Minimally Invasive Hernia Repair in Robot-Assisted Radical Prostatectomy

Introduction and Epidemiology

Inguinal hernias are common, with lifetime prevalence of 25% in men and 3%–5% in women. ¹ Inguinal hernias account for the vast majority of abdominal wall hernias (75%) and 97% of groin hernias. ^{1 –3} The age distribution of inguinal hernias is bimodal, occurring most frequently in patients between the ages of 0–5 and 75–80 years. ¹ Repair of inguinal hernia is one of the most common operations performed in ∼700,000 annually or 28 per 100,000 operations each year in the United States. ⁴ Risk factors for hernia development include history of hernia or hernia repair, older age, male gender, Caucasian race, chronic cough or constipation, abdominal wall injury, smoking, and family history. ⁵ Concomitant hernia repair during pelvic surgery is mostly limited to robot-assisted radical prostatectomy (RARP) through minimally invasive approaches and will be the focus of this review.

Inguinal hernia is a recognized complication of radical prostatectomy. Regan et al. (1996) were the first to show a significantly higher incidence of inguinal hernia after radical prostatectomy when compared with the general population. ⁶ Approximately 20% of patients develop inguinal hernias within 6 months postoperatively. ^{7 –10} This is further verified by other studies that have shown that patients who have undergone radical prostatectomy for the treatment of prostate cancer have a higher incidence of inguinal hernia than prostate cancer patients treated nonoperatively (13.6% vs. 3.1%). ^11,12 Furthermore, patients undergoing combined radical prostatectomy and lymph node dissection are more likely to suffer from inguinal hernia than after lymph node dissection alone. ¹³ Finally, risk for inguinal hernia extends beyond the immediate postoperative period, and may be observed as a long-term complication. ¹⁴

A number of risk factors specific to the radical prostatectomy population have been identified, including previous hernia repair, wound infection, midline incision, low body mass index (BMI), advanced age, and history of cigarette smoking. ^8,10,11 In one study, nearly 30% of patients who required herniorrhaphies at the time of RARP had a previous history of hernia repair. ^15,16 Patients with postoperative wound complications such as hematoma, seroma, and surgical site infection also have a higher rate of inguinal hernia. ¹⁰ Other studies suggest that a lower midline incision increases risk. ^11,14 Stranne and Lodding propose that by disrupting the transversalis, the lower midline incision compromises the deep inguinal ring, leading to herniation. ¹⁴ In addition, Ichioka et al. and Zhu et al. suggest that BMI of less than 23 kg/m² may predispose to hernia after radical prostatectomy; however, the mechanism by which a low BMI may increase the risk of inguinal hernia is unclear. ^11,17 Although the incidence of inguinal hernia is generally higher in smoking populations due to tissue hypoxia and impaired collagen production, ^{18 –20} smoking history has not been found to be a significant predictor of hernia after radical prostatectomy. ^10,15,16

Finally, the incidental finding of an inguinal hernia during laparoscopy is not uncommon. In one study, Watson et al. found that in 100 patients undergoing laparoscopy, the incidence rate of asymptomatic inguinal hernia approached 13%. ²¹ Fukuta et al. found evidence of hernia on the preoperative CT scans in 20.4% of patients undergoing prostatectomy upon retrospective review. ²² This was prospectively studied by Neilson and Walsh who showed that nearly 33% of patients had visible evidence of a dilated inguinal ring or the presence of an existing hernia at the time of radical prostatectomy. ²³ Finley et al. found that only 53% of patients requiring hernia repair at the time of RARP had findings on preoperative examination; the remainder were asymptomatic and hernia discovered incidentally at the time of surgery. ¹⁶ Lepor and Robins assert that the high incidence of inguinal hernia after prostatectomy may be accounted for by failure to diagnose inguinal hernias preoperatively. ²⁴ Fukuta et al. showed that of the 20.4% patients found to have subclinical inguinal hernias before surgery, 55% went on to develop clinically significant hernias postoperatively, an estimated risk of 60.6%. ⁸

Postoperative inguinal hernias are most often indirect, protruding through a defect in the area of the deep inguinal ring lateral to the inferior epigastric vessels, or lateral to Hesselbach's triangle. ^9,13,25 Normally the tensile strength of the transversalis fascia produces a “shutter mechanism” at the myopectineal orifice. ²⁶ Disrupting the normal “shutter mechanism” may lead to compromised integrity of the internal inguinal ring, resulting in a predisposition toward herniation. ^27,28 In patients with an already weak inguinal ring, further disrupting the tensile strength of the abdominal wall with a surgical incision may prove to be the final insult, and result in the development of an inguinal hernia.

