-sided hernias, while urinary problems were mainly a feature of right-sided ones. In another survey, 23% of 160 men with inguinal hernias complained of pain during sexual activity (e4). 17% said that their sex life was moderately or severely impaired. Surgical treatment did not lead to a significant reduction in symptoms; in this study, patients who had symptoms preoperatively still showed significantly more symptoms postoperatively than the control subjects. The preoperative symptoms and the severity of pain in the early postoperative period were important risk factors for chronic pain (4). This is an important matter that should be discussed with patients before surgery. The point is underscored by a further study in which a population at increased risk for postoperative pain was defined preoperatively through the patients’ reaction to standardized thermal stimulation of the skin (5). 12.4% of the patients in this study complained of moderate to severe pain 6 months after surgery.

The pathogenesis of inguinal hernia

Inguinal hernia in adults is now thought to be due to a disturbance of the extracellular matrix. Changes are seen, for example, in matrix metalloproteases and their inhibitors (6), and the patients’ collagen metabolism is disturbed in a characteristic way. The degradation of immature type III collagen is reduced in persons with inguinal hernias compared to controls, while the turnover of type IV collagen in the basal membrane is increased (e5). Parallel findings have been made with regard to the development of cicatricial hernias (e5) and aortic aneurysms (e6). Epidemiologic studies have shown that direct and indirect inguinal hernias differ in that only the former are correlated with cicatricial hernia (7). Although these two entities presumably differ in their pathogenetic mechanisms, we do not yet understand how; this theoretical difference is irrelevant to treatment as currently practiced and is not reflected in the guidelines. Thus, there is no need to differentiate direct from indirect hernias preoperatively (8, 9).

Indications for treatment

The goal of treatment is to improve symptoms and the quality of life in general, and to prevent adverse events such as incarceration, while keeping the rate of surgical complications low. Treatment with a truss does not achieve any of these goals. Surgery can improve the quality of life of patients with symptomatic inguinal hernias (10), even if they are elderly (e7). In patients with asymptomatic hernias that are stationary in size, the danger of incarceration is still often cited as a reason to operate. Two randomized trials and one systematic review addressed this issue in men with primary inguinal hernias, with a period of observation exceeding 10 years (11–13). The rate of conversion from “watchful waiting” to surgery was 72% at 7.5 years in one trial, and 68% at 10 years in the other. In the second trial, separate statistics were reported for patients under and over age 65: in the latter, the rate of conversion was 79%. The rate of incarceration was 0.27% at 2 years and 0.55% at four years. Incarceration had no effect on the rate of complications after emergency reoperative procedures.

Level 1 evidence now invalidates the former general recommendation for surgery in men with asymptomatic, non-progressive inguinal hernias. The alternative, i.e., watchful waiting, must be discussed with the patient. The risk of incarceration should not be cited as a reason to operate (grade B recommendation) (9).

According to the guideline of the European Hernia Society (EHS), primary inguinal hernias in women should be operated on in all cases because of the possibility of a femoral hernia, which cannot be unambiguously diagnosed by clinical and ancillary examinations alone and is incarcerated in up to 30% of cases (evidence level 2, recommendation grade B ) (8, 9, 14).

There have been no good studies of the possible indication for surgery in case of recurrent inguinal hernia. The decision must be made individually, in consideration of the initial technique (with or without a mesh), symptoms, and accompanying morbidity. Recurrences after hernia repair with a mesh that have palpable, well-defined hernia borders may have a greater tendency to be incarcerated than recurrences after suture-based techniques; the indication for a second operation in such cases may, therefore, be stronger. This statement is only supported by level 5 evidence, however, and is thus only a grade D recommendation.

Methods of inguinal hernia repair

Inguinal hernias can be repaired by suture- or mesh-based techniques, through an anterior or a posterior approach, and by either open surgery or laparoscopy/endoscopy. Minimally invasive procedures are always done through a posterior approach and with the use of a mesh; open, suture-based operations are performed through the classic anterior approach. The well-known suturing techniques are those of Bassini, Shouldice, and Desarda (e8). The data on the Desarda technique are still too sparse for a definitive evaluation. The standard mesh-based technique through an anterior approach is that of Lichtenstein. In the discussion below, we will also present data on further techniques—“plug and patch” and the use of special net systems that are used in open procedures to cover both the anterior and the posterior surface.

