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Intravenous Pyelogram (IVP) / Intravenous Urogram (IVU)

Terminology

• IVP = Intravenous Pyelogram / Intravenous Pyelography
• IVU = Intravenous Urogram / Intravenous Urography
• EU = Excretory Urography (also synonymous)
• Strictly, "pyelography" refers to opacification of the collecting system, while "urography" covers the whole tract - kidneys, pelvicalyceal systems, ureters, and bladder

Note: IVP/IVU has been largely replaced by CT Urography (CTU) in most centers where CT is available, as per Radiopaedia and the ACR/RadiologyInfo.org.

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Definition

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Indications

• Ureteric obstruction - identifying severity, site, and cause (e.g., urolithiasis/renal calculi)
• Hematuria (blood in urine) - evaluation of source
• Flank pain / loin pain / renal colic
• Recurrent UTIs
• Upper tract urothelial tumors - evaluating pelvicalyceal and ureteral morphology, especially in patients with bladder urothelial carcinoma
• Papillary necrosis
• Congenital anomalies - horseshoe kidney, duplex collecting system, renal ectopia
• Pre/post-operative ureteric assessment - strictures, injuries
• Renal trauma - in resource-limited settings where CT is unavailable
• Enlarged prostate / obstructive uropathy
• Qualitative renal function assessment

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Contraindications

Absolute

• Known severe allergy to iodinated contrast (previous anaphylaxis)
• Active multiple myeloma (with dehydration)

Relative / Precautions

• Impaired renal function (elevated creatinine / low eGFR) - increased risk of contrast-induced nephropathy (CIN)
• Diabetes mellitus (especially on metformin - stop metformin 48 hours before)
• Dehydration - must be corrected before contrast
• Pregnancy (avoid radiation; not routinely indicated)
• Previous contrast reaction (mild-moderate) - premedicate with steroids + antihistamines
• Barium in intestines from recent barium studies (interferes with imaging)
• Cardiac failure / severe hypertension
• Sickle cell disease
• Thyroid disease (iodine load may precipitate thyroid storm)
• Metformin use (withhold 48 hours before and 48 hours after due to risk of lactic acidosis in setting of CIN)

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Patient Preparation

1. Fasting - NPO (nil by mouth) after midnight the night before; or at least 5 hours prior to examination
2. Bowel preparation - Mild laxative the evening before to reduce fecal/gas shadowing (though evidence shows this does not significantly improve image quality)
3. Hydration - Adequate hydration; mild dehydration was formerly used to concentrate contrast but is no longer recommended as it worsens CIN risk
4. Lab work - Check serum creatinine and eGFR
5. Medications - Withhold metformin; note any medications
6. Allergy history - Document contrast allergy history; obtain informed written consent
7. Emergency equipment - Resuscitation drugs and equipment must be at hand
8. Void before test - Patient should urinate just before the examination (empty bladder helps evaluate filling)

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Equipment and Contrast

• IV access: 18G or 19G cannula (antecubital vein preferred) for bolus injection
• Contrast agent: Water-soluble non-ionic iodinated contrast medium (e.g., iohexol, iopamidol)
  • Non-ionic agents have a far better safety profile than older ionic agents
  • Dose: up to 1.5 mL/kg body weight (commonly 50-100 mL for adults)
• X-ray settings: 65-75 kV range to optimize radiographic contrast; mA 600-1000; exposure time <0.1 second
• Fluoroscopy table and overhead X-ray tube
• Compression device (ureteric compression band) - optional, used to distend the pelvicalyceal systems

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Standard Film Sequence (Technique)

1. Scout Film (Pre-contrast KUB - Kidney, Ureter, Bladder)

• Full-length AP projection from diaphragm to symphysis pubis
• Taken before contrast injection
• Identifies: calcifications (stones), soft tissue masses, bowel gas pattern, bony abnormalities, baseline renal position/size

