Lateral pararectal stoma placement versus transrectal stoma siting for prevention of parastomal herniation
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
To assess if there is a significant difference regarding the incidence of parastomal hernias in lateral pararectal versus transrectal stoma placement. Furthermore, it has to be determined whether a lower herniation rate goes along with an increased incidence of ileus and stenosis.
Background
A parastomal hernia is defined as an incisional hernia related to a stoma. Parastomal herniation is one of the most common stoma‐related complications (Carne 2003). The incidence of parastomal hernias varies greatly between studies, but most likely ranges from 30% to 50% (Israelsson 2008). The consequences and implications of parastomal hernias are highly relevant for patients. Most of the patients suffer from an impaired body image and many have increasing difficulties to apply the stoma bag properly leading to leakage and skin irritation (Martin 1996). In rare cases, bowel incarceration occurs requiring emergency surgery (Cuthbertson 1977). In addition, stomal herniation necessitating reoperation and hospitalization has a negative socioeconomic impact, especially since recurrence rates after surgical correction are high (Israelsson 2008; Tekkis 1999).
Hence, the need for prevention of parastomal herniation is obvious. But how can this be achieved? There has been a lot of debate about possible risk factors, and especially the operative technique has consistently been up for discussion. Today most surgeons believe that transrectal placement is the best site in terms of hernia prevention, however there is no clinical evidence from randomized studies supporting this common view. Thus, we will search the existing literature on this topic in order to collect all relevant data which could possibly lead to a recommendation for the colorectal surgeon. Moreover, we plan to look at other important complications, such as ileus and stenosis. This is of great importance because preventing herniation by placing the stoma through the rectus abdominis muscle could in turn result in more stenotic complications as an adverse outcome.
Due to the scarcity of RCTs we will also review observational studies (Leong 1994; Londono‐Schimmer 1994; Ortiz 1994; Sjodahl 1988; von Smitten 1986; Williams 1990; Eldrup 1982).
Only two of the studies showed a significantly reduced incidence of parastomal herniation if the stoma is sited through the rectus abdominis muscle versus a location lateral to the muscle (Sjodahl 1988; Eldrup 1982). One prospective clinical trial with a total of 29 patients described a novel anatomical approach to stoma formation, the lateral rectus abdominis positioned stoma (LRAPS), involving minimal anterior abdominal wall disruption, which reduced the incidence of early stomal herniation significantly (Stephenson 2009). Recently, the authors published further follow up data presenting parastomal herniation rates of 5% and 10% after 1 year and 2 years respectively (Evans 2011).
Two RCTs with a total of 108 patients have recently approached the question, whether prophylactic implantation of prosthetic mesh concurrently with the index operation could reduce the occurrence of parastomal herniation (Janes 2004; Janes 2009; Serra‐Aracil 2009).
Although the results of these studies support the thesis that implantation of mesh can prevent parastomal herniation, this technique cannot be recommended as a standard practice, since the power of the studies is small and long term complications such as mesh arrosion have yet not been investigated. Furthermore, mesh implantation causes additional costs.
Description of the condition
A parastomal hernia is an incisional hernia related to a stoma (Pearl 1989).
Description of the intervention
Two interventions will be compared with regard to the incidence of parastomal herniation: placement of the stoma lateral to versus through the rectus abdominis muscle.
How the intervention might work
Lateral pararectal stoma placement may have a different incidence of parastomal herniation in comparison to transrectal stoma placement. Since the transrectally positioned stoma is surrounded by the thick muscle layers of the rectus abdominis muscle, one could expect a tighter fit and a reduced incidence of parastomal herniation due to the muscle contractions.
Why it is important to do this review
Parastomal herniation is one of the most common complications after stoma placement. Since parastomal hernias often have a negative impact on the patient’s health and quality of life, the operative techniques should be optimised in order to prevent this postoperative complication. The need for prevention is relevant because the recurrence rates after operative correction of parastomal hernias are considerably high, ranging from 50 to 76% after aponeurotic repair and from 24 to 86% after relocation respectively (Israelsson 2008). Especially patients with a permanent stoma, i.e. after abdomino‐perineal resection for low rectal cancer, suffer from the morbidity caused by parastomal herniation. Many surgical approaches have been attempted and propagated. However, there is still no clinical evidence from RCTs which is the best location site for a stoma. We therefore assume clinical equipoise in regard to the question, where a stoma should be located in relation to the rectus abdominis muscle.
