2. ANATOMY OF URETHRA
• MALE URETHRA IS 18-20 CMS LONG
• EXTENDS FROM BLADDER NECK TILL THE MEATAL OPENING AT PENIS
It has four named regions:
Prostatic urethra:
Is approximately 3 cm in length.
Passes through the prostate gland.
Membranous urethra:
Is approximately 1 cm in length.
Passes through the urogenital diaphragm.
Bulbar urethra
– From inferior aspect of urogenital diaphragm to penoscrotal
junction.
Spongy (penile) urethra:
Passes through the length of the penis.
3.
4. PARTS OF URETHRA
• ANTERIOR URETHRA
-PENILE URETHRA
-BULBAR URETHRA
• POSTERIOR URETHRA
- MEMBRANOUS URETHRA
- PROSTATIC URETHRA
5. PROSTATIC URETHRA
• BEGINS AT INTERNAL URETHRAL ORIFICE &
RUNS VERTICALLY DOWNWARDS
• WIDEST & MOST DILATABLE PART,
NARROWEST WHERE IT JOINS MEMBRANOUS
URETHRA
• VERU MONTANUM IS A MEDIAN
LONGITUDINAL RIDGE OF MUCOUS
MEMBRANE
6. The interior of the prostatic urethra:
On the posterior wall of the prostatic
urethra there are:
• Urethral crest:
A longitudinal ridge.
• Seminal colliculus / Verumontanum:
An enlargement of the urethral crest.
( act as a normal filling defect on RGU )
• Prostatic sinus:
The groove on either side of the
seminal colliculus.
• Prostatic utricle:
A small opening on the midline
of the seminal colliculus.
• Opening of the ejaculatory duct:
One on either side of the prostatic utricle.
6
7. MEMBRANOUS URETHRA
• SHORTEST , NARROWEST & LEAST
DISTENSIBLE PART OF THE URETHRA
• 2-2.5 CMS
• SURROUNDED BY EXTERNAL URETHRAL
SPHINCTER
• THE BULBOURETHRAL GLANDS OF COWPER
ARE PLACED ONE ON EACH SIDE OF
MEMBRANOUS URETHRA
• URETHRAL GLANDS ALSO OPEN HERE
8. PENILE (SPONGY) URETHRA
• LENGTH 14-15 CMS & 6MM DIAMETER
• IT IS DILATED WITHIN THE GLANS PENIS TO
FORM FOSSA NAVICULARIS
• URETHRAL GLANDS OF LITTRE OPEN HERE
9. SPHINCTERS OF URETHRA
• INTERNAL URETHRAL SPHINCTER –
involuntary in nature
• Supplied by sympathetic nerves
• It controls the neck of the bladder & prostatic
urethra above the opening of ejaculatory
ducts
• Made up of smooth muscle fibres
10. • EXTERNAL URETHRAL SPHINCTER- voluntary
in nature
• Supplied by perineal branch of the pudendal
nerve (s2-s4)
• Controls the membranous urethra & is
responsible for voluntary holding of urine
11. Female urethra :-
• Widest at bladder
neck.
• 4-5cms in length
• Narrowest & least
distensible at meatus.
• This forms the
Spinning top
configuration of
urethra on normal
MCU.
12. Contrast media
•Currently used all CM are based on tri-iodinated benzene
ring.
•The iodine provides - radio-opacity
•Other molecule - no radio-opacity but act as carriers of the
iodine.
•Commonly used carriers- Sodium or Meglumin.
•Classification : Nonionic or Ionic
Monomer or Dimer
HOCM or LOCM (high osmolar or
low osmolar)
13. Ionic monomer ( HOCM )
•Consists of - sodium or meglumine cation & tri-iodinated benzoate anion
•Dissociates in water solution into 1 anion & 1 cation. .
•Each anion contains 3 atoms of iodine.
• Iodine: particle ratio = 3:2 (1.5)
• Ex: Urograffin (diatrizoic acid 60% & 76%)
Nonionic monomer ( LOCM )
•Tri-iodinated nonionizing compounds .
•Provides 3 atoms of iodine to 1 osmotically active particle .
• Iodine:particle ratio = 3:1 .
•Not dissociated in water solution.
• Ex: iohexol (omnipaque)
14. Ionic dimer ( LOCM )
•Mixture of sodium & meglumine salts.
•Ionizing double benzene ring.
•Each benzene ring having 3 atoms of iodine.
• So total molecule contains 6 atoms of iodine.
• In solution dissociates into 1 hexa-iodinated anion and 1 cation.
•Iodine: particle ratio = 6:2 or 3:1.
•Ex: Ioxaglic acid ( Hexabrix )
Nonionic dimer ( LOCM )
•Each molecule containing 2 nonionizing tri-iodinated benzene rings.
•Provides 6 atoms of iodine per one particle.
