9.1 Urological Emergencies: Acute Retention, Renal Colic, Torsion & Hematuria

Acute Urinary Retention: Pathophysiology & Catheterization Pathways

Acute urinary retention (AUR) is the sudden, painful inability to voluntarily evacuate urine from a distended urinary bladder. The underlying pathophysiology involves an acute mismatch between detrusor contractile dynamics and bladder outflow resistance. Etiologies are categorized into mechanical outflow obstruction, neurogenic detrusor failure, and pharmacologically mediated smooth muscle alterations:

• Mechanical Outflow Obstruction: Benign prostatic hyperplasia (BPH) is the underlying etiology in greater than 60% of male cases. Additional mechanical causes include prostate adenocarcinoma, urethral stricture disease (frequently secondary to prior gonococcal urethritis or traumatic instrumentation), meatal stenosis, bladder neck contracture, impacted urethral calculi, and obstructing blood clots (clot retention).
• Neurogenic Detrusor Atony: Acute spinal cord injury, cauda equina syndrome, spinal anesthesia, diabetic autonomic cystopathy, and tabes dorsalis or neurosyphilis.
• Pharmacological Precipitants: Anticholinergic medications (atropine, glycopyrrolate, oxybutynin), tricyclic antidepressants (amitriptyline), first-generation sedating antihistamines (diphenhydramine), sympathomimetic alpha-agonists (pseudoephedrine causing internal urethral sphincter spasm), and systemic opioids.

Patients present in extreme distress with severe suprapubic pain, diaphoresis, and a palpable, exquisitely tender, smooth suprapubic mass that is dull to percussion and may extend to the level of the umbilicus. Bedside ultrasonography demonstrates bladder urine volumes typically exceeding 500 to 1,500 mL.

Catheterization vs. Suprapubic Cystostomy

Immediate therapeutic decompression via a standard 14 to 16 French Foley catheter using sterile technique and generous water-soluble lidocaine gel lubricant is the primary intervention. When urethral injury is suspected, avoid blind catheterization before urethral evaluation and obtain urgent urologic assistance. The classic clinical signs of urethral trauma—most commonly encountered following high-energy pelvic ring fractures or direct straddle perineal trauma—include:

1. Blood at the external urethral meatus
2. Perineal, scrotal, or penile hematoma ("butterfly" perineal ecchymosis)
3. High-riding, boggy, or non-palpable prostate on digital rectal examination (DRE)
4. Inability to spontaneously void following pelvic trauma

Repeated or forceful blind catheter attempts can worsen urethral injury and should be avoided. In a stable patient, obtain retrograde urethrography (RUG) to define the injury before catheterization. Arrange prompt bladder drainage with urologic assistance: selected partial injuries may permit a single gentle urethral catheter attempt by an experienced clinician; ultrasound-guided suprapubic drainage is appropriate when urethral drainage is unsafe or unsuccessful. Resuscitation of life-threatening associated injuries takes priority.

Post-Decompression Complications

Following rapid evacuation of substantial urine volumes, clinicians must anticipate two distinct physiological phenomena:

• Transient Hematuria ex Vacuo: Caused by the sudden decompression of stretched, engorged mucosal veins lining the bladder wall. This hematuria is usually mild, self-limiting, and rarely necessitates continuous irrigation.
• Post-Obstructive Diuresis (POD): Characterized by marked, sustained polyuria (> 200 mL/h for two consecutive hours, or > 3,000 mL in 24 hours) resulting from the clearance of accumulated systemic solutes (urea and osmols) combined with transient tubular unresponsiveness to antidiuretic hormone (nephrogenic diabetes insipidus). Management requires close hemodynamic monitoring, strict hourly fluid balance charting, serial serum electrolyte measurements, and intravenous fluid replacement tailored to replace 50% to 75% of hourly urinary output using 0.45% saline to prevent iatrogenic perpetuation of diuresis.

Testicular Torsion: The 6-Hour Golden Window

Testicular torsion represents a surgical emergency arising from the twisting of the spermatic cord along its longitudinal axis, causing initial mechanical occlusion of the pampiniform venous plexus followed rapidly by arterial thrombosis and irreversible hemorrhagic necrosis of testicular parenchyma.

Pathophysiology & Anatomical Predisposition

The fundamental anatomical predisposing defect in more than 85% of cases is the bell-clapper deformity. Under normal developmental anatomy, the tunica vaginalis adheres to the posterior and lateral surfaces of the testis and epididymis, anchoring them firmly to the scrotal wall. In the bell-clapper anomaly, the parietal reflection of the tunica vaginalis inserts abnormally high on the spermatic cord, leaving the entire testis, epididymis, and distal cord free to dangle within the tunica vaginalis cavity like a clapper inside an inverted bell, permitting spontaneous rotation.

