Autoaugmentation peritoneocystoplasty in a sheep model

OBJECTIVE

To report our experience with autoaugmentation peritoneocystoplasty (AAPC) in a sheep model, and to compare the results with autoaugmentation gastrocystoplasty (AAGC) in a sheep model and in paediatric patients.

MATERIALS AND METHODS

Ten 6-month-old male lambs underwent bladder augmentation by detrusorotomy. A flap of parietal peritoneum, dissected from the anterior abdominal wall, was used to cover the bladder mucosa. The sheep were evaluated by urodynamics 6 months after surgery. Bladder compliance (bladder volume/intravesical pressure) was calculated for the bladder capacity at leakage. The urodynamic results were compared with age-matched control sheep and with 12 sheep that had undergone AAGC; the results were assessed using the Mann-Whitney U-test.

RESULTS

In two of the 10 sheep, bladder volumes after AAPC increased by > 100%, although for the group, the mean (range) bladder volume after augmentation, at 159 (42-261) mL, was not significantly different from that before surgery (mean 143 mL). Bladder volumes after AAPC were not significantly different from those in the control sheep (mean 205 mL) but were significantly less than in the AAGC group (mean 317 mL; P < 0.05). Bladder compliance at leak capacity in the AAPC group (mean 5.4 mL/cmH2O) was also not significantly different from the controls (mean 9.1 mL/cmH2O), but was lower than the in the AAGC animals (median 14.6 mL/cmH2O; P < 0.05).

CONCLUSIONS

AAPC in a sheep model does not result in a reliable increase in bladder volume or compliance. The volume and compliance are inferior to those found in bladders augmented by AAGC.

Reconstruction of the portal vein using a peritoneal patch-graft

BACKGROUND

Reconstruction of the portal vein with autologous veins requires extra incisions. Prosthetic material is associated with an increased risk of infection. We therefore created an animal model of portal vein reconstruction using the peritoneum.

METHODS

A 2.5 x 2.5 cm piece of the peritoneum was resected from Landrace pigs weighing 30 to 40 kg and was dipped in 100% alcohol for 10 minutes. The anterior wall of the portal vein measuring 1.2 x 0.6 cm was resected. The peritoneal patch-graft fitting the defect of the portal vein was used to repair it.

RESULTS

All 7 pigs survived the surgery, and were killed at 2, 7, 7, 14, 21, 35 and 49 days, respectively, after surgery. There was no evidence of thrombosis or obstruction of the reconstructed portal vein or any other complications. Complete endothelialization of the patches were noted at day 14.

CONCLUSIONS

Our patch-graft technique using the peritoneum is considered to be a good and safe alternative for reconstruction after partial resection of the portal vein in clinical surgery.

Free peritoneal grafts for patch urethroplasty in male rabbits

PURPOSE

We evaluated the feasibility of urethroplasty using a free peritoneal graft in a rabbit model.

MATERIALS AND METHODS

In 12 male rabbits a urethral defect was created by excising a 3 x 5 mm. portion of the ventral urethral surface. The defect was immediately repaired with a free peritoneal graft harvested via a left flank incision.

RESULTS

There were 2 intraoperative deaths and 1 death on day 8 postoperatively. These animals were excluded from study. The remaining 1, 4 and 4 rabbits were sacrificed 3, 5 and 9 weeks after surgery, respectively. Macroscopic examination of the urethra revealed no stenosis or diverticula, while a fistula was present in 3 of the 9 animals. Histological study of the fistulous tracts showed chronic granulomatous inflammation. In the remaining 6 rabbits there was graft adherence. The inner surface of the graft was uniformly lined with normal urothelium, while in some cases acute inflammatory cells were present in the subepithelial layer.

CONCLUSIONS

Our experience indicates that the ease of harvesting free peritoneal grafts and their satisfactory adherence to the urethra makes them a valid alternative for repairing urethral defects.

Animal experimental study on surgical repair of hypospadias by free peritoneal graft

Surgical repair of hypospadias was successfully performed by using free peritoneal graft in the model of rabbit hypospadias. The results showed that free peritoneal graft used as a substitute for urathra had a high survival rate, and the canal was formed well. Our study demonstrated that peritoneum could be used for the surgical repair of hypospadias and other urethral disorders such as urethral stricture.

Reconstruction of the vena cava with the peritoneum

BACKGROUND

Reconstruction of the vena cava with an autologous vein requires extra incisions. Prosthetic material is associated with an increased risk of infection. We therefore created an animal model of vena cava reconstruction using the peritoneum.

