Nephrology Hypertension

Kidney Transplantation: Diagnosis and Management of Early Graft Dysfunction - Post-Renal Causes and Treatments

Does this patient have early graft dysfunction related to post-renal causes?

What is early graft dysfunction?

Kidney transplantation is the preferred mode of renal replacement therapy for end stage renal disease, with dramatic improvements in patient and graft survival over the last 50 years. In the modern era of immunosuppression, one year patient survival is close to 98%, and one-year allograft survival rates have improved to 90% for deceased donor kidney transplants and 95 % for living donor kidney transplants with some inter-center variability. However, fluctuations in serum creatinine, which is the primary method for monitoring graft function, are frequent, particularly in the first year of transplantation.

Definition: early graft dysfunction

A rise in serum creatinine of 15% or more above baseline defines allograft dysfunction. Urine output, especially in the first few days of transplantation, may also be monitored and a decline to levels of oliguria or anuria may also define early graft dysfunction.

What causes early graft dysfunction?

Early graft dysfunction can be divided into three categories based on the different risk factors :

(1) immediate post-operative graft dysfunction (within the first week of transplantation) (Figure 1)

Figure 1.

Management of oliguria/anuria after transplant.

(2)graft dysfunction in the first 3 months after transplantation (Figure 2)

Figure 2.

Management of elevated serum creatinine in early pre-transplant period (1 week-12 weeks).

(3) graft dysfunction after 3 months of transplantation.

Much like the causes of acute kidney injury, allograft dysfunction can be considered using the pre-renal, post-renal and intrinsic-renal etiologies. This chapter covers early graft dysfunction related to post-renal etiologies; specifically, voiding dysfunction, ureteral obstruction, and urine leak or urinoma. Differential diagnosis is impacted based on the timing post-operatively.Bladder ultrasound can help confirm the diagnosis.

What tests to perform?

Voiding dysfunction

Bladder ultrasound can help confirm the diagnosis.

Ureteral obstruction

Hydronephrosis and mild collecting system dilatation can be seen on renal ultrasound in the post transplant period due to ureteral edema or vesico-ureteral reflux and is not always indicative of obstruction. This can be distinguished with a radionuclide renal scan using furosemide. However, increasing hydronephrosis in an appropriate clinical setting can support a diagnosis of obstruction. A peri-nephric fluid collection can be seen on an ultrasound. Antegrade pyelogram via a percutaneous nephrostomy is the gold standard test and can serve as both diagnostic and therapeutic to evaluate the obstruction.

Urine leak or urinosis

A simple test is to measure the creatinine and urea in the drainage fluid. In the case of a urine leak, the fluid creatinine and urea will be markedly elevated compared to the serum creatinine, which will differentiate it from lymphocele or a seroma, where these levels would be similar to serum.

How should patients with early graft dysfunction related to post-renal causes be managed?

Post renal causes of acute early graft dysfunction include voiding dysfunction and surgical complications, which can be secondary to extrinsic compression from perinephric collection or defect in the collecting system. When suspected, an ultrasound of the allograft and the collecting system can be very useful diagnostically.

The incidence of urological complications after renal transplantation varies from 5 – 14%, with a lot of inter-center variability.

Voiding dysfunction

  • Symptoms of voiding dysfunction may be masked in the pretransplant period secondary to lack of urine output due to renal failure. Bladder outlet obstruction, autonomic dysfunction of bladder especially in diabetics and neurological dysfunction can lead to retention of urine in post transplant period. Patients usually present with signs and symptoms of obstruction, overflow incontinence, recurrent urinary tract infection. Sometimes, they may present asymptomatically with a slowly rising creatinine. Patients with complete obstruction present with rapidly rising creatinine, suprapubic tenderness and anuria. Bladder ultrasound can help confirm the diagnosis. The treatment includes drainage with a foley catheter and urological consultation for definitive treatment.

Ureteral obstruction

  • Several different causes include:

  • Mechanical obstruction

    1. Blood clot

    2. Ureteral slough

    3. Improper implantation of the ureter

    4. Ureteric calculi in the late post transplant period

  • Ureteral stricture

    1. Ischemic necrosis

    2. BK viral infection

  • Extrinsic compression

    1. Perinephric fluid collection- lymphocele, seroma, hematoma, urinoma

    2. Hernia with transplant ureter

  • Diagnosis

    Hydronephrosis and mild collecting system dilatation can be seen on renal ultrasound in the post transplant period due to ureteral edema or vesico-ureteral reflux and is not always indicative of obstruction. This can be distinguished with a radionuclide renal scan using furosemide. However, increasing hydronephrosis in an appropriate clinical setting can support a diagnosis of obstruction. A peri-nephric fluid collection can be seen on an ultrasound. Antegrade pyelogram via a percutaneous nephrostomy is the gold standard test and can serve as both diagnostic and therapeutic to evaluate the obstruction.

  • Treatment

    Treatment includes percutaneous nephrostomy tube or/and ureteral stent placement, sometimes surgical repair or correction is indicated. In the case of extrinsic compression from a perinephric fluid collection, a sample of fluid is obtained under ultrasound or CT guidance, and sent for biochemical analysis to differentiate between urinoma, lymphocele and seroma. Drainage of a lymphocele or seroma by interventional radiology may be sufficient sometimes. If resolution does not occur then surgical exploration and repair is needed. A perinephric hematoma usually requires surgical exploration and evacuation.

Urine leak or urinoma

Urine leaks usually occur because of ischemic necrosis secondary to poor vascular supply or suture failure. It presents usually in the early post-operative period or at the onset of post ATN diuresis in patients with delayed function. It is most commonly seen at the level of distal ureter, but can occur at level of renal pelvis or mid ureter due to the injury at time of procurement.

  • Diagnosis

    Patients may have markedly increased drainage from an indwelling drain (if present) or the incision itself. A simple test is to measure the creatinine and urea in the drainage fluid. In the case of a urine leak, the fluid creatinine and urea will be markedly elevated compared to the serum creatinine, which will differentiate it from lymphocele or a seroma, where these levels would be similar to serum.

    If the incision is not being drained then urine will collect around the site of anastamosis and cause significant allograft tenderness. Serum creatinine will start rising secondary to reabsorption of the creatinine from the leaked urine. A renal ultrasound may show a fluid collection. The fluid should be aspirated in sterile condition and sent for biochemical analysis to help differentiate between lymphocele/seroma and urinoma. A retrograde or an antegrade pyelogram will show contrast leakage in case of urine leak. A renal scan may show leakage of the radioisotope. Contrast will stay within the collecting system in case of lymphocele/seroma or hematoma.

  • A foley catheter is placed immediately to help reduce intravesicular pressure and decompress the bladder. Further management may include a per-cutaneous nephrostomy tube placement, double j ureteral stent placement or surgical repair in consultation with the urological/surgical service.

What happens to patients with early graft dysfunction related to post-renal causes?

If the etiology is correctly identified, and addressed, renal function should return to normal.

How to utilize team care?

The transplant surgical team should be closely involved with these patients. Depending on the diagnosis, the patient may need to be operated on again to correct the underlying issue.

You must be a registered member of Infectious Disease Advisor to post a comment.

Sign Up for Free e-newsletters