Recommendations for patient management after manual reduction of incarcerated inguinal hernia: a literature review

Summary

Introduction: Topic of this review is to provide a systematic overview of the current evidence on the management of patients after manual reduction of an incarcerated inguinal hernia.

Methods: Available literature regarding incarcerated or strangulated inguinal hernias published until March 2019 was obtained and reviewed. 32,021 papers were identified, of which only 20 were of a sufficient value to be used in this review.

Results: The terms ‘incarcerated’ and ’strangulated’ are used interchangeably in the literature making separate analysis of these two entities almost impossible, although manual reduction is very unlikely to be successful when the hernia has strangulated contents. Following successful manual reduction, mesh repair is generally superior compared to pure tissue repair with regard to recurrence rates. Nevertheless, mesh repair is associated with a significant increase in the surgical site infection (SSI) rate, especially when bowel necrosis is present. The laparoscopic approach provides the benefits of avoiding an unnecessary laparotomy and reducing associated morbidity, but it does require the availability of appropriate equipment and an appropriately skilled surgical team.

Conclusion: A mesh repair is generally superior to a pure tissue repair in the surgical management of emergency inguinal hernias, reducing the recurrence rate, but can be associated with an increased risk of SSI depending on the level of contamination. The laparoscopic approach is recommended if an experienced surgical team and necessary equipment are available.

Keywords:

inguinal hernia – incarcerated – strangulated – surgery – laparoscopy – mesh

Introduction

An inguinal hernia presenting as an emergency is a common surgical problem. While the manual reduction under analgesia/sedation (taxis) can buy time to optimise the patient before surgery [1] what to do next remains a surgical dilemma. The surgical approach – open, laparoscopic, laparotomy, and the use of a mesh add to the surgical uncertainty. The aim of this study was to perform a literature review focusing on the management of acute inguinal hernias in adult patients following successful taxis.

Methods

In March 2019 Medline, Scopus, Ovid and Embase were searched for papers related to emergency inguinal hernias. Search terms “groin”, “inguinal”, “strangulated”, “incarcerated”, “irreducible”, “emergency”, “groin/inguinal hernia”, “taxis” and “reduction” were used. The first search, which resulted in 32,021 hits, was carried out by two of the authors of this study; further evaluation was done by all investigators separately. Both titles and abstracts were checked and duplicates, case reports and non-English articles were excluded.  Ninety publications were identified based on the literature review. These were obtained in full-text. The authors reviewed the 90 papers, 20 papers of which were included in this review. 

The definitions were adopted from the Hernia Surg Group Guidelines [2] and were set as “Incarceration: Inability to reduce the hernia mass into the abdomen and Strangulation: The blood supply to the herniated tissues is compromised”. Data was collected on emergency inguinal hernia classifications, patient pathways, use of taxis, surgical approach, surgical findings, mesh use, antibiotic use and clinical outcomes. The definitions of clinical outcomes were taken from the papers reviewed, accepting that variations in such definitions are likely to exist between publications.

Results

Twenty articles were included in the final analysis. No classification for emergency inguinal hernia was found. It was impossible to distinguish between incarcerated and strangulated hernias in most publications due to the incorrect use of these terms. In addition, not all strangulated inguinal hernias contain bowel, so not all such reported hernias demonstrated signs of bowel obstruction. It is assumed that about 1% of groin hernias present as emergencies [3], but only 10% to 20% require bowel resection [4].

Clinical presentation

Clinical examination along with the medical history remained the main diagnostic process.  Ultrasound and CT scanning were reported as an adjunct to confirm the diagnosis. In some cases, it helped revealing other pathology, such as abdominal malignancy, that influenced the surgical plan, although this was rare [5].

Assessment and diagnosis

A number of serum markers for recognising potential bowel ischaemia were identified. 85% of patients with a serum level of D-dimer above 300 ng/ml had bowel ischemia [6]. Serum phosphokinase levels of 140 IU/l and higher (compared to 90 in the control group) together with signs of bowel obstruction were also associated with bowel ischaemia. Body temperature, white cell count, lactate, serum amylase and C-reactive protein levels had little predictive value with regard to bowel ischaemia in relation to the inguinal hernia [6,7].

