Incisional Hernia In Midline Pelvic

The Scar Solution Natural Scar Removal

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Figure 1.33. Abscess secondary to retained lap pad. Two CT sections reveal a large perihepatic abscess (A) secondary to a retained lap pad (B).

ular retained mass presents as multiple polypoidal defects in the bowel lumen as barium insinuates itself into the sponge matrix [78].

Sonography may also detect gossypibomas, either as an incidental finding or as the focus of the examination. When encountered, they present as an echogenic mass with acoustic shadowing [86,89]. The echogenicity is secondary to the numerous interfaces within the sponge [89]. When the acoustic shadowing is related to a palpable mass, the finding is considered diagnostic and appropriate therapy should be instituted [90].

The features of the gossypiboma that become visible on magnetic resonance imaging (MRI) depend on the protein content and nature of the fluid trapped within the sponge matrix [77]. Usually T1- and T2-weighted images will have low signal intensity representing a fibrous rim [77].

Oxidized Cellulose (Surgicel)

Another foreign body that can cause an imaging dilemma, but one that is deliberately left in the abdomen, is Surgicel (Johnson & Johnson Medical, Arlington, TX). This oxidized regenerated cellulose is a topical hemostatic agent that is bioabsorbable. The fiber is knitted into a gauzelike material. It is readily absorbed, chemically inert, and does not incite a foreign body reaction [91,92]. Thrombus forms when blood and the oxidized cellulose come into contact. It then may swell and increase in size. It is used to control capillary or venous bleeding [93]. Surgicel has a bactericidal effect on both aerobic and anaerobic bacteria. Although designed to be removed during surgery, it often is left in the surgical bed [93], especially during laparoscopic procedures [94].

On plain films the oxidized cellulose may be visualized as a linear band of increased density or as a mottled lucency secondary to air being trapped within its gauzelike structure [95] (Fig. 1.34). The latter configuration allows it to mimic an abscess in the surgical bed. A similar feature with a mixed attenuation mass containing a central air collection may be seen in a CT image [94].

Sonography reveals findings similar to those with a retained surgical spine with a highly echogenic mass with posterior reverberation artifact [96]. Some surrounding fluid may also be seen. The mass may mimic a recurrent ovarian malignancy [93] or other neoplasms [97,98].

The MR appearance is variable, depending on the stage of resorption during which the oxidized cellulose is imaged. In the early postoperative period, air trapped between the gauze fibers may result in signal void on both T1- and T2-weighted images [94]. In addition, T1-weighted images reveal a slightly increased signal intensity, while the signal on T2-weighted images is hypointense [94]. This latter finding is important in differentiating Surgicel from an abscess. The latter is markedly intense on T2-weighted images, whereas a Surgicel mass is not enhanced after gadolinium administration [93,94]. One-month follow-up studies revealed a marked decrease in size in half of patients, and complete resolution in a third. In patients in whom the mass decreased in size, the T2-weighted images showed markedly increased signal intensity, while masses were isointense on T1-weighted images [94].

Figure 1.34. Surgicel mimicking an abscess. Supine film of the right upper quadrant (A) and a close-up of the same region (B) reveal multiple small air bubbles in a mottled pattern in this immediately postoperative patient. Although the anomaly could be mistaken for an abscess, the timing suggests a more benign etiology. In this case, the surgeon had implanted Surgicel to aid in hemostasis.

Figure 1.34. Surgicel mimicking an abscess. Supine film of the right upper quadrant (A) and a close-up of the same region (B) reveal multiple small air bubbles in a mottled pattern in this immediately postoperative patient. Although the anomaly could be mistaken for an abscess, the timing suggests a more benign etiology. In this case, the surgeon had implanted Surgicel to aid in hemostasis.

Meshes

Hernia repairs, especially for large recurrent hernias, aim at reestablishing abdominal wall substance and restoring the interaction of the abdominal wall musculature [99]. Various substances have been used to reinforce or reestablish the abdominal wall. These include fascia lata, stainless steel and tantalum metal meshes (Figs. 1.35-1.37), knitted monofilament polypropylene (Marlex) mesh, and an expanded polyte-trafluoroethylene (Gore-Tex) patch [99-101].

