December 2017, VOLUME 209
NUMBER 6

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December 2017, Volume 209, Number 6

Gastrointestinal Imaging

Review

Incisional Hernia Repair: What the Radiologist Needs to Know

+ Affiliations:
1Department of Radiology, University of Michigan, 1500 E Hospital Dr, B1D502, Ann Arbor, MI 48109.

2Department of Surgery, A. Alfred Taubman Health Care Center, University of Michigan, Ann Arbor, MI.

Citation: American Journal of Roentgenology. 2017;209: 1239-1246. 10.2214/AJR.17.18137

ABSTRACT
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OBJECTIVE. Incisional hernias are becoming more prevalent with increases in the obesity of the population and the complexity of abdominal surgeries. Radiologists' understanding of these hernias is limited. This article examines abdominal wall anatomy, surgical techniques, the role of imaging (current and emerging), and complications from the surgical perspective, to enhance to the role of the radiologist.

CONCLUSION. Knowledge of the relevant anatomy, surgical techniques, and postoperative complications in patients with incisional hernial repair can help the radiologist improve care.

Keywords: abdominal wall, giant hernias, hernia, incisional hernia, postoperative complications

An incisional hernia is a protrusion of abdominal viscera through a defect in the abdominal wall myofascial tissues resulting from surgery or trauma [1]. Such hernias are common after abdominal operations, occurring in up to 5–15% of patients after open procedures and in 1–3% of patients after minimally invasive procedures [2]. The incidence of very large or giant hernias is increasing with increases in the obesity of the population and the complexity of abdominal surgeries, presenting a difficult clinical challenge for surgeons. National data from Denmark found that 11% of incisional hernia repairs were for defects larger than 15 cm in diameter [3]. No consistent size criteria exist for defining a giant incisional hernia, with quoted width or length measurements of abdominal wall defects starting at 10–15 cm in diameter [36]. Additional definitions based on hernia sac volume (ranging from 100 to 225 cm2) or the ratio of hernia sac volume to peritoneal volume have also been proposed [4]. Similarly, to date, little consensus has emerged regarding the optimal surgical repair technique, and a wide variety of surgical approaches are currently used, depending on patient characteristics and the preferences of surgeons.

The key question confronting the surgeon is whether a large incisional hernia can be successfully repaired with an acceptable complication rate. Chronic extrusion of the viscera from the intraabdominal cavity leads to decreased abdominal wall myofascial elasticity, muscular retraction or atrophy, and chronically reduced intraabdominal cavity volume (i.e., loss of domain). Forcing the viscera back into a smaller cavity could result in abdominal compartment syndrome with cardiopulmonary compromise or wound dehiscence. Patients with large incisional hernias also often have additional risk factors for postoperative morbidity, such as obesity, diabetes, coexisting infections, skin ulcerations, stomas, and enterocutaneous fistulas.

Given the complex nature of these large hernias, preoperative cross-sectional imaging (especially CT) plays an important role in assessing the likelihood of successful repair and determining the optimal surgical approach. Radiologists should understand what surgeons need to know to effectively contribute to the care of these patients. This article will illustrate the normal anatomy of the anterior abdominal wall, describe the imaging appearance of large hernias, and correlate this information with the common operative techniques used to repair hernias, with particular emphasis placed on tissue separation techniques. We will also provide details about the role of imaging in both planning for surgical repair and preventing postoperative complications.

Abdominal Wall Anatomy
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The anterior abdominal wall has three distinct functional layers that can be distinguished by imaging. The most superficial layer consists of skin and adipose tissues. This layer provides waterproof coverage for the underlying tissues, but it otherwise plays little or no role in repair planning unless there has been a large loss of tissue as a result of infection or necrosis. In the middle is the myofascial layer, which consists of four muscles and their fascial envelopes: the rectus abdominis, the external and internal oblique muscles, and the transversus abdominis (Fig. 1). The rectus abdominis muscle is the largest and most medial, extending from the costal margins to the pubis. Laterally, the three overlapping layers of the external oblique, internal oblique, and transversus abdominis muscles extend from the lateral edge of the rectus to the flanks. The aponeuroses of these three muscles form the anterior and posterior rectus sheaths enveloping the right and left rectus muscles and interdigitate in the midline to form the linea alba. The posterior rectus sheath is absent below the arcuate line in the mid abdomen, rendering the lower abdominal wall weaker and more elastic. The lateral margin of the rectus muscle (i.e., the line separating it from the oblique muscles) is called the semilunar line. The lower margin of the posterior rectus sheath traces the linea semicircularis. In the anterior abdominal wall, the transversus abdominis consists mostly of fascia adherent to the underside of the internal oblique muscle, but laterally, near the flank, it has a muscular component. The mechanical strength of the abdominal wall depends entirely on the integrity of these myofascial layers. The goal of hernia repair is to restore these layers to their normal position and function as much as possible. The third layer is the deep layer of the anterior abdominal wall, which is formed by transversalis fascia, preperitoneal fat, and the parietal peritoneum. This layer is quite elastic. Its chief purpose is to cover and protect the underlying viscera. Its absence after operation can lead to difficult problems with adhesions.

