Subclinical growth of an arteriovenous fistula associated with renal biopsy: a case report
Renal biopsy is not free from complications and patients who undergo this procedure are usually hospitalized to receive intensive care for several days after biopsy. In contrast, after this period, routine follow-up to detect biopsy-associated complications is rarely scheduled, unless the patient develops a clinical manifestation. We describe a case of marked enlargement of arteriovenous fistula in the kidney that occurred many years after renal biopsy. In contrast to the previous cases requiring interventional radiology, our patient showed subclinical growth of fistula over about nine years.
A 24-year-old man with a history of percutaneous renal biopsy was hospitalized for interventional radiology. Gross hematuria emerged shortly after biopsy, but completely disappeared with administration of hemostatic agents and bed rest. Subsequently, the patient had few symptoms for many years. A giant fistula (a gourd-shaped mass, size 26 × 22 and 12 × 11 mm) was unexpectedly detected by ultrasonography performed for examination of an unrelated disorder (slight elevation of serum transaminase) at 9 years after the original biopsy. The fistula was successfully treated with radiological intervention. Thus, subclinical development of complications associated with renal biopsy should be considered, even in an uneventful course.
This case provides a platform to discuss the importance of long-term follow-up of patients after renal biopsy despite of its difficulty.
KeywordsRenal biopsy Renal arteriovenous fistula Interventional radiology
Renal biopsies provide critical clues in diagnosis of renal diseases. However, this procedure is not free from complications, despite technical improvements over time. A recent nationwide study in Norway showed gross hematuria after biopsy in 1.9 % of patients, with 0.9 % needing blood transfusion and 0.2 % requiring surgical intervention or catheterization . There have also been several reports of renal arteriovenous fistula (AVF) after renal biopsy. In most such cases, radiological interventions were performed due to severe clinical manifestations of gross hematuria [2, 3, 4], hemorrhagic shock , severe hypertension [2, 5], and decline of renal function , which all emerged shortly after the biopsy. We herein report a case of marked enlargement of renal AVF that was detected by chance nine years after biopsy and was successfully treated with interventional radiology (IR). In contrast to the previous cases of renal AVF associated with biopsy [2, 3, 4, 5, 6], our patient showed subclinical growth of AVF over about nine years. Thus, this case provides a platform to discuss the importance of long-term follow-up of patients after renal biopsy.
IgA nephropathy was diagnosed based on the findings of renal biopsy. The patient was hospitalized again six months later to receive steroid pulse therapy followed by tonsillectomy  for this glomerulopathy. A striking improvement in urinary abnormalities was gradually achieved, with urinary protein reduced from 4.2 to 0.2 g/day and red blood cells decreased to a level of 5 cells per high-power field in sediment. Ultrasound examination was performed again, but growth of renal AVF was not evident in this period. Following the combination therapy, the patient regularly visited our hospital and took 300 mg dipyridamole and 6 mg candesartan orally each day. The angiotensin II receptor antagonist was prescribed as a renoprotective agent, rather than for a depressor effect. Blood pressure (125/75 mmHg), blood hemoglobin, and serum creatinine remained normal in this period and for over eight years.
Complications associated with renal biopsies are not uncommon. Indeed, nephrologists exert extreme caution early after puncture, especially for the first few days. The guidelines for renal biopsies published by the Japanese Society of Nephrology  recommend a stay of no less than 4 to 7 days in hospital. Postural changes in bed and adoption of a standing position are not allowed for the first hours and almost the entire first day, respectively, based on two studies of biopsy-related complications: Khajehdehi et al.  found that patients with stable hematocrit at 6 h were at low risk for bleeding at 24 h while hospitalized, and Marwah et al.  found that major complications were identifiable in most cases within 12 h. Thus, intensive management is important for a short time after renal biopsy. However, there is little information on appropriate follow-up for patients with a history of renal biopsy after this period.
A number of cases of renal AVF associated with biopsy [2, 3, 4, 5, 6] have been published. In particular, Lorenzen et al.  reported 20 cases of post-biopsy AVF, all of which were successfully treated with IR. In this report, the incidence of AVF after renal biopsy was 1.6 %, but this rate is as high as 16 % in other reports. Lorenzen et al. also highlighted the improvement of renal function after IR, based on a significant decrease in the mean creatinine level from 4.4 to 2.7 mg/dl (p = 0.0014). In our case, IR was initially considered because of gross hematuria, but was not used in light of the subsequent uneventful course. Since 70 % of AVFs occlude spontaneously, medical management in anticipation of spontaneous closure of the fistula may be the best first choice in an asymptomatic patient . In most other IR cases, patients with renal AVF showed severe clinical manifestations including gross hematuria [2, 3, 4], hemorrhagic shock , severe hypertension [2, 5], and decline of renal function .
The present case raises an issue regarding long-term follow-up of patients after renal biopsy. This may not be feasible in practice for all patients and some might not need regular visits, depending on the diagnosis. However, our case shows the possibility of subclinical development of renal biopsy-associated complications indicating a subpopulation of patients that requires periodic examination, even if this is uneventful. Based on our experience, this subpopulation may include patients who are younger and who show clinical manifestations shortly after biopsy.
In conclusion, we have reported a case of marked enlargement of a renal AVF that was found incidentally 9 years after biopsy without clinical manifestations and was successfully treated with IR.
AVF, arteriovenous fistula; CT, computed tomography; IR, interventional radiology; US, ultrasonography
We would like to thank Yuko Suda, Yukari Hoshino, and Aiko Oashi for their excellent assistance with this report.
This study was supported in part by a Grant-in-Aid for Research on Advanced Chronic Kidney Disease, Practical Research Project for Renal Diseases, from the Japan Agency for Medical Research and Development (AMED).
Availability of data and materials
All the data supporting our findings is contained within the manuscript.
MT participated in the nephropathy treatment and drafted the manuscript. ST and TA participated in the nephropathy treatments and worked up the manuscript. HK, AU, SK drafted the manuscript and performed IR therapy. HN was in charge of the IR team. TI, TS, RH, TK, OS participated in the nephropathy treatment. DN is the divisional director and supervised each author. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
Written informed consent was obtained from the patient for publication of this case report. A copy of the written consent is available for review by the Editor of this journal.
Ethics approval and consent to participate
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