2. Injection

• Rapid IV bolus injection of contrast (within 60-90 seconds)
• Patient may feel a warm flush, metallic taste, or nausea - these are normal transient reactions

3. Immediate / Nephrographic Phase (1-2 minutes post-injection)

• Nephrogram film at 1-2 minutes
• Dense opacification of the renal parenchyma - allows assessment of renal outline, size, and cortical thickness
• Both kidneys should opacify equally and simultaneously

4. Early Films (5-minute film)

• Pelvicalyceal systems begin to fill
• Calyceal morphology visible
• Assess for pelviureteric junction (PUJ) obstruction

5. Full-length Film (15-minute film - Pyelographic Phase)

• Collecting systems, renal pelves, and ureters visualized
• Ureteric filling assessed (ureters may fill intermittently due to peristalsis)
• May use ureteric compression to improve pelvicalyceal distension

6. Release Film (Post-compression film)

• After releasing compression, ureters fill completely and contrast washes down
• Entire ureter from renal pelvis to bladder is seen

7. Bladder Film (25-35 minutes post-injection)

• AP view of the bladder when it is well-filled with contrast
• Assesses bladder outline, filling defects, impressions (e.g., enlarged prostate causes a "J-shaped" ureter / "hockey-stick" deformity)

8. Post-micturition Film

• Patient voids, then AP film of bladder is taken
• Assesses: residual urine volume, bladder emptying efficiency, bladder wall thickening, post-void residual

Additional / Delayed Films

• Oblique views - for renal calculi differentiation (to confirm stone is in urinary tract, not overlying bowel/bone)
• Prone film - helps visualize distal ureters (contrast falls anteriorly, ureters fill)
• Delayed films (60 min, 2 hr, 24 hr) - for obstructed kidneys with delayed excretion; help identify level of obstruction
• Tomograms - body section radiography to remove overlying gas/bone shadows (now largely replaced by CT)

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What Normal IVP Shows

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Abnormal Findings

• Delayed/absent nephrogram - obstruction, renal artery stenosis, non-functioning kidney
• Filling defect in ureter - stone, clot, tumor, stricture
• Hydronephrosis / hydroureter - obstruction
• Deviated ureter - retroperitoneal mass, lymphadenopathy
• Clubbed calyces - pyelonephritis, reflux nephropathy
• Papillary filling defects - papillary necrosis
• "Cobblestone" renal outline - chronic pyelonephritis
• Bladder filling defect - tumor, stone, blood clot
• Post-void residual - bladder outlet obstruction (BPH, neurogenic bladder)
• "Hockey-stick" ureter - BPH with elevated bladder base

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Complications

Minor (Common)

• Warm/flushing sensation
• Metallic taste
• Nausea/vomiting
• Itching, urticaria (hives)
• Mild hypotension

Major (Uncommon/Rare)

• Contrast-induced nephropathy (CIN) - rise in serum creatinine within 48-72 hours; risk increases with pre-existing renal impairment, diabetes, dehydration
• Anaphylactoid reaction - bronchospasm, severe hypotension, angioedema, cardiac arrest (incidence ~0.1%; fatal reactions ~1 in 100,000)
• Extravasation of contrast at injection site
• Pulmonary edema (in cardiac patients)
• Thyroid storm (in hyperthyroid patients)

Management of Severe Reaction

• Stop contrast injection immediately
• IV adrenaline (epinephrine) 0.5 mg IM for anaphylaxis
• IV antihistamines (chlorphenamine)
• IV corticosteroids (hydrocortisone)
• Oxygen, IV fluids
• Call crash team if needed

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Advantages of IVP

• Readily available and relatively inexpensive
• Provides both anatomical and functional (excretory) information
• Low radiation dose compared to CT
• Dynamic information about collecting system and ureteric peristalsis

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Limitations

• Largely replaced by CT Urography (CTU), which is superior for:
  • Detecting small stones
  • Soft tissue characterization
  • Staging of tumors
  • Multi-planar reconstruction
• Requires good renal function to excrete contrast
• Bowel gas/fecal loading can obscure detail
• Cannot show periureteric or retroperitoneal pathology
• Radiation exposure (though lower than CT)
• Not suitable in pregnancy (first choice is ultrasound ± MRI)