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Fig. 1 —CT scan of anterolateral abdominal wall above umbilicus in 62-year-old man. Aponeuroses of internal and external oblique muscles form anterior rectus sheath while posterior rectus sheath is formed by aponeuroses of internal oblique and transversus abdominis muscles. Below umbilicus, no posterior rectus sheath is present. Medially, aponeuroses from both sides converge to form linea alba.

This abdominal wall anatomy leads to several physiologic considerations that must be kept in mind during hernia repair operations. First, at rest, the fascial sheaths play the major role in containment. Under stress, the muscles provide most of the containment. Second, the ideal repair technique should restore the myofascial elements and preserve the neurovascular elements. Third, the thin midline fascia makes reconstruction using the linea alba alone prone to failure. Most incisional hernias occur at the linea alba not only because this is the weakest myofascial point but also because most abdominal incisions are made through the midline.

Given their size, large incisional abdominal wall hernias are readily visible on cross-sectional imaging and are even identified occasionally on scout images (Fig. 2). As we will discuss later, in such cases it is important to document the size of the hernia, sac measurements, hernia contents, and, if present, any complications.

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Fig. 2A —65-year-old woman with large incisional abdominal hernia who underwent unenhanced abdominopelvic CT examination.

A, Lateral scout radiograph shows readily apparent large abdominal wall defect.

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Fig. 2B —65-year-old woman with large incisional abdominal hernia who underwent unenhanced abdominopelvic CT examination.

B, Sagittal (B) and axial (C) CT images show narrow neck with hernia sac containing abnormally dilated large bowel loop.

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Fig. 2C —65-year-old woman with large incisional abdominal hernia who underwent unenhanced abdominopelvic CT examination.

C, Sagittal (B) and axial (C) CT images show narrow neck with hernia sac containing abnormally dilated large bowel loop.

Operative Techniques
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A variety of surgical techniques are used for the repair of incisional hernias [17]. These techniques range from primary approximation of the defect with suture repair, with mesh used as an onlay, underlay, or as a bridging patch, to tissue separation techniques such as the anterior component separation (ACS) technique and transversus abdominis release (TAR) [8]. The two latter approaches involve mobilizing the various myofascial components of the abdominal wall to gain elasticity and allow primary fascial closure of the hernia defect with or without mesh reinforcement.

Because of the high rate of recurrence after primary suture repair (more than 60% in one study [9]), this technique has fallen out of favor for incisional hernia repair and is largely reserved for emergent settings and those with gross contamination [10]. The high failure rate has been attributed to tissue tension that leads to local ischemia and tissue breakdown. Equally likely is the proposition that the same metabolic defects in wound healing that led the initial incision closure to fail will cause the second similar repair to fail as well.

A number of studies have shown the superiority of mesh repair techniques in terms of reduced rates of hernia recurrence [9]. As a result, mesh repair has become the mainstay of incisional hernia repair. Mesh is placed in one of four different ways: onlay, inlay, preperitoneal sublay, or intraperitoneal sublay (Fig. S1, a supplemental image, can be viewed in the AJR electronic supplement to this article, available at www.ajronline.org). With the onlay and sublay techniques, which are used in conjunction with primary fascial closure, the mesh overlaps the edges of the fascial closure by several centimeters. The onlay is placed anterior to the rectus sheath, whereas the sublay mesh is placed posterior to the rectus muscle, either in the peritoneal cavity or in the preperitoneal space. In the inlay technique, the mesh is used as a patch spanning the fascial defect with some degree of overlap at the edges and is used when the edges of the defect cannot be reapproximated without undue tension. For very large defects, tissue separation techniques, including the ACS technique and TAR, are done with or without placement of mesh. These tissue separation techniques are described in the remainder of this paragraph. With the ACS approach, mesh is placed as an onlay or underlay. With the TAR technique, the mesh is inserted into the retrorectal or preperitoneal space. Comparison of postoperative results among all the different types of repair is confounded by multiple variables, including the type of mesh material used, unique patient anatomy and risk factors, and the level of experience of the surgeon. At least one meta-analysis has concluded that both primary tissue repair without mesh reinforcement and the inlay technique should be avoided [3]. The authors of the meta-analysis also argued that the sublay placement should be used for large incisional hernias.