The constant flexing of the anterior abdominal wall may lead to weakening and fracturing of the wire mesh. Subsequent fragmentation may lead to migration. The mesh may be extruded externally or even erode into the intestines, causing chronic blood loss and anemia [101]. With newer synthetic meshes, the postoperative problems are more often related to detachment [102], seromas and hematomas [102], and infection [99,102].

Figure 1.35. Metallic mesh for hernia repair. Figure 1.36. Metallic mesh. Supine film of the

Supine film of the abdomen reveals a large metal- abdomen shows a metallic mesh used for the lic mesh in the right upper quadrant, stabilizing repair of a large ventral incisional hernia. the anterior abdominal wall following a subcostal incision. This is an unusual location for an incisional hernia.

Figure 1.35. Metallic mesh for hernia repair. Figure 1.36. Metallic mesh. Supine film of the

Supine film of the abdomen reveals a large metal- abdomen shows a metallic mesh used for the lic mesh in the right upper quadrant, stabilizing repair of a large ventral incisional hernia. the anterior abdominal wall following a subcostal incision. This is an unusual location for an incisional hernia.

Scar Ossification

A very unusual complication of abdominal surgery is heterotopic ossification of midline abdominal scars. This variant of myositis ossificans may actually contain both bony and cartilaginous elements and, much more rarely, bone marrow [103]. Most often supraumbilical longitudinal incisions are involved, with a strong male preponderance (10:1) [104]. The scar lies between the two rectus muscles, bordered anteriorly by the abdominal wall fascia and posteriorly by the anterior parietal peritoneum [104]. No distinct linkage with the type of surgical procedure or the suture material used has been established.

Plain films reveal a calcific or bone density linear structure within the anterior abdominal wall, usually in a subxyphoid location (Figs. 1.38-1.40). Radionuclide studies show uptake of 99mT-labeled pyrophosphate within the incision, even before the calcification or ossification is radiographically evident [105].

CT examination revealed rounded or flat linear ossification, or a combination of the two. When encountered, the rounded form is seen more proximally [103]. Central fat density was occasionally seen, consistent with the presence of bone marrow. Ossification can be noted as early as less than 3 weeks postoperatively and can be progressive.

The MR imaging characteristics were consistent with the underlying pathology [103]. A low intensity rim corresponded with fibrous tissue and/or calcium at the scar periphery. The central signal varies with the fat from marrow elements.

Figure 1.38. Ossified scar. Right posterior oblique abdominal film (A) and left anterior oblique film from a double-contrast enema (B) on the same patient show a linear calcific density in the upper abdomen. This represents an ossified scar.

Figure 1.39. Ossified scar. Supine (A) and right posterior oblique (B) films of the right upper quadrant demonstrate an ossified scar in the upper abdomen. The oblique film (B) demonstrates the rather superficial location of the ossification.

Figure 1.39. Ossified scar. Supine (A) and right posterior oblique (B) films of the right upper quadrant demonstrate an ossified scar in the upper abdomen. The oblique film (B) demonstrates the rather superficial location of the ossification.

Figure 1.40. Ossified scar. Coned-down film of the right upper quadrant shows a linear density with a lucent center. The lucency may represent bone marrow elements within this ossified scar.

Intussusception

Intussusception may occur during the immediate postoperative period without a lead point; Agha reported abnormal bowel motility, electrolyte imbalances, and chronic dilatation of the bowel among these causes [106]. The coiled-spring appearance may be seen with either air [107] or barium [108] (Fig. 1.41) in the intussuscipiens outlining the intussusceptum. On CT examination, a target sign consists of contrast within the lumen of the intussusceptum surrounded by its mucosa. This is enveloped by the fat of the serosa or mesentery, which is further surrounded by contrast and the intestinal wall of the intussuscipiens [109-111]. When visualized longitudinally, the telescoping of the intus-susceptum into the intussuscipiens is readily apparent. Much less frequently encountered is the unusual retrograde intussusception, where the intussusceptum is the distal small-bowel segment, and the intus-suscipiens the more proximal part (Fig. 1.42).

Small Bowel Series Spot Film

Figure 1.41. Postoperative intussusception.

Small-bowel follow-through shows the coiled-spring appearance of an intussusception in the jejunum in the left midabdomen. No leading edge was evident in this recently postoperative patient.

Figure 1.41. Postoperative intussusception.

Small-bowel follow-through shows the coiled-spring appearance of an intussusception in the jejunum in the left midabdomen. No leading edge was evident in this recently postoperative patient.

