One concern regarding radiographic classification systems for parastomal hernias is whether clinically insignificant hernias are being identified due to the increased sensitivity of cross-sectional imaging. Though experience with this radiographic classification system is limited, there appears to be good concordance between radiographically evident parastomal hernias and clinical symptoms. Seo et al. described the rates of clinical and radiographic parastomal hernias in 83 patients undergoing end colostomy. All patients with Type 3 radiographic parastomal hernia (n = 12) were clinically detectable and all were symptomatic; 80% of Type 2 radiographic hernias were clinically detectable, and 75% were symptomatic; and 60% of Type 1 hernias were clinically detectable with 63% being symptomatic [40]. In other series, radiographic Type 3 hernias have been universally identified on physical exam, while Type 2 hernias have a concordance rate of 60–80% with physical exam [25, 38, 40, 41].

The etiology of parastomal hernias is multifactorial and influenced by both technical and patient-related factors. Technical factors, such as the type of stoma created, the size and location of the stoma, the use of fascial anchoring sutures, and preoperative marking by a wound-ostomy nurse, may alter the risk of parastomal hernia development [23, 34, 40, 42–45]. Patient-related factors believed to be associated with parastomal hernia development include obesity, female gender, age, prior abdominal surgery, smoking, poor nutrition, emergency surgery, postoperative sepsis, corticosteroid use, and malignancy [25, 26, 34, 35, 40, 41, 46–48]. Obesity, female gender, poor nutrition, and stoma aperture size have been found on multivariable analyses to be independent risk factors for radiographic parastomal hernia development in retrospective series [25, 40–42].

While most patients with parastomal hernias are asymptomatic, up to a third will undergo surgical repair on an elective basis for bothersome symptoms or occasionally in emergent circumstances due to strangulation or bowel obstruction [35]. In a report of 782 ostomy patients with a median follow-up of 10.5 years, Ripoche et al. identified clinical evidence of parastomal hernias in 25.6% of patients. Only 24% of patients with a parastomal hernia denied the presence of symptoms, and in the three-quarters who were symptomatic, 46% reported pain, 37% stomal appliance problems, 36% leakage, 29% skin irritation, and 20% described psychological and aesthetic concerns secondary to the hernia. Stomal prolapse occurred in 18%, and at least one episode of obstruction was observed in 15% of patients [33]. Liu et al. reported a clinical parastomal hernia rate of 29% at a median follow-up of 29 months, 45% of whom underwent surgical repair for abdominal pain (58%), acute strangulation or bowel obstruction (15%), partial small bowel obstruction (15%), or for elective reasons (12%) [26]. In our own series of 384 consecutive patients undergoing radical cystectomy and ileal conduit diversion, we noted 24% of patients had parastomal hernias on physical exam, 40% of whom were symptomatic. Of the 93 patients with a clinically apparent hernia, an abdominal hernia belt or binder was prescribed for 75 patients (81%), and 16 (17%) were referred for possible surgical repair. Only eight patients (9%) with symptomatic parastomal hernias underwent surgical repair, two of which were performed emergently due to bowel strangulation. Three of the eight repairs developed a recurrent parastomal hernia a median of 13 months (range 10–22 months) later. The low rates of referral may reflect the need to balance the competing issues of advanced disease and short life expectancy in some patients with high recurrence rates and potential morbidity associated with the hernia repair [25].

The negative quality of life issues, morbidity of surgical repair, and relatively high recurrences rates have prompted surgeons to attempt to prevent parastomal hernias from the time of the index operation. There have been five prospective, randomized studies where mesh was placed at the time of stoma formation in an attempt to prevent parastomal hernias, all of which have demonstrated significant reductions in the clinical and radiographic parastomal hernia rates without associated postoperative complications or long-term morbidity [39, 49–51] (Table 6.1).
Four studies used partially absorbable mesh, and the fifth was a phase I trial of a biologic mesh in patients undergoing loop ileostomy with planned reversal 6 months later (Fig. 6.2). The series with the longest follow-up comes from Janes et al. who reported short- and long-term results from their randomized trial. After both 12-month and 5-year follow-up for patients in their randomized trial, they reported significant reductions in the rates of parastomal hernias for patients receiving prophylactic mesh compared to standard surgery [49, 52]. At a minimum of 5-year follow-up, the parastomal hernia rate for those alive with mesh was 13% compared to 81% who had standard surgery (p < 0.001). Over a mean of 72 months of follow-up, no fistulas, strictures, and mesh infections were noted, and no patient has required mesh removal [52].