METHODS

A 2.5 x 2.5 cm piece of peritoneum was resected from 7 pigs weighing 30 to 40 kg. An oval window (long axis: 1.5 cm) was made in the infrarenal vena cava. This was repaired with the peritoneal patch fixed in alcohol.

RESULTS

In 2 animals sacrificed at 5 hours, there was no evidence of thrombosis, but there was fibrin clot on the patches. Two animals sacrificed on day 8 exhibited excellent patency of the vena cava. Complete endothelialization of the patch was noted at day 15. At 6 weeks, the vena cava was healed. No infections or other problems were noted.

CONCLUSIONS

The peritoneum is an accessible and safe substitute for reconstruction of the vena cava.

Organogenesis and tissue regeneration of fallopian tube: a desired metaplastic transformation of mesodermal stem cells in live animal models (dogs)

The capacity of stem cells of peritonium of mesodermal origin to undergo metaplastic transformation and form different tissues developed from mesoderm germ layer is exploited with ulterior motive to use it in the management of human diseases. The excised fallopian tube was replaced with a tube on a stent constructed from autogenous peritoneum from a suitable donor site. The effect of the surroundings environment of the new tissue system to which the peritoneum stem cells are now exposed was studied for 3, 6 and 12 months period in live animal models. The gross and histological studies revealed development of all the component of the wall of the fallopian tube. The lumen of the constructed peritoneal tube was well preserved in its whole length including the anastomotic sites. The scientific rationale of the working hypothesis on which the work is based, is discussed.

[The peritoneal autoplasty of the hernial hili in patients with large strangulated recurrent inguinal-scrotal hernias]

A new method of operative treatment of incarcerated recurring great inguinal-scrotal hernias is proposed with the help of plasty of the posterior wall of the inguinal canal with cicatricial changes to the tissues of the hernial sac. This method was used in operations on 56 patients aged 45-80 years. There were no postoperative recurrences of the disease or lethal outcomes.

Bladder augmentation with urothelial preservation

PURPOSE

Bladder reconstruction is performed because the characteristic properties of a healthy bladder are no longer present. The bladder manifests poor capacity, poor compliance and potential or actual changes in the upper tracts that may lead to damage. Augmentation procedures provide a means to improve capacity and compliance, and they may be performed with catheterizable channels to facilitate bladder emptying. Natural tissues or synthetic materials may be used but urothelial preservation is desirable. Demucosalized augmentation with a gastric flap and auto-augmentation with peritoneum are techniques that have been used in the last 5 years.

MATERIALS AND METHODS

We retrospectively evaluated the records of 13 patients who underwent demucosalized augmentation with a gastric flap and 8 who underwent augmentation with peritoneum from 1992 to 1995. Average age of the 11 girls and 10 boys was 8 years (range 6 to 12). The diagnosis was myelomeningocele in 15 patients, exstrophy in 2, and the VATER association, posterior urethral valves, spinal cord injury and nonneurogenic neurogenic bladder in 1 each. Concurrent procedures included appendicovesicostomy creation, a fascial sling or wrap and ureteroneocystostomy.

RESULTS

Mean followup is 50 months for patients who underwent demucosalized augmentation with a gastric flap and 47 for those who underwent augmentation with peritoneum. Outcome was defined as good-dry for 4 hours, catheterization without difficulty and a stable upper tract; poor-a secondary procedure (augmentation) required because the initial procedure did not improve bladder capacity, compliance, continence or the degree ofhydronephrosis, and fair-dry for less than 4 hours, some problems with incontinence, or compliance 10 ml/cm water or less. Of the patients who underwent demucosalized augmentation with a gastric flap the outcome was good in 5, fair in 4 and poor in 4 who required repeat augmentation. Of the 8 patients who underwent auto-augmentation with peritoneum the outcome was good in 5 and poor in 2, and 1 was lost to followup.

CONCLUSIONS

Augmentation with urothelial preservation may result in a good capacity, compliant bladder in certain patients but a poorly compliant, small capacity bladder in others. Our overall results underscore the lack of understanding of the properties and characteristics of these bladders and of stromal-epithelial interaction that occurs after augmentation. Such an understanding is critical before this procedure can be recommended routinely.

