Parastomal Hernia: Squaring the circle

Ben Griffiths, Head of Colorectal Surgery at Newcastle upon Tyne Hospitals and Ash Bhalla, Laparoscopic Fellow at Royal Victoria Infirmary, write on parastomal hernia, the béte noire of the colorectal surgeon, whose recurrence rate remains unacceptably high.

Introduction

The parastomal hernia (PSH) remains a béte noire of the colorectal surgeon and whilst we have durable, low morbid operations available for groin and midline ventral hernias the quest for the solution to the parastomal hernia continues.

In the UK 20,000 stomas are created annually, with the majority being colostomies. The famous Leeds surgeon John Goligher stated that ‘some degree of herniation around a colostomy is so common that this complication may be regarded as inevitable’ and in modern 21st century colorectal practice we know that up to 48% of patients with a colostomy and 28% with an end ileostomy will form a PSH, with approximately half of these developing symptoms.

The construction of a permanent stoma can have a significant impact on a patients’ overall well-being and health-related quality of life (HrQoL), with this being further impaired in patients who develop PSH. This is usually attributed to the additional issues conferred by the presence of the PSH, including peristomal pain, irritation, stoma leakage, difficulties in applying stomal appliances and cosmetic complaints. In addition, there are the potential risks of strangulation or incarceration requiring urgent surgical attention.

PSH is commonly detected during routine clinical or radiological examination. CT scanning can be used specifically to classify PSH using supine or prone positioning +/- the use of Valsalva manoeuvre. Alternative radiological imaging include US or MRI.

Risk factors

Patient related risk factors include age, obesity, increasing waist circumference, respiratory comorbidity, cancer, diabetes mellitus and the presence of other abdominal wall hernias have all been identified as increasing risk of PSH in the literature. Malnutrition, smoking, ascites and steroid use are additional suggested risk factors. Surgical risk factors include a stoma aperture size of greater than 25mm, emergency surgery and type of stoma. A Cochrane review in 2013 failed to establish whether a trans-rectal stoma is superior to a laterally-placed ostomy with respect to PSH rates [1].

Classification

There are a number of available classification systems available for PSH (Rubin et al, Devlin, Moreno-Matias, Gil and Szcepkowski, European Hernia Society (EHS)). Currently, there are no validated classification systems. The EHS classification system is, however, the most commonly used guideline in clinical practice [2]. The EHS guideline describes PSH between type 1-4, and is based on the size of the hernia defect (> or < 5cm) and the presence, or absence, of a concomitant midline hernia.

Management

Management of PSH is complex with a number of available treatment strategies. There are a number of conservative options available for the management of PSH, including appliance alterations, stoma belt and weight loss strategies. Surgical management is reserved for symptomatic hernias which have failed conservative management or those who present as an emergency. There are a number of restorative and reparative surgical options available in the elective and emergency setting for the management of PSH. Each technique and approach should be appropriately tailored to the patient and surgical setting.

Restorative procedures include restoration of gastrointestinal continuity in combination with definitive repair of the hernia in select patients with the appropriate gastrointestinal anatomy and function.

There are a number of reparative procedures available, including, suture repair, mesh repair and relocation of the stoma, with a number of operative approaches available including open, laparoscopic and robotic. A number of prosthetic mesh options are available, with great debate regarding the optimal approach and both type and placement of mesh. Given the abundance of potential options available, combined with the limited evidence informing PSH repair, it is difficult to be didactic about the preferred techniques.

Direct fascial suture repair is the oldest technique available, and is associated with a high recurrence rate of 69% [3]. This approach should be abandoned in all but the most very challenging emergency circumstances.

The available open techniques include onlay, sublay or intraperitoneal mesh. The evidence base reporting outcomes associated with these techniques is weak, consisting of retrospective case series and cohort studies in small sample sizes, with significant heterogeneity in reporting outcomes regarding technique and mesh type. The largest systematic review of 157 patients undergoing onlay repairs reported a pooled recurrence rate of 17.2%, with an associated mesh infection rate of 2.6% [3]. The majority of these repairs used a keyhole technique in which the mesh is slit and the bowel comes through an aperture in the centre of the repair.

The sublay repair uses a mesh placed between the rectus muscle and the posterior rectus sheath. The outcomes reported with this technique are limited, with Hanson et al reporting outcomes in 42 patients using polypropylene mesh, with a recurrence rate of 6.9% and a 0% mesh infection rate [3].