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IVP vs. CT Urography (CTU)

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Current Status

• In resource-limited settings without CT
• As a follow-up delayed film after CT IVU when obstruction is demonstrated, to confirm level of block
• Annual surveillance post-cystectomy for urothelial carcinoma in some protocols
• Pre-operative ureteral assessment for stricture repair when CT is unavailable

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MCU / MCUG / VCUG - Micturating Cystourethrogram

Terminology

• MCU = Micturating Cystourethrogram
• MCUG = Micturating Cystourethrography
• VCUG = Voiding Cystourethrogram (preferred term in North America)
• RUC = Retrograde Urethrography + Cystogram (combined)
• Cystourethrography = general term

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Definition

1. Filling the bladder with contrast via a urinary catheter
2. Taking films during filling (to detect filling-phase reflux)
3. Taking films during voiding/micturition (to visualize the urethra and detect voiding-phase reflux)

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Indications

In Children (most common indication)

• Recurrent urinary tract infections (UTIs) - to detect vesicoureteric reflux (VUR)
• First febrile UTI in children <5 years (especially in boys)
• Antenatal hydronephrosis - postnatal workup for VUR
• Posterior urethral valves (PUV) - suspected in male infants with poor stream or renal impairment
• Duplex collecting system investigation
• Ureterocele evaluation
• Vesical fistula workup
• Pre- and post-operative assessment for ureteric reimplantation
• Bladder dysfunction (neurogenic bladder)

In Adults

• Urethral stricture - to assess level, length, and severity
• Bladder outlet obstruction - BPH, strictures
• Stress urinary incontinence evaluation
• Bladder trauma / post-pelvic fracture urethral injury
• Post-prostatectomy assessment of anastomosis
• Vesico-vaginal fistula (VVF) or vesico-enteric fistula
• Bladder diverticula
• Post-void residual assessment
• Neurogenic bladder (spinal cord injury, spina bifida)

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Contraindications

Absolute

• Active urinary tract infection (UTI must be treated before the procedure - risk of bacteremia/sepsis during catheterization)
• Urethral trauma with suspected complete transection (retrograde urethrogram is done first instead)
• Known allergy to iodinated contrast (use ultrasound cystography or radionuclide cystography as alternative)

Relative

• Recent lower urinary tract surgery (wait for healing)
• Urethral stricture so tight that catheterization is impossible (try suprapubic approach)
• Pregnancy (use non-radiation alternative if possible)
• Autonomic dysreflexia (spinal cord injury above T5-T6) - bladder filling can precipitate a hypertensive crisis; monitor BP carefully, have nifedipine/alpha-blocker ready

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Patient Preparation

1. Antibiotic prophylaxis - oral antibiotics prescribed 24-48 hours before (to cover catheterization), particularly in children (e.g., trimethoprim, nitrofurantoin, or co-trimoxazole)
2. Urine culture - must be sterile or actively treated before the procedure
3. Consent - written informed consent obtained; radiation exposure explained
4. No bowel prep required (unlike IVP)
5. No fasting required (contrast is not IV)
6. Bladder status - patient should NOT void immediately before the test; some contrast residue helps
7. Metallic objects removed - jewelry, belts off; patient in hospital gown
8. Explain the procedure - especially important in children; parental presence encouraged to reduce anxiety

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Equipment

• Fluoroscopy machine with image intensifier and digital spot film capability
• Urinary catheter: Foley catheter (8F-12F in children; 12F-16F in adults) or simple straight catheter
• Iodinated water-soluble contrast medium (non-ionic preferred): diluted 25-30% solution (commonly diluted with saline to reduce mucosal irritation)
• Contrast infusion via gravity drip set (NOT pressurized injection - fills at physiological pressure)
• Lead aprons for attendants
• Sterile catheterization tray
• Emergency trolley (for contrast reactions)