Regeneration of abdominal wall aponeurosis: new dimension in Marlex peritoneal sandwich repair of incisional hernia

Loss of abdominal wall substance is a major cause of incisional hernia formation. It makes repair of this iatrogenic human ailment a difficult surgical problem. The abdominal wall substance loss has compelled the world's surgical community dealing with this condition to substantiate the repair with extra material such as skin, fascia, wire mesh, and lately biocompatible synthetic mesh. Even though the synthetic mesh is compatible and well tolerated by body tissues, it is not without complications. Regenerative repair in the region of the abdominal wall with substance loss is probably the best repair if it can be achieved. With reasonable success in animal experiments and the positive regenerative capacity of stem cells to transform the peritoneum into an aponeurotic layer, the new technique using a Marlex peritoneal sandwich for repair of large incisional hernias was attempted but was not reported in the article published in the World Journal of Surgery in 1991. The present study is based on experiments on seven mongrel dogs. A suitable embryonal segment of autogenous peritoneum was excised and transferred to the rectus sheath region. The gross appearance of the grafted membrane 3 months after operation revealed tough, thick tissue formation. The histology confirmed the presence of collagen fiber tissue in layers similar to the aponeurosis in the grafted peritoneal membrane. The use of this regeneration in the Marlex peritoneal sandwich technique of repair of large incisional hernias and the scientific rationale of tissue regeneration by desired metaplasia is discussed.

Inferior vena caval resection with autogenous peritoneo-fascial patch graft caval repair: a new technique

BACKGROUND

In the course of oncological surgery, resection of the inferior vena cava (IVC) may be required to obtain an adequate resection margin and to offer the best opportunity of cure. The remaining defect in the IVC may be managed by: (i) primary repair which may lead to subsequent narrowing of the lumen, possibly leading to turbulent flow and thrombus formation; (ii) patch grafting of the defect, which may prevent narrowing. Several synthetic and biosynthetic materials are available as patch grafts and autologous pericardium has also been used.

METHODS

The harvesting and use of the autogenous peritoneo-fascial (APF) graft as an alternative caval patch graft material in the management of defects in the caval wall is proposed. Autogenous peritoneo-fascial caval patch graft repair in six patients was undertaken.

RESULTS

One patient with leiomyosarcoma secondaries in the liver eventually succumbed to the disease. The other five patients are clinically well with no evidence of IVC obstruction or venous aneurysms.

CONCLUSION

Preliminary results show that this new technique of utilizing an APF patch graft for caval repair is clinically a suitable alternative to current biosynthetic and synthetic materials and may in fact be superior in many aspects.

[Study on the replacement of the portal vein of pig with autogeneous-peritoneal tube]

OBJECTIVE

To investigate the possibility of applying autogeneous peritoneal tube in the portal vein reconstruction.

METHODS

Twenty-seven small healthy domestic pigs were used. A section of portal vein about 2.5-3.0 cm long was resected and replaced by autogenous peritoneum tube (APT), autogenous vein and decron artificial blood vessel respectively. Patency and pathological changes of the APT grafts were investigated after the replacement.

RESULTS

Twenty-four animals survived the operation. In the early stage of replacement, the APTs were dilated slightly, the cannual patency rate (CPR) was 12/13(92.3%). 3 months later, the fibrous hypertrophy and thickness were observed. The CPR was 8/10(80%). 2 more months later, the CPR was 4/6(66.7%), which was quite similar to that reconstructed by autogeneous vein. All three pigs which were replaced by decron blood vessel were dead within three to five hours after operation because of portal thrombi found by autopsy. After 12 weeks of replacement, scanning electron microscopy revealed that APT grafts were covered with a layer of endothelial-like cells. Endothelial cells and mesothelial cells were seen under transmitted electronic microscopy.

CONCLUSIONS

The long-term patency of the APTs were slightly lower than that of the autogenous vein, peritoneum might be a perspective self-material for portal vein reconstruction and worth further studying.

Fascioperitoneal graft with T-tube drainage for patching bile duct defects

Reconstruction of choledochal wall defects in an experimental dog model by T-tube plus fascioperitoneal graft and an evaluation of the short-term results were the aims of this study. Twelve randomly selected mongrel dogs of both sexes, having an average weight of 22.15 +/- 1.85 kg, were anaesthetized with ketamine HCI and xylazine and underwent laparatomy. The front wall of choledoch canal were excised with its all layers 0.5 cm in diameter at the distal part of the cystic duct junctions. These defects were repaired by using grafts prepared of the same diameter from the dorsal fascias of rectus muscles and peritoneum. T-tubes were introduced into the common ducts on the proximal part of the grafts. One of the animals died in the postoperative period due to evantration. T-tube cholangiograms on the twelfth day did not indicate any extravasation or stricture. Histopathological examination of the graft regions on the sixtieth day revealed that the epithelialization had commenced on the border between the bile epithelium and grafts. Based on these early findings, it was suggested that if supported by further studies it may be thought of as a clinical method.

Adhesion formation of the parietal and visceral peritoneum: an explanation for the controversy on the use of autologous and alloplastic barriers?