Tissue separation techniques such as ACS and TAR are relatively new procedures, but they have rapidly gained acceptance as effective approaches for repair of very large hernias. These techniques entail mobilization of the layers of the abdominal wall to allow midline fascial closure without tension. ACS begins with dissection of the hernia sac free from the anterior rectus sheath (Fig. 3). Large subcutaneous flaps are then developed from the midline and are extended laterally to expose the anterior rectus sheath and the external oblique aponeurosis. This is followed by division of the external oblique aponeurosis just lateral to the edge of the rectus abdominis, usually extending from the costal margin to the pubis. Dissection of the posterior rectus sheath away from the rectus abdominis muscle is then conducted. To avoid damage to these structures, extra care must be taken because the rectus abdominis muscle has a neurovascular supply that enters posteriorly at the lateral edge of the rectus muscle. Once dissection has freed the rectus abdominis muscle from both the anterior and posterolateral attachments, the rectus muscle is trans-located medially and the fascial defect is repaired using suture closure. Mesh can then be placed in an onlay or underlay fashion.

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Fig. 3A —Anterior component separation technique. (Drawings by Dobbs D, used with permission)

A, Illustration shows large hernia protruding through anterior abdominal wall. This hernia sac is first freed from adjacent tissues in initial dissection.

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Fig. 3B —Anterior component separation technique. (Drawings by Dobbs D, used with permission)

B, Illustration shows exposure of anterior rectus sheath and external oblique muscle as far lateral as possible (arrow).

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Fig. 3C —Anterior component separation technique. (Drawings by Dobbs D, used with permission)

C, Illustration shows separation of external oblique aponeurosis and muscle from internal oblique muscle and aponeurosis as far lateral as possible (arrow).

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Fig. 3D —Anterior component separation technique. (Drawings by Dobbs D, used with permission)

D, Illustration shows separation of rectus abdominis muscle from posterior rectus sheath via longitudinal incision (arrow).

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Fig. 3E —Anterior component separation technique. (Drawings by Dobbs D, used with permission)

E, Illustration shows medial translocation of rectus abdominis muscle followed by midline sutures. Mesh is placed if desired (not shown).

The ACS is performed either as part of an open procedure, by undermining the skin and subcutaneous tissue laterally to expose the external oblique aponeurosis, or endoscopically with the use of small lateral incisions to expose the lateral fascial layers to endoscopic view. The endoscopic or minimally invasive approach uses less dissection, avoiding the creation of large flaps. The open approach, on the other hand, provides an opportunity to excise dystrophic tissue associated with the hernia sac [11]. ACS with mesh has been shown to be superior to mesh repair alone, and ACS with mesh is considered to be superior to ACS alone for the repair of large incisional hernias [3, 7]. These same review series also showed that ACS led to decreased rates of postoperative wound complications. Initial costs are marginally higher with the use of the endoscopic approach because of the higher price of the materials used; however, these costs are thought to be outweighed by the higher morbidity associated with the open approach [12].

TAR involves dissection of the posterior sheath away from the rectus abdominis muscle (Fig. 4). The lateral aspect of the posterior sheath is incised along its length, avoiding injury to the neurovascular bundles, and the muscle fibers of transversus abdominis are divided to enter the preperitoneal plane laterally. Extensive dissection in the preperitoneal plane bilaterally allows closure of the posterior rectus sheath in the midline. Mesh is then placed in the retrorectal or preperitoneal space, and the anterior fascia is closed over the mesh. TAR is typically performed using an open approach, although laparoscopic and robotic-assisted approaches have also been described. The TAR approach avoids creation of large subcutaneous flaps, thereby reducing the risk for abdominal wall seroma or abscess. It also avoids placement of mesh in the intraperitoneal space, thus avoiding adhesions to bowel and other abdominal viscera. TAR is a relatively new procedure that has allowed closure of very large hernia defects that would be difficult to repair using other older approaches.

