Current Urology Reports Journal last June published a review article about the use of biological grafts in Pelvic Organ Prolapse (POP) repair. The authors present specific information on the repair of the different compartments’ prolapses (anterior, middle and posterior) as well as information on complications associated with these procedures. The present article summarizes the information presented in the Current Urology Reports Journal review article.
Defective pelvic floor support causes a downward movement of the pelvic organs, which result in protrusion of the cervix, this condition is called pelvic organ prolapse (POP). There are several factors that could lead to POP including a genetic predisposition, advanced age, increase number of times the patient has given birth (parity), estrogen deficiency, compromised pelvic floor muscle strength and smoking. According to the authors, by the age of 80, 11% of women would require surgery for POP and there is 30% of recurrence after treatment. Patients with the following characteristics have a higher probability of surgical failure: age; parity; smoking; poor tissue quality; state of their immune system and other conditions that could stress the repaired area, such as constipation or chronic cough. In order to improve surgical results of POP repairs, biologic grafts and synthetic meshes were implemented. According to this review, synthetic meshes can present several complications like mesh erosion; while biological grafts have the advantage of being histologically similar to the recipient tissue and also the ability of remodeling tissue in vivo. Furthermore, when compared to methods that do not use implants, the use of biological grafts may decrease the recurrence rate as the repairs will not depend on weakened native tissue for support.
Biological grafts can be classified as autologous or heterologous. Autologous grafts are harvested from the patient’s own body, and include tissues like vaginal epithelium (“lining” tissue) or fibrous tissue from the rectum (rectum fascia) or thighs (fascia lata). These grafts incorporate well into the native tissue and do not present any risk of rejection or disease transmission, however longer operation time is required and there might be complications at the site where the donor tissue was extracted (donor morbidity). Heterologous grafts can be subdivided into allografts and xenografts. Allografts are extracted from cadaveric human tissue, which eliminates the risks of donor morbidity. However, they present slight chances of disease transmission. Xenografts are derived from other species, principally bovine and porcine. Techniques to harvest heterologous grafts are standardized and include using aseptic techniques as well as screening for diseases like HIV and hepatitis and taking cultures while harvesting tissues. On the other hand, the processing methods before implantation are not standardized and there is no consensus on which of the different processing techniques is the most effective.
The most common form of POP is the anterior compartment prolapse, which involves the protrusion of the bladder and/or urethra. Data presented in this review to analyze the success of biological grafts on repairing the anterior compartment shows inconclusive results and the authors suggested that more studies need to be done in order to better investigate this issue. From the available data, PelvicolTM seems to be the most promising of the biological grafts. Middle compartment prolapse takes place at the vaginal apex and may involve different organs including the uterus, vaginal vault, bowel, rectum or bladder. Several techniques may be used to repair these defects. Biological and synthetic grafts have been used in transvaginal and abdominal repairs and the anatomic outcomes of using biological grafts were inferior to using synthetic meshes. More data is also necessary to further investigate the outcomes of these techniques. Posterior compartment prolapse involves the formation of rectoceles (herniation of the anterior rectal into the vagina) and it could present symptoms like constipation and sexual dysfunction. Traditional repair techniques have a high success rate but also present high rates of dyspareunia (painful sexual intercourse). Some studies attempted to assess the use of biological grafts in the rectocele repairs, although the authors did not find enough data to show their benefits.
Complications associated with the use of biological grafts in POP repairs include graft erosions, which usually do not require surgery for repair and seem to be less morbid than the synthetic mesh erosions. But again, studies have not confirmed the superiority of biological grafts over synthetic meshes with respect to decreased complication rates. In July 2011 the U.S. Food and Drug Administration released an update of a previous warning on the serious complications associated with transvaginal placement of surgical mesh to repair POP, which included all porous absorbable and nonabsorbable synthetic material or absorbable biological material. The FDA claims to not have found enough evidence to prove that the use of mesh in POP repairs has better outcome than traditional methods; besides, it may expose patients to higher complication risks. FDA recommendations included better postoperative patient monitoring and changes in the pre-market approval application processes.
Reference
Evaluation of Current Biological Meshes in Pelvic Organ Prolapse Repair. Ashley Cox and Sender Herschorn. Current Urology Reports. 2012. 13:247-255