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Medical Associates  ·  Department of Nephrology ← urinenephrology.org
Nephrology Education Series

Chapter 24: Renal Procedures — Kidney Biopsy and Dialysis Access

Andrew Bland, MD, FACP, FAAP UICOMP · UDPA · Butler COM 2026-08-01 21 min read

Chapter 24: Renal Procedures

Urine Nephrology Now: A Primer for Students in Nephrology Andrew Bland, MD, FACP, FAAP

Nephrology owns two procedures that define the specialty. One establishes a diagnosis that nothing else can establish. The other sustains a patient three days a week for years. Neither is a technical footnote, and both are decided long before anyone picks up a needle.

This chapter teaches how to think about each one — who gets it, who does not, what goes wrong, and how often. The technical choreography matters less than the judgment surrounding it.

Part 1: Percutaneous Kidney Biopsy

Why We Biopsy

Serologies narrow a differential. Tissue closes it. A patient with nephrotic-range proteinuria could have minimal change disease, membranous nephropathy, focal segmental glomerulosclerosis, or amyloid, and the treatments diverge sharply. Crescentic disease on light microscopy with pauci-immune staining sends a patient to cyclophosphamide or rituximab within days; the same clinical picture with dominant mesangial IgA does not.

Common indications:

Indication What the biopsy answers
Nephrotic syndrome in adults Which podocytopathy or deposit disease — MCD, FSGS, membranous, MPGN
Nephritic syndrome with falling GFR IgA vs. ANCA vs. anti-GBM vs. immune complex
Unexplained AKI or suspected RPGN Intrinsic pattern, activity, and whether treatment is still worth giving
Systemic disease with kidney involvement Lupus class, amyloid subtype, vasculitis activity
CKD of unclear etiology Specific pathology when serology and imaging have failed
Transplant dysfunction or surveillance Rejection, recurrence, drug toxicity

When Not to Biopsy

Contraindications are mostly about bleeding into a retroperitoneum you cannot compress.

  • Uncorrectable coagulopathy or active anticoagulation
  • Uncontrolled hypertension — correct the pressure, then biopsy
  • Thrombocytopenia below the institutional threshold
  • Active urinary tract or perinephric infection
  • Small, echogenic, end-stage kidneys — high risk, low diagnostic yield
  • Multiple bilateral cysts (technical) or a single functioning kidney (relative)
The pressure comes first

Uncontrolled hypertension is the contraindication students forget, because the patient looks otherwise ready. Corapi’s meta-analysis of 34 studies and 9,474 biopsies found that studies with a mean systolic pressure at or above 130 mm Hg had higher transfusion rates (1.4% vs 0.1%), though that comparison did not reach significance (P = 0.09) [2]. Treat the number as a signal, not a threshold — and control the pressure before you proceed.

Doing It

The patient lies prone with a bolster under the abdomen, which pushes the lower pole posteriorly and flattens the target. Real-time ultrasound is standard; CT is used when body habitus, prior surgery, or an unfavorable window defeats sonography. The lower pole is chosen deliberately — it is furthest from the hilar vessels.

After local anesthesia, a spring-loaded automated needle is advanced to the capsule and fired at end-inspiration, when the kidney is at the depth the operator planned for. The kidney travels two to three centimeters with respiration, so breath-holding is not a courtesy — it is the difference between cortex and a miss.

Needle gauge is a real trade-off, not a preference. A 2023 systematic review of 15 studies found that a 16-gauge needle yielded significantly more glomeruli than an 18-gauge (pooled SMD 0.61, 95% CI 0.32 to 0.89) and required fewer passes (SMD −0.57, 95% CI −0.97 to −0.18), but carried higher odds of total complications (OR 1.57, 95% CI 1.16 to 2.13) [4]. Corapi’s earlier meta-analysis found the same directional signal at the extreme: 14-gauge needles produced a transfusion rate of 2.1% compared with 0.5% for smaller needles (P = 0.009) [2]. Bigger cores, more bleeding. The choice belongs to the operator and the patient in front of them.