OBJECTIVE

To compare formation of adhesions after injury to both parietal and visceral peritoneum and to determine the benefit of autologous transplants and alloplastic barriers in adhesion prevention.

DESIGN

Experimental prospective animal study and prospective randomized clinical study.

SETTING

An academic research environment.

PATIENT(S)

Forty women undergoing laparoscopy for endometriosis treatment.

INTERVENTION(S)

In 60 rats, either the visceral or parietal peritoneum was injured and covered with autologous peritoneal transplants in half of the animals. The formation of adhesions was assessed 21 days postoperatively. In women, adhesions were evaluated 3 months after surgery with or without placement of alloplastic barriers on visceral lesions.

MAIN OUTCOME MEASURE(S)

Adhesions evaluated according to a scoring system.

RESULT(S)

Adhesions after injury of the visceral peritoneum in rats were significantly more severe than those from the parietal peritoneum. Autologous peritoneal transplants led to fewer adhesions especially after serosal injuries. Female volunteers treated with alloplastic barrier material showed less severe adhesions than the control group.

CONCLUSION(S)

The present data indicate that the potential to form adhesions is significantly higher in visceral than in parietal peritoneal lesions. The development of adhesions after injury to the visceral peritoneum could be reduced by a synthetic barrier material.

A new biologic membrane in cardiovascular surgery

Reconstruction techniques for major vessels and intracardiac defect repair use synthetic grafts or autogenic pericardium. Here, autologous abdominal parietal peritoneum with the overlying posterior rectus sheath as a biologic membrane are evaluated. Twelve adult canines were used. Via a midline subumbilical incision, the parietal peritoneum and overlying posterior rectus sheath were harvested. In the first group of six, the membrane was used to repair the right ventricular infundibulum and perform pulmonary artery annuloplasty. In the second group of six, under cardiopulmonary bypass and moderate hypothermia, the right atrium was opened and a secundum type defect was created. Autopsies performed 90 days after surgery revealed mild intrapericardial adhesions and moderate pericardial reaction over the cardiotomy incisions. The right ventricular outflow tract patch was nonaneurysmal. The interatrial patch was intact without thrombi. Histologic examination revealed intact membrane morphology, fibroblasts, smooth muscle cells, and endothelialization. Proline C14 uptake and autoradiography detected cellular viability of implanted membranes. These findings suggest that the peritoneum with overlying sheath repaired vascular and intracardiac defects and substituted for pericardium. Future studies are needed before clinical use.

Protection of intestinal anastomoses in septic environment with peritoneal graft and polyglycolic acid mesh: an experimental study

We carried out an experimental study in dogs to evaluate the outcome of large bowel anastomosis with 6 stitches (Group C, n : 6) in a septic environment with protection by a polyglycolic acid (PGA) mesh (Group M, n : 12) or peritoneal graft (Group P, n : 12). Thirty dogs were used to compare the techniques. Two dogs in each group were re-operated after 3, 5, 7, 14, 28 and 90 days. They were evaluated for adhesion formation, lumen diameter (anastomotic index), clinical features, histologic appearance and quality of healing at the anastomotic sites. All dogs in group P and group M survived, whereas 2 dogs in the control group died of anastomotic leakage and 3 dogs were re-operated for anastomotic leakage and peritonitis. In group M, one dog was reoperated because of the anastomotic leakage and two dogs were reoperated because of the anastomotic stenosis. Also, 4 anastomoses showed evidence of moderate stenosis. In group P, three anastomoses were graded as minimal stenosis. Histopathologic evaluation showed more complete epithelization, less inflammation, and less adhesion in group P than group M. We could not find any study in the literature that described and compared both techniques. We report here the results of such a study.

Formation of neoureter from peritoneum in live animal model (dog)

Regeneration of ureter in vivo is possible from peritoneal stem cells as both are derivative of embryonal germ layer mesoderm. The peritoneal stem cells are engaged in repair of loss due to normal wear and tear by differentiation and proliferation. With pluripotent nature, they have a capacity to undergo metaplastic transformation to various mesodermal tissues. The intrinsic cell factor along with regional tissue organisers coupled with functional need of the region, a desired metaplastic transformation to ureteric wall components is possible.

Reconstruction of the flexor tendon sheath. An experimental study in rabbits

The role of the tendon sheath in flexor tendon healing was investigated in rabbits. Tendon sheath was reconstructed with syngeneic parietal peritoneum or a non-tanned processed porcine collagen membrane. Resection of the tendon sheath led to adhesions. Reconstruction of the sheath with either graft resulted in a synovial-like lining, resembling a neo-tendon sheath. Even when combined with tendon repair a neo-tendon sheath was seen after reconstruction with both grafts, without adhesions. Subcutaneously implanted processed porcine collagen membrane was completely resorbed in less than 3 months.

