The Modern Management of Incisional Hernias
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CLINICAL REVIEW The modern management of Follow the link from the online version of this article to obtain certi ed continuing medical education credits incisional hernias David L Sanders,1 Andrew N Kingsnorth2 1Upper Gastrointestinal Surgery, Before the introduction of general anaesthesia by Morton of different tissue properties in constant motion has to be Royal Cornwall Hospital, Truro TR1 in 1846, incisional hernias were rare. As survival after sutured; positive abdominal pressure has to be dealt with; 3LJ, UK 2 abdominal surgery became more common so did the and tissues with impaired healing properties, reduced Peninsula College of Medicine and 1 Dentistry, Plymouth, UK incidence of incisional hernias. Since then, more than perfusion, and connective tissue deficiencies have to be Correspondence to: D L Sanders 4000 peer reviewed articles have been published on the joined. [email protected] topic, many of which have introduced a new or modified This review, which is targeted at the general medical Cite this as: BMJ 2012;344:e2843 surgical technique for prevention and repair. Despite audience, aims to update the reader on the definition, doi: 10.1136/bmj.e2843 considerable improvements in prosthetics used for her- incidence, risk factors, diagnosis, and management of nia surgery, the incidence of incisional hernias and the incisional hernias. recurrence rates after repair remain high. Arguably, no other benign disease has seen so little improvement in Unravelling the terminology terms of surgical outcome. Despite the size of the problem, the terminology used to Unlike other abdominal wall hernias, which occur describe incisional hernias still varies greatly. An inter- through anatomical points of weakness, incisional her- nationally acceptable and uniform definition is needed to nias occur through a weakness at the site of abdominal improve the clarity of communication within the medical wall closure. Why, unlike primary abdominal wall her- community and enable publication data and future stud- nias, are the results after repair so poor? Perhaps it is ies to be interpreted properly. Table 1 lists the definitions because in the repair of incisional hernias several prob- of the commonly (mis)used terms. lems need to be overcome: a multilayered wall structure How common are incisional hernias? Table 1 | Definitions of incisional hernia and the commonly (mis)used terminology Incisional hernias are one of the most common com- Term Definition plications after abdominal surgery. The true incidence Incisional hernia Any gap in the abdominal wall, with or without a bulge in the area is difficult to determine, as shown by the wide range of of the postoperative scar, that can be seen or palpated on clinical published figures in the literature. The reasons for this examination or imaging discrepancy are the lack of standardised definition, the Primary incisional hernia An incisional hernia that has not previously been surgically repaired inconsistency of data sources used (which include self Recurrent incisional hernia An incisional hernia that has previously been surgically repaired Trocar site hernia An abdominal wall gap, with or without a bulge in the area of reporting by patients, audits of routine clinical examina- previous cannulation with a laparoscopic trocar, that can be seen tion, and insurance company databases), short length of or palpated on clinical examination or imaging follow-up (often one year), and the subjectivity of clini- Acute wound failure (fascial dehiscence, The acute breakdown or separation of the fascial tissues, with cal examination.2 The reported incidence after a midline evisceration, eventration) resulting protrusion of the intra-abdominal contents through a fascial defect but without the presence of a peritoneal sac; this laparotomy ranges from 3% to 20% and is doubled if 3 usually occurs in the first 2 weeks of wound healing and always the index operation is complicated by wound infection. results in formation of an incisional hernia About 50% of incisional hernias are detected within one Primary abdominal wall hernia (epigastric Hernia of the abdominal wall that is not related to an incision year of surgery, but they can occur several years after- hernia, umbilical hernia, paraumbilical hernia, (usually refined by defining the site of the hernia) 3 4 spigellian hernia) wards, with a subsequent risk of 2% a year. Recurrent abdominal wall hernia (recurrent Recurrence of a primary hernia of the abdominal wall that has been Millions of abdominal incisions are created each year epigastric hernia, umbilical hernia, previously surgically repaired worldwide, so incisional hernias are a major problem, paraumbilical hernia, spigellian hernia) both