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Fig. 4A —Transversus abdominis release. In all panels, blue line denotes intact peritoneum. (Drawings by Dobbs D, used with permission)

A, Illustration shows dissection of posterior sheath away from rectus abdominis muscle (arrow).

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Fig. 4B —Transversus abdominis release. In all panels, blue line denotes intact peritoneum. (Drawings by Dobbs D, used with permission)

B, Illustration shows lateral incision (arrow) along length of rectus abdominis avoiding injury to neurovascular bundles.

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Fig. 4C —Transversus abdominis release. In all panels, blue line denotes intact peritoneum. (Drawings by Dobbs D, used with permission)

C, Illustrations show that fibers of transversus abdominis muscle are divided to free preperitoneal space (C) and that mesh, if desired, is placed in retrorectal or preperitoneal space (green curved line, D). Subsequent midline sutures and skin closure are shown (D).

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Fig. 4D —Transversus abdominis release. In all panels, blue line denotes intact peritoneum. (Drawings by Dobbs D, used with permission)

D, Illustrations show that fibers of transversus abdominis muscle are divided to free preperitoneal space (C) and that mesh, if desired, is placed in retrorectal or preperitoneal space (green curved line, D). Subsequent midline sutures and skin closure are shown (D).

Role of Imaging
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Preoperative and postoperative imaging with respect to incisional hernias is performed for specific indications [1]. Preoperative cross-sectional imaging is useful when the presence of a hernia and its overall size, location, or type are uncertain at physical examination. This is most often encountered in obese patients whose habitus makes palpation of deep abdominal wall structures difficult. Imaging is also performed for determination of the presence or absence of prior mesh or associated fluid collections, evaluation of multiple concurrent fascial defects, or specification of hernia contents and the degree and type of adhesions (i.e., omentum vs bowel). The radiologist should assist the surgeon in determining the quality and quantity of the abdominal wall musculature and the integrity of the muscle and fascia. The relative volume of the hernia compared with the intraabdominal compartment should be estimated, if possible. Information gleaned from the imaging examination complements the physical examination and can help decide the type of operative technique to undertake. For example, if imaging shows that there is significant dystrophic tissue below the superficial layers, the surgeon may choose an open approach instead of a minimally invasive approach. Alternatively, if imaging shows closely adhered bowel loops in the hernia sac, the surgeon may forgo intraperitoneal mesh placement for a more superficial placement.

Radiography, ultrasound, and MRI each have specific areas of utility in the evaluation of incisional hernia. The role of radiography is essentially limited to acute hernia presentation; abdominal radiographs may reveal signs of obstruction or intraabdominal free air. Sonography provides dynamic real-time evaluation in an inexpensive fashion, with no ionizing radiation, and can quantify the size of the hernia neck, musculature thickness, and hernia contents. However, ultrasound is inherently operator dependent, and the results are difficult to replicate in obese patients and patients with very large hernias [13]. MRI occasionally is used with dynamic cine sequences to evaluate herniation with increased intraabdominal pressure (i.e., the Valsalva maneuver) [14]. In particular, MRI is a very useful tool to use for young patients because it involves no radiation and provides superior soft-tissue contrast resolution. Novel imaging techniques are also increasingly used to reduce imaging time and evaluate postrepair complications [1517]. However, data on the use of MRI for hernia care are limited, and, at present, MRI remains relatively more expensive than CT, not readily available, and probably not warranted for routine cases. Therefore, CT remains the primary modality for hernia diagnosis and evaluation of complications. At the expense of ionizing radiation, CT is readily available, less expensive than MRI, less prone to motion-related artifacts, and relatively independent of operator experience. CT examination of hernia complications is also well documented in the literature [1820]. Our CT protocol is presented in Table 1, and suggested reporting guidelines are provided in Table 2.

TABLE 1: Institutional CT Hernia Imaging Protocol
TABLE 2: Proposed Preoperative CT Hernia Imaging Report
Optimizing the Value of Imaging in Hernia Care
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In many cases, preoperative imaging provides essential information for decision making. One of the preoperative decisions that the surgeon needs to make is whether a repair is feasible and, if the answer is yes, to select which surgical approach (ACS or TAR) will be needed. Feasibility is judged on the basis of multiple factors, including the size of the defect relative to the overall size of the anterior abdominal wall, the volume of the hernia sac relative to intraabdominal volume, and the degree of central adiposity (which could suggest how effective weight loss would be in facilitating hernia repair). In addition, imaging can answer the question of whether or not mesh placement should be added to the ACS technique. One proposed imaging parameter is the component separation index [21] (Fig. 5). The component separation index is calculated by determining the angle from a fixed posterior reference point (e.g., the aorta) to the medial edges of the defect and then dividing it by 360°. This index provides a relative standardization of the transverse defect size to the body habitus. With an increasing component separation index, a mesh placement is indicated. A retrospective analysis showed that the patient requiring no mesh had a mean component separation index of 0.11, compared with those requiring mesh in addition to ACS, who had a mean component separation index of 0.21 (p < 0.0001) [21].