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Standard Technique (Step-by-Step Film Sequence)

Step 1: Scout Film (Pre-contrast)

• AP film of pelvis and lower abdomen before contrast
• Establishes baseline: identifies calcifications, bowel gas, bony landmarks, any pre-existing opacities

Step 2: Catheterization

• Aseptic technique
• Catheter inserted into bladder via urethra
• Residual urine drained and measured (note volume)
• Contrast connected by gravity drip (height ~60-90 cm above bladder)

Step 3: Filling Phase (Early Bladder Fill Films)

• Begin fluoroscopic monitoring as contrast flows in
• Early fill film (AP): when bladder is ~half full
  • Check for filling defects, trabeculation
  • Look for early VUR (reflux can occur during filling phase)

Step 4: Full Bladder Films

• When patient feels full / bladder appears adequately filled on fluoroscopy
• AP full bladder film - centered on bladder, to include renal areas
  • Assess bladder capacity, outline, wall contour, diverticula, ureteroceles, filling defects
• Oblique films (both sides) - centered on ureterovesical junctions (UVJs)
  • Best views to detect VUR and assess UVJ morphology
  • Diverticula at posterolateral UVJ visible
• Fluoroscopic spot films during filling to capture any transient reflux

Step 5: Compression

• Optional: ureteric compression can be applied (less common in MCU vs IVP)

Step 6: Voiding Phase - THE KEY PHASE (Micturition Films)

• Catheter is removed (or left in - voiding can occur around the catheter in children without obscuring PUV)
• Patient asked to void
  • Males: turned to left or right anterior oblique (LAO or RAO) position - shows entire urethra: posterior urethra, membranous urethra, bulbar urethra, penile urethra
  • Females: remain supine - AP view shows bladder neck and urethra adequately
• Continuous fluoroscopy during voiding (with fluoroscopic grab/spot films)
• Voiding urethra film (oblique in males): shows entire urethral outline, any strictures, PUV, dilatation, fistula

Step 7: Post-Micturition (Post-Void) Films

• AP bilateral renal view - to check if contrast has ascended to upper tracts (detects high-grade reflux persisting post-void)
• AP bladder view - to assess:
  • Post-void residual urine volume
  • Completeness of bladder emptying
  • Persistent filling defects
• Delayed films at 15-30 minutes if high-grade reflux detected - to differentiate simple reflux from reflux with associated pelviureteric obstruction (PUJ obstruction)

Step 8: Multiple Voiding Cycles

• VUR may not be detected on first voiding cycle
• Repeat 2-3 voiding cycles increases sensitivity: VUR detected in 21% of patients in first cycle; additional 5.5% in second cycle; 2.5% in third cycle
• Especially important when initial study is negative but clinical suspicion is high

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Summary of Standard Films

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Grading of Vesicoureteric Reflux (VUR)

• Grades I-II: Low grade - high spontaneous resolution rate
• Grades III-IV: Moderate - variable resolution
• Grade V: High grade - unlikely to resolve spontaneously; surgical intervention usually required

Source: Campbell Walsh Wein Urology, International Classification of Vesicoureteral Reflux table

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Abnormal Findings on MCU

Bladder

• Trabeculation / thickened irregular walls - bladder outlet obstruction, neurogenic bladder
• Bladder diverticula - outpouchings, often at UVJ ("Hutch diverticulum")
• Filling defects - tumors, stones, blood clots, ureterocele
• Bladder neck hypertrophy - BOO, PUV, BPH
• Fistula - vesico-vaginal, vesico-enteric (contrast outside bladder outline)
• Small bladder capacity - contracted bladder (TB, radiation, interstitial cystitis)

Vesicoureteric Reflux (VUR)

• Contrast ascending into one or both ureters during filling or voiding
• Graded I-V as above
• Reflux nephropathy (renal scarring) occurs with repeated episodes of reflux + infection

