Clinical Features, Diagnosis, Prevention, and Management of Incisional Hernias

Abstract

The incidence of incisional hernia after intra-abdominal surgery is approximately 10–15%. Midline incisions are riskier than other incisions. Smoking, surgical site infections, conditions that impair wound healing, and incorrect surgical technique are among the risk factors, especially obesity. It typically presents as swelling on or near the incision. Computed tomography or ultrasonography can be performed for incisional hernias that cannot be detected by physical examination. Preoperative CT scan is important for the surgical strategy, especially for ventral hernias larger than 10 cm and with loss of space. The surgical strategy may vary depending on the size of the hernia. Tension-free repair is accepted as the standard approach by many authors, and suture repair alone is rarely used. The technique of separating into anterior or posterior components can be used in hernias larger than 10 cm with loss of space. Reconstruction using prosthesis material placed preperitoneally (underlay or sublay) is the most commonly used method today.

1. Introduction

An incisional hernia is defined as a swelling or abdominal wall cavity in the postoperative incision area that can be detected by physical examination or radiological imaging [1]. Incisional hernia occurs in approximately 10 to 15 percent of patients with a previous abdominal incision [2]. It may develop after midline, mc burney, paramedian, or other abdominal incisions [3, 4]. Its incidence varies according to the incision that has been made. In general, the risk of hernia formation in midline incisions is higher than the other incision types [5, 6, 7]. In addition, the risk of incisional hernia formation is higher in upper abdominal incisions compared to lower abdominal incisions [8, 9, 10, 11]. Both patient-related and technical factors play a role in the development of incisional hernias.

1.1 Patient related factors

Age, obesity, smoking, connective tissue diseases, use of immunosuppressive drugs, malnutrition, diabetes, vascular, and other comorbid diseases are factors that increase the risk of having an incisional hernia. Numerous studies have shown that obesity, in particular, increases the risk of having an incisional hernia, and the rate of postoperative complications and recurrence [12, 13, 14, 15, 16, 17, 18].

1.2 Technical factors

Wound infection, excessive wound tension, and not following the abdominal closure principles predispose to the formation of incisional hernia [19]. The incidence of incisional hernia increases in open bariatric surgery and interventions for repairing abdominal aortic aneurysm.

Abdominal closure should be done effectively, neither tension nor ischemia. In order to achieve this, it is necessary to comply with the appropriate suture material and stitch size. The suture should be the smallest, it can be to be strong enough to hold the wound intact [20]. Suture diameter and its type (monofilament, multifilament, or synthetic) is an effective factor on the amount of foreign matter and bacterial accumulation in the wound. It has been proved that nonabsorbable sutures reduce the risk of wound separation and developing a hernia compared to absorbable sutures. Synthetic nonabsorbable monofilament sutures (polypropylene, etc.) are more resistant to infections than multifilament sutures and natural fibers. Therefore, suture composition and structure affect the rate of bacterial absorption and proliferation [20]. Some studies have reported that sutures coated with antimicrobial compounds can reduce surgical site infection rates [21, 22, 23, 24, 25, 26, 27, 28, 29]. However, in other studies, whether the suture was covered or uncoated with antimicrobial compounds did not differ in terms of surgical site infection [25].

The method of closing the abdominal wall is another factor that affects developing an incisional hernia. While stratified closure is defined as the closure of individual components of the abdominal wall (peritoneum, muscular and aponeurotic structures, subcutaneous adipose tissue), mass closure is the closure of other abdominal wall layers as a single structure excluding the skin [30, 31, 32]. Studies have shown that mass closure is associated with a lower incidence of developing an incisional hernia [28, 29, 33]. Other than this, it has been shown that intermittent and uninterrupted closures have different effects on the tension of the wound and perfusion of the tissue. The amount of the suture used depends on the size of each suture (depends on the distance from fascial edge) and gap between sutures. For continuous closure, the total length of the suture should be about four times the incision length [31, 32]. In a randomized study, hernia recurrence was shown to be decreased if the ratio of 1/4 was adhered to [34]. The suture should be placed approximately about 1 cm from the edge of the fascia. The 2015 guidelines of the European Hernia Society recommend reducing the suture width from 10 mm to about 5 to 8 mm [31, 32, 33, 34, 35, 36]. In a randomized study, it was shown that longer suture width increases the risk of developing both incisional hernia and surgical site infection [32]. Studies have shown that the most appropriate method for abdominal wall closure is continuous mass closure using slowly absorbable sutures with a 4:1 ratio of suture length to wound length [37, 38, 39].