• Iodine:particle ratio = 6:1.
•Ex : Iotrol, Iotrolan
15. Adverse Reactions To contrast media
Minor reactions-
•Flushing, nausea, vomiting, , arm pain and mild urticaria, fever
•Of short duration & self-limiting.
•No specific treatment other than reassurance.
• Rx- oral antihistaminic.
Intermediate reactions –
•More serious degrees of the above symptoms.
•Hypotension, vaso vagal shock
•Bronchospasm.
•Rx- Chlorpheniramine for urticaria.
Diazepam for anxiety.
Salbutamol inhalation for bronchospasm.
Hydrocortisone&Adrenaline for anaphylasis.
16. Severe life-threatening reactions ;-
• Severe manifestations of all symptoms discussed above.
• Convulsions& Unconsciousness.
• Laryngeal oedema & pulmonary oedema.
• Bronchospasm.
• Pulmonary &cardiac arrest.
Rx;- Must be urgently & follow the ABC of resucitation.
The airway must be secured.
if require-oxygen, artificial respiration , defibrillation.
Atropine& Adrenaline - cardiac failure.
Hydrocortisone Adrenaline for anaphylasis .
Choice of contrast media
•Always prefer nonionic LOCM over HOCM.
• The only factor inhibiting replacement of HOCM by LOCM is financial.
17. PHYSIOLOGY
• After iv administration, first it diffuses into
extravascular space & is simultaneously
excreted
• Equilibrium is reached between intra &
extravascular space in 10 mins
• Plasma half life is 30-60 mins
• Contrast media are filtered from blood into
Bowman’s capsule by passive glomerular
filtration
18. • In PCT , resorption of sodium & H20 causes 5-
10 times concentration of contrast media
• If patient is on diuretics concentration does
not occur
• In DCT by the action of ADH the concentration
of contrast media further increases
• Liver & intestine excrete 1% of these
compounds.
19. URETHROGRAM
TYPES
Antegrade -VCUG / MCU-
Bladder is filled with contrast via suprapubic or retrograde catheterization and the
urethra is assessed during voiding.
Retrograde urethrography (RGU) –
Contrast is retrogradely injected with the urethral orifice occluded to prevent reflux
of contrast.
Following IVU
21. • CONTRAST MEDIUM
Urograffin 60%.
Pre warming the contrast helps to prevent external
urethral sphincter spasms
• EQUIPMENT
Tilting radiography table.
Fluroscopy / spot film device.
Foley catheter no 8 / knutsson`s clamp.
Syringe
• PREPARATION
Patient micturates prior to the procedure
22. PROCEDURE
• The patient should be positioned obliquely at
45 º with the bottom leg flexed 90 º at the
knee and the top leg kept straight.
• Alternatively, the patient can be supine and, if
using a fluoroscopic C-arm, the C-arm can be
rotated in the vertical plane 45 º degrees
23. • The penile glans and urethral meatus should be cleaned
with antiseptic.
• The Foley catheter is then placed just inside the urethral
meatus so that the Foley catheter balloon rests in the fossa
navicularis.
• With the Foley in position, the catheter balloon is filled
with 1-2 mL of radiopaque contrast or saline solution.
• Overfilling must be avoided, or it will rupture the distal
urethra. (A conscious patient can be asked to alert the
operator if pain accompanies balloon filling).
• The operator then pulls the penis laterally to straighten the
urethra, grasping the penis as distally as possible, and distal
to the inflated balloon.
24. • The catheter-tipped syringe is then filled with
approximately 50 mL of radiopaque contrast,
and 20-30 mL of contrast is injected in a
retrograde fashion.
• Taking a preinjection “scout” film of the
urethra to compare the RUG images is
important.
• Static images of the urethra are taken during
retrograde injection of radiopaque contrast
25. Image interpretation
• Normal retrograde urethrogram (RGU):
• If the radiopaque contrast is injected properly,
the entire anterior and posterior urethra should
be filled with contrast and seen to jet into the
bladder neck. The verumontanum is seen as an
ovoid filling defect in the posterior urethra
• The distal end of the verumontanum marks the
proximal boundary of the membranous urethra
and constitutes the urethra that passes through
the urogenital diaphragm.
26.
27. Affect of patient positioning on the appearance of the
urethra during retrograde urethrography. (a) Retrograde
urethrogram obtained with the patient supine shows the
bulbous urethra as a diverticulum-like outpouching. (b)
On a retrograde urethrogram obtained after the patient
was placed in a steep oblique position with the penis
stretched, the penoscrotal junction and bulbous urethra
have a normal appearance.
28. COMPLICATIONS
Contrast reaction ( due to absorption through
bladder mucosa )
UTI
Urethral trauma or rupture.
Extravasation of contrast – due to use of
excessive pressure in stricture.
29.