Urethra - Males (Oblique Voiding View)

• Posterior Urethral Valves (PUV):
  • Dilated, elongated posterior (prostatic) urethra
  • Linear radiolucent band (the valve itself - Type I PUV: sail/bilobed shape)
  • Narrow bladder neck hypertrophy
  • "Keyhole" / "spinning top" appearance
  • Abrupt transition to narrow anterior urethra
  • Bladder trabeculation + VUR in ~50% of cases
• Urethral stricture: narrowing of urethral lumen (anterior urethra most common - bulbar)
• Urethral diverticulum
• Hypospadias - ventral opening
• Epispadias

Urethra - Females (AP Voiding View)

• Urethral diverticulum - outpouching, common on posterior wall
• "Spinning top" urethra - urethral dilatation from detrusor overactivity / functional obstruction
• Urethrocele

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Complications

Minor

• Discomfort/pain during catheterization (common)
• Hematuria (blood in urine) - self-limiting
• Urinary urgency and dysuria after procedure

Significant

• Urinary tract infection / Pyelonephritis - catheterization can introduce bacteria; prevented by antibiotic prophylaxis
• Bacteremia / Sepsis - rare; risk higher in immunocompromised or if existing UTI
• Urethral trauma - from traumatic catheterization (false passage creation)
• Contrast reaction - rare with intravesical (non-IV) contrast; systemic absorption is minimal; risk increased if vesicoureteric reflux is present (systemic absorption via refluxed contrast)
• Autonomic dysreflexia - in spinal cord injured patients above T5-T6 (see above)
• Psychological distress - especially in children (urethral catheterization is distressing); sedation may be considered

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Radiation Dose

• MCU involves fluoroscopy - continuous real-time X-rays during voiding
• Radiation dose is kept "as low as reasonably achievable" (ALARA principle)
• Modern digital fluoroscopy units minimize exposure
• Attendants in the room must wear lead aprons
• Pregnant staff/attendants should not be in the room
• Alternative to reduce radiation: Radionuclide Cystography (RNC) - lower radiation, equally sensitive for VUR but does not show anatomical detail or urethra

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Alternatives to MCU/VCUG

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MCU vs. RGU (Retrograde Urethrogram)

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Key Clinical Associations (What MCU Diagnoses Best)

• PUV (Posterior Urethral Valves): MCU is the gold standard investigation
• Vesicoureteric Reflux: MCU/VCUG is the definitive test for VUR detection and grading
• Urethral stricture (posterior): MCU is best for posterior; RGU is best for anterior
• Bladder diverticula: MCU shows diverticula well, especially Hutch diverticula at UVJ
• Neurogenic bladder: MCU shows bladder shape ("Christmas tree" bladder), DSD (detrusor-sphincter dyssynergia) on voiding, VUR

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MCU / MCUG / VCUG - Micturating Cystourethrogram

Complete Radiology Reference

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1. DEFINITION & NOMENCLATURE

• Reflux may only occur under voiding pressure
• The urethra is only visible when urine is actively flowing through it

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2. ANATOMY ASSESSED

Bladder

• Capacity and shape
• Wall regularity (smooth vs. trabeculated)
• Bladder neck
• Ureterovesical junctions (UVJs)
• Presence of diverticula, filling defects, ureteroceles

Urethra - Male (4 parts seen on oblique voiding film)

1. Prostatic urethra - from bladder neck to verumontanum; ~3 cm; widest part
2. Membranous urethra - passes through urogenital diaphragm; ~1.5 cm; narrowest (external sphincter here)
3. Bulbar urethra - within the bulb of corpus spongiosum; ~3-4 cm
4. Penile/spongy urethra - within penile shaft to meatus; ~12 cm

Urethra - Female (3 parts; short ~4 cm total)

• Internal urethral meatus
• Mid-urethra (external sphincter zone)
• External meatus Female urethra seen on AP supine voiding view.