2. Classification

Incisional hernias can be classified as anatomically and clinically.

Anatomical classification is made according to the location of the hernia on the abdominal wall. The European Hernia Society (EHS) divides the abdomen into medial and lateral zones for incisional hernias. The medial zone includes the region between the lateral edges of the rectus muscle. This region is divided into five subregions as subxiphoid, epigastric, umbilical, infraumbilical, and suprapubic. The lateral region is divided into four subregions as costal, lateral, iliac, and lumbar regions (Figure 1).

Figure 1.

The European hernia society (EHS) classification for incisional abdominal wall hernias divides the abdomen into a medial zone and a lateral zone. The medial zone, defined as medial to the lateral margin of the rectus sheath, is subdivided into five subzones (subxiphoid, epigastric, umbilical, infraumbilical, and suprapubic). The lateral zone is subdivided into four subzones (subcostal, flank, iliac, and lumbar).

According to size, incisional hernias are classified into three categories: <1 cm, 1 to 10 cm, and > 10 cm [40]. Hernias larger than 10 cm in width are defined as complex or giant ventral hernias. These require additional preparation [41].

Clinical classification – Depending on the clinical picture, incisional hernias can be asymptomatic, reductible, incarcerated, or strangulated.

An incarcerated hernia is a hernia that its contents cannot be reduced to the abdomen due to a narrow opening in the abdominal wall facial defect or adhesions between the contents and the hernia sac [42]. An incarcerated hernia containing an intestinal loop can cause intestinal obstruction [43]. In a population study of more than 23,000 patients followed without surgery, a cumulative rate of incarceration of incisional hernias was reported 1.24% in 1 year and 2.59% in 5 years [44].

Diagnosis – In most patients without obesity, incisional hernia can be diagnosed by physical examination. It is usually recognized by palpation of a bulge on or around the abdominal incision.

Diagnostic evaluation – About the patients we cannot rely on our physical examination, we need a computed tomography (CT) scan or ultrasound of the abdomen and/or pelvis to confirm the presence of the hernia and to identify the contents of the hernia sac. Contrast is not usually required for a CT scan. Ultrasound is less sensitive than CT.

CT imaging – Preoperative CT imaging is recommended for complex ventral hernias with large size and significant loss of space. Repair of such hernias usually requires advanced abdominal wall reconstructive techniques such as disassembly. The volume of the hernial sac and abdominopelvic cavity can be estimated on a CT scan by multiplying the length, width, and depth of each cavity by a factor to estimate the ellipsoid volume [41].

The degree of domain loss has been calculated differently by various authors. When the ratio of hernia sac volume to residual abdominopelvic cavity volume is calculated and if it is 25% and above, preoperative abdominal expansion is required [45]. When the ratio of the hernia sac volume to the entire peritoneal volume is calculated and if it is higher than 20%, it predicts how hard the closure will be [46]. Hernia reduction may lead to serious complications such as persistent hypertension in the abdominopelvic cavity, abdominal compartment syndrome due to visceral edema and postoperative fluid resuscitation.

3. Management

3.1 Acute incarcerated or strangulated hernias

Acute incarcerated or strangulated incisional hernias require immediate surgical repair (Figure 2). The aim of emergency surgery is to resolve the acute problem (intestinal necrosis or obstruction) and to perform a safe and durable repair. The optimal technique of hernia repair depends on the patient’s anatomy, stability, comorbidities, and the degree of operative site contamination. Once the source of the contamination is controlled, surgical repair of the hernia can be done only with suture repair, mesh repair, or incremental repair (placement of absorbable mesh and leaving the hernia to be repaired electively). There is no consensus because the clinical situation is heterogeneous [47].

Figure 2.

Management of ventral hernias.

The best practice for a ventral hernia in a contaminated area is safe and, whenever possible, suture-only or incremental repair. Hernia repair with synthetic mesh has been proved to be safe and effective in the hands of powerful surgeons in these complex cases [48]. The role of biological and biosynthetic networks has not yet been defined.

Asymptomatic incisional hernias – Patients with asymptomatic or minimally symptomatic ventral hernias can be followed nonoperatively if they are hesitate to have a surgery [49, 50]. However, these patients should be informed that the lifetime risk of acute presentation can be high and for most patients, nonsurgical follow will fail after the first 2 years [49, 51, 52].

Symptomatic incisional hernias – Surgical repair is recommended for patients with symptomatic ventral hernias. However, in patients with comorbidities such as smoking, diabetes, obesity, and obstructive pulmonary diseases, surgery can be temporarily delayed. Such restrictions are relative contraindications and can be relieved by preoperative optimization [53].