Use of tubularized peritoneal free grafts as urethral substitutes in the rabbit

As an alternative to bladder mucosa, free grafts of tubularized peritoneum were used as urethral substitutes in a rabbit model of hypospadias. In group 1, six mature rabbits underwent partial penile urethrectomy followed by interposition of a 2-cm-long peritoneal-lined tube graft. These animals had urethrograms performed at 3 months and were killed at 6 (n = 4) or 12 (n = 2) months. In group 2, six rabbits underwent total penile urethrectomy with placement of 3-cm-long grafts. These animals were killed 1 to 4 weeks after surgery. Clinical assessment and gross examination of the 12 rabbits showed no urinary retention, two small fistulas at the proximal anastomosis, and no strictures or diverticular. At 6 and 12 months (group 1) the urethra had healed completely and the graft edges were not visible. In group 2, 1 to 4 weeks after surgery the graft was intact and the interface between the graft and native urethra was visible. Histological studies of the grafts were compared with control peritoneum. At 1 week, a high-density single-cell layer was present. Beginning at 2 weeks, a multilayered epithelium was present, which became more organized in the older grafts. Neovascularity became visible in the subepithelial layer at 2 weeks. Acute inflammatory cells were present early and were replaced by a palisading layer of lymphocytes and plasma cells in the older grafts. Minimal fibrosis was observed. Tubularized peritoneal free grafts are a promising new urethral substitute. Graft placement is technically simple. Replacement of the peritoneum by a multilayered epithelium resembling transitional epithelium occurs early after graft placement. As much as 1 year later, minimal scarring is present.

Results of modified laparoscopically assisted neovaginoplasty in 18 patients with congenital absence of vagina

Construction of a neovagina using pelvic peritoneum via a laparoscopically assisted approach was used in 18 patients with congenital absence of the vagina. A better operative procedure is reported, which was modified from our preliminary technique, and the results of treatment are evaluated. Pelvic peritoneum was used for construction of a vagina, replacing a laparotomy by a minimally invasive laparoscopic approach. During follow-up, the advantages of our procedures are: (i) minimal likelihood of 'poor take' or later contraction because an autograft peritoneal epithelial line is used; (ii) minimal short and long term care is required; (iii) the technique is simple in experienced hands and has all the well-recognized benefits of minimal invasive surgery; (iv) the average length of neovagina is adequate and patency and depth can be maintained with minimal dilatation; (v) the neovagina, with epithelial lining resembling that of a normal vagina, facilitates comfortable sexual intercourse; (vi) the procedure is unaccompanied by dyspareunia or scarring, which are frequently associated with other techniques; (vii) less emotional stress and better cosmetic and economic benefits are noted.

Experimental evaluation of peritoneum and pericardium as dural substitutes

Although many substances have been tested in the search for an ideal dural substitute, an entirely satisfactory material has still not been found. The authors report an experimental study involving the closure of dural defects in rabbits with biomaterials developed from pig peritoneum and pericardium. Macroscopic and histologic examination, performed over a period between 15 and 45 days after implantation showed slight or no adhesion between the graft material and the cortex. No infection, CSF leakage, fistula or toxicity was noticed. The results demonstrated that these biomaterials could be used as satisfactory dural substitutes.

Short phase efficacy of autologous peritoneum as a pericardial substitute

The risks associated with resternotomy are largely related to loss of pericardial integrity. No satisfactory substitute for pericardium has been identified. The structural similarity between pericardium and peritoneum prompted an assessment of the latter as a biologic substitute. Two peritoneal patches were harvested from four juvenile swine, which then underwent left thoracotomies. In each pig, two pericardial defects were created and repaired with fresh and glutaraldehyde treated autologous peritoneal patches. Three weeks post operatively, the chest and abdomen were re-explored and the patches evaluated. In all cases, extrapericardial adhesions were insignificant. On gross examination of the intrapericardial surfaces, the fresh patches appeared smooth and glistening, with neither degenerative changes nor adherence to the epicardium. The treated patches were easily separated from the epicardium in two cases, but the other two patches were moderately to severely adherent. Histologic examination demonstrated well preserved morphology in all patches. C proline uptake and autoradiography revealed preserved fibroblast viability in the fresh patches. Intra abdominally, in all cases, there was complete reperitonealization without adhesion formation. In conclusion, fresh autologous peritoneum performed well as a pericardial substitute after heart surgery.