Diagnosis of pancreas rejection: cystoscopic transduodenal versus percutaneous computed tomography scan-guided biopsy

Indications, Techniques, and Barriers for Pancreas Transplant Biopsy: A Consensus Perspective From a Survey of US Centers

BACKGROUND

Pancreas transplant biopsy practices for the diagnosis of rejection or other pathologies are not well described.

METHODS

We conducted a survey of staff at US pancreas transplant programs (March 22, 2022, to August 22, 2022) to assess current program practices and perceptions about the utility and challenges in the performance and interpretation of pancreas allograft biopsies.

RESULTS

Respondents represented 65% (76/117) of active adult pancreas transplant programs, capturing 66% of recent pancreas transplant volume in the United States. Participants were most often nephrologists (52%), followed by surgeons (46%), and other staff (4%). Pancreas allograft biopsies were performed mostly by interventional radiologists (74%), followed by surgeons (11%), nephrologists (8%), and gastroenterologists (1%). Limitations in the radiologist's or biopsy performer's comfort level or expertise to safely perform a biopsy, or to obtain sufficient/adequate samples were the two most common challenges with pancreas transplant biopsies. Pancreas transplant biopsies were read by local pathologists at a majority (86%) of centers. Challenges reported with pancreas biopsy interpretation included poor reliability, lack of reporting of C4d staining, lack of reporting of rejection grading, and inconclusive interpretation of the biopsy. Staff at a third of responding programs (34%) stated that they rarely or never perform pancreas allograft biopsies and treat presumed rejection empirically.

CONCLUSIONS

This national survey identified significant variation in clinical practices related to pancreas allograft biopsies and potential barriers to pancreas transplant utilization across the United States. Consideration of strategies to improve program experience with percutaneous pancreas biopsy and to support optimal management of pancreas allograft rejection informed by histology is warranted.

Endoscopic visualization of graft status in patients with pancreas transplantation

BACKGROUND

Enteric drainage into the recipient duodenum in pancreas transplantation (PT) can identify the graft duodenum by endoscopy. This study aimed to identify the characteristic endoscopic findings associated with graft failure or acute rejection in patients with PT.

METHODS

We reviewed the medical records of patients who underwent PT with duodenoduodenostomy (DD) between January 2015 and August 2019. During this period, there were 44 PTs with DD in 42 patients; 122 endoscopies were performed and analyzed.

RESULTS

Overall, pancreatic graft survival was 82% at a mean follow-up of 27 months (range 6-55 months). There were 8 graft failures and 10 acute rejections. In all 8 graft failures, a deep ulcer covered with fibrinous exudates of the graft duodenum was confirmed on endoscopy. Diffuse erythema inside the graft duodenum was observed in 8 of 10 acute rejections. The factors associated with acute rejection were elevated serum lipase level (OR 8.5, p = 0.02) and diffuse erythema inside the graft duodenum on endoscopy (OR 20.5, p < 0.01) in multivariate analysis.

CONCLUSIONS

In PT with DD patients, graft failure can be visualized by endoscopy, and diffuse erythema inside the graft duodenum may be a finding of acute rejection.

Technical factors that minimize the occurrence of early graft failure in pancreas transplantation

Pancreatic transplantation is the only treatment for insulin-dependent diabetes resulting in long-term euglycemia without exogenous insulin. However, pancreatic transplantation has become debatable following the improvements in the results of islet transplantation and artificial pancreas. Therefore, surgeons who perform pancreas transplants require the best surgical technique that can minimize technical failure. We aimed to report our experiences with pancreatic transplantations. We transplanted 65 pancreatic grafts between 2015 and 2020. Except for one death due to hypoxic brain damage after surgery, no postoperative technical failure was observed. We usually perform duodeno-duodenal anastomosis using the transperitoneal approach, with retrocolic placement of the graft pancreas. There was no leakage from the duodenum even after immunologic graft failure. To prevent venous thrombosis, which is the most common cause of technical failure, we used the inferior vena cava for anastomosis and added graft venoplasty with a patch of donor vena cava or aortic interposition graft to the bench procedure; subsequently, there were no cases of technical failure due to thrombosis post-transplantation. Therefore, the 1-year graft survival (insulin-free) rate was more than 95%. The improving the surgical technique will maintain pancreatic transplantation as the best treatment for insulin-dependent diabetes. This article is protected by copyright. All rights reserved.

