Can the procedure for prolapsing hemorrhoids (PPH) be done twice? Results of a porcine model

Background: The procedure for prolapsing hemorrhoids (PPH) is a new surgical method for the treatment of symptomatic hemorrhoids. In cases of recurrent prolapse, the performance of a second PPH may result in a ring of mucosa and submucosa between the two circular staple lines. In this study, we used a porcine model to assess whether PPH can be safely performed twice. Methods: Five adult pigs underwent two PPH procedures in one session, leaving a ring of ∼1 cm of mucosa between the two staple lines. One month later, the pigs were examined under anesthesia. The anal canal was assessed using the following four methods: (a) clinical examination, (b) evaluation of mucosal blood perfusion at different levels of the anal canal via a laser Doppler flow detector, (c) measurement of concentrations of hydroxyproline and collagen to check for fibrosis, and (d) histopathological examination. Results: At the completion of the study period, all five pigs showed no clinical evidence of anorectal dysfunction. On examination under anesthesia 1 month after surgery, there was no evidence of anal stenosis in any of the pigs. The mean mucosal blood flow between the two staple lines did not differ significantly from the flow measured proximally and distally (394 vs 363 and 339 flow units, respectively; p = NS). The collagen levels, based on hydroxyproline concentration, were 81 mcg/ mg between the staple lines, compared to 82 and 79 proximally and distally, respectively (p = NS). There was no significant difference in degree of fibrosis, as assessed histopathologically, between specimens taken from the ring between the staple lines and specimens taken from the area external to the staple lines. Conclusions: The results of this porcine model suggest that a second synchronous PPH is feasible. A controlled experience involving human subjects is required to determine the safety and usefulness of this technique in cases of metachronous application for recurrent or residual hemorrhoids.