Upper Tracts (if reflux present)

• Ureters
• Renal pelvis and calyces
• Bilateral renal areas included on post-void film

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3. INDICATIONS

In Children (primary indication)

• Recurrent UTIs - especially in children <5 years, to detect VUR
• First febrile/upper tract UTI - particularly males (any age) and females <5 years
• Antenatal hydronephrosis - postnatal VUR workup
• Suspected posterior urethral valves (PUV) - male infants, poor urinary stream, palpable bladder, bilateral hydronephrosis on USS
• Duplex collecting system / ureteral duplication evaluation
• Ureterocele assessment
• Spina bifida / neurogenic bladder - assess detrusor-sphincter dyssynergia (DSD)
• Pre- and post-operative assessment for anti-reflux surgery (ureteric reimplantation)
• Vesical fistulae
• Ambiguous genitalia - urogenital sinus evaluation

In Adults

• Urethral stricture - level, length, degree, site (especially posterior)
• Bladder outlet obstruction (BPH, stricture)
• Post-pelvic fracture urethral distraction injury
• Post-prostatectomy - assess anastomotic leak/stricture
• Stress urinary incontinence - bladder neck descent, urethral hypermobility
• Neurogenic bladder (SCI, MS, diabetes) - assess DSD, capacity, VUR
• Vesico-vaginal fistula (VVF) or vesico-enteric fistula
• Bladder diverticula
• Pre-renal transplant workup (reflux nephropathy patients)
• Trauma to lower urinary tract
• After metoidioplasty or phalloplasty (transgender males) - VCUG is the initial examination of choice

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4. CONTRAINDICATIONS

Absolute

• Active urinary tract infection - catheterization risks bacteremia/septicemia; treat first (UTI must be sterile or actively treated)
• Complete urethral transection (pelvic fracture) - do retrograde urethrogram (RUG/ASU) first; MCU risks worsening injury or false passage
• Known severe allergy to iodinated contrast - use radionuclide cystography or contrast-enhanced ultrasound cystography instead

Relative

• Recent urethral/bladder surgery - allow healing first
• Severe urethral stricture preventing catheterization - attempt suprapubic approach or RUG first
• Pregnancy - radiation risk; substitute ultrasound or MRI if possible
• Autonomic dysreflexia (SCI above T5-T6) - bladder filling triggers massive sympathetic discharge: severe hypertension, bradycardia, diaphoresis, flushing. Precautions:
  • Pre-treat with nifedipine or alpha-blocker
  • Have urinary catheterization kit ready for emergency bladder drainage
  • Continuous BP monitoring during procedure

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5. PATIENT PREPARATION

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6. CONTRAST MEDIUM

• e.g., Urografin 60% diluted, Omnipaque (iohexol), Ioversol (Optiray)
• Dilution: Urografin 60% diluted 1:3 with normal saline = 15% solution (roughly 25-30% iodine concentration)
• Intravesical contrast (not IV) - systemic absorption is minimal unless significant VUR is present

Contrast Volume - Bladder Capacity Estimation

• < 1 year: Weight (kg) × 7 = capacity in mL
• < 2 years: (2 × age in years + 2) × 30 = capacity in mL
• > 2 years: (Age in years ÷ 2 + 6) × 30 = capacity in mL

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7. EQUIPMENT

• Fluoroscopy unit with image intensifier (II) and digital subtraction/spot-film capability
• Urinary catheter:
  • Children: 5F-8F infant feeding tube or Foley catheter
  • Adults: 12F-16F Foley catheter or straight (nelaton) catheter
• Sterile catheterization tray (antiseptic, drapes, gloves, syringe, lubricating gel with lignocaine/lidocaine)
• IV contrast + normal saline for dilution
• Gravity infusion set (IV giving set connected to contrast bag/bottle)
• Lead aprons for all attendants in room
• Emergency drugs and resuscitation equipment (for contrast reaction)
• Fluoroscopy table capable of tilting (to upright/standing position for voiding in some protocols)

