Residency · Residency · General Surgery

Transplant Surgery Fundamentals for the General Surgery Resident

Introduction

Transplant surgery represents one of the greatest achievements in modern medicine. While most general surgery residents will not pursue transplant fellowships, all general surgeons encounter transplant recipients in their practice and may participate in organ procurement. Understanding the fundamentals of organ transplantation, immunosuppression, and the management of surgical complications in transplant recipients is essential. This lecture covers kidney, liver, and pancreas transplantation with emphasis on concepts relevant to the general surgery resident.

Principles of Organ Transplantation

Organ Allocation

The United Network for Organ Sharing (UNOS) administers the Organ Procurement and Transplantation Network (OPTN) in the United States. Deceased donors fall into two categories: brain death donors (DBD), defined by irreversible cessation of all brain function and representing the most common deceased donor type, and donation after circulatory death (DCD), involving controlled withdrawal of life support with organ procurement after circulatory arrest, where warm ischemia time is a critical variable. Living donors are used primarily for kidney (the most common) and liver (left lateral segment or right lobe) transplantation, requiring extensive medical and psychosocial evaluation with donor safety as the paramount concern.

Histocompatibility and Crossmatching

ABO blood group compatibility is generally required, though ABO-incompatible transplantation is possible with desensitization protocols. The Human Leukocyte Antigen (HLA) system, part of the major histocompatibility complex on chromosome 6, is central to transplant immunology, with HLA-A, B, and DR being the most important antigens. Better HLA matching correlates with improved graft survival, especially for kidney transplants.

Crossmatch testing mixes recipient serum with donor lymphocytes to detect preformed donor-specific antibodies (DSA). A positive crossmatch is generally a contraindication to transplantation because of the risk of hyperacute rejection. The Panel Reactive Antibody (PRA) measures the percentage of the donor population against which the recipient has preformed antibodies; a high PRA indicates a sensitized patient for whom finding a compatible donor is more difficult. Virtual crossmatch uses single-antigen bead assays to identify specific HLA antibodies and allows rapid compatibility assessment.

<image>Diagram illustrating the immunologic basis of transplant rejection, showing the direct and indirect pathways of allorecognition: donor antigen-presenting cells activating recipient T cells (direct pathway), and recipient APCs processing donor antigens and presenting them to recipient T cells (indirect pathway), with downstream effector mechanisms including T-cell-mediated rejection and antibody-mediated rejection with complement activation</image>

Kidney Transplantation

Indications and Evaluation

Kidney transplantation is indicated for end-stage renal disease from any cause, with diabetes being the most common, followed by hypertension, glomerulonephritis, polycystic kidney disease, and IgA nephropathy. Transplantation offers improved survival with a 50% mortality reduction over dialysis, better quality of life, and lower long-term cost. Preemptive transplantation before dialysis initiation provides the best outcomes. Contraindications include active malignancy, active infection, severe uncorrectable cardiac disease, active substance abuse, and inability to comply with immunosuppression.

Surgical Technique

The kidney allograft is placed heterotopically in the iliac fossa, usually on the right side, and does not require native nephrectomy. The renal artery is anastomosed end-to-side to the external iliac artery, and the renal vein is anastomosed end-to-side to the external iliac vein. Ureteral implantation uses the Lich-Gregoir ureteroneocystostomy technique with an anti-reflux tunnel, stented with a double-J ureteral stent for 4 to 6 weeks. Operative time is 2 to 3 hours, and cold ischemia time should be kept under 24 hours for deceased donors.

Complications

Delayed graft function (DGF), defined as the need for dialysis within the first week, is more common with DCD kidneys and prolonged cold ischemia but usually recovers. Vascular complications include renal artery thrombosis causing immediate graft loss, renal vein thrombosis, and renal artery stenosis presenting with hypertension and graft dysfunction and treated with angioplasty or stenting. Urologic complications include urine leak from the ureteroneocystostomy, ureteral stricture, and lymphocele, which is the most common fluid collection and is treated with percutaneous drainage or laparoscopic fenestration.