The degree of ischemic injury is directly governed by the duration of torsion and the number of complete rotations (ranging from 180° to 720°). Testicular microvascular viability adheres to the 6-hour golden window:

• Detorsion within 6 hours: > 90% testicular salvage rate
• Detorsion at 6 to 12 hours: ~50% salvage rate
• Detorsion at 12 to 24 hours: < 20% salvage rate
• Detorsion beyond 24 hours: < 10% salvage rate (orchiectomy almost universally required)

Clinical Presentation & Physical Discriminators

Testicular torsion classically manifests during peak periods of testicular growth—most frequently in adolescent males aged 12 to 18 years, with a secondary peak during the neonatal period. The clinical presentation is marked by the sudden onset of severe, unremitting, unilateral scrotal or lower quadrant abdominal pain, often awakening the patient from sleep or triggered by vigorous physical exertion or mild trauma. Systemic autonomic symptoms, including nausea, vomiting, and tachycardia, occur in over 60% of cases.

Physical examination demonstrates the following pathognomonic triad of signs:

• High-Riding, Transversely Oriented Testis: Twisting of the spermatic cord shortens the longitudinal cord length, drawing the affected testis superiorly within the hemiscrotum and tilting it into an abnormal horizontal orientation.
• Absent Cremasteric Reflex: Stroking the ipsilateral superior-medial thigh fails to elicit cephalic retraction of the testis. The absence of the cremasteric reflex is the single most sensitive physical examination finding for testicular torsion (approaching 99% sensitivity).
• Negative Prehn Sign: Manual elevation of the affected hemiscrotum over the pubic symphysis fails to relieve or actively worsens the scrotal discomfort (a positive Prehn sign, wherein elevation relieves pain, is classically associated with acute epididymitis).

Diagnostic Dilemma & Operative Mandate

While high-resolution color Doppler ultrasonography (demonstrating absent or significantly diminished parenchymal arterial flow with elevated resistive indices) provides high diagnostic accuracy, imaging must never delay immediate surgical intervention when clinical suspicion is high. If an ultrasound machine or qualified radiologist is not instantly available, the patient must be transferred directly to the operating room for emergency scrotal exploration.

Manual detorsion (the "open-book" maneuver) may be attempted at the bedside while the surgical suite is mobilized. Because the vast majority of testes rotate inward toward the median raphe (medial rotation), the clinician rotates the affected testis outward from medial to lateral (similar to opening the pages of a book: clockwise for the left testis, counterclockwise for the right testis as viewed from below). Successful manual detorsion yields prompt relief of pain and return of normal vertical orientation, but it never replaces surgical exploration.

Operative Technique: Bilateral Scrotal Exploration & Orchidopexy

Surgical exploration is performed through a midline raphe or transverse hemiscrotal incision. Upon opening the tunica vaginalis, the hemiscrotum is inspected and the cord untwisted. Viability is assessed after wrapping the testis in warm, saline-soaked gauze sponges for 10 to 15 minutes and administering 100% supplemental oxygen. Signs of viability include restoration of pink color, bleeding on parenchymal puncture with a needle, and visible pulsation.

• If viable: The testis is preserved and secured to the underlying dartos musculature using a three-point fixation orchidopexy with permanent, non-absorbable sutures (such as 3-0 or 4-0 polypropylene).
• If non-viable (black, necrotic tissue without bleeding upon incision of the tunica albuginea): An orchiectomy is performed to prevent autoimmune anti-sperm antibody formation and chronic pain.
• Mandatory Contralateral Orchidopexy: Because the bell-clapper anomaly is anatomically bilateral in up to 80% of patients, exploration and three-point fixation orchidopexy of the contralateral, asymptomatic testis is mandatory during the same operative sitting.

Urolithiasis & Obstructive Sepsis: Emergency Decompression

Renal colic results from the acute luminal impaction of a urinary calculus within the ureter, triggering ureteral smooth muscle spasm, proximal hydroureteronephrosis, and acute distension of the renal capsule. Patients experience excruciating paroxysmal flank or loin pain radiating anteriorly and inferiorly along the anatomical distribution of the genitofemoral and ilioinguinal nerves (dermatomes T10–L1) toward the ipsilateral groin, scrotum, or labia majora.

Diagnostic Modality of Choice

The diagnostic gold standard for acute flank pain is an unenhanced, low-dose, non-contrast helical computed tomography scan of the kidneys, ureters, and bladder (non-contrast CT KUB). Non-contrast CT KUB achieves greater than 98% sensitivity and specificity, accurately identifying stone size, density (measured in Hounsfield units), exact anatomical location (ureteropelvic junction, pelvic brim crossing, or ureterovesical junction), and secondary signs of acute obstruction (perinephric stranding, renal enlargement, hydroureter). Plain abdominal radiography (KUB) misses radiolucent uric acid stones and small stones obscured by bowel gas. Renal ultrasonography is reserved as the primary screening tool in pregnant women and pediatric populations to avoid ionizing radiation.

The Obstructive Urosepsis Emergency

The clinical presence of an obstructing calculus accompanied by urinary tract infection or systemic sepsis constitutes an absolute urological emergency. An obstructed, infected collecting system functions as an undrained, pressurized closed-space abscess (pyonephrosis). Intrapelvic pressures rapidly exceed renal venous and lymphatic back-pressures, forcing bacteria and endotoxins directly into the systemic circulation and precipitating rapid septic shock, disseminated intravascular coagulation (DIC), and multi-organ dysfunction syndrome.