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Fig. 5A —Component separation index. This index is determined by calculating defect angle from fixed posterior reference point (e.g., aorta) to medial edges of defect and then dividing this angle by 360°. (Drawings by Dobbs D, used with permission)

A, Illustration shows normal anterolateral abdominal wall musculature.

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Fig. 5B —Component separation index. This index is determined by calculating defect angle from fixed posterior reference point (e.g., aorta) to medial edges of defect and then dividing this angle by 360°. (Drawings by Dobbs D, used with permission)

B, Illustrations show abnormal anterolateral abdominal wall musculature (shaded area) with relatively low component separation index (≤ 0.11) that likely requires no mesh placement (B) and with large component separation index (≥ 0.21) that likely requires mesh placement (C).

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Fig. 5C —Component separation index. This index is determined by calculating defect angle from fixed posterior reference point (e.g., aorta) to medial edges of defect and then dividing this angle by 360°. (Drawings by Dobbs D, used with permission)

C, Illustrations show abnormal anterolateral abdominal wall musculature (shaded area) with relatively low component separation index (≤ 0.11) that likely requires no mesh placement (B) and with large component separation index (≥ 0.21) that likely requires mesh placement (C).

Preoperative risk stratification is a difficult clinical task. CT-based morphomics analysis has been used to provide helpful data in this regard [22, 23] (Fig. 6). Morphomics analysis uses landmarks (e.g., the osseous spine, muscle contour, and muscle or fat at the interface) and automated algorithms to identify different regions of the body, their volume, and their density. Research has shown that increased subcutaneous fat area, total body area, and total body circumference lead to increased odd ratios for infection at the surgical site. Similar analysis has also shown that muscular (e.g., psoas) bulk may be an accurate measure of the perioperative functional status of the patient, with less muscle bulk shown to be associated with prolonged recovery and increased postoperative complications [24, 25]. Morphomics analysis holds the potential to create potential relative comparisons of hernia volume to abdominal compartment volume, which may be a better indicator of operative success, postoperative complications such as dehiscence or recurrence, or both outcomes.

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Fig. 6A —Contours in morphomics analysis. (Drawings by Dobbs D, used with permission)

A, Illustrations show preoperative (A) and postoperative (B) evaluation of measurements. Dashed line represents distance between anterior and posterior abdominal wall; blue line, total body circumference; and orange line, total fascial circumference. Preoperative evaluation of these measurements has been shown to have predictive value regarding patient's risk for postoperative complications.

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Fig. 6B —Contours in morphomics analysis. (Drawings by Dobbs D, used with permission)

B, Illustrations show preoperative (A) and postoperative (B) evaluation of measurements. Dashed line represents distance between anterior and posterior abdominal wall; blue line, total body circumference; and orange line, total fascial circumference. Preoperative evaluation of these measurements has been shown to have predictive value regarding patient's risk for postoperative complications.

Postoperative Complications
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Complications after hernia repair are broadly classified into three categories: immediate complications, loss-of-domain complications, and site-related complications (Table 3). Most of the immediate postoperative complications are similar to those associated with other intraabdominal surgeries and are mainly affected by the perioperative hematologic and functional status of the patient. Enterocutaneous fistulas, however, are more dependent on the bowel anatomy of the patient (e.g., bowel injury, tethering, or even proximity to the surgical site) rather than functional status (Fig. S2, which can be viewed in the AJR electronic supplement to this article, available at www.ajronline.org)

TABLE 3: Postoperative Hernia Repair Complications

Loss-of-domain complications occur either in the early postoperative state or in late stages. These are likely more common with giant incisional hernias. Abdominal compartment syndrome, in particular, is a dreaded complication in the repair of large hernias. This syndrome occurs when the chronically herniated viscera are reduced into the small intraabdominal cavity, increasing pressure on the vascular structures. This compromises venous return as well as arterial flow leading to a wide range of end-organ damage. Imaging plays very little, if any, role in the detection or diagnosis of this complication. Diagnosis is made on a clinical basis with the identification of the combination of hypotension, tachycardia, oliguria, and increased bladder pressures. Other loss-of-domain complications, such as renal failure or prolonged ventilation (caused by compression factors), are also diagnosed clinically.

