Incisional hernia

Incisional hernia

These arise through a defect in the musculofascial layers of the abdominal wall at the site of a postoperative scar. Thus, they may appear anywhere where a laparotomy has been made. Incidence and aetiology Incisional hernias have been reported in 10–50% of laparot omy incisions and 1–5% of laparoscopic port-site incisions. Factors predisposing to their development include patient factors (genetic collagen disorders, obesity , general poor healing due to maln utrition, immunosuppression or steroid therapy , chronic cough, cancer), wound factors (poor quality tissues, wound tension, wound infection) and surgical factors (inappropriate suture material, poor closure technique). An incisional hernia usually starts as disruption of the mus culofascial layers of a wound in the early postoperative period. This may progress rapidly to full thickness wound dehiscence, usually heralded by a serosanguineous discharge around the sixth postoperative day , but mor e commonly the event passes unnoticed if the overlying skin wound has healed securely . A visible swelling may take weeks, months or years to appear. Many incisional hernias may be preventable by ensuring healthy wound edges, minimal wound tension and good sur gical technique as described by the European Hernia Society abdominal wall closure guidelines. The small-stitch, small-bite technique is recommended, and the role of prophylactic mesh in high-risk patients is also a current area of researc h. Clinical features Incisional hernias commonly appear as a localised swelling involving part of a surgical scar but may present as a di ff use bulging of the whole length of the incision ( Figure 64.25 Alternatively there may be several discrete hernias along the length of the incision, but even with apparently singular hernias unsuspected defects are frequently found at operation ( Figure 64.26 ). Incisional hernias tend to increase steadily in - - - Summary box 64.16 - Incisional hernia /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF ). size with time, and the overlying skin may become thin and atrophic. Local trauma and microvascular damage to skin may lead to ulceration. Episodes of intestinal obstruction are common because there are usually coexisting internal

Figure 64.25 A large incisional hernia involving the full length of the incision. Figure 64.26 Multiple defects along the line of the scar, seen at laparoscopy. Incidence 10–50% after surgery Aetiology includes patient, wound and surgeon factors Wide variation in size Multiple defects within the same scar are very common Obstruction is common but strangulation is rare Open and laparoscopic repairs possible