Graft dysfunction in simultaneous pancreas kidney transplantation (SPK): Results of concurrent kidney and pancreas allograft biopsies

Simultaneous pancreas and kidney transplants offer significant therapeutic advantages but present a diagnostic approach dilemma in the diagnosis of rejection. Because both organs are from the same donor, the kidney has been treated traditionally as the "sentinel" organ to biopsy, presumably representing the status of both allografts. Truly concurrent biopsy studies, however, are needed to confirm this hypothesis. We examined 101 concurrent biopsies from 70 patients with dysfunction in either or both organs. Results showed concurrent rejection in 23 of 57 (40%) of cases with rejection; 19 of 57 (33.5%) and 15 of 57 (26.5%) showed kidney or pancreas only rejection, respectively. The degree and type of rejection differed in the majority (13 of 23, 56.5%) of cases with concurrent rejection, with the pancreas more often showing higher rejection grade. Taking into account pancreas dysfunction, a positive kidney biopsy should correctly predict pancreas rejection in 86% of the instances. However, the lack of complete concordance between the 2 organs, the discrepancies in grade and type of rejection, and the tendency for higher rejection grades in concurrent or pancreas only rejections, all support the rationale for pancreas biopsies. The latter provide additional data on the overall status of the organ, as well as information on nonrejection-related pathologies.

Surgery of pancreas transplantation

PURPOSE OF REVIEW

The surgical techniques of pancreas transplantation have been evolving and significantly improved over time. This article discusses different current techniques and their modifications.

RECENT FINDING

At this time, the most commonly used technique is systemic venous drainage (for venous outflow) and enteric drainage (for management of exocrine pancreatic secretions). However, new modifications of established techniques such as gastric or duodenal exocrine drainage and venous drainage to the inferior vena cava continue to be introduced.

SUMMARY

This article provides a state-of the-art review of the most prevalent up-to-date surgical techniques as well as a synopsis of their specific risks and benefits. The article also provides the most current registry data regarding utilization of different surgical techniques in the United State and worldwide.

Laparoscopic Biopsies in Pancreas Transplantation

As there is no precise laboratory test or imaging study for detection of pancreas allograft rejection, there is increasing interest in obtaining pancreas tissue for diagnosis. Pancreas allograft biopsies are most commonly performed percutaneously, transcystoscopically, or endoscopically, yet pancreas transplant surgeons often lack the skills to perform these types of biopsies. We have performed 160 laparoscopic pancreas biopsies in 95 patients. There were 146 simultaneous kidney-pancreas biopsies and 14 pancreas-only biopsies due to pancreas alone, kidney loss, or extraperitoneal kidney. Biopsies were performed for graft dysfunction (89) or per protocol (71). In 13 cases, an additional laparoscopic procedure was performed at the same operation. The pancreas diagnostic tissue yield was 91.2%; however, the pancreas could not be visualized in eight cases (5%) and in 6 cases the tissue sample was nondiagnostic (3.8%). The kidney tissue yield was 98.6%. There were four patients with intraoperative complications requiring laparotomy (2.5%) with two additional postoperative complications. Half of all these complications were kidney related. There were no episodes of pancreatic enzyme leak and there were no graft losses related to the procedure. We conclude that laparoscopic kidney and pancreas allograft biopsies can be safely performed with very high tissue yields.