What Counts as an Adequate Specimen

Two to three cores, each roughly one to two centimeters, is the usual target. Adequacy is counted in glomeruli, not in tissue length — the sample must contain enough cortex to make a focal disease detectable. The Mayo Clinic/Renal Pathology Society consensus report on classification and reporting of glomerulonephritis sets out how these specimens should be handled and described [5].

Tissue is divided three ways, and the division is time-sensitive:

Study Medium What it shows
Light microscopy Formalin-fixed, paraffin-embedded Proliferation, sclerosis, crescents, fibrosis
Immunofluorescence Snap-frozen in OCT Immune deposits — IgG, IgA, IgM, C3, C1q, kappa, lambda
Electron microscopy Glutaraldehyde-fixed Deposit location, foot process effacement, GBM architecture
Clinical Pearl

Medullary tissue is not a diagnosis. If the pathologist reports predominantly medulla, the needle went too deep or too central, and the sample cannot exclude a focal glomerular lesion [5]. Send fresh tissue for immunofluorescence immediately — that pathway is the one that degrades if it sits.

Complications and — More Useful — Their Timing

The rates students memorize come from two literatures that do not fully agree, and the disagreement is the lesson.

Whittier and Korbet studied 750 consecutive ultrasound-guided native biopsies over nineteen years, with all patients observed 23 to 24 hours. Complications occurred in 98 patients (13%): 50 minor (6.6%) and 48 major (6.4%). One patient died, a rate of 0.1% [1].

Corapi’s meta-analysis of 9,474 biopsies performed with automated devices and real-time ultrasound found macroscopic hematuria in 3.5% (95% CI 2.2% to 5.1%) and erythrocyte transfusion in 0.9% (95% CI 0.4% to 1.5%) [2].

Manno’s prospective cohort of 471 patients reported bleeding of any kind in 34.1%, but almost all of it was radiographic hematoma (33.3%); major complications requiring transfusion, angiography, or nephrectomy occurred in six patients (1.2%), with no deaths [3].

Read those three together and the picture resolves. Detectable bleeding is common. Bleeding that changes management is not.

The single most practically important finding in this literature is about the clock. Whittier and Korbet timed every complication: 42% had declared themselves by 4 hours, 67% by 8 hours, 85% by 12 hours, and 89% by 24 hours [1]. Their conclusion follows directly — an observation period of 8 hours or less risks missing at least a third of complications [1].

Six hours is not enough

A widespread outpatient practice discharges patients after four to six hours. Whittier and Korbet’s data show roughly a third of complications appear after the 8-hour mark [1]. If your service discharges early, the patient needs explicit instructions and a reachable phone number, not reassurance.

Who bleeds? Here the two best cohorts disagree, and neither is wrong.

  • Whittier and Korbet found that on multivariate analysis only baseline serum creatinine predicted complications: a creatinine of 5.0 mg/dL or higher carried an odds ratio of 2.3 (95% CI 1.3 to 4.1, P < 0.005) [1].
  • Manno found no predictive value for creatinine. In that cohort the independent predictors were female sex (adjusted OR 2.05, 95% CI 1.26 to 3.31, P = 0.004), younger age (AOR 0.80, 95% CI 0.68 to 0.94, P = 0.006), and higher baseline partial thromboplastin time (AOR 1.26, 95% CI 1.02 to 1.54, P = 0.032) [3].
  • Corapi’s pooled study-level analysis supports the renal-function signal: studies with a mean creatinine at or above 2.0 mg/dL had transfusion rates of 2.1% versus 0.4% (P = 0.02) [2].

Two of three point at kidney function. The honest teaching position is that advanced renal insufficiency raises risk, that no single variable identifies the patient who will bleed, and that a clean coagulation panel does not buy you a shortened observation [1][3].

Arteriovenous fistula formation within the kidney is a recognized post-biopsy finding, usually small, usually asymptomatic, and usually managed by watching it [6]. Whittier’s review of biopsy complications covers the full range and their management [6]. Symptomatic lesions — persistent gross hematuria, high-output physiology, refractory hypertension — go to angiographic embolization rather than surgery [6].

Reading the Report

A biopsy report is a structured argument, and it is read in a fixed order [5].