In light of these controversies a systematic review of the available studies is considered justified to efficiently integrate existing information and provide data for rational decision making, as well as to increase power and precision of estimates of treatment effects and potential adverse outcome.
Objectives
To assess if there is a significant difference regarding the incidence of parastomal hernias in lateral pararectal versus transrectal stoma placement. Furthermore, it has to be determined whether a lower herniation rate goes along with an increased incidence of ileus and stenosis.
Methods
Criteria for considering studies for this review
Types of studies
Randomised controlled trials (RCTs) will be preferred. Due to the scarcity of this study type, observational studies and case series will also be included. Up to date (June 2011) a preliminary search revealed only two RCTs looking at the use of prosthetic mesh for prevention of parastomal herniation (Janes 2004; Janes 2009; Serra‐Aracil 2009).
Types of participants
All individuals receiving a temporary or permanent abdominal wall stoma for any reason in either the elective or the emergency setting will be included with no regard to the underlying disease.
Types of interventions
Two interventions will be compared in regard to the incidence of parastomal herniation: placement of the stoma lateral to versus through the rectus abdominis muscle.
Types of outcome measures
Primary outcomes
Occurrence of parastomal herniation.
Secondary outcomes
Stoma‐related morbidity, especially stenosis, obstruction, prolapse, necrosis, retraction, fistulization, and skin irritation; stoma‐related mortality.
Search methods for identification of studies
Electronic searches
We will search for published and unpublished randomized controlled trials, observational studies and case series without language restrictions using the following electronic databases: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE via Pubmed (1966 onwards) and EMBASE via OVIDSP (1980 onwards). Searches will be carried out using medical subject headings (MeSH) and free text words. The following trial registries will be searched for ongoing studies: clinicaltrials.gov, www.who.int/ictrp/en (apps.who.int/trialsearch), www.germanctr.de (drks‐neu.uniklinik‐freiburg.de/drks_web).
This search will be adapted for each database:
("Enterostomy"[Mesh] OR "Surgical Stomas"[Mesh] OR ("colostomy"[MeSH Terms] OR "colostomy"[All Fields]) OR ("colostomy"[MeSH Terms] OR "colostomy"[All Fields] OR "colostomies"[All Fields]) OR ("ileostomy"[MeSH Terms] OR "ileostomy"[All Fields]) OR ("ileostomy"[MeSH Terms] OR "ileostomy"[All Fields] OR "ileostomies"[All Fields]) OR ("enterostomy"[MeSH Terms] OR "enterostomy"[All Fields]) OR ("enterostomy"[MeSH Terms] OR "enterostomy"[All Fields] OR "enterostomies"[All Fields]) OR ("surgical stomas"[MeSH Terms] OR ("surgical"[All Fields] AND "stomas"[All Fields]) OR "surgical stomas"[All Fields] OR "stoma"[All Fields]) OR ("surgical stomas"[MeSH Terms] OR ("surgical"[All Fields] AND "stomas"[All Fields]) OR "surgical stomas"[All Fields] OR "stomas"[All Fields]) OR parastoma[All Fields] OR parastomal[All Fields] OR anuspraeter[All Fields] OR (artificial[All Fields] AND ("anal canal"[MeSH Terms] OR ("anal"[All Fields] AND "canal"[All Fields]) OR "anal canal"[All Fields] OR "anus"[All Fields])) OR (preternatural[All Fields] AND ("anal canal"[MeSH Terms] OR ("anal"[All Fields] AND "canal"[All Fields]) OR "anal canal"[All Fields] OR "anus"[All Fields]))) AND ("Hernia"[Mesh] OR ("hernia"[MeSH Terms] OR "hernia"[All Fields]) OR ("hernia"[MeSH Terms] OR "hernia"[All Fields] OR "hernias"[All Fields]) OR ("hernia"[MeSH Terms] OR "hernia"[All Fields] OR "herniation"[All Fields])) AND ("humans"[MeSH Terms] AND Randomized Controlled Trial[ptyp])
Searching other resources
The reference lists of all relevant studies including reviews will be screened, too.