Diagnosis and Treatment of Pancreas Rejection

Despite significant improvement in pancreas allograft survival, rejection of the pancreas remains a major clinical problem. In addition to cellular rejection of the pancreas, antibody-mediated rejection of the pancreas is now a well-described entity. The 2011 Banff update established comprehensive guidelines for the diagnosis of acute and chronic AMR. The pancreas biopsy is critical in order to accurately diagnose and treat pancreas rejection. Other modes of monitoring pancreas rejection we feel are neither sensitive nor specific enough. In this review, we examine recent advances in the diagnosis and treatment of pancreas rejection as well as describe practical diagnostic and treatment algorithms.

Banff schema for grading pancreas allograft rejection: working proposal by a multi-disciplinary international consensus panel

Accurate diagnosis and grading of rejection and other pathological processes are of paramount importance to guide therapeutic interventions in patients with pancreas allograft dysfunction. A multi-disciplinary panel of pathologists, surgeons and nephrologists was convened for the purpose of developing a consensus document delineating the histopathological features for diagnosis and grading of rejection in pancreas transplant biopsies. Based on the available published data and the collective experience, criteria for the diagnosis of acute cell-mediated allograft rejection (ACMR) were established. Three severity grades (I/mild, II/moderate and III/severe) were defined based on lesions known to be more or less responsive to treatment and associated with better- or worse-graft outcomes, respectively. The features of chronic rejection/graft sclerosis were reassessed, and three histological stages were established. Tentative criteria for the diagnosis of antibody-mediated rejection were also characterized, in anticipation of future studies that ought to provide more information on this process. Criteria for needle core biopsy adequacy and guidelines for pathology reporting were also defined. The availability of a simple, reproducible, clinically relevant and internationally accepted schema for grading rejection should improve the level of diagnostic accuracy and facilitate communication between all parties involved in the care of pancreas transplant recipients.

Pancreas graft drainage in recipient duodenum: preliminary experience

Pancreas graft survival has continuously improved over the years to become a main treatment option of uncontrolled complicated diabetes. Rejection remains the major challenge as it often goes unnoticed until severe damage of the graft manifests itself by elevated blood sugar. Pancreas enzymes monitoring in the blood and in the urine is a sensitive marker of rejection but lack of specificity. Biopsy remains the gold standard. Cystoscopy-guided biopsy of bladder-drained pancreas has a good success rate for obtaining tissue but the vesical drainage exposes to metabolic and urologic morbidity. Percutaneous pancreas biopsy can be performed with a low morbidity rate but severe complications can occur. We discuss a technique of pancreas transplantation with the drainage of exocrine secretions of the pancreatic graft in the recipient duodenum, which permits easy monitoring of the graft by upper endoscopy of the duodenum.

Pancreas and islet cell transplantation

Transplantation of the pancreas or islet cells constitutes surgical treatment for patients with type 1 diabetes mellitus. Pancreas transplantation is now an established procedure for the surgical treatment of diabetes mellitus. Islet cell transplantation has the potential to be the procedure of choice once it becomes more routine because of the minimal surgery involved. Included in this chapter are the pathophysiology of diabetes, rationale for transplantation, and the surgical procedure itself.

Interventional procedures in whole organ and islet cell pancreas transplantation

Pancreas organ transplantation has been a therapeutic option for the treatment of diabetes mellitus for over a decade. More recently, percutaneous injection of isolated pancreas islet cells via the portal vein has been developed as an exciting minimally invasive alternative procedure to whole organ transplantation, and one where the interventional radiologist may play a major role. This chapter reviews the role of image guided intervention in the whole organ pancreas transplant and describes the evolving technique of percutaneous islet cell transplantation.

Pancreas Transplants: Experience with 232 Percutaneous US-guided Biopsy Procedures in 88 Patients

PURPOSE

To retrospectively assess the authors' experience with percutaneous ultrasonographic (US)-guided biopsy of pancreas transplants.