  1. Adequacy — how many glomeruli, how many cores.
  2. Light microscopy — the pattern. Mesangial, endocapillary, or extracapillary proliferation; segmental, global, or nodular sclerosis; fibrinoid necrosis.
  3. Immunofluorescence — the mechanism. Linear IgG points to anti-GBM disease; granular capillary-wall IgG and C3 to membranous or post-infectious GN; full-house staining including C1q to lupus; dominant mesangial IgA to IgA nephropathy; absent staining with crescents to ANCA vasculitis; a single restricted light chain to paraprotein-related disease.
  4. Electron microscopy — the location. Subepithelial, subendothelial, mesangial, or intramembranous deposits each map to a short list.
  5. Chronicity — interstitial fibrosis and tubular atrophy. This is the prognostic section, and in an advanced case it is the section that decides whether immunosuppression is offered at all.

Disease-specific scoring systems attach here: the Oxford classification for IgA nephropathy [7] and the revised ISN/RPS classification for lupus nephritis [8] convert the descriptive report into a treatment decision.

Part 2: Hemodialysis Vascular Access

The Three Options

Feature Fistula (AVF) Graft (AVG) Tunneled catheter (CVC)
Time to usable Months Weeks (early-cannulation grafts sooner) Immediate
Maturation failure Common, higher in older patients Uncommon Not applicable
Infection risk Lowest once working Intermediate Highest
Maintenance burden Frequent reintervention Frequent thrombosis and reintervention Dysfunction, thrombolytic, exchange
Cardiac effect High-output flow can burden a failing heart Similar concern None
Best fit Long expected survival, good vessels Permanent access needed, poor veins, shorter timeline Short horizon, bridging, exhausted sites, strong preference

Comparative risk gradient across these three options is drawn from Ravani 2013 [10] and the 2019 KDOQI vascular access guideline [17].

The Maturation Reality

“Place a fistula” sounds like one event. It is a program.

The NIH Hemodialysis Fistula Maturation Study followed 602 enrolled participants, with maturation ascertained in 535. Among participants already on dialysis, unassisted maturation was 29% at 3 months, 67% at 6 months, and 76% at 12 months; among predialysis CKD participants the same figures were 10%, 38%, and 58% [9]. Median time from creation to maturation was 115 days overall (IQR 86 to 171), and it differed by indication — 105 days for those with kidney failure, 170 days for predialysis CKD [9].

The reintervention burden is the part that gets left out of the counseling conversation. Roughly 37.7% of the kidney-failure participants underwent a procedure to facilitate maturation or manage a complication before the fistula ever matured, and 47.5% of the fistulas that did mature required further intervention to maintain patency [9]. Functional patency of matured fistulas was 87% at one year (95% CI 83.2% to 90.2%) and 75% at two years (95% CI 69.7% to 79.7%) [9].

Clinical Pearl

During the months a fistula is maturing, the patient is dialyzing through a catheter. Attempting a fistula does not remove the line — it adds a surgery on top of it and keeps the line until the fistula works, if it ever does [9].

“Fistula First” and Its Confounding Problem

The hierarchy was built on real associations. Ravani’s systematic review pooled 62 cohort studies and 586,337 participants and found a consistent gradient of catheter > graft > fistula: catheter versus fistula carried a relative risk of 1.53 (95% CI 1.41 to 1.67) for all-cause mortality, 2.12 (95% CI 1.79 to 2.52) for fatal infection, and 1.38 (95% CI 1.24 to 1.54) for cardiovascular events [10].

Those authors also graded the risk of bias in the underlying studies as high, with selection bias called out specifically [10]. That caveat is the hinge of the entire topic. The association is not in doubt. The causal reading is.

Sicker patients are less likely to receive a fistula and less likely to mature one. They crash onto dialysis with poor vessels and a short horizon, and they end up on catheters. Comparing catheter patients to fistula patients therefore compares sicker people to healthier people and credits the difference to hardware [14].

