An ultrasound-guided percutaneous renal biopsy is an important tool in nephrology practice to confirm diagnosis, recommend therapy, determine treatment outcome, and establish the degree of active and chronic changes.^1,2 Percutaneous renal biopsy provides valuable information for the prognosis and management of patients. Renal biopsy has advanced with the addition of tools and technology that optimize the result. The real-time ultrasonography to localize the kidney and automated biopsy needles have improved considerably the safety of both procedure and its numbers considerably.^3–6

For the ultrasound-guided percutaneous renal biopsy to be successful, adequate pre-procedure evaluation of patient, preparation for the procedure, and post-procedure monitoring are essential. The indications for performing a renal biopsy are determined by the presented clinical manifestations. Although ultrasound-guided percutaneous kidney biopsy is a safe procedure, minor or major complications could occur.¹ Some studies have reported significant complications in less than 1% of patients;^7,8 contrarily, some studies have reported higher rates of complications.^9–11

We conducted this single-center observational study to assess the indications for ultrasound-guided percutaneous renal biopsy and to find out the rate of complications associated with it. We evaluated whether the number of minor and major complications is comparable to that reported in the literature.

The study enrolled 229 of the 261 patients who underwent renal biopsy at the institute. A total of 32 patients were excluded, as they did not satisfy the inclusion/exclusion criteria. Of the 229 patients, 136 were males and 93 were females. The mean age of the patients was 39.86 ± 15.22 years.

The most frequent indications for renal biopsy were nephrotic syndrome (76; 33.2%), subnephrotic proteinuria with azotemia (32; 14%), unexplained azotemia, proteinuria, and hematuria (31; 13.5%; Table 1).

The most commonly observed post-percutaneous renal biopsy complications were pain (89; 38.86%), hematoma (13; 5.67%), gross hematuria (11; 4.8%), and hypotension (5; 2.2%; Table 2). A statistically significant relation between hematoma and azotemia (P = 0.03) was observed (Table 3). No statistically significant relationship was recorded between frequency of complications and age groups or hypertension (Tables 4 and 5). The gross hematuria was resolved within 24 h post-biopsy in eight of the 11 (3.49%) patients without any hemodynamic instability.

Most patients had a mean change of <1 and ≥1–<2 mg/dL in hemoglobin from baseline to post-biopsy (57.6% and 24.5%, respectively; Table 6). However, no substantial difference was observed in the overall change in the mean value of hemoglobin from baseline to post-biopsy. The mean change of ≥2 mg/dL in hemoglobin from baseline to post-biopsy was observed in 13 (5.7%) patients.

In all, 6 (2.62%) patients developed major complications, and 2 of the 6 (0.87%) patients underwent an invasive procedure (Table 7). Three (1.31%) patients with gross hematuria developed major complications—pseudoaneurysm with persistent hematuria, urinary bladder clot, and persistent hematuria 30 h post-biopsy. The patient who developed pseudoaneurysm with persistent hematuria for 3 days, complicated by hypotension, required angiographic localization of bleed with embolization and 3 units of blood transfusion for hemodynamic instability. The patient who developed clot in the urinary bladder after hematuria with retention of urine required cystoscopy to remove clot. The third patient with persistent hematuria for 30 h post-biopsy with hypotension also required blood transfusion.

Three of the five patients with hypotension required blood transfusion. One of these three patients had pseudoaneurysm, requiring embolization of the feeder artery, and two patients required intravenous normal saline. No procedure-related mortality was recorded in our study.

Renal biopsy is an important decision-making tool in nephrology practice. Although percutaneous renal biopsy is a safe procedure, minor or major complications could take place. Various factors are associated with the occurrence of complications during and post-biopsy. This prospective single-center study aimed to assess indications for percutaneous ultrasound-guided renal biopsy and associated post-biopsy complications.