Emergency management dictates immediate, aggressive resuscitation and urgent urinary tract decompression:

1. Broad-spectrum intravenous antimicrobials (e.g., piperacillin-tazobactam or ceftriaxone plus an aminoglycoside) started immediately following blood and urine cultures.
2. Emergent source control via one of two decompression modalities:
   • Retrograde Ureteral Double-J (JJ) Stenting: Inserted cystoscopically under fluoroscopic visualization past the obstructing calculus into the renal pelvis.
   • Percutaneous Nephrostomy (PCN): Placed under ultrasound and fluoroscopic guidance directly into the renal calyx by an interventional radiologist or urologist; preferred in severely unstable septic shock, failed retrograde stenting, or severe purulent pyonephrosis.
3. Definitive Stone Treatment Ban: Ureteroscopy, laser lithotripsy, and extracorporeal shock wave lithotripsy (ESWL) are strictly contraindicated during the acute presentation of obstructive sepsis. Manipulating or fragmenting the calculus in an infected system worsens bacteremia and endotoxemia; definitive stone clearance is scheduled electively 2 to 4 weeks after complete resolution of infection.

Macroscopic Hematuria: Malignancy Workup & Clot Retention

Macroscopic (gross, visible) hematuria is the presence of sufficient blood in the urine to cause visible red, brown, or tea-colored discoloration. In adults, painless gross hematuria carries a greater than 20% to 30% risk of underlying malignancy—predominantly urothelial cell carcinoma (transitional cell carcinoma) of the bladder, renal pelvis, or ureter, as well as renal cell carcinoma (RCC) and advanced prostate cancer.

Diagnostic Protocol

Every adult patient presenting with an episode of painless macroscopic hematuria must undergo a comprehensive, two-pronged diagnostic evaluation:

1. Flexible Cystoscopy: Direct endoscopic visual inspection of the urethral mucosa, prostate, bladder floor, trigone, and ureteral orifices. Cystoscopy detects papillary lesions, but flat carcinoma in situ may be invisible. Urine cytology and appropriate bladder biopsies help identify and confirm CIS.
2. Multiphasic CT Urography (CTU): High-resolution contrast-enhanced computed tomography encompassing unenhanced, nephrographic, and delayed excretory phases. The excretory phase provides optimal visualization of the upper tract urothelium (calyces, renal pelvis, ureters) to exclude filling defects.

Emergency Management of Clot Retention

Clot retention occurs when extensive intravesical hemorrhage produces massive blood clot organization, occluding the internal urethral meatus and bladder neck. Initial bedside management requires:

• Placement of a large-bore, rigid-walled catheter (20 to 24 French) with wide drainage eyes (preferably a 3-way catheter).
• Vigorous manual bladder irrigation using a 60 mL catheter-tip Toomey syringe and sterile 0.9% normal saline. All organized clots must be systematically aspirated until the returning effluent is completely clear.
• Following clot clearance, initiation of continuous bladder irrigation (CBI) with sterile normal saline via the third lumen of the catheter, titrating the infusion rate to keep the drainage light pink and prevent recurrent clot assembly.

Priapism: Ischemic vs Non-Ischemic Differentiation

Priapism is a persistent, involuntary penile erection lasting longer than 4 hours that is unrelated to sexual stimulation. It is divided into two distinct pathophysiological entities:

• Ischemic (Low-Flow, Veno-Occlusive) Priapism: Represents > 95% of cases and constitutes a compartment syndrome of the corpora cavernosa. Venous outflow occlusion results in static, deoxygenated blood trapped within the cavernosa. Over 12 to 24 hours, progressive hypoxia, hypercapnia, and acidosis cause irreversible trabecular smooth muscle necrosis, corporal fibrosis, and permanent erectile dysfunction. Common etiologies include sickle cell disease (highly prevalent in the Caribbean), hematological malignancies, and pharmacological agents (intracavernosal prostaglandins, PDE-5 inhibitors, trazodone, antipsychotics). Corporal blood aspiration reveals dark, viscid blood with pH < 7.25, pO2 < 30 mmHg, and pCO2 > 60 mmHg. Immediate management includes corporal blood aspiration and irrigation with room-temperature 0.9% normal saline, followed by intracavernosal injection of the alpha-1 adrenergic agonist phenylephrine (100 to 500 mcg every 3 to 5 minutes, up to 1 hour under cardiac monitoring), proceeding to surgical shunting (Winter, Al-Ghorab, or Quackels shunt) if refractory.
• Non-Ischemic (High-Flow, Arterial) Priapism: Arises from dysregulated, uncontrolled cavernous arterial inflow secondary to traumatic laceration of the cavernous artery (fistula formation) from straddle or perineal trauma. The erection is typically semi-rigid, painless, and not an ischemic emergency. Cavernous blood is bright red (arterial: pH > 7.40, pO2 > 90 mmHg, pCO2 < 40 mmHg). Management is conservative or via superselective transcatheter arterial embolization.