MATERIALS AND METHODS

Data from 232 percutaneous US-guided pancreas transplant biopsies performed in 88 patients were retrospectively reviewed. Biopsies were typically performed on an outpatient basis by using local anesthesia. Considerations included the indication for the biopsy, the type of pancreas transplant, the number of needle passes, the size of the biopsy needle, the use of aspirin, and the success of the biopsy. Important complications were detailed.

RESULTS

Of the 232 biopsies performed, 78 were for clinically indicated reasons and 154 were for surveillance purposes. The number of biopsy procedures per patient ranged from one to nine (mean, 2.6). Two needle passes were performed in 196 (84.5%) of the biopsy procedures. Almost all biopsies (ie, 228 [98.3%]) were performed by using an 18-gauge biopsy device. Adequate pancreatic tissue was obtained in 223 (96.1%) of the procedures. One hundred sixty-seven biopsies (72.0%) were performed while patients were receiving therapeutic aspirin. Six biopsies (2.6%) resulted in clinically important complications: three cases of intraabdominal hemorrhage and one case each of gross hematuria, allograft pancreatitis, and severe pain requiring overnight hospitalization. Two of the four bleeding complications occurred while patients were receiving therapeutic aspirin.

CONCLUSION

US-guided biopsy of pancreas transplants yielded tissue that was adequate more than 96% of the time. Important complications in this study were few (2.6%) and did not appear to be related to aspirin use.

Duodenal histology for monitoring treatment of acute rejection in pancreaticoduodenal allografts in rats

BACKGROUND

Although the value of duodenal histology as a means to diagnose acute rejection in pancreaticoduodenal allografts has been validated, it is not known how the duodenum responds to antirejection treatment in comparison with the pancreas.

METHODS

Diabetic Lewis rats received a pancreaticoduodenal allograft. Cyclosporine was given for 5 days and then discontinued for 2 days (group 1), for 4 days (group 2), for 6 days (group 3), for 8 days (group 4), for 9 days (group 5), and for 10 days (group 6). Two animals of each group were killed for histology at the end of immunosuppressive-free intervals. In the remaining rats, rejection was treated with methylprednisolone on 3 consecutive days. Duodenal histology was compared with pancreatic morphology before and after treatment of rejection.

RESULTS

Duodenal histology had a positive and negative predictive value of 100% for detection of acute rejection in the pancreatic portion of the graft. After antirejection treatment, duodenal morphology was however less accurate (positive predictive value, 96%; negative predictive value, 67%). The Spearman correlation coefficient (p) of duodenal and pancreatic rejection grades was higher before antirejection treatment (p=1.0) than thereafter (p=0.724). Considering interstitial and vascular changes separately, vascular rejection correlated to a higher extent than interstitial rejection between the two portions of the graft (p=0.725 vs. p=0.677).

CONCLUSIONS

Duodenal histology accurately predicts the initial diagnosis of rejection of the pancreas. However, after treatment of acute rejection, duodenal morphology is more likely to recover from rejection than the pancreas. Awareness of this phenomenon might be important for the interpretation of duodenal follow-up biopsies.

Pancreas after kidney transplants in posturemic patients with type I diabetes mellitus

Pancreas after previous kidney (PAK) transplants are an attractive option for type 1 diabetic patients because of the short waiting time and use of living kidney donors. Factors associated with the increased success rate of PAK transplants in four immunosuppressive eras were analyzed. Between July 1, 1978, and April 30, 2000, 406 PAK transplants were performed in posturemic patients. Four immunosuppressive eras were analyzed: (1) the precyclosporine era, era 1 (n = 65; 16%); (2) the cyclosporine era, era 2 (n = 109; 27%); (3) the tacrolimus era with monoclonal or polyclonal antibody induction therapy, era 3 (n = 104; 26%); and (4) the tacrolimus era with monoclonal and polyclonal antibody induction therapy, era 4 (n = 128; 31%). Patient and graft survival, rejection, and technical failure rates were calculated. Patient survival rates have remained high over time, from 91% (era 1) to 96% (era 4) at 1 yr posttransplant. Pancreas graft survival rates with primary cadaver transplants have significantly increased, from 17% (era 1) to 81% (era 4) at 1 yr. The rate of graft loss from rejection has significantly decreased, from 78% (era 1) to 9% (era 4) at 1 yr. Results were best when donors and recipients were matched for at least one antigen per HLA locus. Kidney graft survival was higher in PAK transplant recipients compared with diabetic recipients of kidney transplants alone from the time of the kidney as well as the pancreas transplants. PAK recipients now enjoy >80% graft survival at 1 yr. This improvement in outcome results from better immunosuppression, good matching, and close posttransplant monitoring for rejection.