We observed that the most common indications for percutaneous renal biopsy were nephrotic syndrome (33.2%), subnephrotic proteinuria with azotemia (14%) unexplained azotemia, and proteinuria with hematuria (13.5%). These results were consistent with the studies reporting indications and epidemiologic data of renal biopsies in India.^12–15 The percentage of patients with other indications was consistent with that observed in some other studies.^16,17

We observed a lower risk of major complications (2.6%). Similar to our results, a prospective study also reported that percutaneous renal biopsy was associated with a 5% risk of major complications.¹⁸ Although the risk of major complications in our study was much lower, it can be due to the comparatively smaller sample size (229 in our study vs. 5304 patients). However, unlike the results of our study, the researchers reported that a decrease in hemoglobin level of ≥2 mg/dL was the most frequently observed post-biopsy complication. Furthermore, they reported that higher plasma creatinine levels, liver disease, and higher number of needle passes were the risk factors for major complications.¹⁸

In our study, pain was the most commonly reported post-biopsy complication (38.86%) whereas hematoma occurred in 5.67% of patients, and of these 2.2% of patients developed a major complication. The observed rate of hematoma was within the range reported by other studies (4–33% of patients).^19,20 Also, the percentage of patients with hematoma developing major complications was similar to results of cited studies that reported major complications in 1.9% of patients with hematoma.

Hematoma can be subcapsular, retroperitoneal, or, rarely, due to injury of the lumbar vessels. The post-procedural ultrasound investigation is important to capture the hematoma. The hematoma usually leads to minor or major post-procedure developments. Hence, it is considered a predictor of bleeding-related complications; however, no significant relationship has been found between the size of hematoma and the extent of bleeding.^21–23 It can be asymptomatic or associated with hematuria, flank pain, anemia, or shock.

Hematuria is a very common complication of percutaneous biopsy. Microscopic hematuria occurs in almost all patients whereas gross hematuria occurs in 5–9% patients.²² Hematuriacan increase due to uncontrolled hypertension or uremia. Hematuria usually resolves spontaneously within 2 days, but in approximately 0.5% patients, it may persist for 2–3 weeks. Sometimes, gross hematuria is observed in patients a few days after the biopsy, which resolves with rest.²² We observed gross hematuria in 11 (4.8%) patients, and 3 (1.31%) of these developed major complications. Our results are also consistent with a study conducted among 750 patients, in which hematuria was reported in 35 (4.6%) patients, and 12 (1.6%) of these patients required blood transfusion or invasive procedure.²⁰

Percutaneous renal biopsy is sometimes associated with severe complications. Hence, pre-procedure evaluation of patients to avoid complications is imperative.^6,24 The pre-procedure evaluation must include the history of bleeding diathesis, recent use of nonsteroidal anti-inflammatory drugs (NSAID), control over hypertension, recent pyelonephritis or skin infections near the biopsy site, and the ability to comply with instructions during the biopsy.²⁵ The complete blood count, platelets, and PT/INR are evaluated prior to procedure on a routine basis. Although bleeding time has no significant correlation to surgical bleeding,²⁶ biopsy complications are mainly related to bleeding. Moreover, Stiles et al. performed renal biopsies without evaluating bleeding time, and demonstrated that the bleeding time does not significantly alter the rates of major complications.²⁷ The post-renal bleeding complications are typically related to the blood vessels of the perinephric area or the collecting system and rarely to the lumbar or mesenteric artery.¹⁹

Manno et al. prospectively evaluated the predictive value of demographics, clinical data, baseline chemistry, and needle size for the risk of post-renal biopsy complications in 471 patients.¹⁹ They concluded that only gender, age, and baseline partial thromboplastin time (PTT) showed a significant predictive value but the other variables investigated did not have any predictive value. Although we did not evaluate the predictive value of these factors, we did not observe any significant statistical relations between the frequency of complications and age groups or pre-existing hypertension.

A study performed percutaneous renal biopsies in 394 native kidneys and concluded that observation of patients for 23–24 h is optimal, but observation for 8 h or lesser period is unsafe for missing approximately 20% of complications.²⁸ Contrarily, the literature review shows that 3% of complications occur within 8 h and that 91% occur within 24 h of procedure.²⁹ We observed patients for 24 h post-biopsy. Biopsy-related infections are rare; and no infections were observed in our study.³⁰

Ultrasound-guided renal needle biopsy is an essential tool in nephrological practice. It is imperative in the diagnosis and therapeutic management of patients. It is a highly standardized invasive procedure associated with a high technical success rate and a relatively small number of minor or major complications. The most common indications for renal biopsy were nephrotic syndrome, subnephrotic proteinuria with azotemia, unexplained azotemia with proteinuria and hematuria, and subnephrotic proteinuria. The incidence of major complications was low. No procedure-related mortality was recorded in our study.