One-page cheat sheet: BPH and urinary retention

Benign prostatic hyperplasia (BPH) and urinary retention are Step “bread and butter”: common presentations, classic drug choices, and a handful of testable contraindications that show up everywhere (medicine, surgery, OB). This is your quick-hit, shareable one-page cheat sheet—built to help you recognize the pattern fast and pick the right next step.

The 10-second picture: what BPH is (and isn’t)

BPH = benign hyperplasia of the periurethral (transition zone) prostate → compresses the prostatic urethra → lower urinary tract symptoms (LUTS) and sometimes acute urinary retention (AUR).

Not cancer (prostate adenocarcinoma usually arises in the peripheral/posterior zone and is often asymptomatic early).

Visual mnemonic (fast + sticky)

“Pee can’t PASS” = BPH LUTS

Think: Prostate Around urethra Squeezes Stream.

One-liner: BPH increases urethral resistance → bladder works harder → hesitancy, weak stream, incomplete emptying, nocturia.

Symptoms: obstructive vs irritative (test this like a reflex)

Obstructive (can’t get it out)	Irritative (bladder is angry)
Hesitancy	Frequency
Weak stream	Urgency
Intermittency	Nocturia
Straining	Dysuria (can occur, but consider UTI)
Incomplete emptying

High-yield clue: Post-void residual (PVR) elevated in obstruction (e.g., BPH, neurogenic bladder).

Acute urinary retention (AUR): the “don’t miss” scenario

Presentation

Sudden inability to urinate + suprapubic pain/distention
May have overflow dribbling (paradoxical incontinence)

Immediate management (Step-style)

Bladder decompression with Foley catheter (or suprapubic catheter if urethral catheterization is contraindicated/unsuccessful)
Start an $\alpha_1$ blocker (e.g., tamsulosin) to improve chance of successful trial of void
Evaluate triggers (meds, constipation, infection)

High-yield warning: After relieving chronic obstruction, watch for post-obstructive diuresis (polyuria, electrolyte shifts).

“Gotchas” that precipitate retention (common test stems)

Meds that worsen urinary retention (think: “can’t squeeze bladder or urethra too tight”)

Anticholinergics (e.g., diphenhydramine, TCAs, oxybutynin) → ↓ detrusor contraction
$\alpha$ -agonists/decongestants (e.g., pseudoephedrine) → ↑ internal sphincter tone
Opioids → urinary retention
Anesthesia/post-op state → retention
Constipation (mechanical + autonomic effects)

BPH pharmacology: the core Step 1/2 table

Two main drug classes (know MOA + side effects + who to choose)

Drug class	Examples	What it relaxes/changes	When it works	Signature adverse effects	High-yield pearls
$\alpha_1$ blockers	Tamsulosin (more $\alpha_{1A}$ -selective), alfuzosin, doxazosin, terazosin	Relaxes smooth muscle in prostate & bladder neck → ↓ outflow resistance	Days	Orthostatic hypotension, dizziness; ejaculatory dysfunction (esp. tamsulosin)	Great for rapid symptom relief. More BP effects with nonselective agents.
5- $\alpha$ -reductase inhibitors	Finasteride, dutasteride	↓ conversion testosterone → DHT → shrinks prostate over time	Months	↓ libido, ED, gynecomastia	Decreases PSA (classically ~50% after months). Best if enlarged prostate.

Memory hook:

“TAMsulosin TAMes the muscle” (fast relaxation)
“FINasteride FINishes DHT” (slow shrink)

Combination therapy (very testable)

Use $\alpha_1$ blocker + 5- $\alpha$ -reductase inhibitor when:

Significant symptoms and
Enlarged prostate (e.g., high PSA due to BPH, large volume on exam/imaging)

Rationale: fast relief + long-term size reduction.

Surgical/procedural management (Step 2 basics)

When to consider procedure

Refractory symptoms despite meds
Recurrent urinary retention
Recurrent UTIs due to obstruction
Bladder stones
Hematuria from BPH
Hydronephrosis / renal insufficiency from obstruction

Classic procedure

TURP (transurethral resection of the prostate)
- Complications to recognize:
  - Retrograde ejaculation
  - Erectile dysfunction (less common than ejaculation issues)
  - TURP syndrome: dilutional hyponatremia from absorption of hypotonic irrigation fluid → confusion, nausea, hypertension, bradycardia

Rapid-fire differentials (BPH vs prostatitis vs prostate cancer)

Condition	Key clues	Key exam/lab	Management hint
BPH	LUTS, progressive; usually afebrile	Smooth, enlarged, non-tender prostate	$\alpha_1$ blocker ± 5-ARI; TURP if complications
Acute bacterial prostatitis	Fever, chills, perineal pain, dysuria	Tender, boggy prostate; ↑ WBC	Fluoroquinolone or TMP-SMX; avoid vigorous prostate massage
Prostate cancer	Often asymptomatic early; later bone pain	Hard/nodular prostate; ↑ PSA	Diagnosis via biopsy; treat based on stage

“Stones tie-in”: why retention matters in renal land

Chronic bladder outlet obstruction (like BPH) can lead to:

Urinary stasis → UTIs
Bladder stones (especially with incomplete emptying)
Hydronephrosis → postrenal AKI in severe cases

Mini USMLE-style one-liners (shareable)

AUR + suprapubic pain → catheter now, ask questions later.
Need quick LUTS relief → tamsulosin (days).
Need to shrink a big prostate → finasteride/dutasteride (months) and PSA drops.
BPH + decongestants/anticholinergics = retention trap.
Post-TURP confusion → think hyponatremia (TURP syndrome).

Quick “choose the next best step” algorithm

Acute urinary retention?
→ Foley catheter (or suprapubic) + start $\alpha_1$ blocker
Stable LUTS (no red flags):
- Mild: lifestyle, watchful waiting
- Moderate-severe: $\alpha_1$ blocker
- Large prostate / high progression risk: add 5-ARI
Complications or refractory symptoms:
→ TURP / procedure