Novel approaches toward early diagnosis of islet allograft rejection

BACKGROUND

The inability to diagnose early rejection of an islet allograft has previously proved to be a major impediment to progress in clinical islet transplantation. The need to detect early rejection will become even more relevant as new tolerance-inducing protocols are evaluated in the clinic. We explored three novel approaches toward development of early diagnostic markers of islet rejection after islet allotransplantation.

METHODS

(a) Canine islet allograft transplant recipients were immunosuppressed for 1 month, then therapy was withdrawn. Serum glutamic acid decarboxylase antigen (GAD65), an endogenous islet protein, was monitored daily with a CO2 release assay. (b) Rodent islets were genetically engineered to express a unique foreign protein (beta-galactosidase) by using adenoviral vectors, and after allograft transplantation, the viral-specific protein was measured in serum using optical luminescence. (c) Rodents receiving islet allografts were immunosuppressed temporarily, and daily glucose tolerance tests were followed until graft failure occurred.

RESULTS

(a) Although serum monitoring of GAD65 antigen demonstrated elevated levels preceding loss of graft function in preliminary studies, the effect was not reproducible in all animals. (b) Genetically engineered rodent islets demonstrated normal insulin kinetics in vitro (insulin stimulation index 2.57+/-0.2 vs. 2.95+/-0.3 for control islets, P=ns), and purified viral protein products had a stable half-life of 8 hr in vivo. After islet allotransplantation, there were two peak elevations in serum viral proteins, confirming that an intra-islet "sentinel signal" could be detected serologically during acute rejection. There was no lead-time ahead of hyperglycemia, however. (c) Daily sequential intravenous glucose tolerance (IVGT) tests demonstrated evidence of allograft dysfunction (decline in KG) with a 2-day lead time to hyperglycemia (2.58+/-0.3 vs. 1.63+/-0.2%/min, respectively, P<0.001), with an accuracy of 89%, sensitivity of 78%, and specificity of 95%.

CONCLUSIONS

Of the three diagnostic tests, metabolic assessment with an abbreviated IVGT was the most effective method of demonstrating early islet dysfunction due to rejection.

Pancreatic transplantation and subsequent graft surveillance by pancreatic portal-enteric anastomosis and temporary venting jejunostomy

OBJECTIVE

To evaluate portal-enteric (PE) pancreas and kidney transplantation with venting jejunostomy (VJ) for its efficacy, safety, and reproducibility.

SUMMARY BACKGROUND DATA

Simultaneous pancreas and kidney transplantation for patients with long-standing insulin-dependent diabetes mellitus that progresses to renal failure has revolutionized their treatment and quality of life. A current clinical focus is to refine the technical aspects of this procedure. Simultaneous pancreas and kidney transplantation with PE anastomosis with VJ appears to offer several advantages over bladder drainage. VJ allows initial decompression of the enteric anastomosis, monitoring of pancreatic function by ostomy amylase, and simple access for endoscopic evaluation and biopsy of the allograft.

METHODS

Simultaneous pancreas and kidney transplantation with VJ was performed in 21 patients from December 1996 to October 2000 at Willis Knighton/LSU Regional Transplant Center. All patients had long-standing insulin-dependent diabetes mellitus and subsequent renal failure. They were evaluated at the time of surgery by a multidisciplinary transplant team and monitored for numerous factors, including length of hospital stay, immunosuppressive regimen, and ischemia times. All patients had intermittent visual and biochemical evaluation of pancreatic secretions monitored by means of the VJ.