According to a recent meta-analysis of open suture-based and open mesh-based techniques, the Shouldice repair is associated with a lower recurrence rate than other popular suture-based techniques, such as that of Bassini (7% vs. 4.3%) (15), but the recurrence rate of suture-based techniques in general is four times higher than that of mesh-based techniques (4% vs. 0.9%).

It is unambiguously stated in the guidelines of the European Hernia Society (EHS) (8, 9) and the Danish Hernia Database (14) that mesh-based techniques have a lower recurrence rate than suture-based techniques (evidence level 1); therefore, for adult patients, either the Lichtenstein procedure or an endoscopic/laparoscopic technique (if the surgeon has the necessary expertise) is recommended as the standard for hernia repair in adults (recommendation grade A). The Danish recommendations go so far as to advise against the use of suture-based techniques in general. Persons aged 18 to 30 also benefit from mesh-based techniques, and registry studies have shown that such techniques have no effect on male fertility (e9).

Comparisons of open, mesh-based techniques

The EHS guidelines of 2009 (8) mentioned only the Lichtenstein technique, as adequate data on other techniques were not yet available. The 2014 update (9) additionally addresses the more recent trials of the “plug and patch” and polypropylene hernia system (PHS) techniques. These were compared with the standard Lichtenstein repair in multiple randomized trials and are equivalent to it in rates of recurrence and chronic postoperative pain, with follow-up ranging from 1 to 4 years (evidence level 1, recommendation grade B).

Comparison of laparoscopic/endoscopic techniques (TAPP versus TEP)

In the 2009 guidelines, the extraperitoneal approach (TEP) was preferred to the transabdominal approach (TAPP) because of a supposedly lower complication rate (Figure) (8), but this has been clearly refuted since. According to the guidelines of the International Endohernia Society (IEHS) (16), the two approaches have similar rates of severe complications and recurrences (evidence level 1) and can thus be considered clinically equivalent (recommendation grade A). There is no need for further debate over which of these two techniques to use, but the surgeon must have the requisite expertise in whichever one he or she mainly uses. The learning curve for laparoscopic/endoscopic hernia repair is longer than that for open repair by the Lichtenstein technique (evidence level 3–4) (8, 17).

Figure

The operative field in a transabdominal inguinal hernia repair procedure

Differences in the treatment of inguinal hernia

Guidelines based on solid evidence are now available, yet their recommendations are not uniformly followed by surgeons in the United States and Canada (18). The EHS recommends open surgery for primary, unilateral inguinal hernia in a male patient (9). It was found in two meta-analyses that TEP has a significantly higher recurrence rate than Lichtenstein repair (9, 19), but this conclusion was based on the findings of a Scandinavian randomized multicenter trial in which a single participating surgeon accounted for 33% of the recurrences after TEP (20). Once this surgeon’s results are set aside, the difference disappears. The meta-analysis of O’Reilly et al. (19) did not reveal any disadvantage of TAPP in terms of recurrence rates, and the laparoscopic/endoscopic techniques were superior to the open techniques with regard to chronic postoperative pain. As mentioned above, one trial (5) revealed a significantly lower rate of chronic pain after TAPP than after Lichtenstein repair; in this study, a group of patients at increased risk for postoperative pain was identified preoperatively by means of their response to a standardized noxious stimulus. The authors concluded that patients in this group should undergo laparoscopic/endoscopic rather than open surgery.

An American registry study addressed the question of perioperative complication rates after open versus endoscopic/laparoscopic primary hernia repair (21). In 37 645 patients, 16.9% of whom underwent endoscopic/laparoscopic surgery, there was no difference between the two types of procedure in 30-day morbidity or mortality (evidence level 2). Complications arose in about 1% of patients, severe complications in 0.5%. The mortality was 0.02% for laparoscopic and 0.05% for open procedures.

Inguinal hernias in women are a special case. Analysis of data from a Danish registry (22) revealed that recurrent femoral hernias arise in women only after surgery by an open anterior approach (evidence level 2). Earlier analyses of data from the Danish Hernia Database led to a general recommendation of endoscopic/laparoscopic surgery for female patients because of a high recurrence rate after Lichtenstein repair (recommendation grade B) (14).