Liver Transplantation

Indications

Chronic liver disease indications include cirrhosis from hepatitis C (historically the most common cause, now declining with direct-acting antiviral therapy), alcohol-associated liver disease (now the most common indication), NASH/MAFLD, primary biliary cholangitis, primary sclerosing cholangitis, and autoimmune hepatitis. Acute liver failure indications include acetaminophen toxicity (the most common cause in the US), viral hepatitis, drug-induced liver injury, Wilson disease, and Budd-Chiari syndrome. Hepatocellular carcinoma within Milan criteria (a single lesion 5 cm or smaller, or 2 to 3 lesions each 3 cm or smaller, with no vascular invasion and no extrahepatic spread) receives MELD exception points. Metabolic diseases such as familial amyloidosis, maple syrup urine disease, and primary hyperoxaluria are also indications.

MELD Score and Allocation

The MELD score is calculated from bilirubin, INR, creatinine, and sodium, and predicts 90-day mortality from liver disease. It is used for organ allocation, with the highest MELD receiving the highest priority. MELD-Na, which incorporates serum sodium, better predicts waitlist mortality. Exception points are allocated for conditions where MELD underestimates disease severity, such as hepatocellular carcinoma and hepatopulmonary syndrome.

Surgical Technique

The recipient hepatectomy is the most challenging part of the operation, particularly in the setting of portal hypertension with extensive collaterals. The piggyback technique, which is the most commonly used approach, preserves the recipient IVC by anastomosing the donor suprahepatic IVC to a common cuff of recipient hepatic veins. The classical technique removes the recipient IVC with the liver and requires venovenous bypass during the anhepatic phase. After caval anastomosis, the portal vein, hepatic artery, and bile duct anastomoses are completed sequentially. Biliary reconstruction is performed as a duct-to-duct choledochocholedochostomy when feasible (the preferred approach) or as a Roux-en-Y hepaticojejunostomy when duct-to-duct is not possible, such as in primary sclerosing cholangitis or significant size mismatch.

Complications

Primary non-function, occurring in 2 to 5% of cases, is graft failure requiring re-transplantation. Hepatic artery thrombosis (HAT) is the most feared vascular complication because the bile ducts rely entirely on arterial blood supply; it may cause biliary necrosis, abscess, and graft loss, with early HAT requiring re-transplantation at an incidence of 3 to 5%. Portal vein thrombosis is less common and may present with ascites and variceal bleeding. Biliary complications include anastomotic stricture (the most common biliary complication at 10 to 15%), bile leak, and non-anastomotic strictures from ischemic cholangiopathy associated with HAT or DCD grafts.

<image>Surgical illustration of orthotopic liver transplantation showing the piggyback technique with the donor liver in position, labeled vascular anastomoses (suprahepatic IVC to hepatic vein cuff, portal vein end-to-end, hepatic artery end-to-end), and biliary reconstruction with duct-to-duct choledochocholedochostomy over a T-tube, with the recipient IVC preserved</image>

Pancreas Transplantation

Pancreas transplantation is indicated for type 1 diabetes mellitus and is most commonly performed as a simultaneous pancreas-kidney (SPK) transplant. It can also be performed as pancreas after kidney (PAK) or pancreas transplant alone (PTA). The surgical technique involves placing the whole-organ pancreas in the pelvis. Arterial reconstruction uses a donor iliac artery Y-graft connecting the SMA and splenic artery. Venous drainage is to the iliac vein (systemic) or SMV (portal). Exocrine drainage may be to the bladder, which allows urinary amylase monitoring, or to the intestine (enteric drainage), which reduces metabolic complications. Complications include thrombosis (the most common cause of early graft loss), pancreatitis, leak, and rejection. SPK provides the best long-term graft survival at 85% at 5 years, with insulin independence in over 80% of recipients.

Immunosuppression

Induction Therapy

Lymphocyte-depleting agents such as anti-thymocyte globulin (ATG/Thymoglobulin) deplete T cells and are used in high immunologic risk patients, though they carry higher infection and malignancy risk. IL-2 receptor antagonists such as basiliximab target activated T cells with lower potency but fewer side effects and are used in low immunologic risk patients.

Maintenance Immunosuppression (Triple Therapy)

Calcineurin inhibitors (CNIs) form the backbone of maintenance immunosuppression. Tacrolimus, the most commonly used agent, or cyclosporine inhibits T-cell activation via the calcineurin-NFAT pathway. Nephrotoxicity is the most important side effect, and therapeutic drug monitoring is required. Antimetabolites, primarily mycophenolate mofetil (MMF) or mycophenolic acid, inhibit inosine monophosphate dehydrogenase to block purine synthesis in lymphocytes, with GI side effects (diarrhea) and bone marrow suppression as the main adverse effects. Corticosteroids such as prednisone provide anti-inflammatory and immunosuppressive effects and are tapered over weeks to months, though many programs now use steroid-sparing or steroid-avoidance protocols to reduce metabolic side effects.