FIGuRE 1.42. Retrograde intussusception. Spot film from a small-bowel series shows a filling defect with a coiled-spring appearance in the proximal ileum. Fluoroscopic evaluation showed this to be changeable and functional in origin.

Herniation

Incisional hernias, also known as iatrogenic, postoperative, or cicatricial hernias, occur in a variety of clinical settings (Table 1.2) [112]. Like most hernias, incisional ones may incarcerate, with all the morbidity and mortality that accompanies that complication (Figs. 1.43 and 1.44).

Table 1.2. Etiology of incisional hernias.

Wound infection Wound dehiscence

Increased intra-abdominal pressure in the early postoperative phase (e.g., coughing) Atypical incision Advanced age Preexisting conditions Collagen vascular diseases Uremia Obesity Diabetes Ascites Source: Ref. 112.

Midline Pelvic

Figure 1.43. Small-bowel obstruction secondary to an incisional hernia.

Supine film of the abdomen reveals markedly dilated loops of small bowel secondary to an incisional hernia.

Figure 1.44. Incarcerated incisional hernia. Two adjacent CT sections (A, B) through the upper pelvis reveal a loop of small bowel incarcerated within a midline anterior abdominal wall incision. Note the thickened wall of the involved small bowel indicating vascular compromise. A small-bowel obstruction is also evident.

Figure 1.44. Incarcerated incisional hernia. Two adjacent CT sections (A, B) through the upper pelvis reveal a loop of small bowel incarcerated within a midline anterior abdominal wall incision. Note the thickened wall of the involved small bowel indicating vascular compromise. A small-bowel obstruction is also evident.

Although with the advent of laparoscopic surgery the size of the defects in the anterior abdominal wall (Fig. 1.45) has diminished greatly in comparison to those from conventional laparoscopy, inci-sional hernias may occur through the trochar sites (Fig. 1.46).

Bowel Herniation Through Incision

Figure 1.45. Laparoscopic cholecystectomy instruments and insertion sites.

Single intraoperative film from a cystic duct cholangiogram performed during a laparascopic cholecystectomy demonstrates the various trochar insertion sites utilized in this technique.

Figure 1.45. Laparoscopic cholecystectomy instruments and insertion sites.

Single intraoperative film from a cystic duct cholangiogram performed during a laparascopic cholecystectomy demonstrates the various trochar insertion sites utilized in this technique.

Intraoperative Cholangiogram Instruments

Figure 1.46. Trochar hernia. Two CT sections through the pelvis show a defect in the anterior abdominal wall adjacent to the umbilicus (A) through which the small bowel is herniating. This is due to prior puncture by a trochar for a laparoscopic cholecystectomy. The large extent of the hernia is evident on the more caudal section (B).

Figure 1.46. Trochar hernia. Two CT sections through the pelvis show a defect in the anterior abdominal wall adjacent to the umbilicus (A) through which the small bowel is herniating. This is due to prior puncture by a trochar for a laparoscopic cholecystectomy. The large extent of the hernia is evident on the more caudal section (B).

Internal postoperative hernias are not true hernias. Instead they represent a disordered clustering of bowel in an abnormally created peritoneal recess [112]. No hernia sac is present. These abnormalities may be seen on 0.2 to 2.9% of autopsies of patients who had undergone surgery [112,113]. They represent approximately half of all internal hernias. They may be seen going through the transverse mesocolon following Billroth II surgery, or other gastroenterostomy (Figs. 1.47 and 1.48). Other sites include the iliac bone through a bone graft donor site (Fig. 1.49), as well as other osseous defects. Following a nephrectomy, bowel may enter the now-empty renal fossa. Postoperative hernias are often asymptomatic [112]. When the herniation is intermittent, nonspecific abdominal complaints may be intermittent as well.

Figure 1.47. Internal postoperative hernia. Film from an upper GI series shows a dilated stomach superiorly, and dilated loops of small bowel adjacent to the greater curvature. The latter represent herniated small bowel through a postoperative defect in the transverse mesocolon.

Figure 1.48. Postoperative transmesocolic hernia. Dilated small bowel is demonstrated in the upper abdomen as it is incarcerated within a transverse mesocolic defect. The defect, the result of a stab wound to the abdomen, was used to bring up a loop of small bowel for a complex diversion procedure.

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