Surgical outcomes

Patients’ comorbidities and delayed admission contributed significantly to worse surgical outcomes. The risk of strangulation doubles for every 24 hours of delay. Other risk factors for bowel resection are age and dementia [8]. Some older studies report mortality rates up to 20% in case of bowel strangulation after 24 hours and nearly 40% after 72 hours [9,10], reaching as high as 80% when bowel has already perforated, there is pus in the hernia sack, or in cases of faecal contamination of the abdominal cavity. More recently, mortality between 5−27% was reported depending on the extent or length of bowel necrosis [11]. A midline laparotomy was a significant risk factor for post-operative mortality and morbidity. Men have a higher rate of bowel resection compared to women [3,11,12].

Mesh repair is recommended by the Hernia Surg Group Guidelines in elective repair as it is superior to non-mesh repair in the number of recurrences [2]. A number of studies compared the outcomes of mesh versus non-mesh techniques in the treatment of incarcerated inguinal hernias both after a successful and unsuccessful taxis. A meta-analysis published in 2014 summarising the findings of 9 previously published papers (out of which only 2 were RCTs) has found a statistically lower SSI rate in the mesh group compared to the non-mesh group [13]. Bessa et al. have published a retrospective analysis where only 1 out of 31 patients undergoing mesh repair after a resection of ischaemic bowel developed a mesh infection and the mesh had to be explanted 6 months later [12]. Another randomised controlled trial (2018) has reported that the mesh infection rate was growing with a higher degree of bowel necrosis. However, in Grade I (no perforation and sterile exudate in the hernia sack) patients there was no difference in the wound infection rate between the mesh and non-mesh repair groups (13.5% x 9.9%). Overall, the wound morbidity was significantly more common in the mesh repair group (47.1% x 22.1%) [11].

A retrospective study focusing solely on patients with gangrenous bowel at the time of surgery reported the SSI rate of 15% and a nearly 7% mesh removal rate [16]. Three more recent retrospective studies identified bowel resection, symptoms duration over 24 hours and bacteria in the hernia sack [15], obesity [11], bowel resection and male sex [8] as risk factors for developing a SSI. While SSI had a reported incidence between 6−25%, most of the infections were identified in the laparotomy wounds or superficially in groin incisions [8,11,15]. Non-mesh techniques have also been shown to take significantly longer to perform (92 min vs 66 min) [14].

The use of a laparoscopic approach was reported both to assess the intra-abdominal content after hernia reduction and to perform a hernia repair. There is little evidence on the merits of such surgery, but the laparoscopic approach appears to be associated with a longer operative time (150 min vs 85 min on average) in studies reported to date [17].

In studies that mentioned the antibiotic protocol during treatment, most offered single-dose perioperative antibiotic therapy represented by either an aminopenicillin or a 1st generation cephalosporin. One study reported prolonged prophylaxis when bowel resection was performed and a synthetic mesh used (4−7 days) [18].

Discussion

There is a clear lack of scientific evidence to inform on the management of this common surgical diagnosis. However, a number of suggestions, extracted from the available literature, could be made to aid the decision making when considering inguinal hernias in the emergency setting.

Attempts at taxis in the acute setting are suggested [1]. If successful, then surgery can be scheduled based on the local surgical expertise. Serum markers to assess viability of the sac contents have little if any additional clinical benefit and clinical and radiological findings should be given more importance than those. Appropriate resuscitation, correction of any anti-coagulation therapy as necessary and prophylactic antibiotics are recommended.

The surgical approach will depend on the surgeon’s skills, availability of resources and patient factors. While there are no clear contra-indications to laparoscopy, a case by case analysis of patient related factors, such as for example multiple previous abdominal surgery, will influence the decision making [19]. However, with the awareness that infarcted bowel is a major risk factor for morbidity and mortality, surgery when this is suspected should be undertaken in a timely manner, by appropriately trained staff. This includes the use of critical care in the post-operative period as necessary.

