Page Kidney Phenomenon following Kidney Graft Biopsy

Percutaneous renal allograft biopsy is commonly performed as a protocol or diagnostic biopsy after kidney transplantation to detect rejection, recurrence of kidney disease, infection and calcineurin inhibitor (CNI) nephrotoxicity [1,2]. It is generally considered as a safe procedure under ultrasound guidance. However, some complications associated with this procedure can occur. Most common complications are minor and can be managed conservatively. Major complications can occur in about 1% of cases [3,4], which may require blood transfusion, interventional procedure or even surgical exploration. Page kidney phenomenon is one of the rare but serious complications, in which the renal parenchyma is tamponade and its perfusion is compromised as a result of haematoma formation under the renal capsule. This will lead to deterioration in kidney function and graft loss if the diagnosis and management are delayed [5]. Therefore, early recognition of page kidney phenomenon is crucial as prompt evacuation of the haematoma can prevent graft loss and allow complete recovery of renal function [6]. Here we reported two cases of page phenomenon after kidney graft biopsy in our institution. The literatures were also reviewed.


Introduction
Percutaneous renal allograft biopsy is commonly performed as a protocol or diagnostic biopsy after kidney transplantation to detect rejection, recurrence of kidney disease, infection and calcineurin inhibitor (CNI) nephrotoxicity [1,2]. It is generally considered as a safe procedure under ultrasound guidance.
However, some complications associated with this procedure can occur. Most common complications are minor and can be managed conservatively. Major complications can occur in about 1% of cases [3,4], which may require blood transfusion, interventional procedure or even surgical exploration. Page kidney phenomenon is one of the rare but serious complications, in which the renal parenchyma is tamponade and its perfusion is compromised as a result of haematoma formation under the renal capsule. This will lead to deterioration in kidney function and graft loss if the diagnosis and management are delayed [5]. Therefore, early recognition of page kidney phenomenon is crucial as prompt evacuation of the haematoma can prevent graft loss and allow complete recovery of renal function [6].
Here we reported two cases of page phenomenon after kidney graft biopsy in our institution. The literatures were also reviewed.

Case 1
A 62-year-old lady with end stage kidney disease due to

Discussion
Percutaneous renal biopsy has been increasingly used as a protocol biopsy after kidney transplantation. It is also commonly performed to diagnose the underlying pathology when the renal function deteriorates. However, it is associated with some potential complications such as haematuria, urinary tract obstruction by clots, formation of pseudoaneurysm and/or arteriovenous fi stula and peri-graft or subcapsular haematoma. The incidence of the complications ranged from 0.7% to 30% [6], whereas the major complication requiring interventional procedure was about 1% [5].
The Page kidney phenomenon was fi rst described by Dr. Page in an experimental model in 1939 [7]. In the experiment, cellophane was wrapped around a native kidney leading to the constriction in renal parenchyma and hypertension [7]. In the context of kidney transplantation, Page kidney phenomenon can occur spontaneously after kidney transplantation [8,9], after percutaneous kidney graft biopsy [5,[10][11][12], or after trauma to the allograft [13]. It can also occur in a native kidney [14]. There is a paucity of reports describing subcapsular haematoma following kidney graft biopsy [5,8,[10][11][12]. It has the same effect as demonstrated in the Page kidney experiment.
The haematoma compresses on the renal parenchyma as a   Wanic-Kossowska et al [15]. reported 3 cases of Page kidney phenomenon in consecutive 800 renal biopsies; two of cases developed subcapsular haematoma and one developed a huge peri-kidney haematoma. In addition, Chung et al [12]. reported 4 cases of Page kidney phenomenon in 518 renal transplant biopsies. The page kidney phenomenon may develop almost immediately after percutaneous renal biopsy. However, it could have delay presentation sometimes such as 10 days following biopsy [11], as in our case 1.
Given the rarity of page kidney phenomenon, its diagnosis can be easily missed. In our opinion, an acute pain over the graft with reduction in urine output is an alert for suspicion of Page kidney phenomenon after percutaneous biopsy. Urgent investigation should be performed with Doppler US of the kidney graft and blood test for Cr level. It was also suggested that elevation in blood pressure is the hallmark of presentation due to the activation of renin-angiotensin system [12,16,17].
In our experience, Doppler US is a useful modality for prompt diagnosis in the setting of percutaneous kidney graft biopsy. The absence or reversal of diastolic blood fl ow with elevated resistance index is a specifi c feature of Page kidney phenomenon although differential diagnoses also include acute tubular necrosis, acute rejection and renal vein thrombosis [3].  [18,19].
In conclusion, Page kidney phenomenon is a rare but serious complication after renal graft biopsy. It should be considered as medical emergency. The patient should be fully informed about the symptoms of Page kidney phenomenon when subject to percutaneous kidney graft biopsy. Doppler US is an acute useful modality for prompt diagnosis. The early recognition of Page kidney phenomenon and prompt surgical intervention is fundamental to prevent the graft loss.