Not all randomized trials of prophylactic mesh placement at the time of stoma formation have demonstrated equivalent results. Vierimaa et al. reported on 83 patients randomized to have a dual layer mesh placed in the intraperitoneal onlay position at the time of laparoscopic end-colostomy formation versus traditional stoma formation. The primary end points for the trial were to measure both clinical and radiographic parastomal hernia rates with secondary end points being stoma-related morbidity and need for surgical parastomal hernia repair. The authors noted a significant reduction in clinical parastomal hernias for those receiving mesh compared to those having standard surgery (14.3% versus 32.3%; p = 0.049); however, the rates of radiographic parastomal hernias as assessed by CT imaging were not different (51.4% versus 53.1%; p = 1.00) [53].

Non-randomized series of consecutive patients receiving prophylactic mesh at the time of index surgery have recently been published. Styrke reported a single institution, 10-year consecutive series of 114 patients having prophylactic mesh placed in the sublay (retrorectus) position at the time of open radical cystectomy and ileal conduit formation. After a median follow-up of 35 months, they reported a clinical parastomal hernia rate of 14% in 58 evaluable patients and no mesh-related complications [54]. In contrast to other investigators, Nikberg et al. did not identify a difference in clinical or radiographic parastomal hernia rates after introducing prophylactic sublay mesh for all patients undergoing end colostomy at their institution beginning in 2007. When compared to matched patients having traditional surgery (n = 135) between 1997 and 2007, those having prophylactic mesh (n = 71) after 2007 had the exact same clinical parastomal hernia rates (25%; p = 0.953) and radiographic parastomal hernia rates (53%; p = 0.176). The degree of herniation on cross-sectional imaging (containing omentum or bowel in the hernia sac) was similar for those having mesh placed and those having standard surgery (80% versus 61%; p = 0.155). On multivariable analysis, these authors found BMI to be an independent risk factor for development of parastomal hernia (HR = 1.09, 95% CI = 1.00–1.18) [55]. Ultimately, the degree to which placement of prophylactic mesh at the time of ileal conduit construction reduces parastomal hernia rates should be established in the setting of a randomized controlled trial.

There is significant debate regarding whether the ureterointestinal anastomoses should be constructed in a non-refluxing or refluxing manner. The principle behind constructing non-refluxing anastomoses is to protect the kidneys and upper tracts from sustained high pressures and to prevent ascending bacteriuria. This was particularly relevant for patients undergoing ureterosigmoidostomy, which diverts the urine into a high-pressure system, but has become less of a concern with the development of lower pressure, high-capacity continent reservoirs and for patients undergoing conduit urinary diversion. There appears to be a greater risk of gradual renal deterioration from ureterointestinal anastomotic strictures than from reflux of urine into the upper tracts. Non-refluxing anastomoses are associated with twice the rate of strictures than refluxing anastomoses, irrespective of the type of bowel segment used. Rates of ureterointestinal strictures with a refluxing anastomotic repair range from 1.7 to 3.6% compared to the 13–29% described with the LeDuc non-refluxing anastomosis technique [56]. Approximately half of patients with strictures will require surgical intervention, leading some surgeons to conclude that the greater risk to the upper tracts is ureterointestinal anastomotic stricture rather than reflux. In a group of 126 patients followed over 25 years with Kock reservoirs, Jonnson and colleagues concluded that the type of diversion does not significantly impact long-term kidney function as long as any potential strictures are recognized and treated [57]. Refluxing anastomoses are technically simpler to complete and have not been associated with significant rates of upper tract deterioration, thus making them the procedure of choice for ureterointestinal anastomoses [58–62].

Ureterointestinal strictures occur in 3–29% of patients depending on the anastomotic technique used and the length of follow-up reported. Most strictures are felt to be due to ureteral ischemia and will occur within the first 1–2 years after surgery irrespective of the type of anastomosis performed. These strictures are typically asymptomatic and only identified by changes in creatinine levels over time or on surveillance imaging studies [63–66]. Minimizing mobilization and devascularization of ureters is of paramount importance in reducing the risk of postoperative strictures. Care must be taken in routing the left ureter under the descending colon or through an avascular segment of its mesentery, which should be considered when passing the ureter beneath the colon might cause excessive angulation or place the anastomosis on tension.