Bilateral inguinal hernias should be repaired with an endoscopic/laparoscopic technique; this conclusion was reached in 2010 on the basis of results from a case series, compared with those in the literature (e10). The EHS recommends accordingly in its guidelines (8), despite a level of evidence of only 2C in the older Oxford classification. The same recommendation was made as early as 2004 by the National Institute for Health and Care Excellence in the United Kingdom; a survey in Scotland, however, revealed that it was poorly implemented (e11). Current recommendations for the treatment of primary inguinal hernia are summarized in Table 1.

Table 1

Treatment options for primary inguinal hernia

Recurrent inguinal hernia is another special case. Its proper management depends on the type of initial surgery, as presented in Table 2. Anterior inguinal scarring after surgery by an anterior approach makes a posterior approach preferable for the reoperation, and vice versa; the results reported in the literature bear out this common-sense conclusion. A Swedish registry study (23) revealed a significantly lower rate of second recurrences when an endoscopic/laparoscopic approach was used after prior anterior surgery, rather than a repeated anterior approach. After prior posterior surgery, however, a repeated posterior approach yielded equivalent results to an anterior approach. The EHS recommends endoscopic/laparoscopic surgery for recurrences after prior surgery through an anterior approach (24).

Table 2

Treatment options for recurrent inguinal hernia

Mesh technology and aspects of surgical technique

As mentioned above, a meta-analysis has shown that the use of a mesh does not increase the likelihood of chronic pain (15). The important attributes of modern meshes have been summarized by Klinge (25) (Table 3).

Table 3

Required properties of modern mesh materials, such as polypropylene and polyvinylidene fluoride

Histopathologic study of hernia meshes explanted from human patients has shown that they possess the desired properties (26). The markedly reduced foreign-body reaction to polyvinylidene fluoride (PVDF) has been demonstrated in long-term animal experiments, as has the effect of polypropylene (PP) and PVDF on collagen synthesis (e12). PVDF visualization with supramagnetic iron ions is not merely of scientific interest; it can also be used as a diagnostic aid for the evaluation of complications (27).

In summary, large-pore meshes are associated with reduced chronic pain after open inguinal hernia surgery (28) (evidence level 1). Although this has not yet been demonstrated for laparoscopic/endoscopic surgery (29) (evidence level 1), large-pore meshes are recommended in such cases as well, by analogy (16).

The utility of self-adhesive meshes cannot yet be definitively assessed. The Lichtenstein technique requires fixation with non-resorbable material (e13); mesh fixation is largely unnecessary in laparoscopic/endoscopic hernia repair (e14) (evidence level 1). In a Swedish study, fixation with short-term resorbable material (e.g., when a self-adhesive mesh was used) yielded a higher recurrence rate than fixation with long-term resorbable or non-resorbable material (30). The follow-up intervals in the studies on self-adhesive meshes and on glue fixation in the Lichtenstein technique were too short (about 1 year) (31, 32), but they did reveal that gluing causes significantly less chronic pain (evidence level 1).

Special cases: incarcerated inguinal hernia

Incarcerated inguinal hernia can and must be differentiated from irreducible hernia on the basis of the severe pain that it causes, acute onset, and (sometimes) clinical evidence of acute bowel obstruction. It is an indication for immediate surgery. An evaluation of the Danish hernia registry, compared to the hospital registry, revealed that incarcerated hernias are not always treated with the requisite speed even in western Europe (33). From 2003 to 2005, 158 patients died after emergency surgery for an incarcerated inguinal hernia. 60% had been symptomatic for more than 48 hours. In 41%, the inguinal area had not been examined at the time of hospital admission; 35% had been admitted to medical rather than surgical wards; and only 23% had undergone surgery within 8 hours of admission. These frightening statistics reveal a problem that is surely not limited to Denmark and underscore the vital importance of thorough physical examination and of surgical consultation in the interdisciplinary emergency room.

The results of surgery for incarcerated hernia were analyzed in a retrospective study of 166 consecutive patients (e15) with inguinal (50.6%), femoral (25.9%), umbilical (22.3%), and other kinds of hernia (1.2%). A mesh was used in 38.5%. Multivariate analysis revealed that the need for bowel resection was the single independent risk factor for morbidity. The use of a mesh did not alter the rate of any type of complication.