3.2 Surgical treatment of incisional hernias

Incisional ventral hernia < 1 cm – Usually occurs at laparoscopic trocar sites. Mesh repair is recommended for all ventral incisional hernias, including those less than 1 cm. Repairing such hernias with stitches will likely result with a recurrent hernia.

Ventral hernias from 1 to 10 cm – The most common incisional hernias in daily practice fall into this category. Mesh reinforcement is required for these hernias. The surgical approach and mesh selection depend on the clinical situation and the surgeon’s preference. Open or minimally invasive mesh repair can be performed for incisional hernias which are 1 to 4 cms. While open repair is preferred in frail patients, minimally invasive repair is preferred in patients who are at risk of developing obesity or other wound infections. Minimally invasive mesh repair is performed for ventral hernias which are 4 to 10 cm [54].

Large (>10 cm in width) or complex hernias – Large or complex incisional hernias are difficult to repair [55]. These hernias can be repaired using minimally invasive underlay, open inlay, or component separation techniques.

Underlay meshes are used on standard laparoscopic repairs. Although it has advantages such as less pain, healing fast, and having lower infection rate, swelling continues at the defect site when intra-abdominal pressure increases. Repair of large defects with mesh has been shown not to reduce abdominal and back pain and respiratory problems when compared to component separation, which restores the dynamic muscle component to the abdominal wall.

In patients with large incisional hernias and patients with space gap, we recommend using advanced techniques such as component separation to achieve primary fascial closure prior to mesh augmentation, rather than using inlay mesh to bridge a facial defect.

The decomposition, pioneered by Ramirez [56], is used to repair the large and complex midline abdominal wall defects and has the advantage of restoring abdominal wall function. Component separation involves dividing the anterior or posterior rectus sheaths and/or portions of the lateral oblique muscle to allow the rectus abdominis muscle to advance by about 10 cm from each side to allow a fascial closure under physiological tension [56, 57, 58].

The decision to separate its components is made based on physical examination and cross-sectional imaging. Depending on the width of the hernia and the surgeon’s experience and preference, any dissection technique can be chosen.

Typically, hernias less than 7 cm do not require a component separation (Figure 3) and can usually be repaired with an open, laparoscopic, or robotic approach with intraperitoneal mesh, or with an open or robotic approach with retrorectus mesh, as described by Rives and Stoppa. Such hernias can also be repaired using open techniques with onlay mesh [58].

Figure 3.

Determining the need for component separation in ventral hernia repair.

Hernias that are 7 to 10 cm typically do not require a component separation for the midline facial approach and can be repaired laparoscopically with a large piece of intraperitoneal mesh or with an open retromuscular approach. If necessary, an open or robotic TAR can be added to ensure closure of the posterior rectus sheath. A ratio of rectus width to hernia width > 2 reliably predicts that the fascia can be closed with a Rives–Stoppa repair alone, with no further myofascial loosening in nearly 90% of cases [59].

Hernias larger than 10 cm might require separation of the anterior or posterior component for both the rectus approach (midline closure) and posterior facial approach, depending on the compliance of the abdominal wall. This can be accomplished with open anterior component separation or open or robotic TAR.

Location of the mesh – Mesh can be placed over the fascia (onlay), between the rectus muscles and the peritoneum/posterior rectus sheath (sublay), under the peritoneum (underlay or intraperitonealonlay), or between the fascial margins (inlay) [60] (Figure 4). While onlay and sublay techniques use an open or robotic surgical approach, an underlay technique can be performed open, laparoscopically, or robotically. The mesh bridging inlay technique is used only when the facial defect is too large to be primarily closed with any other technique.

Figure 4.

Mesh locations: (A) onlay, (B) sublay, (C) underlay, and (D) inlay. The blue line depicts mesh location.

Randomized studies have proved that both recurrence and complication rates were higher with onlay andinlay meshes than with sublay and underlay meshes [61].

Mesh sizes – The mesh used for ventral hernia repair should cover >5 cm from each side for open repair of ventral incisional hernias and > 5 cm for all laparoscopic repairs. For laparoscopic repair, other guidelines suggest that the radius of the mesh should be four times the radius of the fascial defect being addressed [62].

