Our data showed that: (1) 7.1% (53/751) of patients developed PIH after RRP, LRP or RALP treatment and 83.0% (44/53) of them occurred in the first 2 years. (2) Right indirect inguinal hernia was the dominant type which developed in 34 of all 53 (64.2%) patients. (3) RRP and senior age were prone to promote the formation of PIH and advanced preoperative clinical T-stage, however, was the protective factors for PIH which needs further consolidation.
Hernia compromise the quality of life for the common morbidity such as pain, intestinal dysfunction, ischemia of the hernia contents and may even lead to the incarcerated or strangulated hernia which require surgery in emergency. Nearly 9% patients with inguinal hernia require urgent surgery[16].Additionally, a bowel resection will be inevitable in 15% of incarcerated hernias.[17].Consequently, PIH should be deemed as a complication we could not neglect. Takashige Abe et al.[7] reported a PIH incidence with 17% and 14% after RRP and LRP compared with 1.4% in radiotherapy group. Lee et al found an inguinal hernia rate of 3.4% after RALP in a 1026-cases review[18]. Our data is consistent with previous literatures. The present data demonstrated that the incidence of PIH in RRP group was much higher than in both LRP and RALP groups. The length of low midline incision was recognized as a risk factor for occurrence of PIH in 2008[19].We, therefore, attributed this results to the advantages of minimally invasive technique (LRP or RALP) for making five to six 8-12mm trocar incisions instead of one 10-12cm incision in RRP presumptively.
The precise mechanism of PIH occurrence remains obscure; many antecedent conjectures had been discussed. The dissection of retropubic (Retzius) space is ineluctable during prostatectomy in all technique, Nomura suggested that transversalis fascia, posterior layer of the rectus sheath and subjacent endopelvic fascia, in where the weakest part of posterior inguinal wall locate, are damaged during retropubic exposure. Additionally, stretching of Hesselbach’s ligament results in loosening the strength of internal ring and the formation of PIH[20]. Since the invention of laparoscopic and robotic assisted technique, it rapidly took place of RRP and become the most prevalent prostatectomy option, which provides surgeons with a wider vivid 3D view of operative area, magnified anatomy of pelvis, flexible arm allowing them to achieve exposure with less damage and dissection to the tissues and vessels. Compared to traditional RRP methods, maximum conservation of the physiological construction of the Retzius space and less alteration of myopectineal orifice action were gained owing to accurate controllability of minimally invasive instruments [21]. Eventually, we prefer LRP and RALP regarding its better oncological and complication outcomes [23].
The causative reason for PIH is multifactorial. So far, only one meta-analysis had been published, in which the increasing age, low body mass index, subclinical inguinal hernia, previous inguinal hernia repair and anastomotic stricture were recognized to be predisposed to higher incidence of PIH[24].However, only the senior age was identified as a risk factor to PIH occurrence. Similar to the general population[25], the risk of PIH increases with age as well. Admittedly, aging and regression of the muscles and connective tissues around deep inguinal ring moderate supportive strain of abdominal wall. To our surprise, advanced clinical T-stage appeared to be the protective factor for PIH development. We suggested that it is probably related to older age in T1/T2/T3 patient, 69.04±6.41 compared to 67.06±6.94 in T4 patients(P=0.009).We perceived that longer operative time would let everlasting insufflation pressure cause more damage to transversalis fascia, but no significant relation was observed.
Our data also showed a dominance of right-side hernia after prostatectomy, more than half (69.8%) of patients with PIH on right groin. The same result was found by other investigator likewise [3, 26]. It was hypothesized that the adherence of sigmoid colon and pelvic floor near to left internal ring protect celiac contents from herniating[27].
The best way to prevent PIH after prostatectomy remains debatable. Hori et al. bluntly detached peritoneum at the internal ring so as to isolate spermatic cord, merely 3% of RRP patients in prevented group developed PIH compared to 19% in non-prevented group[28]. Another effective procedure, opening the spermatic sheath and releasing approximately 5 cm bilateral vas deferens and spermatic vessels from the peritoneum, resulted in 0.87% PIH rate in prevented group while 15.7% non-prevented patients suffered from PIH, was introduced by Koike in 2013[29]. The conceivable principle of these manipulations was that the scar tissues formed by isolating the spermatic cord could easily help to strengthen the internal ring. All these techniques should be viewed as valuable adjuncts for high-risk patients in need of prostatectomy.
Our study had several limitations that should be addressed. The number of patients per groups was not homogenously divided as this was a retrospective study with results based on database and medical records. Moreover, imaging examination was not applied for every prostatectomy patient, the asymptomatic PIH may not be detected, so the true incidence rate of PIH should be higher. Besides, as a potential risk factor, prostate volume information was incomplete to take further statistical analysis. Lastly, RALP technique was introduced to our centre for merely 2 years, case number was not as many as LRP group, long-term investigation will be necessary in the future.