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8. TECHNIQUE - STEP-BY-STEP FILM SEQUENCE

Step 1: Scout / Preliminary Film

• AP pelvis and lower abdomen before any contrast
• Patient supine
• Purpose:
  • Establishes baseline
  • Identifies calcifications (urolithiasis, phleboliths)
  • Shows bowel gas, bony anomalies (spina bifida, sacral agenesis)
  • Detects foreign bodies
  • Ensures correct centering and exposure

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Step 2: Catheterization

• Patient lies supine on fluoroscopy table
• Aseptic technique strictly maintained (Betadine/chlorhexidine prep, sterile drapes)
• Lignocaine gel instilled into urethra for analgesia
• Catheter inserted into bladder via urethra (confirm in bladder: urine drains freely)
• Residual urine volume measured and recorded
• Contrast infusion set connected; gravity drip commenced

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Step 3: Early Filling Film (Minimally Filled Bladder)

• Taken a few seconds after contrast begins to flow
• View: AP
• Bladder ~25% filled
• Purpose:
  • Ureteroceles (best seen when bladder is partially filled - may be obscured when fully distended)
  • Bladder tumors / filling defects (clearer at early fill)
  • Early reflux during the filling phase
• Important: Fluoroscopic screening continues throughout filling; any transient reflux captured as spot films

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Step 4: Full Bladder Films (Cystogram Phase)

• Centered on bladder; includes lower ureters and renal areas
• Assesses: bladder outline, wall, capacity, filling defects, diverticula, bladder neck position

• Patient rotated 40-45° to each side
• Centered on each ureterovesical junction (UVJ)
• Critical for VUR detection: UVJs best seen in oblique
• Shows: diverticula at posterolateral UVJ (Hutch diverticula), ureteroceles
• Any reflux seen: oblique spot films taken to grade and document

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Step 5: Voiding Phase Films (THE DEFINING PHASE)

Male Patients - Oblique Voiding Film

• Patient turned to left or right anterior oblique (LAO or RAO) position - usually 35-45°
• This unfolds the entire urethra into a single plane so all 4 parts are visible in one film
• Continuous fluoroscopy + spot films taken during voiding

• Bladder neck opens - funnel-shaped
• Prostatic urethra: widest segment, smooth margins
• Membranous urethra: narrowest point (external urethral sphincter indentation - normal finding)
• Bulbar urethra: wide
• Penile urethra: uniform caliber
• Variation in caliber = normal (does NOT indicate stricture unless focal and persistent)

Female Patients - AP Supine Voiding Film

• Patient remains supine
• AP projection adequate to see short female urethra
• Bladder neck descent and urethral opening assessed
• Urethral diverticula visible on voiding

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Step 6: Post-Void (Post-Micturition) Films

• Centered on bilateral renal fossae (upper abdomen)
• Taken immediately after voiding
• Purpose: Check for contrast ascending to upper tracts (high-grade VUR reaching pelvicalyceal system, which may be seen only at end of voiding or just after)
• If high-grade reflux seen: take delayed films at 15-30 minutes to differentiate:
  • Simple VUR (contrast drains quickly)
  • VUR + pelviureteric junction (PUJ) obstruction (contrast persists in dilated upper tract)

• Assesses post-void residual urine
• Bladder wall for residual filling defects
• Complete vs. incomplete bladder emptying

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Step 7: Repeat Voiding Cycles (if required)

• VUR is not always detected on the first voiding cycle
• Evidence shows:
  • 21% of total VUR cases detected on first void
  • Additional 5.5% detected on second void
  • Additional 2.5% on third void
• Especially important when clinical suspicion is high but first cycle is negative
• Catheter may be reinserted and bladder refilled for additional cycles

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9. SUMMARY OF COMPLETE FILM SERIES

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10. VUR GRADING - INTERNATIONAL CLASSIFICATION (1981)

• Reflux during filling phase only = less significant
• Reflux during voiding phase only = more significant (higher intravesical pressure)
• Reflux during both phases = most significant clinically