McDonald and Huggins performed the first combined open prostatectomy and hernia repair through two incisions in 1949. ²⁹ In 1989, Schlegel and Walsh reported simultaneous inguinal hernia repair during surgery on the bladder and prostate. ³⁰ Since then several studies have examined the safety and feasibility of simultaneous inguinal hernia repair with standard laparoscopic extraperitoneal, transperitoneal, or combined prostatectomy. ^{23,31 –35} Recent studies have examined herniorrhaphy combined with RARP ^15,16,36 . Finley et al. showed that hernia repair at the time of RARP is quick, with no change in postoperative pain or narcotic use, resulting in no significant change in length of hospital stay and few complications. ^15,16 Smaller studies have shown similar results. ^{36 –38}

Preoperative physical examination and abdominal computed tomography may be used to identify inguinal hernias with a 42.5% and 96.3% sensitivity, respectively. ²⁴ Systematic detection and repair of inguinal hernia during radical prostatectomy reduce the risk of subsequent inguinal herniation. Initial studies indicate that concomitant herniorrhaphy at the time of RARP is feasible and safe.

Pros and Cons of Concomitant Hernia Repair During Prostatectomy

Inguinal herniation is a common and potential complication that has significant impact on morbidity rate and use of healthcare resources after radical prostatectomy. Inguinal hernias may lead to complications such as bowel obstruction and/or strangulation requiring emergent open surgery; however, this risk is extremely low. More commonly, patients undergo elective repair due to symptomatic pain. Symptomatic hernias are generally treated by open or laparoscopic repair. Mean operative times for a subsequent hernia repair, either laparoscopic or open, range from 45 to 111 minutes, ³⁹ whereas repair during radical prostatectomy adds ∼15 minutes. ¹⁶ Furthermore, delayed hernia repair after radical prostatectomy may be difficult as scarring in the preperitoneal space may render a subsequent hernia repair difficult. Stranne et al. performed a modified hernia repair on patients with evidence of herniation at the time of prostatectomy, using a figure-of-eight suture placed between the transversus arch and the iliopubic tract to narrow the opening of the internal ring. This decreased the incidence of postoperative inguinal hernia by 62%. ⁴⁰

The main arguments against hernia repair at the time of radical prostatectomy include the risk of mesh infection, postoperative pain or neuralgia, postoperative adhesions, and lack of experience. Furthermore, there is evolving evidence that suggests that patients with asymptomatic or minimally symptomatic inguinal hernias may be managed expectantly without surgery. ^41,42 The risk of infection arises from the possibility that the mesh may come into contact with urine in the presence of a vesicourethral anastomotic leak. Peritoneal integrity cannot be restored after the bladder is dropped from the abdominal wall during laparoscopic transperitoneal prostatectomy. However, review of 2500 consecutive laparoscopic transperitoneal inguinal herniorrhaphies using mesh found no instances of mesh infection. ⁴³ In addition, a meta-analysis of eight randomized-controlled trials showed fewer wound infections and no significant difference in wound infections requiring mesh removal in laparoscopic vs open hernia repairs. ⁴⁴ Even in clean contaminated or contaminated fields, the incidence of mesh infection remains surprisingly low, although the composition of the mesh may impact the ultimate need for mesh removal. ⁴⁵ Although the combined extraperitoneal laparoscopic radical prostatectomy and intraperitoneal inguinal hernia repair with mesh presents a method by which contamination may be avoided, ³¹ there is little evidence that such a complex approach is warranted. Studies examining concomitant inguinal hernia repair with mesh and radical retropubic prostatectomy have shown no instances of mesh infection. ^29,32,34,46 Furthermore, urine may be sterilized preoperatively with appropriate antibiotic treatment in patients with positive urine cultures, presumably further decreasing the risk of mesh infection.

Risk of bowel adhesions and possible fistulization remain a legitimate concern when prosthetic mesh is used for inguinal hernia repair. There are two methods by which this may be reduced. First, reperitonealization may be safely achieved during time of prostatectomy to avoid contact of mesh with intraperitoneal structures. Second, using adhesion-resistant, coated mesh is another solution that reduces risk of adhesion formation while avoiding related postoperative complications. Finley et al. did not experience mesh-related complications in patients undergoing simultaneous RARP and inguinal hernia repair. ^15,16

Contraindications to inguinal hernia repair performed during RARP are similar to those for RARP and laparoscopic surgery, including inability to tolerate general anesthetic, coagulopathy, intraabdominal infection, peritonitis, and previous pelvic surgery (relative).

Technique

RARP is currently the most commonly performed laparoscopic minimally invasive pelvic urologic procedure in the United States. The robotic approach is the most commonly used technique for concomitant inguinal hernia repair. It offers several advantages including a three-dimensional view, 10 × magnification facilitating observation, better ergonomics, and improved maneuverability than standard laparoscopy. This procedure can be performed by either the urologist or with the assistance of a general surgeon depending on surgeon comfort and experience.

