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ARTICLE
Role of Synthetic Mesh Renorrhaphy and Neocapsule Reconstruction to Salvage Posttransplant Severely Damaged Renal Allografts

Objectives: As the recipient pool continues to rise, it is vital to conserve donor organs whenever possible. Injured renal allografts continue to be discarded for a variety of reasons, and salvaging potentially useable grafts is of utmost importance. Little information is available on outcomes of salvaged allografts. Here, we present an easily replicable technique to salvage damaged renal allografts using polyglactin mesh.

Materials and Methods: Polyglactin woven mesh was used to salvage 4 otherwise irreparably injured allografts. In the first case, unidentified extracorporeal shockwave lithotripsy-induced microfractures 2 months before procurement of a deceased-donor kidney led to significant capsular injury. In the second case, rapid recovery of a deceased-donor kidney limited evaluation, and severe capsular rupture was diagnosed after perfusion. In the third case, an anticoagulated pediatric recipient received a living related-donor kidney from his mother, and a biopsy-induced hematoma 2 months posttransplant led to severe capsular denudation. In the fourth case, a pumped kidney from a donor after cardiac death developed severe focal capsular denudation. In each case, a keyhole hilar-sparing incision was made in an industry-standard 12 × 12-inch polyglactin mesh sheet, which was then fitted and sutured in a vest-over-pants method to provide a scaffold for hemostasis and capsular healing. Topical hemostatic agents were added in the first and fourth cases. Patients were followed longitudinally.

Results: All allografts were successfully salvaged using our technique, and none developed Page kidney, hydronephrosis, urinoma, or hemorrhage. At last follow-up, recipient 1 had kidney loss 7 years postrepair secondary to chronic allograft nephropathy, recipient 2 was lost to follow-up at 1 year with normal renal function, and recipients 3 and 4 had normal renal function at years 3 and 7 posttransplant.

Conclusions: This simple technique using readily available materials can salvage allografts that would have been potentially explanted or discarded.


Key words : Kidney transplant, Renal allograft repair, Renal capsule injury

Introduction

As the demand for renal allografts continues to outpace supply, new and innovative techniques are necessary to salvage previously unusable donor organs. The increased use of expanded criteria donors to increase the donor pool has partially supplanted organ shortages; however, it has also increased the use of marginal renal allografts. Despite this, per United Network for Organ Sharing data, over 95 000 patients remain on transplant wait lists with approximately 20 000 kidney transplants performed in 2017.1

The use of marginal allografts has also increased risks of pretransplant, intratransplant, and post­transplant complications. One such complication, renal allograft denudation causing allograft loss due to spontaneous rupture, is a rare but serious entity, with a documented incidence of 0.5% to 4.5% in the most recent literature.2,3 Most spontaneous ruptures occur because of hyperacute and acute rejection episodes, whereas other causes include traumatic capsular denudation, acute tubular necrosis, and renal vein thrombosis.4 Review of the current literature has revealed case reports of successful salvage using direct suturing of the parenchyma, which is not always feasible in cases of total capsular loss or deep laceration and which can cause loss of parenchymal tissue due to suturing and ischemia from pressure apposition.

Here, we present our novel technique of vest-over-pants (VOP) synthetic mesh repair of renal allograft capsular injuries as an option to salvage otherwise irreparably damaged donor allografts. This technique does not involve direct parenchymal suturing, which minimizes the risk of parenchymal ischemia, and can be performed in vivo in the posttransplant setting, obviating the need for allograft explant. Using this technique, we were able to salvage 4 allografts damaged due to injuries identified in a postimplant setting. These injuries were either not identifiable during backbench surgery or occurred de novo posttransplant.

Materials and Methods

Patients
Between 2001 and 2016, 4 cases of allograft rupture and capsular injury in the posttransplant setting were successfully salvaged by a single surgeon using the VOP technique. The causes of rupture, presentations, repair techniques, and outcomes were tracked longitudinally and analyzed.

In the first case, extracorporeal shockwave litho­tripsy in the donor done 2 months before donation resulted in multiple microfractures, which went uniden­tified grossly on backbench surgery. The unidentified microfractures caused diffuse subca­psular bleeding immediately postperfusion, leading to multiple graft ruptures. A VOP mesh neocapsule was created, and the organ was successfully salvaged for transplant.

In the second case, the graft of note was procured as a rapid recovery protocol from a trauma victim, with only a single-phase computed tomography scan of the donor kidneys available before procurement. On backbench surgery, a small subcapsular hematoma was seen. After perfusion, expansion of a hematoma from an underlying, previously undocumented grade 3 parenchymal laceration was noted, resulting in graft rupture. The use of VOP mesh repair allowed successful transplant of the allograft.

