Emergency Medicine Hub / Renal & Genitourinary • 3 min read • 3 sections

Acute Urinary Retention, Urologic Instrumentation & Priapism

Mastery of emergency urologic presentations and instrumentation: acute urinary retention (AUR), difficult catheterization algorithms (Coudé tip, lidocaine instillation, flexible cystoscopy), percutaneous suprapubic cystostomy, ischemic vs. non-ischemic priapism aspiration and phenylephrine irrigation, and paraphimosis reduction.

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High-Acuity

Acute Urinary Retention (AUR)

Diagnosed when post-void bladder ultrasound volume > 300-500 mL in a patient unable to void. Immediate decompression with 16-18 Fr Foley catheter.

Difficult Male Catheterization

Step 1: Instill 10-20 mL of 2% lidocaine jelly with a penile clamp for 5-10 min (anesthesia + lubrication + stretches urethra). Step 2: Use 16-18 Fr Coudé catheter with curved tip pointed anteriorly (towards 12 o'clock). Step 3: Call urology for guidewire/flexible cystoscopy. If obstructed or false passage -> Percutaneous Suprapubic Cystostomy.

Post-Obstructive Diuresis

Urine output > 200 mL/hr for > 2 consecutive hours following bladder decompression. Monitor electrolytes (severe hypokalemia, hypomagnesemia, hyponatremia) and replace 50% of hourly urine output with 0.45% NS if volume depleted.

Ischemic Priapism

Painful, rigid penile shaft with soft glans penis lasting > 4 hours. Cavernosal blood aspiration reveals dark, deoxygenated blood. Irrigate with Phenylephrine 100-500 mcg/mL (inject 1 mL every 3-5 minutes, max 1,000 mcg in 1 hour; monitor blood pressure and ECG).

Paraphimosis Reduction

Urologic emergency where retracted foreskin constricts coronal sulcus. Apply ice and manual circumferential compression for 5-10 minutes to reduce edema, then grasp foreskin with index/middle fingers while pushing glans backward with thumbs. If refractory: puncture glans with 20G needle (Dundee technique) or dorsal slit under local block.

Coudé Catheter

Curved tip catheter designed to navigate past enlarged prostatic lobes.

Balanitis & Balanoposthitis

Inflammation of glans penis (balanitis) or glans + foreskin (balanoposthitis), common in uncircumcised diabetics; treat with hygiene and topical clotrimazole or hydrocortisone.

Bottom-Line Clinical Pearl

In ischemic (low-flow) priapism (a true compartment syndrome of the penis), do not delay aspiration: cavernous blood gas reveals hypoxemia and acidemia (pO2 < 30, pCO2 > 60, pH < 7.25). Aspirate blood until bright red, then inject diluted Phenylephrine (100-500 mcg/mL) intracavernosally q3-5min. For acute urinary retention in men with BPH, a Coudé-tip catheter oriented anteriorly bypasses the hypertrophied median lobe.

EMERGENCY: Ischemic Priapism Time Window

Ischemic (low-flow) priapism is a compartment syndrome of the corpora cavernosa. Beyond 12 hours, marked cellular edema and thickening of the sinusoidal trabeculae occur; beyond 24 to 48 hours, irreversible corporal fibrosis, cavernous thrombosis, and permanent impotence develop. Perform immediate needle aspiration and intracavernosal phenylephrine irrigation!

Priapism: Ischemic (Low-Flow) vs. Non-Ischemic (High-Flow)

Characteristic	Ischemic Priapism (Low-Flow, 95% of cases)	Non-Ischemic Priapism (High-Flow, 5%)
Pathophysiology	Impaired venous outflow -> stasis, ischemia, acidosis, and compartment syndrome	Unregulated cavernous arterial inflow from AV fistula (typically post-straddle trauma)
Etiologies	Sickle cell disease, trazodone, PDE-5 inhibitors + cocaine, antipsychotics (chlorpromazine)	Blunt perineal or penile trauma, arterial laceration
Pain & Rigidity	Excruciatingly painful; corpora cavernosa fully rigid; glans penis and corpus spongiosum flaccid	Painless or mild discomfort; semi-rigid/tumescent penis
Cavernosal Blood Gas (CBG)	Dark deoxygenated venous blood: $pH < 7.25$, $pCO_2 > 60\text{ mmHg}$, $pO_2 < 30\text{ mmHg}$	Bright red arterial blood: $pH > 7.40$, $pCO_2 < 40\text{ mmHg}$, $pO_2 > 90\text{ mmHg}$
Emergency Management	Medical Emergency: Dorsal nerve block -> 19G needle aspiration at 2 or 10 o'clock -> Phenylephrine irrigation (100-500 mcg/mL) -> Winter/Al-Ghorab surgical shunt	Elective/Non-emergent: Ice, observation; elective outpatient embolization by interventional radiology if persistent

Percutaneous Suprapubic Cystostomy Technique

Indicated when transurethral catheterization fails due to strictures, severe BPH, or urethral trauma:

1. Prerequisites: Bladder must be distended and palpable or clearly visualized on ultrasound at least 4-5 cm above pubic symphysis (contraindicated in empty bladder, prior lower abdominal surgery with bowel adhesions, or pelvic hematoma). 2. Technique: Prep and drape suprapubic area. Inject 10-15 mL 1% lidocaine 2 cm superior to pubic symphysis in midline while continuously aspirating until urine return confirms bladder entry. 3. Insertion: Make a 0.5 cm vertical skin nick. Under real-time ultrasound guidance, advance the trochar-catheter assembly or Seldinger needle angled 60° caudally toward the pelvis. Confirm urine return, advance guidewire, dilate tract, and feed the 14-16 Fr suprapubic catheter into bladder. Inflate balloon with 5-10 mL sterile water and secure to abdominal wall.

Clinical Pitfalls

Inflating the Foley balloon in the urethra: If urine return is not seen before balloon inflation, the balloon may be inflated within the prostatic urethra, causing severe urethral rupture and hemorrhage; ALWAYS advance the catheter to the hub before inflating the balloon!
Clamping the catheter after rapid decompression: The historic myth that rapid bladder decompression causes hemorrhagic cystitis has been debunked; rapid total bladder drainage is safe and relieves severe sympathetic hypertension.

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