Impact of Peritoneal Closure on Inguinal Hernia Incidence After Robot-Assisted Radical Prostatectomy

Abstract

Background/Objectives: Inguinal hernia (IH) is a common complication after robot-assisted radical prostatectomy (RARP), significantly impacting patients’ quality of life. This study aimed to evaluate whether peritoneal closure reduces the incidence of IH after RARP. Methods: A retrospective analysis was conducted on 772 patients who underwent transperitoneal RARP between April 2018 and March 2023. Patients with a history of IH surgery were excluded. Peritoneal closure, introduced in December 2021, was performed during the final steps of RARP in 144 patients. The incidence of IH was compared between patients with and without peritoneal closure. Multivariate analysis was performed to identify significant predictors of IH. Results: IH occurred in 73 patients (9.5%)—5 (3.5%) in the peritoneal closure group and 68 (10.8%) in the no peritoneal closure group. Multivariate analysis revealed that the absence of peritoneal closure (hazard ratio [HR] = 4.55, p = 0.04) and low body mass index (BMI < 23 kg/m²; HR = 2.51, p = 0.001) were significant predictors of IH. The two-year IH-free survival rate was 96.5% in the peritoneal closure group and 89.2% in the no peritoneal closure group. Conclusions: Peritoneal closure significantly reduces the incidence of IH after RARP. This simple and effective technique may serve as a valuable preventive measure against postoperative IH, potentially improving surgical outcomes and patient quality of life. Further studies are warranted to confirm these results in diverse patient populations.

1. Introduction

Inguinal hernia (IH) is a recognized issue that arises after radical prostatectomy (RP), impacting both recovery and quality of life [1,2,3,4,5,6]. Among the various surgical techniques, RARP (robot-assisted radical prostatectomy) has gained widespread adoption due to its minimally invasive nature and improved precision. However, the incidence of IH following RARP remains a concern, with reported rates ranging from 7% to 21% [7,8]. This complication not only causes discomfort and inguinal pain but may also necessitate additional surgical interventions, thereby increasing healthcare costs and patient burden [8].

The development of IH following RARP is influenced by multiple factors. The surgical process during RARP may compromise the musculoaponeurotic structures surrounding the internal inguinal ring, increasing the likelihood of herniation. Aging-related deterioration of these structures further exacerbates the risk [9]. Moreover, key contributors to IH development include a low body mass index (BMI) and the presence of a history of IH surgery [10,11,12]. Despite advances in surgical techniques, the prevention of IH remains a critical challenge for urologists.

Several strategies have been proposed to mitigate the risk of IH following RARP. Soma et al. demonstrated that processus vaginalis transection (PVT) combined with peritoneal closure significantly reduces IH incidence [2]. Similarly, Lee et al. suggested that plugging the internal inguinal floor can prevent postoperative IH [11]. While these approaches have shown promise, they often involve additional surgical steps, potentially prolonging operative time and increasing complexity. Thus, there is a need for simpler and more efficient techniques that can be seamlessly integrated into the RARP procedure.

Building upon previous findings, we hypothesize that peritoneal closure alone, performed during the final steps of RARP, could effectively reduce the incidence of IH. By restoring the peritoneum to its original state, this technique aims to diminish outward pressure on the inguinal area and prevent herniation. Since December 2021, we have implemented peritoneal closure selectively in patients undergoing RARP. This retrospective study examines the occurrence of IH in patients who received peritoneal closure compared to those who did not, aiming to assess its effectiveness as a preventive strategy.

The findings of this study not only contribute to the growing body of literature on IH prevention but also provide insights into the potential of peritoneal closure as a standard practice in RARP.