Source: Campbell Walsh Wein Urology, International Classification of Vesicoureteral Reflux

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11. NORMAL MCU FINDINGS

Bladder

• Smooth, regular outline
• Dome-shaped superiorly
• No filling defects, no trabeculations
• UVJs: smooth, no contrast ascending ureters
• Normal capacity (see formulas above)
• Complete or near-complete emptying post-void

Urethra - Normal Male (Oblique Voiding View)

• Bladder neck: opens smoothly into funnel shape
• Prostatic urethra: widest segment; smooth walls; verumontanum seen as a small central filling defect on posterior wall (normal)
• Membranous urethra: narrow "waist" at external sphincter level - this is a normal indentation, not a stricture
• Bulbar urethra: wide, smooth
• Penile urethra: uniform caliber
• Fossa navicularis (distal penile): slightly wider (normal)
• Caliber variation throughout the urethra = normal

Urethra - Normal Female

• Short, smooth
• Bladder neck closes adequately

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12. ABNORMAL MCU FINDINGS

Bladder Abnormalities

Vesicoureteric Reflux (VUR)

• Contrast seen ascending into one or both ureters
• Grade I-V as above
• Primary VUR: congenital UVJ failure (90% of cases)
• Secondary VUR: BOO (PUV), neurogenic bladder, ureteral duplication, ureterocele

Male Urethra Abnormalities

Posterior Urethral Valves (PUV) - Specific MCU Signs:

• Dilated elongated prostatic urethra
• Bladder neck hypertrophy (appears narrow compared to dilated posterior urethra)
• Abrupt transition to narrow anterior urethra
• Trabeculated thick-walled bladder
• Bilateral hydroureteronephrosis
• VUR in ~50% (often unilateral at first)
• Linear radiolucent band = the valve itself

Female Urethra Abnormalities

Urethra - General

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13. MCU vs. RGU / ASU (Ascending Urethrogram)

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14. CHOKE CYSTOURETHROGRAPHY (Modified MCU - Adults)

• After filling bladder with contrast, patient is asked to void
• A penile clamp or digital compression is applied to the distal penis during voiding
• This creates back-pressure, forcing urethra to distend maximally
• Particularly useful for: subtle strictures, urethral diverticula in males
• Must be done with caution; released immediately if patient is in distress

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15. COMPLICATIONS

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16. RADIATION AND ALTERNATIVES

Radiation Considerations

• MCU involves fluoroscopy (real-time continuous X-rays) - ionizing radiation exposure to gonads
• Radiation dose kept to minimum (ALARA principle):
  • Short screening times
  • Tightly collimated beam
  • Use digital pulsed fluoroscopy (lower dose than continuous)
  • Minimize number of spot films
  • Use lowest acceptable mA and kV settings
• All attendants in room must wear lead aprons
• Pregnant staff/attendants must NOT be in room

Alternatives to MCU (Lower/No Radiation)

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17. KEY CLINICAL RULES TO REMEMBER

1. Never end MCU without a voiding film - VUR may only appear under voiding pressure
2. Always take bilateral renal fossae view post-void - high-grade reflux may reach kidneys only at end of voiding
3. Oblique views for males during voiding - posterior and anterior urethra cannot both be seen on AP alone
4. Multiple voiding cycles increase sensitivity - especially when first void is normal but suspicion remains
5. MCU is the gold standard for PUV and VUR - CT, USS, and MRI cannot replace it for these diagnoses
6. Dilute contrast to ~25-30% - undiluted contrast is too opaque and can mask subtle findings (overlapping structures)
7. Gravity filling only - pressurized injection risks bladder rupture and artificially elevates intravesical pressure
8. Treat UTI before MCU - catheterization with active UTI risks bacteremia/urosepsis
9. Antibiotic cover is mandatory in most protocols
10. VUR grading: use first MCU for grade - subsequent studies (RNC) for follow-up to reduce radiation