Step 2 CK · Surgery

Urologic Emergencies & Stones (Clinical)

Name: Urologic Emergencies & Stones (Clinical)
Creator: Veli Bakalov, MD

When acting beats imaging: torsion, retention, the infected stone, and more

Surgery·Urology·5 min read·9 high-yield points·Reviewed by Veli Bakalov, MD @HemeOncBuddy

Study materialsNo account needed

Card deckActive-recall cards · quick checks · quiz

High-yield

Testicular torsion: sudden pain, high-riding horizontal testis, absent cremasteric reflex, negative Prehn sign → surgical detorsion within 6 h plus bilateral orchiopexy; do not wait for ultrasound.
Epididymitis: gradual onset, positive Prehn sign, intact cremasteric reflex, dysuria; treat by likely organism: STI (usually under 35) → ceftriaxone 500 mg IM once plus doxycycline for 10 days; enteric only (usually over 35, E. coli) → levofloxacin for 10 days; insertive anal sex → ceftriaxone plus levofloxacin.
Acute urinary retention (BPH, anticholinergics, opioids, postoperative, neurologic) → immediate bladder catheterization, which is diagnostic and therapeutic.
Renal colic → noncontrast CT (ultrasound in pregnancy and children); stones under 5 mm usually pass with hydration and tamsulosin; over 10 mm → lithotripsy or ureteroscopy; staghorn → percutaneous nephrolithotomy.
Obstructing stone plus fever or pyuria = urologic emergency → IV antibiotics and nephrostomy tube or ureteral stent; remove the stone only after the infection clears.
Calcium oxalate is most common and radiopaque; struvite staghorns form in alkaline urine with urease-positive Proteus; uric acid is radiolucent in acidic urine (alkalinize); cystine forms hexagonal crystals.
Fournier gangrene (diabetic, perineal crepitus, pain out of proportion, necrosis) → emergent debridement plus broad-spectrum antibiotics.
Ischemic priapism (over 4 h, painful, rigid; sickle cell, trazodone, PDE5 inhibitors) → corporal aspiration and intracavernosal phenylephrine; high-flow priapism after trauma is painless and less urgent.
Paraphimosis (foreskin trapped behind the glans, often after catheterization) → manual reduction, dorsal slit if that fails.

The acute scrotum

Testicular torsion. Sudden, severe unilateral testicular pain (often waking the patient, with nausea and vomiting), a high-riding testis with a horizontal lie, an absent cremasteric reflex, and a negative Prehn sign (no relief with elevation). It peaks in adolescents with a bell-clapper deformity, in which the testis is not anchored to the tunica vaginalis and can twist on its cord.

Act before imaging. Torsion is a surgical emergency: explore and detorse within 6 hours to salvage the testis, then perform bilateral orchiopexy, because the contralateral side shares the deformity. Salvage rates fall sharply after 6 hours, so a clinical diagnosis goes straight to the operating room. If Doppler ultrasound is obtained in an equivocal case, it shows decreased or absent testicular blood flow. A nonviable testis is removed.

Manual detorsion (rotating the testis outward, like opening a book) can buy time when the operating room is delayed, but it never replaces surgical exploration and orchiopexy.

Three causes of scrotal pain

Feature	Testicular torsion	Epididymitis	Torsion of appendix testis
Onset	Sudden, severe	Gradual; often dysuria	Subacute, localized
Exam	High-riding testis, horizontal lie	Tender epididymis, normal lie	Tender upper-pole nodule, "blue dot" sign
Cremasteric reflex	Absent	Intact	Intact
Prehn sign	Negative (no relief)	Positive (relief with elevation)	Not helpful
Doppler	Decreased or absent flow	Increased flow	Normal testicular flow
Management	Detorsion within 6 h, bilateral orchiopexy	Antibiotics	Analgesics; self-limited

Epididymitis therapy by likely organism (CDC 2021). Men under 35 usually have Chlamydia or gonorrhea: treat with ceftriaxone 500 mg IM once plus doxycycline 100 mg twice daily for 10 days. Men over 35 usually have Escherichia coli or other enteric organisms (often with BPH or instrumentation): treat with levofloxacin 500 mg daily for 10 days, only when gonorrhea is excluded, because a fluoroquinolone alone does not cover it. Men who practice insertive anal sex need coverage of both: ceftriaxone plus levofloxacin.