incisional hernias are shallow and wide-necked. As with any hernia type, strangulation is most likely when the fibrous defect is small and the sac is large. Treatment Asymptomatic incisional hernias may not require treatment. The wearing of an abdominal binder or belt often provides symptomatic relief and may prevent the hernia from increas ing in size. Many patients with an incisional hernia have other comorbidities and discussion around the balance of benefits and risks of surgery is important. The decision to operate and choice of technique should always be agreed between the patient and the surgeon and patients’ preferences need to be respected. Repair of large and/or complex incisional hernias can be extremely challenging; in such cases advice from, or referral to, a colleague with a special interest in abdominal wall reconstruction should be considered. Each patient undergoing an elective incisional hernia repair should be optimised for surgery . In many centres, patients undergo formal multidisciplinary team assessment and this is likely to become the standard of care in the coming year So-called ‘prehabilitation’ includes weight loss if the patient is obese, smoking cessation, fitness improvement and core strength exercising. Loss of 7% of total bodyweight achieves a significant improvement in metabolic state, and 5 /uni00A0 kg of body weight is said to create about one extra litre of space inside the adult male abdomen (0.5 litres in women). Prevention of incisional hernia The risk of incisional hernia may be reduced by improving the patient’s general condition preoperatively where possible, e.g. smoking cessation, weight loss for obesity or improving nutritional status in undernourished individuals. Closing the fascial layers with good technique and materials is important. For years it has been advised that sutures should be 1 /uni00A0 cm back from the wound edge and 1 /uni00A0 cm apart, but recent work has shown that lower incisional hernia rates and reduced infection rates are gained when smaller and closer bites are used: 5 /uni00A0 mm apart and 5–8 /uni00A0 mm back from the wound edge, with care taken to incorporate fascia only in the suture bites (no muscle) and to minimise excessive suture tension. A 2/0 slowly resorbable suture is also recommended rather than traditional heavier and/or non-absorbable materials (see Chapter 7 ). There is no evidence that interrupted sutures are better or worse than continuous. However, if continuous suturing used, the tissue bites must not be too near the fascial edge or pulled too tight because they may cut out. The optimal ratio of suture length to wound length is 4:1. If a ratio of less than this is achieved, the suture bites are likely to be too far apart and/ or too tight (and vice versa). Drains should be brought out through separate incisions and not through the wound itself because this prevents fascial apposition and increases the risk of hernia formation. Studies in obese patients undergoing bariatric surgery have suggested that placement of a prophylactic mesh in patients Alcino Lazaro da Silva , contemporary , surgeon, Vitoria, Brazil. reduce that risk. Use of prophylactic mesh ma y reduce the risk of parastomal herniation, which occurs in up to 50% of patients. Principles of surgical repair For repair of most incisional hernias, both open and laparoscopic options are available. A number of principles apply , irrespective of the technique used. First, the repair - should cover the whole length of the previous incision. Second, approximation of the musculofascial layers should be done with minimal tension; third, prosthetic mesh should be used to reduce the risk of recurrence. Mesh may be contraindicated in a contaminated field, e.g. in the event of perforation of strangulated bowel, but mesh may still be used in a clean-contaminated field, such as after an elective bowel resection, if strict hygiene measures are observed and appropriate prophylactic antibiotics are given. Open repair The previous incision is opened along its full length to reveal any clinically unsuspected defects. The hernial sac, its neck s. and the margins of the defect are fully exposed. The sac can be opened, contents reduced, local adhesions divided and any redundant sac excised to allow safe fascial closure. Simple suture techniques without the use of prosthetic mesh for reinforcement, even with the overlapping re pair of Mayo or the layered closure of da Silva, are not recommended because of the unacceptable risk of recurrence. However, they may be the only option in the presence of gross contamination, where mesh is contraindicated. Mesh should ideally be used in a tension-free manner to augment primary fascial closure and not used to ‘bridge’ a gap between fascial edges as the unsupported mesh centrally will inevitably bulge outwards postoperatively , giving the appearance of recurrence. However, if the mesh-to-defect area ratio is su ffi ciently large, i.e. there is su ffi cient circumferential overlap of mesh in relation to the size of the defect, then a bridging repair is generally secure. Mesh can be placed in one of several planes, as for primary ventral hernia repair. The simplest approach is an onlay mesh but this carries the risk of mesh exposure and contamination in the event of wound infection or wound breakdown. Furthermore, placement of a large onlay mesh requires elevation of large skin flaps, which increases the risk of wound seroma and overlying skin ischaemia. Intraperitoneal mesh placement is di ffi cult at open surgery and mesh in direct contact with the intra-abdominal organs is prone to complications such is as adhesive bowel obstruction, erosion into adjacent organs and bowel fistulation. The retromuscular plane is preferred by many surgeons. Laparoscopic repair Great advances have been made in applying laparoscopic tech - niques to incisional hernia repair. Laparoscopy and division of adhesions is initially performed, hernia contents are reduced and the fibrous margins of the hernia defect(s) are exposed. Often the falcif orm ligament and median umbilical fold need defect(s) with sutures before reinforcing with mesh, while others simply ‘bridge’ the defect with no attempt at closure. Larger defects are more di ffi cult to close, but bridging large defects is associated with bulging of the mesh postoperatively , often referred to as ‘pseudo-recurrence’ ( Figure 64.27 small hernias can be safely fixed without closing the defect, as the large mesh to defect area ratio will help to minimise mesh bulging and recurrence. The mesh is placed directly onto the peritoneum deep to the abdominal wall muscles, fixed in place with tissue glue, sutures or staple/tacks and is known as an IPOM repair. Special meshes with anti-adhesion coatings must be used, so-called ‘tissue separating’ meshes, and these are generally expensive. In the presence of dense peritoneal adhesions, the laparo scopic surgeon needs to take great care because injury to the bowel is possible and may not be recognised. If occult bowel injury does occur it can lead to postoperative peritonitis.