Antegrade and retrograde endoscopic as well as open surgical approaches have been described to address ureterointestinal strictures. Both endoscopic or antegrade dilation and incision of strictures have been described with success rates of 20.0% to 50.0% versus 44.4% to 63.0%, respectively. The best results with endoscopic management have been seen with short (< 2 cm) distal strictures in kidneys with preserved renal function at the time of intervention; endoscopic treatment of strictures in renal units with less than 25% differential function is associated with poorer outcomes [66–71]. At 3 years follow-up, endoscopic management of ureterointestinal strictures has a reported continued success rate of only 32% [72]. Open surgical approaches have success rates approaching 90% but are the most invasive and technically challenging. It is important to evaluate the excised segment of stenotic ureter and bowel for the presence of malignancy when performing an open repair.

Ileum and colon are associated with the fewest electrolyte disturbances, have the greatest amount of redundancy, are easily mobilized to any portion of the abdomen or pelvis, and have excellent blood supplies. Both segments have the same metabolic abnormalities due to the absorption of ammonium chloride resulting in a hyperchloremic metabolic acidosis. Patients with impaired renal function can develop lethargy, anorexia, weight loss, and long-term risk for bone demineralization leading to osteopenia. Symptomatic metabolic acidosis can be treated with alkalinizing agents, maintaining good hydration, and minimizing dwell time of urine in the conduit. The terminal ileum is responsible for absorption of bile salts, fat-soluble vitamins (K, A, D, and E), and the absorption of vitamin B-12. If excessive lengths of ileum are used for diversion, patients can develop steatorrhea, vitamin B-12 deficiency, and dehydration.

The use of the terminal ileum for construction of either a continent cutaneous reservoir or orthotopic neobladder can place the patient at risk for vitamin B-12 deficiency. Ideally, the segment of ileum utilized for the conduit should be taken from an area proximal to the terminal ileum to avoid this complication. Vitamin B-12 absorption occurs primarily in the terminal ileum, and deficiency can result in irreversible neurologic and hematologic derangements. From baseline levels vitamin B-12 depletion is a slowly occurring event after loss of the terminal ileum, often taking 3–5 years to drop to a level sufficiently low enough to produce symptoms [73–76]. It is our practice to monitor B-12 levels on an annual basis and to replace on a yearly basis beginning at year 3 after urinary diversion.

Chronic acidosis after urinary diversion occurs in 5.5–13.3% of patients at a mean follow-up of 51 months and can result long term in bone demineralization and osteomalacia [77]. Decreased intestinal absorption of calcium can occur with resection of longer segments of ileum. Bone minerals, such as calcium and carbonate, act as buffers against hydrogen ions, leading to decreased skeletal calcium content. Chronic acidosis will induce vitamin D deficiency, resulting in bone mineralization defects, and finally the acidic environment activates resorption of bone by osteoclasts [78–81]. Laboratory values may show elevated alkaline phosphatase and reduced serum calcium and phosphate levels [79, 82]. Patients can present with a variety of issues related to bone demineralization ranging from being asymptomatic to pain in weight bearing joints to having fractures. Women and those patients undergoing urinary diversion at a young age when bone growth is not yet complete appear to be at highest risk for the complications associated with bone demineralization. Patients with impaired renal function are at risk for acidosis which may be worsened after urinary diversion. Radiographic evidence of bone demineralization may take years to develop. Serial measurements of bone mineral density by DEXA scan may demonstrate subtle alterations over time, but this needs to be further studied in prospective manner. Symptomatic patients should have their acid-base status corrected as a first step, which may also result in remineralization of the bone; however, those failing to respond should be managed with calcium supplements and vitamin D [83–85]. Oral sodium bicarbonate should be considered for patients with a base deficit of −2.5 mmol/l to reduce the likelihood of developing bone sequelae from chronic acidosis.

Despite six decades of experience with ileal conduit urinary diversion, medical and surgical complications are common and can negatively impact patients’ quality of life. Urologists must have a thorough understanding of the principles of urinary diversion, meticulous attention to detail during the index operation, and comprehensive long-term follow-up to help reduce the early and late complications associated with this urinary reconstruction.