RESULTS

Of the 21 patients, 10 were women and 11 were men. Four patients were black and 17 were white. The mean age at transplantation was 38 years; average human leukocyte antigen (HLA) match was one; and average cold ischemia time was 12 hours. The median hospital stay was 16 days. Four episodes of postoperative bleeding requiring exploration occurred in four patients. Postoperative wound infections developed in four patients. There were 12 episodes of rejection in nine patients. All patients with suspected acute pancreatic rejection underwent endoscopy by means of the VJ and duodenal biopsy for evaluation. Two patients lost pancreatic function subsequent to kidney failure, one secondary to noncompliance and the other as a result of hemolytic-uremic syndrome. Patient, kidney, and pancreatic survival rates were 100%, 90%, and 90%, respectively. The mean follow-up period was 25 (range 2-48) months.

CONCLUSION

The authors believe that PE pancreatic drainage with VJ is a more physiologic method to perform pancreatic transplantation than bladder drainage. PE drainage allows rapid diagnosis of acute rejection and anastomotic leak and provides a simple way to monitor ostomy amylase and transplant duodenal bleeding. This technique is safe and has minimal associated complications.

Lessons learned from more than 1,000 pancreas transplants at a single institution

OBJECTIVE

To determine outcome in diabetic pancreas transplant recipients according to risk factors and the surgical techniques and immunosuppressive protocols that evolved during a 33-year period at a single institution.

SUMMARY BACKGROUND DATA

Insulin-dependent diabetes mellitus is associated with a high incidence of management problems and secondary complications. Clinical pancreas transplantation began at the University of Minnesota in 1966, initially with a high failure rate, but outcome improved in parallel with other organ transplants. The authors retrospectively analyzed the factors associated with the increased success rate of pancreas transplants.

METHODS

From December 16, 1966, to March 31, 2000, the authors performed 1,194 pancreas transplants (111 from living donors; 191 retransplants): 498 simultaneous pancreas-kidney (SPK) and 1 simultaneous pancreas-liver transplant; 404 pancreas after kidney (PAK) transplants; and 291 pancreas transplants alone (PTA). The analyses were divided into five eras: era 0, 1966 to 1973 (n = 14), historical; era 1, 1978 to 1986 (n = 148), transition to cyclosporine for immunosuppression, multiple duct management techniques, and only solitary (PAK and PTA) transplants; era 2, 1986 to 1994 (n = 461), all categories (SPK, PAK, and PTA), predominantly bladder drainage for graft duct management, and primarily triple therapy (cyclosporine, azathioprine, and prednisone) for maintenance immunosuppression; era 3, 1994 to 1998 (n = 286), tacrolimus and mycophenolate mofetil used; and era 4, 1998 to 2000 (n = 275), use of daclizumab for induction immunosuppression, primarily enteric drainage for SPK transplants, pretransplant immunosuppression in candidates awaiting PTA.

RESULTS

Patient and primary cadaver pancreas graft functional (insulin-independence) survival rates at 1 year by category and era were as follows: SPK, era 2 (n = 214) versus eras 3 and 4 combined (n = 212), 85% and 64% versus 92% and 79%, respectively; PAK, era 1 (n = 36) versus 2 (n = 61) versus 3 (n = 84) versus 4 (n = 92), 86% and 17%, 98% and 59%, 98% and 76%, and 98% and 81%, respectively; in PTA, era 1 (n = 36) versus 2 (n = 72) versus 3 (n = 30) versus 4 (n = 40), 77% and 31%, 99% and 50%, 90% and 67%, and 100% and 88%, respectively. In eras 3 and 4 combined for primary cadaver SPK transplants, pancreas graft survival rates were significantly higher with bladder drainage (n = 136) than enteric drainage (n = 70), 82% versus 74% at 1 year (P =.03). Increasing recipient age had an adverse effect on outcome only in SPK recipients. Vascular disease was common (in eras 3 and 4, 27% of SPK recipients had a pretransplant myocardial infarction and 40% had a coronary artery bypass); those with no vascular disease had significantly higher patient and graft survival rates in the SPK and PAK categories. Living donor segmental pancreas transplants were associated with higher technically successful graft survival rates in each era, predominately solitary (PAK and PTA) in eras 1 and 2 and SPK in eras 3 and 4. Diabetic secondary complications were ameliorated in some recipients, and quality of life studies showed significant gains after the transplant in all recipient categories.