4. Open anterior component separation technique

Posterior rectus sheath is cut 1 to 2 cm from lateral to the medial border of the rectus muscle, starting from the costal margin and continuing below the arcuate line where the posterior sheath becomes continuous with the peritoneum and transversalis fascia. Next, the external oblig muscles should be divided. It is made through an incision about 1 to 2 cm length from lateral of the linea semilunaris. The external oblig muscle is not always divided in its entire length; instead, the length of the cleavage can be adjusted according to the location of the facial defect in the midline.

Releasing the underlying internal oblig/transversus abdominis muscle apparatus from the divided external oblig muscle reveals an avascular plane. The midline facial approach should be attempted after each myofascial relaxation, not after the division of both the posterior rectus sheaths and the EO muscles. Further myofascial relaxation should be avoided after a tension-free midline approach that has been achieved. After adequate myofascial relaxation is achieved, the fascia should be closed with a slowly absorbable monofilament suture. After a sufficiently large mesh is fixed to the external oblig muscle edge, an absorbent drain is placed on the mesh and the skin is closed (Figure 5).

Figure 5.

Component seperation technique: A(Hernia sac), B(external oblig muscles be divided), C(Posterior rectus sheath is cut 1 to 2 cms from lateral to the medial border of the rectus muscle), D(After adequate myofascial relaxation is achieved, the fascia should be closed with a slowly absorbable monofilament suture), E(mesh location).

5. Separation technique to open posterior components (rives: stoppa retrorectus dissection and transverse abdominis release (TAR))

The operation begins with a large midline laparotomy that includes the patient’s previous scar. During myofascial dissection, intra-abdominal adhesions are completely dissolved and the internal organs are released from the abdominal wall and a wide towel is laid on the intestine. After the towel is placed, the edges of the facial defect are determined and the length/width is measured.

Five Kocher clamps are then placed on the medial edge of a rectus. Using a toothed forceps, the posterior rectus sheath is retracted and cut just beside the rectus margin to expose the underlying muscle hub. The entire medial edge of the posterior rectus sheath should be separated and the medial edge of the rectus muscle should be exposed. The retrorectus area is developed using firm but gentle traction on the anterior and posterior rectus sheaths and cautery to control small epigastric perforators. The lateral extension of this space is marked by large neurovascular bundles and deep lower epigastric vessels, especially in the upper and lower directions of this dissection, before the vessels progress toward the rectus muscle hub. Typically, there is one large medial neurovascular perforator that can be sacrificed in the superior third of the retrorectus space, but the remainder should be preserved if possible. Neurovascular bundles define the lateral extension of the retrorectus space, and their preservation prevents accidental division of the lineasemilunaris, a devastating complication of this technique. At this point, if the posterior rectus sheath is sufficiently medialized to the midline and the contralateral dissection allows isolation of the internal organs, then the Rives–Stoppa dissection alone is sufficient. If the release is not sufficient until this stage, transverse abdominis release is started. The posterior lamella of the internal oblique (IO) and transversus abdominis (TA) muscle departs just from medial to the neurovascular bundles marking the lineasemilunaris. After the transversusabdominis muscle is completely separated from the transversus fascia from cranial to caudal, the posterior rectus sheath is reapproximated and the mesh is placed on it and fixed. After the anterior rectus is approached in the sheath, a drain is placed and the skin is closed (Figure 6).

Figure 6.

Transversus abdominis release (TAR): A(Retrorectus plane dissected), B(Transversus Abdominis muscle fibers divided), C(Plane of dissection), D(Sublay mesh placed).

Anterior component separations should not be performed in conjunction with posterior component separation (e.g., TAR) as this might significantly destabilize the abdominal wall and cause permanent disability.

Separation into both anterior and posterior components can also be done laparoscopically or robotically.

6. Presurgery assistants

Preoperative adjuvants (such as botulinum toxin injection or tissue expansion) were used to facilitate fascial and/or abdominal wall closure when the ratio of hernia volume to peritoneal volume was above 20–25%.

Botulinum toxin – Botulinum neurotoxin type A (BoNT-A) can be used preoperatively to relax the lateral abdominal wall muscles [63].

There is no consensus on which patients would benefit from BoNT-A injections prior to ventral hernia repair. However, many authors indicate that preoperative BoNT-A can be used in patients with a hernia volume to peritoneal volume ratio > 20 to 25% [64]. This should be done at least 2 weeks before attempting ventral hernia repair.

Tissue expanders – Tissue expansion is done by placing a silicone balloon under subcutaneous tissue or fascia followed by an injection of saline to inflate the balloon to expand the local tissue in preparation for local reconstruction. It should begin at least 6–12 weeks before hernia repair. Complications such as device infections or flap necrosis may occur in 15% of patients [65, 66].