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renal.aki.post-renal.v1

Acute Kidney Injury — Post-renal (Obstructive) Mechanism

nephrologyacuteadultpediatricpregnancy
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Care setting:

Encounter flow

12/12 authored

Canonical 12-phase frame with authored status for this dossier.

Current phase

Frame

Detailed

Confirm AKI by KDIGO 2012 staging AND obstruction profile on imaging (hydronephrosis / bladder distention / new anuria) (KDIGO 2012 AKI)

Inputs
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Advance rule
Set
Advance when

KDIGO criteria met + post-renal pivot suspected

Patient inputs (12)

Age + sex drive BPH vs gyn-malignancy probability (AUA BPH 2021)

KDIGO staging + Cr response to decompression (KDIGO 2012 AKI)

Required to compute Cr ratio for KDIGO stage (KDIGO 2012 AKI)

Anuria / oliguria / fluctuating output suggests obstruction (KDIGO 2012 AKI)

Hemodynamic screen — obstructed-infected kidney → urosepsis (AUA Stone 2016)

Hyperkalemia from oliguria + obstructive AKI; AEIOU criterion (KDIGO 2012 AKI)

Hematuria → stone; pyuria → infected obstruction → STAT decompression (AUA Stone 2016)

First-line — hydronephrosis + bladder distention (KDIGO 2012 AKI)

Post-void residual >300 mL supports outlet obstruction (AUA BPH 2021)

BPH history + recent anticholinergic / decongestant exposure (AUA BPH 2021)

Cervical / prostate / colorectal / bladder cancer with progressive ureteral compression (KDIGO 2012 AKI)

Iatrogenic ureteral injury / radiation-induced fibrosis (KDIGO 2012 AKI)

* = hard-required. Engine cannot meaningfully run until these are filled.

Severity triggers (12)

12 need judgement
  • informationallife_threateningbilateral_ureteral_or_single_kidney_obstruction
    Bilateral ureteral obstruction OR obstruction of solitary kidney — STAT decompression with PCN or retrograde stent (KDIGO 2012 AKI; AUA Stone 2016 PMID 27238616)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereBPH_AUR
    BPH-associated acute urinary retention — palpable suprapubic bladder + post-void residual >300 mL + recent anticholinergic/decongestant/opioid exposure (AUA BPH 2021 PMID 34384237)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverepelvic_malignancy_compression
    Pelvic / retroperitoneal malignancy with progressive ureteral compression (cervical, prostate, colorectal, bladder, lymphoma, retroperitoneal sarcoma) (KDIGO 2012 AKI)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereretroperitoneal_fibrosis
    Retroperitoneal fibrosis (Ormond disease) — periaortic soft tissue encasing ureters; idiopathic or secondary (IgG4-related, drug-induced ergot, malignancy) (KDIGO 2012 AKI)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereurolithiasis_obstructive
    Obstructive urolithiasis — colic + hydronephrosis + stone on CT KUB; infected stone is surgical emergency (AUA Stone 2016 PMID 27238616)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereiatrogenic_ureteral_injury
    Iatrogenic ureteral injury — post-hysterectomy, colectomy, pelvic radiation, ureteroscopy; new oliguria + flank pain + urinoma (KDIGO 2012 AKI)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverefungus_ball_immunocompromised
    Fungus ball obstruction (typically Candida) in immunocompromised / chronic catheterization — hydronephrosis + funguria + AKI (KDIGO 2012 AKI)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverepost_obstructive_diuresis
    Post-obstructive diuresis — UOP >200 mL/h × 2-3h post-decompression with electrolyte wasting (Na, K, Mg, PO4); replace 50-75% UOP with 0.45% NaCl (KDIGO 2012 AKI)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderateneurogenic_bladder_high_PVR
    Neurogenic bladder (SCI, MS, DM, post-stroke, MSA) with high PVR + recurrent retention → AKI (KDIGO 2012 AKI)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderateblood_clot_obstruction
    Obstructive blood clots in collecting system — gross hematuria + flank pain + AKI (post-TURP, bladder tumor, anticoagulant-related) (KDIGO 2012 AKI)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatepediatric_PUJ
    Pediatric pelviureteric junction obstruction — antenatally diagnosed or symptomatic (flank pain, UTI, hematuria) with hydronephrosis (KDIGO 2012 AKI)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatepregnancy_hydronephrosis_physiologic
    Pregnancy-associated hydronephrosis — physiologic right > left from gravid uterus + progesterone effect; pathologic if AKI + pain (KDIGO 2012 AKI; AUA Stone 2016)
    Trigger could not be auto-evaluated — needs clinician judgement.

Workflow calculators

Run this disease's risk and dosing calculators inline.