In the third case, the recipient, who was receiving anticoagulants because of underlying hyperhomo­cysteinemia, MTHFR mutation, and elevated factor VIII, developed a skiving-injury-induced subcapsular hematoma after interventional radiology attempted to drain a suspected small, infected lymphocele 2 months posttransplant. This hematoma in turn caused new hydronephrosis, increased creatinine levels, and caused new-onset anemia, which necessitated multiple blood transfusions. Further expansion of the hematoma prompted surgical exploration. Intra­operatively, complete capsular denudation was discovered with laceration caused by the needle. In this case, a topical hemostatic agent was used in conjunction with the VOP mesh neocapsule due to the patient’s increased risk of bleeding as a result of anticoagulant therapy.

In the fourth case, an allograft procured from a donor after cardiac death was placed on a perfusion pump. At the time of backbench surgery, a 1-cm, clear subcapsular bleb was discovered and thought to be a simple perfusion fluid collection. This was left undisturbed. The recipient received heparin drip postoperatively because of the patient’s high risk of thrombophilia. On posttransplant day 1, a routine ultrasonographic scan showed a large, perigraft fluid collection resembling a hematoma; the patient also had decreased urine output. On reexploration, the area of the aforementioned bleb developed into a hematoma with focal capsular denudation and separation of the capsule from the rest of the kidney. The hematoma was drained, and VOP mesh repair with application of hemostatic agent led to successful salvage of the graft. Table 1 shows further information on the 4 patients.

Technique
For the VOP technique, first, the areas of graft rupture and decapsulation are carefully evaluated (Figure 1 and Figure 2). An industry-standard 12 × 12-inch polyglactin woven mesh for repair is then prepared by incising it vertically to approx­imately half its height at the midline starting from the inferior border. Next, the apex of this incision is cut out in a circular fashion to give it a keyhole configuration (step 1 in Figure 3). This allows the mesh to completely envelop the allograft without compromising the hilar structures. The mesh is then fitted from the medial aspect of the allograft, after sliding it under the allograft from the lateral aspect (step 2 in Figure 3; Figure 4). A hemostatic agent is applied next to any lacerations in the parenchyma (Figure 5). The 2 tails of mesh created by the keyhole midline incision are then wrapped around the concave surface of the graft to the convex surface laterally (step 3 in Figure 3). Importantly, care is taken to wrap the allograft snugly without constricting the parenchyma to avoid the risk of Page kidney development. The mesh is then closed at its lateral edges with a running, 0 polydioxanone suture in a VOP manner by starting from 1 pole to the other pole of the kidney (step 4 in Figure 3). This closure is then carried out to the poles by overlapping the 2 tails. The excess mesh is then cut to size so that the graft is now completely covered without any gaps. Although hemostatic agents were used in 2 cases in which the recipients were deemed to be of high risk because of coagulopathy, it is the experience of the authors that hemostatic agents are not necessary for hemostasis in appropriately selected individuals, where graft compression provided by the neocapsule is sufficient.

Results

The use of the VOP technique allowed all 4 allografts to be successfully salvaged. None of the patients developed repair-associated complications of parenchymal or collecting system compression, including Page kidney, hydronephrosis, urinoma, or hemorrhage. Ultrasonography after graft repair in 3 of 4 cases (those with documented follow-up) confirmed resolution of hematoma, with no evidence of hydronephrosis in any case. Two patients had allograft biopsies after graft repair through the neocapsule without associated difficulties or complications. To our knowledge, this is the first documented evidence of successful needle biopsy through a mesh neocapsule into a solid organ in the medical literature. At most recent follow-up, 1 patient had graft loss at 7 years after graft repair due to chronic allograft nephropathy. Another patient was lost to follow-up at 1 year, at which time normal renal function was shown. The remaining 2 patients showed normal renal function at 7 and 3 years posttransplant.

Discussion

Spontaneous renal allograft rupture is a rare but serious entity, with a documented incidence of between 0.5% and 4.5% in the most recent studies.2,3 Most spontaneous ruptures occur because of hyperacute and acute rejection episodes and because of acute tubular necrosis and vein thrombosis.4 In addition, trauma to the parenchyma that is not identifiable on external inspection (patients 1 and 2) or capsule (patients 3 and 4) can lead to graft loss due to expansion and rupture. In our series, we did not have any spontaneous ruptures due to rejection, but generic principles of the VOP technique may potentially lend themselves to usage in this scenario, as the compression provided is uniformly distributed over the whole parenchyma, obviating suture use to close the lacerations.