Three studies take that reading apart:

  • Brown 2017 analyzed 115,425 incident hemodialysis patients aged 67 and older. The fistula-first group had the expected advantage (HR 0.50). The decisive comparison is the group that attempted a fistula, had it fail, and started dialysis on a catheter anyway — dialyzing through a catheter, exactly like the reference group — who still had lower mortality (HR 0.66) [11]. Patients who merely qualified for an attempt did better even without a working fistula [11].
  • Quinn 2017 adjudicated cause of death in 2,300 Canadian incident patients. If catheters killed through line sepsis, access-related deaths should dominate. They did not: 14 of 617 deaths, roughly 2%, were access-related [12].
  • Lyu 2022 applied a target-trial-emulation framework to 19,867 elderly patients. Conventional weighting reproduced the fistula advantage; an instrumental-variable analysis using surgeon proclivity — a design built to address unmeasured confounding — found no association between access type and mortality, sepsis, or hospitalization [13].

Quinn and Ravani had already named the problem in 2014, arguing that the certainties behind fistula-first were fading under exactly this kind of scrutiny [14].

The confounding tell

When a group whose fistula failed — and who therefore dialyze through a catheter — still outperforms the catheter-first group, the benefit cannot be living in the fistula [11]. It is living in whatever made those patients candidates. Carry that model into every access conversation.

What Randomization Has Shown

Randomized evidence in this space is thin and specific.

Aitken’s trial [15] randomized 121 patients requiring urgent access to an early-cannulation graft or a tunneled catheter. Culture-proven bacteremia at 6 months occurred in 10 of 61 catheter patients (16.4%) versus 2 of 60 graft patients (3.3%) — a risk ratio of 0.2 (95% CI 0.12 to 0.56, P = 0.02) [15]. Mortality was also lower in the graft arm (5% vs 16%, RR 0.3, 95% CI 0.08 to 0.45, P = 0.04), and costs did not differ significantly (P = 0.24) [15]. Note the appraisal caveats: a single-center trial of 121 patients, powered for a bacteremia reduction from 24% to 5%, with an author affiliated with the graft manufacturer [15]. The direction is credible; the magnitude in a 121-patient trial is not precise.

The fistula-versus-catheter question in older starters has resisted randomization altogether. The ACCESS-HD pilot trial set out to compare a fistula strategy against continued catheter use in older patients across 12 centers, and its primary endpoint was feasibility, not a clinical outcome. It could not recruit — the largest single reason eligible patients declined was that they preferred to keep the catheter they already had. Its clinical outcomes are secondary, underpowered, and hypothesis-generating only. (As of the last reference verification of this site’s mastery review in July 2026, the ACCESS-HD report was not yet PubMed-indexed; treat these figures as provisional and see the linked mastery review for the full appraisal.)

The AV Access Trial is currently testing fistula versus graft in older adults on hemodialysis, and its published protocol describes the design [16]. That comparison — not fistula versus catheter — may be the one randomization can actually answer.

The Framework That Replaced the Slogan

The 2019 KDOQI vascular access guideline retired the rigid hierarchy in favor of the ESKD Life-Plan and the principle of the right access, in the right patient, at the right time, for the right reasons [17].

Three questions drive the decision [17]:

  1. What is the expected survival and trajectory? A robust patient with years ahead collects the fistula’s back-loaded benefit. A frail patient with a short horizon may never reach it.
  2. What are the vessels and the timeline? Poor veins push toward a graft. An urgent need with no mature option means a bridging catheter regardless of preference.
  3. What does the patient want? ACCESS-HD demonstrated this is not a footnote — it was the dominant reason a randomized trial could not be run.
The high-output trap

In an older patient with reduced ejection fraction or pulmonary hypertension, a high-flow upper-arm fistula can worsen high-output physiology [17]. The gold-standard access can be the wrong access on hemodynamic grounds alone.

Examining an Access

Every dialysis patient encounter includes this exam, and it takes fifteen seconds.