2. Materials and Methods

2.1. Patient Selection

We retrospectively reviewed 819 patients who underwent transperitoneal RARP from April 2018 to December 2022. Of these, 47 patients with a history of IH surgery were excluded from the analysis, and 772 patients were included in the final analysis. All patients provided informed consent for elective surgery. This observational study was conducted in accordance with the STROBE guidelines and the Declaration of Helsinki. The study was approved by the National Cancer Center Institutional Review Board (Approval number: 2018-159, approved on 6 August 2018), which covered a retrospective analysis of patients who underwent RARP from April 2018 to December 2022. In accordance with Japanese ethical guidelines, written informed consent was not required for this retrospective study using anonymized data. Instead, an opt-out method was employed: study information was posted on the hospital website, and patients were given the opportunity to decline participation.

2.2. Surgical Procedure

Multiple surgeons performed RARP using the da Vinci robotic system (Intuitive Surgical, Sunnyvale, CA, USA) with a six-port approach. Pelvic lymph node dissection (PLND) was carried out in patients who had more than two high-risk factors according to the National Comprehensive Cancer Network (NCCN) classification. Nerve sparing (NS) was performed according to the surgeon’s judgment based on the location of the cancer and risks involved. The pneumoperitoneal pressure was kept between 8 mmHg and 15 mmHg. All surgeries were performed either by expert surgeons or by residents under the direct supervision of expert surgeons to ensure consistency and surgical quality.

Peritoneal closure, introduced in December 2021, is performed during the final step of RARP. In our case, it was performed only in patients who did not undergo PLND. The incised peritoneum was closed using a continuous running suture with 3-0 barbed thread, starting from one edge of the incision to the other. The suture was clipped midway and at the end to maintain tension and secure closure. No drains were placed in patients undergoing peritoneal closure. The incised peritoneum was sutured with 3-0 barbed suture, clipped midway and at the end.

2.3. Data Collection

To evaluate potential risk factors, data collection focused on clinical variables including age, BMI, history of smoking, history of abdominal surgery, eastern cooperative oncology group performance status (ECOG-PS), the presence of neoadjuvant hormone therapy, initial prostate specific antigen (iPSA), clinical T stage, Gleason score, surgical time, amount of blood loss, and the performance of PLND or NS. Postoperatively, patients were followed up regularly. The patients who developed IH after RARP were diagnosed with unilateral or bilateral IH. They were then referred to another hospital for surgery.

Continuous variables such as age, BMI, iPSA, and surgical time were divided into two groups based on their median values (BMI: 23 kg/m², age: 70 years, iPSA: 15 ng/mL, surgical time: 170 min) to facilitate the interpretation of the data and ensure balanced distribution across groups.

2.4. Endpoints

The primary objective of this study was to comprehensively evaluate the occurrence of postoperative inguinal hernia (IH), specifically focusing on its incidence as the designated primary endpoint. Patients were monitored during outpatient follow-up visits, with the frequency and timing of these visits tailored based on their postoperative prostate cancer condition and PSA levels. At our institution, urologists detected cases of postoperative IH through careful examinations conducted during these routine outpatient follow-ups. For the purposes of this research, we concentrated on the incidence of IH occurring within the first two years following RARP. This time frame was chosen because earlier studies have indicated that the likelihood of developing postoperative IH is elevated during this specific period [6].

2.5. Statistical Analysis

The statistical analyses in this study were performed using version 4.2.1 of the R statistical software (R Foundation, Vienna, Austria). To analyze categorical variables, the Chi-square test or Fisher’s exact test was used, depending on the data distribution and sample size. For continuous variables, either the t-test or the Mann–Whitney U test was applied, based on whether the data followed a normal distribution. To assess how different factors influence the risk of developing IH within two years following RARP, we utilized both univariate and multivariate Cox proportional hazard regression models. Additionally, the Kaplan–Meier method was utilized to estimate IH-free survival rates, and the log-rank test was used to determine whether there were significant differences in these survival rates between patients who underwent peritoneal closure and those who did not. Statistical significance was defined as a two-tailed p value below 0.05.

3. Results

The baseline characteristics of the 772 patients who underwent RARP are summarized in

Table 1. Baseline characteristics compared to peritoneal closure and no peritoneal closure in the patients who underwent RARP (N = 772).