A further retrospective study of 234 patients with incarcerated inguinal hernia, nearly all of whom underwent mesh-based repair, was published very recently (34). Bowel resection was needed in 13.7% of cases. 14 patients (6%) had wound infections. The recurrence rate was only 0.9% on clinical follow-up, with a median observation time of 62.5 months. The authors concluded that mesh-based repair of incarcerated inguinal hernia is reasonable and safe even if bowel resection is needed.

The question whether to use a mesh to repair an incarcerated inguinal hernia was also addressed in a systematic review of 9 individual studies, 2 of which were randomized trials (35). The MINORS scores of the non-randomized studies ranged from 9 to 19 out of 24 points (mean, 14.1). The recurrence rate was found to be 5 times higher without a mesh than with one, and the infection rate was significantly lower in the mesh group. There was no difference between repair with and without a mesh in the small number of patients who needed bowel resection. The authors concluded that mesh-based repair is needed in all cases of incarcerated inguinal hernia.

Patient-specific risk factors for recurrence

Highly relevant information for both the choice of surgical technique and patient information before surgery has been obtained from the analyses of case registries with high-quality data. Open technique is an independent risk factor for recurrence, as is the rare situation of a direct hernia in a female patient (22). Sliding hernia in a male patient is significantly correlated with postoperative recurrence (36). Reoperation is twice as common for direct hernias than for indirect ones (37). These results have been confirmed by multivariate analyses of data from 70 000 to 85 000 patients and in a meta-analysis of data from 375 620 patients (38). In summary, direct hernia, female sex, recurrent hernia, and cigarette smoking are all independent factors favoring recurrent herniation (or a second recurrent hernia).

Chronic pain

In this section, we will discuss only the prevention of chronic pain, because its diagnosis and treatment generally require systematic interdisciplinary collaboration (39, 40), an adequate discussion of which could fill a separate article.

The use of endoscopic/laparoscopic technique helps prevent chronic pain (5, 19). Large-pore mesh has been shown to be beneficial for the prevention of chronic pain after open surgery and is analogously recommended when endoscopic/laparoscopic technique is used (16, 28).

Adequate analgesia immediately after surgery is important, as patients who report pain of a level higher than 3 on the Visual Analog Scale in the early postoperative period are six times as likely to develop chronic pain thereafter; this finding was statistically significant (4). In this study, the frequency of chronic pain was 1.25% after TEP and 1.29% after TAPP. Pain after inguinal hernia surgery should be documented in a structured fashion on the Visual Analog Scale and treated with adequate, adapted analgesic medication.

This review cannot cover every aspect of inguinal hernia surgery exhaustively. Rather, it is intended to provide an overview of current surgical methods, and to show that no single method is appropriate for all patients. Every surgeon dealing with this disease should have technical mastery of both open surgery and endoscopic/laparoscopic methods, so as to practice in conformity to the existing guidelines and thereby give patients the best possible treatment in the light of current scientific knowledge.

The lifetime risk
of developing an inguinal hernia is 3% for women and 27% for men.

Evidence-based treatment
Physical examination of the groin is an obligate part of every general physical examination, not only when patients complain of abdominal pain.

Dynamic ultrasonography
Inguinal hernia is primarily diagnosed by physical examination. Dynamic ultrasonography is used if necessary.

Pathogenesis
Inguinal hernia is not a rupture of the groin; rather, it is due to an abnormality of the extracellular matrix.

Men vs. women
For primary, asymptomatic, non-progressive inguinal hernia in a man (as opposed to a woman), watchful waiting is a valid option.

Mesh-based technique
A mesh-based repair with the Lichtenstein technique or a laparoscopic/endoscopic repair is recommended for primary inguinal hernia. These methods have lower recurrence rates than alternative methods, and comparable complication rates.

Different treatments
Unilateral primary inguinal hernia can be treated either by open surgery or by endoscopy/laparoscopy; the latter seems preferable because of the lower frequency of chronic postoperative pain.

Indications
The classic indications for endoscopy/laparoscopy are inguinal hernia in a woman, bilateral inguinal hernia, and recurrent hernia after a prior anterior approach.

Mesh technology
Large-pore meshes are obligatory. In laparoscopic/endoscopic hernia repair, as opposed to the Lichtenstein technique, they do not need to be fixed in most cases.