Data collection and analysis
Selection of studies
Studies identified from the described literature search for potential inclusion will be independently assessed for eligibility by JH and FH.
Data extraction and management
JH and FH will extract the data for the review independently. Disagreements will be resolved by discussion with a third author (PK). In addition to the outcomes, population characteristics (such as sex, age, underlying disease, obesity (BMI > 30 kg/m²) and type of stoma (ileostomy versus colostomy, end ostomy versus loop ostomy) will be evaluated. We will assess the methodological quality of the trials independently using risk of bias tables without masking of trial authors.
Assessment of risk of bias in included studies
The methodological quality of the trials will be assessed on sequence generation, allocation concealment, blinding of participants, personnel, and outcome assessors, incomplete outcome data, selective reporting, and other sources of bias if applicable (Higgins 2011). Since this assessment tool was developed for randomized trials, it is not necessarily appropriate for non randomized trials. Therefore, we plan to use the Newcastle‐Ottawa Scale to assess the risk of bias in non randomized trails (Wells 2011).
Measures of treatment effect
Presence of parastomal herniation will be treated as dichotomous variable. For dichotomous variables, the risk ratio (RR) will be calculated with 95 % confidence intervals (CI).
Unit of analysis issues
The unit of analysis will be each patient recruited into the trials.
Dealing with missing data
Dealing with missing data we will contact the trial authors to ask for the missing information. Moreover, we will conduct sensitivity analyses for dichotomous outcomes based on the consideration of the "best‐case" and the "worst‐case" scenarios, as recommended by Gamble and Hollis (Gamble 2005). Dealing with missing individual participant data from randomized trials we will consider to perform an intention‐to‐treat analysis. Finally, we will discuss the potential impact of missing data in the discussion section.
Assessment of heterogeneity
Chi‐squared test will be used for assessment of statistical heterogeneity. Statistical significance will be determined by a P value of 0.10. Even more relevant than the assessment of heterogeneity is the quantification of its impact on the meta‐analysis. Thus, we will apply the I² value to quantify the inconsistency of the included studies (Deeks 2011). An I² value of > 30% represents moderate (30‐60%), substantial (50‐90%) or even considerable (75‐100%) heterogeneity.
Assessment of reporting biases
Reporting biases occur if the dissemination of research findings is influenced by the nature and direction of trial results. There are several types of reporting bias: publication bias, multiple publication bias, time lag bias, location bias, citation bias, language bias, and outcome reporting bias (Sterne 2011). We will search different trial registries in order to avoid reporting biases (see Electronic Searches).
To assess whether small‐study effects are present in our systematic review, we will use a funnel plot and statistical tests for funnel plot asymmetry. Publication bias is minimum if the plot resembles a funnel with base down.
Data synthesis
From the analysis options in Rev Man version 5 we will apply the DerSimonian and Laird random‐effects method assuming that the effects being estimated in the different studies are not identical, but follow some distribution (DerSimonian 1986). The random‐effects model estimates the extent of variation among the intervention effects of the included studies (Deeks 2011).
Subgroup analysis and investigation of heterogeneity
We plan to conduct the following subgroup analyses:
Ileostomy versus colostomy. End ostomy versus loop ostomy. Obesity (BMI > 30 kg/m²), overweight (BMI >25, <30 kg/m²) versus normal weight (BMI > 20, < 25 kg/m²).
Sensitivity analysis
Sensitivity analysis investigates how the variation in the output of a statistical model depends on the different variations in the inputs of the model. We will perform sensitivity analyses for the following issues:
‐ Risk of bias in included trials (high versus low)
‐ Level of standardization of stoma surgery (standardized procedure mentioned vs. no mentioning of standardization)
Where sensitivity analyses identify particular decisions or missing data that had a major influence on the findings of the review, we will contact trial authors in order to obtain the missing information and gain a higher level of certainty with regard to the interpretation of the findings.