	Total (N = 773)	No Peritoneal Closure (N = 628)	Peritoneal Closure (N = 144)
	Number (%) or Median (Range)	Number (%) or Median (Range)	Number (%) or Median (Range)	p Value
Age	71 (66–75)	70.1 (66–75)	70.3 (65–76)	0.674
BMI	23.4 (21.8–25.3)	23.4 (21.9–32.4)	23.2 (21.5–25.3)	0.157
ECOG-PS
0	767 (99.4)	624 (99.4)	143 (99.3)	1
1	5 (0.6)	4 (0.6)	1 (0.7)
The presence of smoking history	559 (72.4)	453 (72.7)	106 (73.6)	0.917
The presence of abdominal surgical history	139 (18.0)	117 (21.8)	22 (25.9)	0.402
iPSA	8.4 (5.8–13.1)	7.5 (5.9–14.1)	7.5 (5.4–9.8)	<0.001
Clinical T stage
1	57 (7.4)	41 (6.6)	16 (11.1)	0.197
2	527 (68.4)	436 (69.9)	89 (61.8)
3	176 (22.8)	141 (22.6)	34 (23.6)
4	8 (0.1)	5 (0.01)	4 (2.8)
Primary Gleason score
3	310 (43.3)	256 (42.2)	54 (49.1)	0.100
4	365 (51.0)	316 (52.1)	49 (44.5)
5	39 (5.4)	33 (5.4)	6 (5.5)
Secondory Gleason score
3	360 (46.1)	227 (40.3)	21 (29.2)	0.249
4	329 (42.1)	259 (46.0)	41 (56.9)
5	91 (11.1)	76 (13.5)	10 (13.9)
Total Gleason score
6	116 (15.0)	97 (15.4)	19 (13.3)	0.146
7	367 (47.4)	305 (48.6)	61 (42.7)
8	160 (20.7)	119 (18.9)	40 (28.0)
9	118 (15.2)	94 (15.0)	23 (16.1)
10	10 (1.3)	10 (1.6)	0 (0)
NCCN risk classification
≤Low	54 (7.2)	39 (6.2)	15 (10.5)	<0.001
Intermediate	341 (44.2)	263 (41.8)	79 (55.2)
High	277 (35.9)	232 (37.0)	45 (31.5)
Very high	98 (12.7)	94 (15.0)	4 (2.8)
The presence of neoadjuvant hormone therapy	477 (61.8)	324 (52.2)	53 (39.0)	0.006
Postoperative IH within 2 years	73 (9.4)	68 (10.8)	5 (3.5)	0.012
Surgical time (min)	163 (137–191)	166 (140–194)	146 (120–175)	0.014
Blood loss (mL)	75.5 (30–169.2)	85.0 (32.8–176.3)	59.5 (18.0–124.5)	<0.001

RARP: robot-assisted radical prostatectomy, ECOG-PS: Eastern Cooperative Oncology Group performance status, BMI: body mass index, iPSA: initial prostate specific antigen, NCCN: national comprehensive cancer network, IH: inguinal hernia. p value of <0.05 was considered to be statistically significant.