in terms of morbidity and socioeconomic cost. Ventral hernia This term should not be used owing to the historical confusion with Although exact figures are unknown, it is estimated that the definition; In Europe the term ventral hernia has been used interchangeably with incisional hernia; in the United States the each year 10 000 repairs are performed in the United term has been used to describe any abdominal wall hernia other Kingdom and 100 000 are performed in the United than in the groin States.5 SUMMARY POINTS SOURCES AND SELECTION CRITERIA Incisional hernias are a common complication of abdominal surgery We searched PubMed from 1970-2012 and Embase and the Cochrane Library from inception using the terms “hernia” and Incisional hernias can occur many years after the index operation “incisional” (using the Boolean operator AND) and “ventral” Surgical site infection doubles the risk of incisional hernia (using the Boolean operator OR). The reference lists were also used to identify studies of interest. Both authors independently In case of uncertainty, ultrasonography can help confirm the diagnosis before specialist referral identified publications for inclusion and differences were Laparoscopic repair is generally reserved for small hernias (fascial defect <10 cm), although some resolved by discussion. We gave priority to research published in surgeons report good results with larger defects the past five years and highly regarded older publications. BMJ | 12 MAY 2012 | VOLUME 344 37 CLINICAL REVIEW Table 2 | Patient related risk factors for developing an incisional hernia ning suture is the best option for closure of laparotomy incisions.13-15 The use of monofilament slowly resorbable Risk factor Proposed effects on wound healing Age >65 years Reduced tissue perfusion and reduced collagen formation suture material versus non-absorbable or braided material Sex Some studies suggest that male sex is a risk factor, although others have found no decreases the rate of incisional hernias and reduces the difference between the sexes4 7 incidence of postoperative pain and wound infection.13-15 Atherosclerosis Reduced perfusion to the wound Experimental studies and randomised clinical trials Diabetes Reduced inflammatory response; alterations in microcirculation and granulation tissue have shown that a suture length to wound length ratio of Obesity Increased intra-abdominal pressure; obesity related comorbidities, such as diabetes and at least 4:1, and not more than 5:1, minimises the risk of increased risk of surgical site infection incisional hernia.16-18 Traditional surgical teaching recom- Renal failure Metabolic factors, which prevent formation of normal granulation tissue mends that continuous sutures are placed 10 mm from the Protein deficiency Important for collagen development wound edge and 10 mm apart.17 However, recently this Vitamin C deficiency An important cofactor in the biosynthesis of collagen Immunosuppression Alterations in normal tissue regeneration technique has increasingly been challenged. The large Smoking Alteration in the formation and degradation of collagen, vasoconstriction, and increased tissue bites have been shown to be associated with an mechanical stress from coughing increase in the amount of necrotic tissue and slackening of Drugs and other Drugs and treatments that cause immunosuppression or reduced vascular perfusion, the stitches, resulting in increased risk of wound infection treatments such as steroids, chemotherapy, and radiotherapy; warfarin, which reduces vitamin K and the development of an incisional hernia.19 20 In a large dependent cell-cell adhesion and cell cycle regulation randomised controlled trial, small stitches placed 4-6 mm Who is at risk? from the wound edge and 4 mm apart (in the aponeurotic Until recently, incisional hernias were thought to result layer only) minimised the risk of incisional hernias from mainly from a technical failure in the surgical closure of the 18% to 5.6% (P<0.001) and reduced wound infection rates abdominal wall.6 However, we now know that a complex by 50% (from 10.2% to 5.2%; P<0.02).21 This is currently array of patient related, surgical, and postoperative vari- being evaluated in a multicentre randomised controlled ables influence their development. These variables share trial.16 Most surgeons still use the large bite method and a common denominator—they all influence normal wound adoption of the small bite technique will be a major shift healing (table 2). Most of the evidence on risk factors has in surgical practice. been determined by retrospective studies, and the relative importance of many of the proposed risk factors is poorly Postoperative factors understood. Surgical site infection is commonly documented as the most important independent risk factor for the develop-