Emergencies
In any emergency (or even elective) admission to the hospital, examination of the inguinal region by an experienced surgeon is essential when indicated.

Patient-specific risk factors for recurrence

• female sex
• direct hernia
• sliding hernia in males
• cigarette smoking
• already recurrent hernia

Chronic pain
The probability of chronic pain can be lowered by certain technical intraoperative measures and by adequate early postoperative analgesia.

Conflict of interest statement

Prof. Berger has received reimbursement of meeting participation fees, as well as travel and accommodation expenses and honoraria for the preparation of scientific presentations, from med update GmbH.

Manuscript submitted on 19 July 2015, revised version accepted on
19 January 2016.

Translated from the original German by Ethan Taub, M.D.

Corresponding author
Prof. Dr. med. Dieter Berger
Klinik für Viszeral-, Thorax- und Kinderchirurgie
Klinikum Mittelbaden/Balg
Balgerstr. 50, 76532 Baden-Baden, Germany

@Supplementary material
For eReferences please refer to:
www.aerzteblatt-international.de/ref0916

References

1. Robinson A, Light D, Nice C: Meta-analysis of sonography in the diagnosis of inguinal hernias. J Ultrasound Med 2013; 32: 339–46

2. Robinson A, Light D, Kasim A, Nice C: A systematic review and meta-analysis of the role of radiology in the diagnosis of occult inguinal hernia. Surg Endosc 2013; 27: 11–8

3. Perez Lara FJ, Del Rey MA, Oliva MH: Do we really know the symptoms of inguinal hernia? Hernia 2014; 5: 19.

4. Bansal VK, Misra MC, Babu D, et al.: A prospective, randomized comparison of long-term outcomes: chronic groin pain and quality of life following totally extraperitoneal (TEP) and transabdominal preperitoneal (TAPP) laparoscopic inguinal hernia repair. Surg Endosc 2013; 27: 2373–82

5. Aasvang EK, Gmahle E, Hansen JB, et al.: Predictive risk factors for persistent postherniotomy pain. Anesthesiology 2010; 112: 957–69

6. Antoniou GA, Tentes IK, Antoniou SA, Simopoulos C, Lazarides MK: Matrix metalloproteinase imbalance in inguinal hernia formation. J Invest Surg 2011; 24: 145–50

7. Henriksen NA, Sorensen LT, Bay-Nielsen M, Jorgensen LN: Direct and recurrent inguinal hernia are associated with ventral hernia repair: a database study. World J Surg 2013; 37: 306–11

8. Simons MP, Aufenacker T, Bay-Nielsen M, et al.: European Hernia Society guidelines on the treatment of inguinal hernia in adult patients. Hernia 2009; 13: 343–403

9. Miserez M, Peeters E, Aufenacker T, et al.: Update with level 1 studies of the European Hernia Society guidelines on the treatment of inguinal hernia in adult patients. Hernia 2014; 18: 151–63

10. Magnusson J, Videhult P, Gustafsson U, Nygren J, Thorell A: Relationship between preoperative symptoms and improvement of quality of life in patients undergoing elective inguinal herniorrhaphy. Surgery 2013

11. Chung L, Norrie J, O’Dwyer PJ: Long-term follow-up of patients with a painless inguinal hernia from a randomized clinical trial. Br J Surg 2011; 98: 596–9

12. Fitzgibbons RJ, Jr., Ramanan B, Arya S, et al.: Long-term results of a randomized controlled trial of a nonoperative strategy (watchful waiting) for men with minimally symptomatic inguinal hernias. Ann Surg 2013; 258: 508–15

13. Mizrahi H, Parker MC: Management of asymptomatic inguinal hernia: a systematic review of the evidence. Arch Surg 2012; 147: 277–81

14. Rosenberg J, Bisgaard T, Kehlet H, et al.: Danish Hernia Database recommendations for the management of inguinal and femoral hernia in adults. Dan Med Bull 2011; 58: C4243

15. Amato B, Moja L, Panico S, et al.: Shouldice technique versus other open techniques for inguinal hernia repair. Cochrane Database Syst Rev 2012; 4: CD001543