. Pelvic lymph node dissection (PLND) was performed in 206 cases, and nerve-sparing (NS) was performed in 123 cases, including 101 with unilateral sparing and 22 with bilateral sparing. Peritoneal closure was performed in 144 cases where PLND was not conducted. In contrast, the group without peritoneal closure showed higher initial prostate-specific antigen (iPSA) levels (p < 0.001), elevated NCCN risk classifications (p < 0.001), and increased blood loss (p < 0.001). Additionally, surgical time was significantly shorter in the peritoneal closure group compared to the no closure group (median 146 min vs. 166 min, p = 0.014). Postoperatively, 73 patients developed IH within two years. Among them, 5 had undergone peritoneal closure, whereas 68 had not demonstrated a significantly lower incidence in the closure group (3.5% vs. 10.8%, p = 0.012). Out of the 73 patients who developed IH, 44 (60.3%) had right-sided, 15 (20.5%) had left-sided, and 14 (19.2%) had bilateral. To account for the potential confounding effect of PLND, we conducted a subgroup analysis limited to patients who did not undergo PLND. In this subset, IH occurred in 46 of 429 patients (10.7%) in the no peritoneal closure group and 5 of 137 patients (3.6%) in the peritoneal closure group, showing a significantly lower incidence in the peritoneal closure group (p = 0.010). In the univariate analysis, the absence of peritoneal closure (hazard ratio [HR] = 4.35, 95% confidence interval [CI] = 1.39–14.1, p = 0.012) and a low BMI (<23 kg/m²) (HR = 2.45, 95% CI = 1.40–4.29, p = 0.0023) was significantly associated with the occurrence of IH within two years post-RARP (

Table 2. Univariate and multivariate analysis of preoperative clinical factors for IH after RARP.

	Univariate Analysis			Multivariate Analysis
Variables	HR	95% CI	p Value	HR	95% CI	p Value
Age, year
<70	Ref
≥70	1.24	0.75–2.02	0.40
BMI, kg/m2
≥23	Ref
<23	2.45	1.40–4.29	0.002	2.51	1.43–4.40	0.001
Smoking
No	Ref
Yes	0.86	0.52–1.44	0.58
Abdominal surgical history
No	Ref
Yes	1.14	0.66–1.97	0.64
iPSA, ng/ml
<15	Ref
≥15	0.94	0.52–1.69	0.84
Surgical time, min
<170	Ref
≥170	1.09	0.72–1.66	0.69
Neoadjuvant hormone
No	Ref
Yes	1.24	0.77–1.98	0.38
Peritoneal closure
Performed	Ref
No Performed	4.35	1.39–14.1	0.012	4.55	1.11–18.9	0.04
PLND
No performed	Ref
Performed	1.20	0.72–2.00	0.49
NS
No performed	Ref
Performed	0.48	0.21–1.1	0.087

IH: inguinal hernia, RARP: robot-assisted radical prostatectomy, BMI: body mass index, iPSA: initial prostate specific antigen, PLND: pelvic lymph node dissection, NS: nerve sparing, HR: hazard ratio, CI: confidence interval. p value of <0.05 was considered to be statistically significant.

). Similarly, multivariate analysis showed that the absence of peritoneal closure (HR = 4.55, 95% CI = 1.11–18.9, p = 0.04) and low BMI (HR = 2.51, 95% CI = 1.438–4.40, p = 0.001) was independently linked to a higher risk of developing IH within two years after RARP.

The Kaplan–Meier analysis illustrated the IH-free survival rates within two years for patients with and without peritoneal closure (Figure 1). The two-year IH-free survival rates were 96.5% in the peritoneal closure group and 89.2% in the no closure group (log-rank p = 0.012).

4. Discussion

IH after RARP is less common than complications such as urinary incontinence or erectile dysfunction. Nonetheless, it represents a significant postoperative issue, affecting a considerable number of patients. Preventing IH can reduce the need for further surgical interventions and improve patients’ overall well-being. This retrospective analysis revealed a notably reduced incidence of IH in patients who underwent peritoneal closure during RARP compared to those who did not.

Several factors and risk elements associated with IH after RARP have been identified [5,6]. IH notably occurs more frequently on the right side. Majima et al. [5] explained this finding as being due to the attachment of the sigmoid colon to the pelvic floor after RARP [6]. Similar to earlier research, this study identified a greater incidence of IH on the right side compared to the left. (p = 0.024). Furthermore, patients with a low BMI (<23 kg/m²) were found to have a significantly higher incidence of postoperative IH in our cohort. This may be attributed to reduced subcutaneous fat and decreased abdominal wall muscle mass in individuals with lower BMI, which can result in diminished support for the myopectineal orifice and Hasselbach’s triangle [10]. Consequently, this anatomical weakness may facilitate the protrusion of abdominal contents and increase the likelihood of IH development. These findings are consistent with previous studies identifying low BMI as a significant risk factor for IH after radical prostatectomy. In our study, the univariate analysis showed a p value of 0.002, and the multivariate analysis showed a p value of 0.001 (Table 2).