RISK_STRATIFICATIONoptionalDrives severity classification
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Recommended regimen

Post-renal AKI — STAT decompression → underlying treatment → post-obstructive diuresis management → recovery (KDIGO 2012 AKI; AUA Stone 2016; AUA BPH 2021)
axis: postrenal_decompression_and_recoverystep 1 - Step 1 — Immediate decompression (level-appropriate)
Selected step "Step 1 — Immediate decompression (level-appropriate)" — Confirmed obstructive AKI — bladder distention OR hydronephrosis + AKI
  • foley_catheter
    first line
    mechanical_decompression
    triggers: outlet_obstruction, bph_aur, neurogenic_bladder_high_pvr
    AUA BPH 2021 PMID 34384237 — foley relieves outlet obstruction immediately; document residual volume drained
  • percutaneous_nephrostomy
    first line
    mechanical_decompression
    triggers: ureteral_obstruction, infected_obstruction, failed_retrograde_stent
    AUA Stone 2016 PMID 27238616 — PCN preferred over stent for infected obstruction + emergent decompression
  • retrograde_ureteral_stent
    first line
    mechanical_decompression
    triggers: ureteral_obstruction_non_infected, pregnancy_obstruction
    AUA Stone 2016 — equivalent to PCN for non-infected ureteral obstruction; preferred in pregnancy

outpatient playbook — drug actions (3)

  1. 1. tamsulosin maintenance
    0.4 mg PO daily • PO • daily
    trigger: BPH post-AUR
    AUA BPH 2021
  2. 2. finasteride if large prostate
    5 mg PO daily • PO • daily
    trigger: Prostate volume >40 cc / recurrent AUR
    AUA BPH 2021 — long-term reduction
  3. 3. prednisone taper for RPF
    Per protocol taper × 6 mo • PO • daily taper
    trigger: RPF on imaging
    RPF guideline; surveillance MRI/CT q3-6 mo

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: Cr rise with anuria / oliguria / fluctuating output (KDIGO 2012 AKI); Suprapubic fullness / distention + acute urinary retention (AUA BPH 2021 PMID 34384237); Flank pain ± renal colic ± hematuria — obstructive uropathy (AUA Stone 2016 PMID 27238616).

Objective

- No vitals, labs, or imaging entered for this encounter.

Assessment

**Acute Kidney Injury — Post-renal (Obstructive) Mechanism** (renal.aki.post-renal.v1).
Phenotype framing: Sub-phenotypes: bilateral ureteral obstruction / single-kidney obstruction / BPH-AUR / pelvic malignancy compression / RPF / urolithiasis / neurogenic bladder / iatrogenic injury / clot / fungus ball / pediatric PUJ / pregnancy / post-obstructive diuresis (KDIGO 2012 AKI; AUA Stone 2016)
Scope: Confirm AKI by KDIGO 2012 staging AND obstruction profile on imaging (hydronephrosis / bladder distention / new anuria) (KDIGO 2012 AKI)

No severity triggers fired against current inputs.

Plan

Regimen axis: **Post-renal AKI — STAT decompression → underlying treatment → post-obstructive diuresis management → recovery (KDIGO 2012 AKI; AUA Stone 2016; AUA BPH 2021)** — step "Step 1 — Immediate decompression (level-appropriate)".
1. foley_catheter (mechanical_decompression, first line) — AUA BPH 2021 PMID 34384237 — foley relieves outlet obstruction immediately; document residual volume drained
2. percutaneous_nephrostomy (mechanical_decompression, first line) — AUA Stone 2016 PMID 27238616 — PCN preferred over stent for infected obstruction + emergent decompression
3. retrograde_ureteral_stent (mechanical_decompression, first line) — AUA Stone 2016 — equivalent to PCN for non-infected ureteral obstruction; preferred in pregnancy

Setting playbook (outpatient) — Post-AKI recovery + chronic obstruction surveillance (stent rotation, BPH med titration, RPF taper, oncologic stenting) (AUA BPH 2021; AUA Stone 2016; KDIGO 2024 CKD)
4. tamsulosin maintenance 0.4 mg PO daily PO daily — BPH post-AUR (AUA BPH 2021)
5. finasteride if large prostate 5 mg PO daily PO daily — Prostate volume >40 cc / recurrent AUR (AUA BPH 2021 — long-term reduction)
6. prednisone taper for RPF Per protocol taper × 6 mo PO daily taper — RPF on imaging (RPF guideline; surveillance MRI/CT q3-6 mo)

Non-pharmacologic actions:
- Urology q3-6 mo for stent rotation (AUA Stone 2016)
- Stone metabolic workup post-recurrent stone (AUA Stone 2016)
- Oncology coordination if malignant compression (KDIGO 2012 AKI)
- Permanent monitoring for solitary kidney + bilateral obstruction risk (KDIGO 2012 AKI)