16. Bittner R, Montgomery MA, Arregui E, et al.: Update of guidelines on laparoscopic (TAPP) and endoscopic (TEP) treatment of inguinal hernia (International Endohernia Society). Surg Endosc 2015; 29: 289–321

17. Bittner R, Arregui ME, Bisgaard T, et al.: Guidelines for laparoscopic (TAPP) and endoscopic (TEP) treatment of inguinal Hernia (International Endohernia Society (IEHS)). Surg Endosc 2011; 25: 2773–843

18. Trevisonno M, Kaneva P, Watanabe Y, et al.: A survey of general surgeons regarding laparoscopic inguinal hernia repair: practice patterns, barriers, and educational needs. Hernia 2015;19: 719–24

19. O’Reilly EA, Burke JP, O’Connell PR: A meta-analysis of surgical morbidity and recurrence after laparoscopic and open repair of primary unilateral inguinal hernia. Ann Surg 2012; 255: 846–53

20. Eklund AS, Montgomery AK, Rasmussen IC, Sandbue RP, Bergkvist LA, Rudberg CR: Low recurrence rate after laparoscopic (TEP) and open (Lichtenstein) inguinal hernia repair: a randomized, multicenter trial with 5-year follow-up. Ann Surg 2009; 249: 33–8

21. Saleh F, Okrainec A, D’Souza N, Kwong J, Jackson TD: Safety of laparoscopic and open approaches for repair of the unilateral primary inguinal hernia: an analysis of short-term outcomes. Am J Surg 2014; 208: 195–201

22. Burcharth J, Andresen K, Pommergaard HC, Bisgaard T, Rosenberg J: Direct inguinal hernias and anterior surgical approach are risk factors for female inguinal hernia recurrences. Langenbecks Arch Surg 2014; 399: 71–6

23. Sevonius D, Gunnarsson U, Nordin P, Nilsson E, Sandblom G: Recurrent groin hernia surgery. Br J Surg 2011; 98: 1489–94

24. Zannoni M, Luzietti E, Viani L, Nisi P, Caramatti C, Sianesi M: Wide resection of inguinal nerves versus simple section to prevent postoperative pain after prosthetic inguinal hernioplasty: our experience. World J Surg 2014; 38: 1037–43

25. Klinge U, Park JK, Klosterhalfen B: ’The ideal mesh?’. Pathobiology 2013; 80: 169–75

26. Klosterhalfen B, Klinge U: Retrieval study at 623 human mesh explants made of polypropylene – impact of mesh class and indication for mesh removal on tissue reaction. J Biomed Mater Res B Appl Biomater 2013; 101: 1393–8

27. Kuehnert N, Kraemer NA, Otto J, et al.: In vivo MRI visualization of mesh shrinkage using surgical implants loaded with superparamagnetic iron oxides. Surg Endosc 2012; 26: 1468–75

28. Sajid MS, Leaver C, Baig MK, Sains P: Systematic review and meta-analysis of the use of lightweight versus heavyweight mesh in open inguinal hernia repair. Br J Surg 2012; 99: 29–37

29. Currie A, Andrew H, Tonsi A, Hurley PR, Taribagil S: Lightweight versus heavyweight mesh in laparoscopic inguinal hernia repair: a meta-analysis. Surg Endosc 2012; 26: 2126–33

30. Novik B, Nordin P, Skullman S, Dalenback J, Enochsson L: More recurrences after hernia mesh fixation with short-term absorbable sutures: A registry study of 82 015 Lichtenstein repairs. Arch Surg 2011; 146: 12–7

31. Zhang C, Li F, Zhang H, Zhong W, Shi D, Zhao Y: Self-gripping versus sutured mesh for inguinal hernia repair: a systematic review and meta-analysis of current literature. J Surg Res 2013; 185: 653–60

32. de Goede B, Klitsie PJ, van Kempen BJ, et al.: Meta-analysis of glue versus sutured mesh fixation for Lichtenstein inguinal hernia repair. Br J Surg 2013; 100: 735–42

33. Kjaergaard J, Bay-Nielsen M, Kehlet H: Mortality following emergency groin hernia surgery in Denmark. Hernia 2010; 14: 351–5

34. Bessa SS, Abdel-Fattah MR, Al-Sayes IA, Korayem IT: Results of prosthetic mesh repair in the emergency management of the acutely incarcerated and/or strangulated groin hernias: a 10-year study. Hernia 2015;19: 909–14