RARP involves the anatomical repositioning of the bladder and surrounding structures, affecting the internal inguinal ring (IIR), which functions similarly to an inguinal sphincter [13]. Adhesive inflammation resulting from RARP can lead to sphincteric insufficiency and herniation of the inguinal canal. Peritoneal closure may help to maintain the bladder in its original anatomical position by reducing factors that could lead to displacement [14]. Previous research has suggested that peritoneal closure prevents the opening of the IIR by distributing tension uniformly across the peritoneal layers surrounding the IIR [2,15]. This method is believed to specifically reduce tension in the IIR, spreading it across the entire suture line. We hypothesize that restoring the peritoneum to its state prior to incision will prevent the descent of the intestinal tract through the hernia orifice.

This study compared the two-year incidence of IH after RARP between the peritoneal closure and no peritoneal closure groups, using multivariate analysis to evaluate the effectiveness of peritoneal closure. The analysis showed a significantly higher incidence of IH in the no peritoneal closure group, highlighting the protective effect of peritoneal closure. To further validate our findings, we performed a subgroup analysis focusing only on patients who did not undergo PLND, since peritoneal closure was not performed in PLND cases. Even within this more homogeneous group, the incidence of IH was significantly lower in the peritoneal closure group (3.6%) compared to the no closure group (10.7%) (p = 0.010), supporting the protective effect of peritoneal closure.

Peritoneal closure not only repositions the bladder and prevents the opening of the IIR but it may also reduce the risk of urinary leakage into the intra-abdominal space.

Various strategies have been explored to lower the incidence of IH following RARP. Among these, peritoneal closure has gained attention for its potential to reduce IH risk. Unlike approaches that combine multiple techniques, this study focuses on evaluating peritoneal closure as a standalone method. This approach aims to provide a simpler and more efficient option that can be easily incorporated into routine surgical practice.

This study has several limitations. Firstly, it is a retrospective analysis performed at a single institution. Since the data on IH occurrence was extracted from medical records, there is a possibility that some cases of IH were not identified. Second, peritoneal closure has only recently been introduced, resulting in a shorter observation period compared to previous studies; further long-term follow-up is needed. Third, in patients of bilateral occurrence, it is not known which side occurred IH first at the time of diagnosis. Fourth, postoperative IH was diagnosed based on physical examination by experienced urologists, without the routine use of imaging studies. This approach may have led to underdiagnosis, particularly in obese patients. Future studies should consider incorporating imaging modalities such as ultrasonography or CT to enhance diagnostic accuracy. Finally, variations in surgeon experience may have influenced surgical outcomes, as the procedures were performed by both senior surgeons and residents under supervision. This potential bias should be considered when interpreting the results.

This study suggests that peritoneal closure during RARP may reduce the incidence of postoperative inguinal hernia. While these findings indicate the potential benefit of this simple technique as a preventive measure, the retrospective nature of the study and potential selection biases limit definitive conclusions. Further prospective, randomized studies are warranted to confirm the efficacy of peritoneal closure in reducing the risk of postoperative IH and to clarify its role in surgical practice.

5. Conclusions

This retrospective study suggests that peritoneal closure during robot-assisted radical prostatectomy may reduce the incidence of postoperative inguinal hernia. Although these findings are promising, the limitations of this study, including its retrospective design and potential selection bias, should be taken into account.

Future prospective randomized studies with larger and more diverse patient populations are needed to confirm the preventive effect of peritoneal closure on postoperative inguinal hernia. In addition, long-term follow-up will be important to evaluate the durability and safety of this approach.