The benefits of laparoscopy include the visualisation of the contents within the hernia sac, and their viability upon reduction. If there is non-viable bowel, then the operation can be continued laparoscopically or converted to open surgery as necessary. The open approach may be via a conventional groin incision or a lower midline laparotomy [20]. Up to 50% of reported laparotomies during open repair of incarcerated groin hernias do not lead to bowel resection, and laparotomy per se is associated with higher morbidity [20]. Care should be taken to avoid this approach, unless there is clear indication to do so. Additional benefits of the laparoscopic approach include a shorter hospital stay, and fewer surgical site events such as haematoma and seroma development. However, a laparoscopic repair of incarcerated groin hernias typically involves more skilled and senior staff to undertake the surgery. Risks connected to laparoscopy (especially visceral and vascular injuries) are well known and while there are no reported cases in acute inguinal hernia surgery relating to such complications, they are likely to be higher in the emergency setting. An open cut-down approach, Hasson technique, to the abdominal cavity for laparoscopy is suggested.

The use of a mesh in the emergency setting is a calculated risk of hernia repair with a lower risk of recurrence, versus the risk of mesh infection and likely prolonged morbidity and the possible need for mesh explantation. The concept of keeping the site of bowel resection away from the site of hernia repair makes some sense. A recent report proposed the two windows theory based on a principle that during surgery for incarcerated / strangulated groin hernia the bowel resection part is performed through a different wound to the repair site to minimize the risk of contamination [16]. The authors demonstrated a reduction of surgical site infection from 15% to 4% and eliminated the need for mesh removal. The use of a large pore synthetic mesh is suggested [2]. The use of a slowly resorbable mesh and a biological mesh is also an option, although these meshes carry a significant economic cost with little evidence of benefit to date over a permanent synthetic mesh in this setting.  However, the type of mesh to be used in this situation was outwith the scope of the current study. Nevertheless, in the presence of faecal peritonitis or gross contamination, it is suggested that a mesh is not used. While surgical site infection is relatively common in this type of surgery, infection of the mesh and the need for explanation are relatively uncommon. Continuing antibiotics, with drainage of any collections that may occur around the mesh may allow mesh salvage in some cases.

Hernioscopy is a novel approach suggested as an option during open surgical management of an incarcerated groin hernia with spontaneous reduction. ‘Laparoscopy’ is performed through the hernia sac and the viability of the bowel can be assessed without the need for a laparotomy or conventional laparoscopy [21,22].

Limitations

This review demonstrates the lack of available literature on the management of incarcerated / strangulated inguinal hernias. The lack of clear definitions of ‘incarcerated’ versus ‘strangulated’ in many reports made the pooling of data from trials impossible. Most studies were rated as low or very low quality according to GRADE. No information was found on the learning curve of emergency hernia surgery or patient reported outcomes.

Conclusion

There is very little evidence in the literature to make any clear recommendations. While there are benefits to a laparoscopic approach, open surgery may be a better option for an individual patient with factors making a laparoscopic approach more difficult. The use of a mesh is generally safe, but the decision on its use should be made on a case by case basis. High morbidity and mortality of patients treated for strangulated hernias in the emergency setting makes it a challenging condition and should be treated with due care and diligence.

Further studies with a more accurate use of terminology are needed to give a clearer picture of the true incidence of incarcerated and strangulated hernias. The need for an international registry is clear to inform on the role and importance of taxis as well as reporting on the various complications and long-term results in this condition to aid future management decisions.

Conflict of interests

The authors declare that they have no conflict of interest in connection with this paper and that the article has not been published in any other journal, except congress abstracts and clinical guidelines.

MUDr. Barbora East

3. chirurgická klinika FN v Motole

V úvalu 84

150 06 Praha 5

e-mail:barbora.east@fnmotol.cz