  • Look — swelling, collateral veins across the chest or shoulder (a sign of central stenosis), aneurysmal dilation, skin thinning over a puncture site, erythema.
  • Feel — a continuous thrill along the length of the access. Loss of thrill precedes loss of bruit, so serial palpation detects stenosis earlier than auscultation.
  • Listen — a continuous low-pitched bruit. A high-pitched, discontinuous, or systolic-only bruit suggests stenosis.
  • Ask the unit — rising venous pressures, difficulty achieving prescribed blood flow, prolonged bleeding after needle removal, or recirculation are the earliest functional signs of a failing access. Surveillance and referral thresholds are set out in the 2019 KDOQI vascular access guideline [17].
Protect the veins before they are needed

The 2019 KDOQI guideline recommends against using forearm and upper-arm veins suitable for vascular access for venipuncture or PICC placement in patients with CKD stage 4 or 5 [17]. A PICC placed for convenience in a patient approaching dialysis can permanently remove that arm from the access plan. Ask about kidney function before any upper-extremity line goes in.

Part 3: Peritoneal Dialysis Catheter

A soft, cuffed catheter is tunneled into the peritoneal cavity with the tip directed into the pelvis, where gravity and the deepest recess of the abdomen give the best drainage. Placement may be open surgical, laparoscopic, percutaneous, or peritoneoscopic; the ISPD 2019 access guideline reviews technique selection, catheter configuration, and adjunctive maneuvers such as rectus sheath tunneling and omentopexy [18].

Break-in. The ISPD 2019 guideline recommends a break-in period of at least two weeks before elective initiation, allowing the exit site and cuffs to heal and reducing early leak [18]. Urgent-start programs shorten this deliberately, accepting a higher early leak risk in exchange for avoiding a hemodialysis catheter [18].

Mechanical problems cluster early and are mostly about position and pressure:

Problem Mechanism Typical management
Poor drainage Tip migration out of the pelvis, omental wrapping, constipation Treat constipation first; imaging; reposition or replace [18]
Early leak Defect at the insertion site under fill pressure Reduce fill volume, supine exchanges, or pause; surgical repair if large [18]
Hernia Chronically raised intra-abdominal pressure Observe if small and asymptomatic; repair if symptomatic [18]
Exit-site or tunnel infection Colonization along the catheter tract Topical and systemic therapy per ISPD 2023; catheter removal if refractory [19]

Infection. Peritonitis presents as cloudy effluent with abdominal pain, and the effluent — not the pain — is the diagnostic sample. Send cell count with differential, Gram stain, and culture before starting empiric intraperitoneal antibiotics. The ISPD 2022 peritonitis guideline sets out empiric regimens, duration, and the indications for catheter removal [20]; the ISPD 2023 catheter-related infection update covers exit-site and tunnel infection specifically [19].

Clinical Pearl

Cloudy effluent is peritonitis until proven otherwise, and the culture must be drawn before the first antibiotic dose [20]. Relapsing peritonitis with the same organism, refractory peritonitis, and fungal peritonitis are catheter-removal indications, not antibiotic-escalation indications [20].

Bringing It Together

Three procedural decisions recur across a nephrology career, and each one is a judgment before it is a technique.

Biopsy is worth doing when the result will change management, and the risk it carries is real but small — macroscopic hematuria near 3.5% and transfusion near 0.9% in pooled data [2], with roughly a third of complications declaring after the 8-hour mark [1].

Vascular access is chosen for a patient, not for a registry. The observational survival advantage of the fistula is inflated by selection [10][11][12][13]; the maturation burden is heavier than the slogan implies [9]; and the framework to use is the ESKD Life-Plan [17].

The PD catheter rewards planning — a two-week break-in, an honest conversation about hernia and leak risk, and a low threshold to sample cloudy effluent [18][20].

📖 Ready for a Deeper Dive?

Explore these Lecture Series modules, Student Handouts, and Clinical Mastery reviews:

References

  1. Whittier WL, Korbet SM. Timing of complications in percutaneous renal biopsy. J Am Soc Nephrol. 2004;15(1):142-147. PMID: 14694166
  2. Corapi KM, Chen JL, Balk EM, Gordon CE. Bleeding complications of native kidney biopsy: a systematic review and meta-analysis. Am J Kidney Dis. 2012;60(1):62-73. PMID: 22537423
  3. Manno C, Strippoli GF, Arnesano L, et al. Predictors of bleeding complications in percutaneous ultrasound-guided renal biopsy. Kidney Int. 2004;66(4):1570-1577. PMID: 15458453
  4. Zhan T, Lou A. Comparison of outcomes of an 18-gauge vs 16-gauge ultrasound-guided percutaneous renal biopsy: a systematic review and meta-analysis. Ren Fail. 2023;45(2):2257806. PMID: 37724553
  5. Sethi S, Haas M, Markowitz GS, et al. Mayo Clinic/Renal Pathology Society Consensus Report on Pathologic Classification, Diagnosis, and Reporting of GN. J Am Soc Nephrol. 2016;27(5):1278-1287. PMID: 26567243
  6. Whittier WL. Complications of the percutaneous kidney biopsy. Adv Chronic Kidney Dis. 2012;19(3):179-187. PMID: 22578678
  7. Trimarchi H, Barratt J, Cattran DC, et al. Oxford Classification of IgA nephropathy 2016: an update from the IgA Nephropathy Classification Working Group. Kidney Int. 2017;91(5):1014-1021. PMID: 28341274
  8. Bajema IM, Wilhelmus S, Alpers CE, et al. Revision of the International Society of Nephrology/Renal Pathology Society classification for lupus nephritis: clarification of definitions, and modified National Institutes of Health activity and chronicity indices. Kidney Int. 2018;93(4):789-796. PMID: 29459092
  9. Huber TS, Berceli SA, Scali ST, et al. Arteriovenous fistula maturation, functional patency, and intervention rates. JAMA Surg. 2021;156(12):1111-1118. PMID: 34550312
  10. Ravani P, Palmer SC, Oliver MJ, et al. Associations between hemodialysis access type and clinical outcomes: a systematic review. J Am Soc Nephrol. 2013;24(3):465-473. PMID: 23431075
  11. Brown RS, Patibandla BK, Goldfarb-Rumyantzev AS. The survival benefit of “fistula first, catheter last” in hemodialysis is primarily due to patient factors. J Am Soc Nephrol. 2017;28(2):645-652. PMID: 27605542
  12. Quinn RR, Oliver MJ, Devoe D, et al. The effect of predialysis fistula attempt on risk of all-cause and access-related death. J Am Soc Nephrol. 2017;28(2):613-620. PMID: 28143967
  13. Lyu B, Chan MR, Yevzlin AS, Gardezi A, Astor BC. Arteriovenous access type and risk of mortality, hospitalization, and sepsis among elderly hemodialysis patients: a target trial emulation approach. Am J Kidney Dis. 2022;79(1):69-78. PMID: 34118301
  14. Quinn RR, Ravani P. Fistula-first and catheter-last: fading certainties and growing doubts. Nephrol Dial Transplant. 2014;29(4):727-730. PMID: 24327565
  15. Aitken E, Thomson P, Bainbridge L, et al. A randomized controlled trial and cost-effectiveness analysis of early cannulation arteriovenous grafts versus tunneled central venous catheters in patients requiring urgent vascular access for hemodialysis. J Vasc Surg. 2017;65(3):766-774. PMID: 28236919
  16. Murea M, Gardezi AI, Goldman MP, et al. Study protocol of a randomized controlled trial of fistula vs. graft arteriovenous vascular access in older adults with ESKD on hemodialysis: the AV Access Trial. BMC Nephrol. 2023;24(1):43. PMID: 36829135
  17. Lok CE, Huber TS, Lee T, et al. KDOQI Clinical Practice Guideline for Vascular Access: 2019 Update. Am J Kidney Dis. 2020;75(4 Suppl 2):S1-S164. PMID: 32778223
  18. Crabtree JH, Shrestha BM, Chow KM, et al. Creating and maintaining optimal peritoneal dialysis access in the adult patient: 2019 update. Perit Dial Int. 2019;39(5):414-436. PMID: 31028108
  19. Chow KM, Li PK, Cho Y, et al. ISPD catheter-related infection recommendations: 2023 update. Perit Dial Int. 2023;43(3):201-219. PMID: 37232412
  20. Li PK, Chow KM, Cho Y, et al. ISPD peritonitis guideline recommendations: 2022 update on prevention and treatment. Perit Dial Int. 2022;42(2):110-153. PMID: 35264029

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