Side Effects of Immunosuppression

Infection risk includes opportunistic infections such as CMV, BK virus, Pneumocystis jirovecii pneumonia, and fungal infections, with prophylaxis using valganciclovir (CMV), trimethoprim-sulfamethoxazole (PJP), and antifungals as indicated. Malignancy risk includes post-transplant lymphoproliferative disorder (PTLD, associated with EBV), skin cancers (with squamous cell carcinoma exceeding basal cell carcinoma, reversing the ratio seen in the general population), and Kaposi sarcoma. Metabolic complications include new-onset diabetes after transplant (NODAT, particularly with tacrolimus and steroids), hyperlipidemia, hypertension, and osteoporosis. CNI nephrotoxicity causes afferent arteriolar vasoconstriction and chronic tubulointerstitial nephropathy, representing a major cause of chronic graft dysfunction in kidney transplant and renal failure in non-renal transplant recipients.

Rejection

Hyperacute rejection occurs within minutes to hours and is caused by preformed donor-specific antibodies against donor HLA, leading to complement-mediated thrombosis and immediate graft loss. It is prevented by crossmatch testing. Acute cellular rejection (ACR) occurs days to months after transplantation and is T-cell mediated. It is diagnosed by biopsy using the Banff classification and treated with pulse steroids, with refractory cases treated with ATG. Acute antibody-mediated rejection (AMR) is caused by donor-specific antibodies, shows C4d deposition on biopsy, and is treated with plasmapheresis, IVIG, rituximab, and bortezomib. Chronic rejection develops over months to years with progressive graft dysfunction from combined immune and non-immune factors, manifesting as transplant glomerulopathy in kidney or vanishing bile duct syndrome in liver, with limited treatment options.

General Surgery in the Transplant Recipient

Transplant recipients present atypically because immunosuppression blunts inflammatory signs, warranting a lower threshold for imaging and intervention. Cholecystitis occurs at higher incidence due to cyclosporine and is treated with standard laparoscopic cholecystectomy, though altered biliary anatomy must be considered in liver recipients. Appendicitis may present with atypical location in kidney recipients because the graft is in the right lower quadrant. Diverticulitis has higher incidence and a more severe course in transplant recipients, with a lower threshold for operative management. Wound healing is impaired by steroids and immunosuppression, requiring careful tissue handling and consideration of delayed primary closure in contaminated cases.

<image>Summary table of the three major immunosuppressive drug classes used in transplant maintenance therapy: calcineurin inhibitors (tacrolimus, cyclosporine) with mechanism, monitoring parameters, and key toxicities; antimetabolites (mycophenolate, azathioprine) with mechanism and side effects; and corticosteroids with metabolic complications, arranged as a visual reference card with drug interactions and monitoring requirements</image>

Clinical Pearls

All general surgeons should be familiar with organ procurement surgery and may be called upon to assist or perform procurement procedures. Hepatic artery thrombosis is the most feared vascular complication after liver transplant because the biliary tree depends entirely on arterial blood supply. Tacrolimus nephrotoxicity is a major cause of chronic renal dysfunction in all solid organ transplant recipients. Transplant recipients present atypically due to immunosuppression, and a low threshold for imaging and intervention should be maintained. Post-transplant malignancy surveillance is essential, with squamous cell carcinoma being the most common malignancy and PTLD (EBV-associated) the most dangerous early malignancy.

References

1. Abecassis M, Bartlett ST, Collins AJ, et al. Kidney transplantation as primary therapy for end-stage renal disease: a National Kidney Foundation/Kidney Disease Outcomes Quality Initiative (NKF/KDOQI) conference. Clin J Am Soc Nephrol. 2008;3(2):471-480.
2. Jadlowiec CC, Taner T. Liver transplantation: current status and challenges. World J Gastroenterol. 2016;22(18):4438-4445.
3. Halloran PF. Immunosuppressive drugs for kidney transplantation. N Engl J Med. 2004;351(26):2715-2729.
4. Matas AJ, Smith JM, Skeans MA, et al. OPTN/SRTR 2013 Annual Data Report: Kidney. Am J Transplant. 2015;15(Suppl 2):1-34.

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