CONCLUSIONS

Patient and graft survival rates have significantly improved over time as surgical techniques and immunosuppressive protocols have evolved. Eventually, islet transplants will replace pancreas transplants for suitable candidates, but currently pancreas transplants can be applied and should be an option at all stages of diabetes. Early transplants are preferable for labile diabetes, but even patients with advanced complications can benefit.

Trends and perspectives in pancreas and simultaneous pancreas and kidney transplantation

Pancreas transplantation is still the best option to achieve normoglycaemia and insulin independence in patients with type I diabetes. As a result of improvements in surgical techniques, immunosuppression and patient selection, one year survival rates of 95, 83, and 88% for patient, pancreas, and kidney survival, respectively, are reported for patients with simultaneous pancreas and kidney transplantation. The main goals for the future are to reduce postoperative morbidity, to identify the relevant indications for single pancreas transplantation, to adopt the best surgical technique for individual patients' needs (bladder versus enteric drainage with or without portal venous delivery of insulin), and to develop immunosuppressive strategies with low nephrotoxic and diabetogenic potential.

The role of percutaneous biopsy in detection of pancreatic transplant rejection

The purpose of this study was to investigate the effectiveness and safety of percutaneous pancreatic transplant biopsy guided by ultrasound alone or with a combination of computerized tomography (CT) for pancreas localization and ultrasound for needle placement. We also compare our finding on the use of 18-gauge and 20-gauge needles for percutaneous pancreatic transplant biopsy. In 42 attempted biopsies performed on 21 patients, two different imaging modalities were used. Twenty-seven attempted biopsies were performed under the guidance of ultrasound alone, and 15 used a combination of ultrasound and CT. Of the 27 ultrasound-guided biopsies. 24 produced at least one sample adequate for histopathological analysis for an 89% biopsy success rate. Of the 15 biopsies guided by combined ultrasound and CT, 11 produced adequate samples for a 73% success rate. For all biopsies, an 83% success rate was found. In assessing the use of 18-gauge versus 20-gauge needles, 86 out of 110 tissue cores were adequate for histopathological analysis for a 78% yield. In 27 biopsy attempts using the 18-gauge needle, 75 tissue cores were obtained, for an average of 2.8 cores per biopsy. Fifty-seven pancreas samples collected using the 18-gauge needle were adequate for pathological evaluation for a 76% yield. With 15 biopsy attempts using the 20-gauge needle, 35 tissue cores were collected, for an average of 2.3 cores per biopsy. Twenty-nine pancreas specimens obtained from using the 20-gauge needle were adequate for analysis for an 83% yield. No major complications occurred. Only one incidence of minor complication was reported for a 2% complication rate. The only complication was local, mild bleeding at the biopsy site in one case. Air within the transplant pancreas as revealed by post-biopsy scans and streaky density appearing adjacent to the biopsy site occurred in a total of four cases and were not included. No complications were reported that required any invasive intervention. We conclude that percutaneous biopsy guided by ultrasound is a safe, simple, and effective method to detect pancreatic transplant rejection. Our results for biopsies compare favorably with other reported techniques in terms of effectiveness, complication rates, and ease of use. With its high success rate and low complications, ultrasound-guided percutaneous biopsy is an excellent method to sample pancreatic transplant.