After completion of transperitoneal RARP and pelvic lymph node dissection, the myopectineal orifice should be inspected for the presence of a hernia. We recommend the transperitoneal approach followed by a modified Stoppa technique. ⁴⁷ After dissection and reduction of the hernia sac, a nonabsorbable flat mesh is placed to cover the entire myopectineal orifice. For direct hernias, a cone-shaped mesh or an appropriately sized flat mesh sheet may be secured to Cooper's ligament inferiorly and then along the superolateral borders to the rectus sheath. A 5 mm laparoscopic absorbable tacking device may be used through assistant port to secure the flat mesh along the pubic bone. Alternatively, an interrupted suture placed along the superolateral portions of the mesh suffices without the need for the tacking device. For indirect hernias, mesh should be sutured between the iliopubic tract and transverse arch lateral to the inferior epigastric vessels. In addition, there is evidence that when appropriately sized and positioned, the mesh can be left in place without fixation. ⁴⁸ By eliminating fixation, damage to structures within the “triangle of doom” (containing the external iliac vessels) and the “triangle of pain” (containing the lateral femoral cutaneous, genitofemoral, and femoral nerves) may be avoided.

Reperitonealization may reduce the risk of mesh adhesion to bowel; however, risks of other complications (such as visceral injury) may outweigh possible benefit. Reperitonealization may be achieved by fixing the peritoneal edge near the epigastric vessels while the midline incision is closed to avoid stretching the vesicourethral anastomosis. In a smaller cohort of just four patients, Joshi et al. reported oversewing the mesh with peritoneum with no complications, arguing that this technique may prevent fistula and adhesion formation. ³⁶

A totally extraperitoneal approach has been well described for laparoscopic hernia repair. ^32,46,49 In this approach, the spermatic cord vessels and vas deferens are isolated and dissected away from the hernia sac and peritoneum. This creates a space from the pubic symphysis to the anterior superior iliac spine over which mesh may be positioned. This approach allows for the use of standard polypropylene mesh without the need for fixation with staples or sutures. Recently, this approach was analyzed in RARP, and when compared with standard laparoscopic prostatectomy with a similar repair, the results showed longer operative times only in those patients undergoing bilateral hernia repairs, and no other differences were seen. ⁵⁰

Operative Variables and Complications

Joshi et al. reported additional operating time for hernia repair from 15 to 40 minutes. ³⁶ Ludwig et al. reported a mean additional 32 minutes. ³⁸ All other operative and postoperative variables including estimated blood loss and length of stay were unchanged among patients undergoing concomitant RARP and herniorraphy. Finley et al. found no significant difference in analgesic use, whereas Teber et al. found that patients undergoing laparoscopic radical prostatectomy with laparoscopic hernia repair had increased analgesic requirements. In their study, pain medication requirements were especially higher among patients who underwent transperitoneal rather than extraperitoneal procedures. ^32,46

Finley et al. showed that patients undergoing simultaneous RARP and robotic hernia repair had no reported inguinal, scrotal, or testicular pain or paresthesia. They observed one incidence of postoperative urine leakage after reperitonealization during transperitoneal hernia repair. ^15,16 Smaller, more recent studies have reported no herniorrhaphy or mesh-related complications with a mean follow-up of 33 months. ³⁶ In a cohort of 26 patients, Ludwig et al. reported one anterior mesh seroma that resolved spontaneously. ³⁸ Similarly, among cohorts undergoing laparoscopic radical prostatectomy and hernia repair, no complications related to hernia repair have been observed. ^31,32,34,51

Rates of Recurrence After Repair

There is conflicting evidence regarding rates of recurrence after laparoscopic hernia repair. It has been previously reported that rates of recurrence are higher in laparoscopic vs open hernia repair. ³⁵ Yet, others have reported fewer complications and recurrence rates in patients undergoing laparoscopic repair than in those undergoing open repair. ⁵² A meta-analysis comparing eight randomized-controlled trials showed no significant difference in recurrence rates. ³⁹

Finley et al. reported one recurrence 4 months after hernia repair with RARP in a patient who underwent hernia repair with placement of an umbrella mesh. The mesh was noted to have migrated upon subsequent open repair. ¹⁶ They have discontinued the use of umbrella mesh and have seen no further recurrences when using flat, coated mesh, sutured over the hernia defect at multiple points. Similar recurrence rates are noted in three other studies documenting combined RARP and herniorrhaphy as well as after combined open or laparoscopic prostatectomy and hernia repair. ^{31,32,34,36,38,51}