Wound-related complications are common in the postoperative state and occur either in the early or late stages. Although cellulitis, skin necrosis, and ulceration are easily diagnosed clinically, imaging plays a critical role in evaluation of any deep abdominal wall or intraperitoneal fluid collections. Even though imaging cannot include or exclude the presence of infection in postoperative fluid collections, it can provide information on the size and extent of the fluid collection. It also helps determine any mass effect, the presence of any adjacent structures that impede percutaneous drainage, or the presence of any concurrent complications (Fig. 7). On occasion, it is difficult to evaluate clinically whether the postoperative abdominal wall bulge is simply diastasis (Fig. 8) or a recurrent hernia. Imaging performed both in the standard venous phase and during the Valsalva maneuver is very helpful in differentiating these entities.

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Fig. 7A —73-year-old woman with postoperative abscess who underwent contrast-enhanced abdominopelvic CT examination.

A, Axial contrast-enhanced CT scans obtained at level of iliac crests show presence of postoperative fluid collection just adjacent to sublay mesh extending to subcutaneous tissues.

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Fig. 7B —73-year-old woman with postoperative abscess who underwent contrast-enhanced abdominopelvic CT examination.

B, Axial contrast-enhanced CT scans obtained at level of iliac crests show presence of postoperative fluid collection just adjacent to sublay mesh extending to subcutaneous tissues.

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Fig. 7C —73-year-old woman with postoperative abscess who underwent contrast-enhanced abdominopelvic CT examination.

C, Axial contrast-enhanced CT image obtained during Valsalva maneuver shows diastasis of rectus muscles.

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Fig. 8A —35-year-old man with postoperative rectus diastasis who underwent contrast-enhanced abdominopelvic CT examination.

A, Preoperative axial contrast-enhanced CT image through mid abdomen shows normal-appearing linea alba.

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Fig. 8B —35-year-old man with postoperative rectus diastasis who underwent contrast-enhanced abdominopelvic CT examination.

B, Postoperative axial contrast-enhanced CT scan shows unchanged appearance of linea alba with new sublay mesh.

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Fig. 8C —35-year-old man with postoperative rectus diastasis who underwent contrast-enhanced abdominopelvic CT examination.

C, Axial contrast-enhanced CT scan obtained during Valsalva maneuver shows linea alba and sublay mesh and easily identifies diastasis of rectus muscles. Such diastasis in young patients is typically treated conservatively when symptoms are absent.

Mesh-related complications, including fluid collections, infection, or recurrence, are included in the wound-related complications category [13]. Visualization of the mesh itself is highly dependent on the material (density and structure) and the thickness of that material [26, 27]. Sagittal reconstructed CT images are often helpful for detecting the margins of a mesh and its relationship to native abdominal wall structures. When visualized, it is important to document the presence of a mesh, even if uncomplicated, because it may affect future surgeries. The radiologist should also document the position of the mesh in relation to the fascial defect and compare any changes to the prior imaging, if available. Fluid collections, either superficial or deep to the mesh, are common in the immediate postoperative period and result from the accumulation of serous fluid in the empty sac or the potential space resulting from the iatrogenic manipulation permeated through the mesh [27]. Because imaging cannot definitively exclude a superimposed infection in these collections, it is important to rely on the clinical symptomology and examination. A clinical seroma classification system recently has been proposed, and this may increasingly guide clinical intervention [28].

Conclusion
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Incisional hernias, especially the large and complex types, continue to present a surgical challenge. Although imaging has not traditionally played a significant role in the diagnosis or management of such hernias, this role may increase with the prevalence of obesity and the increasing incidence of these hernias. Radiologists' awareness of imaging findings affecting perioperative decision making and the surgical techniques available for hernia repair will likely contribute to improved image interpretation and clinically relevant reporting.

Based on presentations at the Society of Abdominal Radiology 2016 annual meeting, Waikoloa, HI, and the Radiological Society of North America 2016 annual meeting, Chicago, IL.

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FOR YOUR INFORMATION

A data supplement for this article can be viewed in the online version of the article at: www.ajronline.org.

Address correspondence to K. R. Parikh ().

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