Acute urinary retention

Presentation. Sudden inability to void, suprapubic pain, and a palpably distended bladder. Precipitants include BPH, anticholinergics and opioids (and sympathomimetics such as decongestants), the postoperative state, and neurologic causes such as cord compression.

Management. Immediate bladder catheterization is both diagnostic and therapeutic; a bladder scan documents the retained volume. If a urethral catheter cannot pass, place a suprapubic catheter. After decompression, watch for postobstructive diuresis. In BPH, starting an α-blocker before a trial without the catheter improves the chance of voiding.

Kidney stones

Renal colic. A ureteral stone causes severe colicky flank pain radiating to the groin, hematuria, and a patient writhing in pain (unlike peritonitis, where patients lie still). Noncontrast CT of the abdomen and pelvis is the gold-standard test; ultrasound is used first in pregnancy and children to avoid radiation. NSAIDs are first-line analgesia.

Under 5 mm: usually passes spontaneously with hydration and tamsulosin (medical expulsive therapy).
5–10 mm: may need intervention if it does not pass.
Over 10 mm or refractory: shockwave lithotripsy or ureteroscopy.
Staghorn calculi: percutaneous nephrolithotomy.

The infected obstructing stone. An obstructing stone with superimposed urinary infection (fever, pyuria) means pyonephrosis and impending urosepsis. Other reasons for urgent intervention are AKI, obstruction of a solitary kidney, and intractable pain or vomiting.

RecognizeObstructing stone plus fever or pyuria.
ResuscitateIV fluids and IV antibiotics covering gram-negatives.
Decompress emergentlyPercutaneous nephrostomy tube or ureteral stent.
Remove the stone laterDefinitive treatment only after the infection clears.

Infected obstructing stone

Never treat the stone itself (lithotripsy, ureteroscopy) in an infected, obstructed system before it is drained.

Stone chemistry

Stone	Setting	Imaging and crystals	Prevention or treatment
Calcium oxalate	Most common; hypercalciuria, hypocitraturia, fat malabsorption (enteric hyperoxaluria)	Radiopaque; envelope-shaped crystals	Fluids, thiazide for hypercalciuria, citrate; keep normal dietary calcium
Struvite	Urease-producing organisms (Proteus, Klebsiella) in alkaline urine; staghorn calculi	Radiopaque; coffin-lid crystals	Remove the whole stone and treat the infection
Uric acid	Acidic urine; gout, high cell turnover	Radiolucent: missed on plain film, seen on CT	Alkalinize the urine to dissolve; allopurinol if hyperuricosuric
Cystine	Children with cystinuria	Hexagonal crystals	Hydration, urinary alkalinization

General prevention. High fluid intake is the cornerstone for every stone type, with less sodium and animal protein. Restricting dietary calcium backfires, because gut calcium binds oxalate and limits its absorption.

Fournier gangrene and penile emergencies

Fournier gangrene. This is polymicrobial necrotizing fasciitis of the perineum and genitalia, typically in diabetic or immunocompromised men. Findings are severe pain out of proportion to the exam, crepitus, skin necrosis, and systemic toxicity.

Treat Fournier gangrene with emergent wide surgical debridement plus broad-spectrum IV antibiotics; do not delay surgery for imaging, because delay is fatal. Repeat debridement is often needed.

Priapism is an erection lasting more than 4 hours, and the key question is ischemic or not.

Ischemic vs non-ischemic priapism

Feature	Ischemic (low-flow)	Non-ischemic (high-flow)
Mechanism	Trapped venous blood; a compartment syndrome of the corpora	Unregulated inflow from a cavernosal artery fistula
Causes	Sickle cell disease, trazodone, PDE5 inhibitors, intracavernosal injections	Perineal or penile trauma
Exam	Painful, rigid	Non-painful, less rigid
Corporal blood gas	Dark, hypoxic, acidotic	Bright red, arterial
Treatment	Emergent corporal aspiration and intracavernosal phenylephrine	Less urgent: often observation or embolization

Paraphimosis. A retracted foreskin trapped behind the glans causes painful glans edema and venous congestion, a true emergency. Reduce it manually by compressing the glans to squeeze out the edema and pulling the foreskin forward; perform a dorsal slit if reduction fails. It is often iatrogenic, when the foreskin is not replaced after catheterization or examination.

Paraphimosis (foreskin stuck behind the glans) is the emergency; phimosis (foreskin that cannot be retracted) usually is not, and it is physiologic in young boys.