AVOID / contraindication checks:
- No_blind_diuretic_before_decompression (KDIGO 2012 AKI)
- Replace_only_50_75_percent_of_post_obstructive_uop (KDIGO 2012 AKI)
- STAT_decompression_for_infected_obstruction (AUA Stone 2016)
- No_NSAIDs_during_recovery_phase (KDIGO 2012 AKI)
- Avoid_iodinated_contrast_during_AKI_recovery (KDIGO 2012 AKI)
- Renal_dose_aminoglycosides (KDIGO 2012 AKI)
- Retrograde_stent_preferred_in_pregnancy_over_PCN (AUA Stone 2016)

Monitoring

Regimen monitoring:
- hourly UOP post decompression (KDIGO 2012 AKI)
- BMP q6 12h during post obstructive diuresis (KDIGO 2012 AKI)
- K Mg PO4 replacement during PO diuresis (KDIGO 2012 AKI)
- daily Cr until stable (KDIGO 2012 AKI)
- monitor for recurrence after stent removal (AUA Stone 2016)

Setting (outpatient) monitoring:
- eGFR + UACR q3-6 mo × 1 year post-AKI (KDIGO 2024 CKD)
- BP at each visit (KDIGO 2024 CKD)
- Imaging per phenotype — US for stent, CT for RPF, urography for tumor (AUA Stone 2016)

Follow-up plan: Urology / nephrology / oncology follow-up by phenotype; permanent monitoring of solitary kidney + bilateral obstruction risk; stone metabolic workup; BPH med-rec; review anticholinergic burden (AUA Stone 2016; AUA BPH 2021; KDIGO 2024 CKD)
- Close-out criterion: Specialty follow-up + patient education complete

Monitoring phase: Strict I/O hourly post-decompression (post-obstructive diuresis); BMP q6-12h; Cr trajectory; replace 50-75% UOP with 0.45% NaCl during PO-diuresis; AVOID 100% replacement (perpetuates diuresis) (KDIGO 2012 AKI)

Disposition

Current setting: outpatient — Post-AKI recovery + chronic obstruction surveillance (stent rotation, BPH med titration, RPF taper, oncologic stenting) (AUA BPH 2021; AUA Stone 2016; KDIGO 2024 CKD)

Disposition criteria:
- Continue urology + nephrology co-management if chronic stent / single kidney (AUA Stone 2016)
- Transition to PCP if full recovery + no obstruction at 12 mo (KDIGO 2012 AKI)

Escalation triggers (move to higher acuity):
- Sustained eGFR <60 at 3 mo → neph.ckd.core.v1 (KDIGO 2024 CKD)
- Recurrent obstruction → repeat imaging + intervention (AUA Stone 2016)
- RPF imaging progression on steroids → mycophenolate / tamoxifen alternative

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] Bilateral ureteral obstruction OR obstruction of solitary kidney — STAT decompression with PCN or retrograde stent (KDIGO 2012 AKI; AUA Stone 2016 PMID 27238616)
- [SEVERE] BPH-associated acute urinary retention — palpable suprapubic bladder + post-void residual >300 mL + recent anticholinergic/decongestant/opioid exposure (AUA BPH 2021 PMID 34384237)
- [SEVERE] Pelvic / retroperitoneal malignancy with progressive ureteral compression (cervical, prostate, colorectal, bladder, lymphoma, retroperitoneal sarcoma) (KDIGO 2012 AKI)

Citations

- KDIGO 2012 AKI Guideline + AUA Surgical Management of Stones 2016 + AUA LUTS/BPH 2021 + STARRT-AKI / AKIKI for RRT timing [PMID:22890468](https://pubmed.ncbi.nlm.nih.gov/22890468/)
- Cited evidence (PMID 32668114) [PMID:32668114](https://pubmed.ncbi.nlm.nih.gov/32668114/)
- Cited evidence (PMID 27181456) [PMID:27181456](https://pubmed.ncbi.nlm.nih.gov/27181456/)
- Cited evidence (PMID 27238616) [PMID:27238616](https://pubmed.ncbi.nlm.nih.gov/27238616/)
- Cited evidence (PMID 34384237) [PMID:34384237](https://pubmed.ncbi.nlm.nih.gov/34384237/)

Last reconciled with current guidelines: 2026-05-22.
References
  • KDIGO 2012 AKI Guideline + AUA Surgical Management of Stones 2016 + AUA LUTS/BPH 2021 + STARRT-AKI / AKIKI for RRT timing — PMID:22890468
  • Cited evidence (PMID 32668114) — PMID:32668114
  • Cited evidence (PMID 27181456) — PMID:27181456
  • Cited evidence (PMID 27238616) — PMID:27238616
  • Cited evidence (PMID 34384237) — PMID:34384237