35. Hentati H, Dougaz W, Dziri C: Mesh repair versus non-mesh repair for strangulated inguinal hernia: systematic review with meta-analysis. World J Surg 2014; 38: 2784–90

36. Andresen K, Bisgaard T, Rosenberg J: Sliding inguinal hernia is a risk factor for recurrence. Langenbecks Arch Surg 2015; 400: 101–6

37. Andresen K, Bisgaard T, Kehlet H, Wara P, Rosenberg J: Reoperation rates for laparoscopic vs open repair of femoral hernias in Denmark: a nationwide analysis. JAMA Surg 2014; 149: 853–7

38. Burcharth J, Pommergaard HC, Bisgaard T, Rosenberg J: Patient-related risk factors for recurrence after inguinal Hernia repair: A systematic review and meta-analysis of observational studies. Surg Innov 2015; 22: 303–17

39. Berger D: Diagnostics and therapy of chronic pain following hernia operation. Chirurg 2014; 85: 117–20

40. Lange JF, Kaufmann R, Wijsmuller AR, et al.: An international consensus algorithm for management of chronic postoperative inguinal pain. Hernia 2015; 19: 33–43

e1. Fitzgibbons RJ, Forse RA: Clinical practice. Groin hernias in adults. N Engl J Med 2015; 372: 756–63

e2. Burcharth J, Pedersen M, Bisgaard T, Pedersen C, Rosenberg J: Nationwide prevalence of groin hernia repair. PLoS One 2013; 8: e54367

e3. Miller J, Cho J, Michael MJ, Saouaf R, Towfigh S: Role of imaging in the diagnosis of occult hernias. JAMA Surg 2014; 149: 1077–80

e4. Tolver MA, Rosenberg J: Pain during sexual activity before and after laparoscopic inguinal hernia repair. Surg Endosc 2015; 29: 3722–5

e5. Henriksen NA, Mortensen JH, Sorensen LT, et al.: The collagen turnover profile is altered in patients with inguinal and incisional hernia. Surgery 2015; 157: 312–21

e6. Antoniou GA, Giannoukas AD, Georgiadis GS, et al.: Increased prevalence of abdominal aortic aneurysm in patients undergoing inguinal hernia repair compared with patients without hernia receiving aneurysm screening. J Vasc Surg 2011; 53: 1184–8

e7. Pierides G, Mattila K, Vironen J: Quality of life change in elderly patients undergoing open inguinal hernia repair. Hernia 2013; 17: 729–36

e8. Desarda MP: Physiological repair of inguinal hernia: a new technique (study of 860 patients). Hernia 2006; 10: 143–6

e9. Hallen M, Westerdahl J, Nordin P, Gunnarsson U, Sandblom G: Mesh hernia repair and male infertility: a retrospective register study. Surgery 2012; 151: 94–8

e10. Wauschkuhn CA, Schwarz J, Boekeler U, Bittner R: Laparoscopic inguinal hernia repair: gold standard in bilateral hernia repair? Results of more than 2800 patients in comparison to literature. Surg Endosc 2010; 24: 3026–30

e11. Shaikh I, Olabi B, Wong VM, Nixon SJ, Kumar S: NICE guidance and current practise of recurrent and bilateral groin hernia repair by Scottish surgeons [In Process Citation]. Hernia 2011; 15: 387–91

e12. Klink CD, Junge K, Binnebosel M, et al.: Comparison of long-term biocompability of PVDF and PP meshes. J Invest Surg 2011; 24: 292–9

e13. Amid PK: The Lichtenstein repair in 2002: an overview of causes of recurrence after Lichtenstein tension-free hernioplasty. Hernia 2003; 7: 13–6

e14. Teng YJ, Pan SM, Liu YL, et al.: A meta-analysis of randomized controlled trials of fixation versus nonfixation of mesh in laparoscopic total extraperitoneal inguinal hernia repair. Surg Endosc 2011; 25: 2849–58

e15. Venara A, Hubner M, Le NP, Hamel JF, Hamy A, Demartines N: Surgery for incarcerated hernia: short-term outcome with or without mesh. Langenbecks Arch Surg 2014; 399: 571–7