Despite its rarity, renal allograft rupture is a relatively well-documented clinicopathologic entity in modern literature. In a case review by McCausland and associates, 95 cases of spontaneous graft rupture were identified from 8558 patients accrued from various studies, with a listed incidence of 1.11%.5 None of the cases had nonrejection, trauma-mediated allograft injury as a primary cause of renal allograft rupture. Indeed, limited evidence exists in the current literature of traumatic renal allograft injuries. In most cases, blunt injuries to allografts result in subcapsular hematomas or small, easily controllable capsular defects, thus obviating the need for extensive capsular repairs.6-9 As such, we did not find any reports of trauma-induced extensive capsular repairs in the current medical literature. However, the use of synthetic mesh neocapsule to repair extensive native solid-organ injuries is well documented in the literature.

Delany and colleagues first documented the use of a synthetic mesh neocapsule in animal models as a novel technique to avoid splenectomy in otherwise nonsalvageable injuries.10 Further animal models demonstrated the efficacy of various mesh neocap­sular repair techniques in achieving hemostasis and providing scaffolding for capsule regeneration in extensive native renal injuries.11-13 In addition, animal studies further documented superiority of Vicryl mesh repairs without parenchymal sutures in maintaining renal function without the requisite tissue fibrosis and parenchymal atrophy associated with renorrhaphy techniques using parenchymal sutures.14 Chopin and associates first reported the use of polyglycolic acid mesh in humans for the treatment of ruptured renal allografts.15 In all 4 cases described in our study, mesh wrapping with added hemostatic agent achieved immediate hemostasis, and 3 of 4 grafts retained satisfactory function at 1-year follow-up. Since this first report,15 various techniques have been proposed with generally positive results, including omental, fascia lata, and human dura tissue patches, autologous tissue packing with bundling suture, and mesh capsules with purse-string and other suturing techniques.16,17 Despite these results, there have been no studies to our knowledge to support mesh neocapsule repair of traumatic injuries in the renal allograft. Therefore, our case series is also unique as it provides long-term outcomes of such repair and also the safety of performing an allograft biopsy through such neocapsules.

Nonrejection-mediated allograft capsular injuries may also be stratified based on the time interval after implantation, that is, those that occur immediately after perfusion and those that present in a delayed (posttransplant) setting. Once an immediate post­perfusion allograft capsular injury is discovered, there are generally 3 options for treatment depending on the severity of injury. These options are explant with subsequent backbench repair and reim­plantation, in situ repair, or explantation with loss of organ. In situ repair, as demonstrated in our series, is obviously preferable, as it avoids the morbidity and technical difficulties of explant-reimplant, as well as further damage to the graft via reperfusion injury and added ischemia time. This technique also prevents repeated vascular anastomosis and its associated complications. In the delayed setting, options generally include conservative management with close observation and medical management as well as the options listed above. In previous case reports of traumatic and transplant biopsy-induced injuries, hematomas have been treated conservatively, in some cases with variable results or treated operatively in cases of graft or life-threatening dysfunction. In our series, however, all injuries were deemed to be extensive enough to be graft threatening, and the extensive nature of capsular denudation in each case necessitated the deve­lopment of this novel approach to salvage the grafts.

Our series is unique in that in vivo documented traumatic injuries were successfully repaired with a hilar-sparing mesh neocapsule. The technique used (VOP imbrication) ensured a complete, snug fit over the graft without constriction of parenchyma. In addition, we documented the first successful biopsy through a mesh neocapsule in 2 cases without associated adverse effects to the grafts. These findings are of clinical significance given that there are currently no standardized methods for repair of damaged renal allografts in recipients.

There are no reports to our knowledge of repairs to posttransplant-recognized traumatic injuries of the allograft. In all 4 cases described in our report, traumatic injuries were graft threatening and were either not identified before postimplant unclamping or developed in the posttransplant setting. In addition, the grafts were successfully salvaged in all cases without the need for further ischemia via explant and backbench repair and showed good function without any identified long-term sequelae. In the 3 cases that had longer follow-up data, graft function was maintained without any evidence of hydronephrosis or Page kidney after repair.

Conclusions

In limited and highly selected cases, the VOP technique was safe and feasible for in situ repair using an off-the-shelf mesh. Use of this method can potentially salvage renal allografts that have been recognized as damaged in the posttransplant setting. Further studies are needed to further elucidate the effectiveness and other limitations of utilizing mesh repair to salvage damaged renal allografts.


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DOI : 10.6002/ect.2019.0308


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From the Department of Urology, The University of Toledo, Toledo, Ohio, USA
Acknowledgements: The authors have no financial conflicts of interest to report. There were no grants or financial support used in any way to fund this study.
Corresponding author: Damian Garcher, 3000 Arlington Ave, Mailstop 1091, Toledo, OH 43614, USA
Phone: +1 419 383 3505
E-mail: Damian.garcher@utoledo.edu