A study into the prevention of parastomal herniation
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A hernia frequently complicates abdominal stoma formation. The aetiology of parastomal herniation is claimed to be multi-factorial but currently only age and trephine diameter have been shown to independently predict its development. Open or laparoscopic repair of a symptomatic parastomal hernia is frequently challenging and is associated with unsatisfactory recurrence rates. As a result, many affected patients are managed non-operatively. Prevention of parastomal herniation by prophylactic mesh reinforcement of the stoma site is a new strategy that may reduce its incidence. Manual mesh implantation, however, is thought to increase the operating time and is considered cumbersome, particularly in laparoscopic surgery. As a result, routine reinforcement of the stoma site is not currently standard practice within the National Health Service. Thus, there is a need for a simple and quick technique for stoma formation which avoids creating an oversized defect and simultaneously reinforces the trephine with mesh. The aims of this thesis included: (i) understanding the aetiopathogenesis of parastomal herniation, assessing its impact on patients’ quality of life and examining the outcomes associated with current therapeutic strategies in order to find novel therapies that may lead to its prevention; (ii) assessing the safety, reproducibility and efficacy of the Stapled Mesh stomA Reinforcement Technique (SMART) in preventing parastomal herniation and (iii) investigating the contribution of the rectus abdominis muscle to the development of herniation. A detailed literature review of PubMed and Medline databases confirmed that stoma formation through the rectus muscle is complicated by parastomal herniation in 50%-80% of 4 cases. Surgeons have underestimated its impact on patients’ quality of life. There is no conclusive evidence that alternative techniques (e.g. extraperitoneal, lateral rectus abdominis positioned stoma) are superior. Open and laparoscopic parastomal hernia repair have similar recurrence rates up to 50%. Prophylactic reinforcement of the stoma trephine with mesh in the sublay or subperitoneal position is safe and appears to reduce the herniation rate but it is difficult laparoscopically and does not address the issue of trephine size when a defect <25mm is associated with a reduced herniation risk. The Stapled Mesh stomA Reinforcement Technique (SMART) obviates the technical issues associated with routine stoma formation and reinforcement. In a pilot study with patients at high risk for herniation, SMART was found to be safe and reproducible and reduced the herniation rate to 18%. Preliminary results of the international multicentre randomised controlled trial in all patients undergoing permanent stoma formation show that SMART reduces the herniation rate compared to the standard technique, without added morbidity and minimal impact on the operating time. A radiological study assessing the contribution of the rectus abdominis muscle into the development of parastomal herniation showed that the abdominal musculature undergoes postoperative changes consistent with atrophy with postoperative muscle density being higher in patients without parastomal herniation. In conclusion, at this moment in time, prophylactic mesh reinforcement should be offered to all patients undergoing elective permanent stoma formation. The SMART procedure has the potential to change current surgical practice. The contribution of the rectus muscle to the development of herniation warrants further research since improving muscle repair and regeneration may result in therapeutic benefits.
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