Open intraperitoneal repair is not widely reported, with a pooled analysis of 45 patients reporting a recurrence rate of 7.2%, with a 2.2% mesh infection rate [3]. The Sugarbaker technique is a type of intraperitoneal technique, in which the stoma is lateralized against the abdominal wall by a flap of mesh, thus avoiding the need to put a hole in the mesh. Reported rates of recurrence with this technique are 15% with a 0% mesh infection [3].
Emerging techniques include the Pauli repair, which uses the lateralizing flap-valve mesh position within the plane between transversus abdominus (TA) and the peritoneum after a TA release [4]. This has the theoretical advantage of reproducing the advantages of the Sugarbaker configuration but without the need for an intraperitoneal mesh. Early results have shown competitive early recurrence rates, however, there are concerns regarding mesh erosion [5].

The evidence for minimally invasive approaches, including laparoscopic and robotic, is limited and is reported by a small number of authors. The most commonly employed techniques reported laparoscopically are the Sugarbaker and keyhole repairs. Reported recurrence rates laparoscopically are 11.6% and 34.6% respectively [3]. A modification of the two techniques combined is the Sandwich repair with the use of 2 meshes. Initial reports of this technique are associated with a recurrence rate of 2.1% and 0% mesh infection rate [3].

Relocation of the stoma is a potential management strategy, however, it has fallen out of favour, due to the potential risk of parastomal hernia at the new stoma site and a significant incisional hernia risk at the original closure site.

Prophylaxis

The high incidence of parastomal herniation combined with the unsatisfactory results obtained from reparative and restorative procedures has led to emphasis now being placed on preventative strategies, including the use of prophylactic mesh.

Reduction in the size of the stoma aperture site at time of stoma formation has been investigated as a potential preventative strategy. The SMART trial examined the use of a pre-specified, uniform disk cut in the middle of a mesh using a circular stapler as a preventative strategy for the development of PSH [6]. A second UK based trial, the START trial, is investigating the use of suture reinforcement of the trephine as a preventative strategy [7]. The results of these trials are currently awaited.

The use of prophylactic mesh has gained significant momentum and has been extensively investigated over the last few years. A meta-analysis of 10 trials reported a significant reduction in PSH from 36.6% in the non-mesh group to 16.4% in the mesh group (p=0.02) without differences in SSI, stomal stenosis or necrosis [9]. However, the results of this meta-analysis must be interpreted with caution due to the significant heterogeneity in technique, mesh type and placement and follow up amongst the included studies. Given, the promising results associated with prophylactic mesh placement the EHS guidelines have ‘strongly recommended’ its use in the elective setting [9].

Interest has also been revived in the construction of an extra-peritoneal colostomy after a recent meta-analysis found a significant reduction in PSH from 17.8% to 6.3% with the formation of an extra-peritoneal tunnel [10]. However, the morbidity associated with this technique is poorly documented.

Future Research

The opportunity for future research in PSH management and prevention is vast given the methodological limitations of the current evidence base.

The Cipher study is a UK two-phase cohort study looking at current practice in stoma formation. This study aims to standardise the manner in which techniques and outcomes are reported in PSH surgery, including the development of a patient-reported outcome measure specifically for use in this cohort of patients. These reporting measures will then be used in a prospective cohort study to evaluate variation in current clinical practice. The importance of standardised reporting, and more importantly, patient-centred reporting has been acknowledged by a number of researchers, with the recently, completed Danish trial reporting patient experience and symptomology in patients with PSH [11]. Of course, there are a number of trials which will continue to focus on surgical technique, with the Swiss StoKo trial assessing the use of implantation of a novel propylene flexible ring at the time of colostomy formation [12]. The announcement of the ESCP Parastomal Hernia study is a timely addition to these above studies, and will provide us with a broader perspective on surgical strategies employed to prevent and manage PSH on a large scale.

Summary

PSH is a common complication of stoma formation, with a significant impact on HrQoL due to a range of symptoms. There are a number of available surgical techniques including restorative, reparative and preventative. Despite the vast number of available options for the repair of PSH the recurrence rate remains unacceptably high. The current evidence base supporting these different techniques is significantly limited by methodological constraints, including study design, small sample sizes, multiple iterations of surgical technique and heterogeneity in outcome reporting and follow up. To address all these issues requires considerable research including standardization of technique and outcome reporting, development of specific patient-reported outcomes and appropriate evaluation of all potential strategies. Current research is making significant steps towards this, with the ESCP Parastomal cohort study making a significant contribution. Following on from this, it is hoped surgical technique and strategies will be appropriately evaluated within suitably designed studies, to provide an answer which will translate into clinical practice, and ultimately improve patient outcomes.

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