30. Role of urethrography in stricture
• Accurately delineates the anatomy of urethra.
• Location, number and extent of the strictures are
very well displayed
• Delineation of the bladder neck and urethra is best
achieved on the MCU in the oblique projection.
• Secondary changes in the bladder.
• To demonstrate the VUR
• Visualisation of any associated fistulas.
33. Urethral calculi
Mostly expelled from bladder into the urethra during voiding- migrant calculi.
Primary calculi may be seen in association with urethral stricture or urethral
diverticulum.
Symptoms include weak stream, dysuria, and hematuria.
RGU usually depicts a rounded filling defect in the urethra.
34. Tuberculous urethritis
Descending infection and renal tuberculosis is
evident.
In the acute phase, there is urethral discharge
with associated involvement of the epididymis,
prostate, and other parts of the urinary system.
In chronic phase patients present with
obstructive symptoms secondary to urethral
strictures.
May lead to periurethral abscesses, which,
unless treated, produce numerous perineal and
scrotal fistulas- Watering can perineum.
Retrograde urethrography typically
demonstrates an anterior urethral stricture
associated with multiple prostatocutaneous and
urethrocutaneous fistulas.
35. Gonococcal urethral stricture. Retrograde
urethrogram reveals a segment of irregular,
beaded narrowing in the distal bulbous urethra
with opacification of the left Cowper duct.
36. Blunt Urethral Trauma
Classified Anatomically as - Anterior
- Posterior
Anterior urethral injury
MC iatrogenic (due to instrumentation)
May occur if pt falls on a blunt object or direct injury to
perineum
Straddle Injury - compression of urethra against
anterior pelvic ring
Posterior urethral injury results from
A crushing force to the pelvis
Is associated with pelvic fractures.
37. Goldman & Sander classification (Based on findings at retrograde urethrography)
• Type I injury
Rupture of the puboprostatic ligaments which stretches the prostatic
urethra
Continuity of the urethra is maintained
38. Type II injury (15%)
The membranous urethra is torn above an intact urogenital diaphragm, which
prevents contrast material extravasation from extending into the perineum
39. Type III injury (MC)
The membranous urethra is ruptured but the injury extends into the proximal
bulbous urethra because of laceration of the urogenital diaphragm
Extravasation not only into the pelvic extraperitoneal space but also into the
perineum.
41. Type V injury
Injury to the Anterior urethra - partial or complete.
Extravasation seen to penile soft tissue.
42. MICTURATING CYSTOURETHROGRAM
• Voiding cystourethrogram demonstrates the
lower urinary tract & helps to detect VUR ,
bladder pathology , congenital or aquired
anamolies of bladder
• It is performed by passing a catheter through
the urethra into the bladder, filling the
bladder with contrast material and then taking
radiographs while the patient voids.
43. INDICATIONS
• CHILDREN:
• RECURRENT UTI
• VOIDING DIFFUCULTIES
• VUR
• MENINGOMYELOCELE, SACRAL AGENESIS,
RECTAL ANAMOLIES
• BASELINE STUDY PRIOR TO LOWER URINARY
TRACT SURGERY
44. • POST OP EVALUATION OF URETERIC
ABNORMALITIES
• PELVIC TRAUMA
• IN RENAL FAILURE TO EXCLUDE REFLUX
• POSTERIOR URETHRAL VALVE OR POLYP
• CONGENITAL ANAMOLIES OF BLADDER &
URETHRA.
45. ADULTS
• Trauma to urethra
• Urethral stricture
• Urethral diverticulum
• Recurrent UTI
• Reflux nephropathy prior to renal transplant
• Follow up patients of spinal cord injury
• Stress incontinience
46. Contrast media
• The estimated volume of contrast medium to be given during the
examination is determined mainly by the age of the child except for
children less than one year of age in whom it is determined by
weight.
Less than one year,
Weight (kg) × 7 = capacity (ml)
Less than two years,
(2 × age in years + 2) × 30 = capacity (ml)
More than two years,
(Age in years/2 + 6) × 30 = capacity (ml)
47. • Contrast media: Water soluble contrast media
like urograffin 60% is used which is diluted
with normal saline in 1:3 ratio.
EQUIPMENT
- Preferably under fluroscopy.
- Foley`s catheter & syringe
- In infants – feeding tube no 5 – 7 F
• Preparation : none , rule out acute UTI.
48. Procedure
• Using a sterile technique , a catheter is introduced into
the bladder.
• A 5f feeding tube with side holes are used for children
and in older children or adults 8f r 10 f catheters are
used .
• In girls after initial inspection of perineum to identify
any local genitilia abnormalities (cystoceles or labial
fusion ) the catheter is introduced..
• When it enters the bladder a varying amount of urine
will flow through it .if no flow a catheter is introduced
till urine is obtained.
49. Suprapubic pressure Is sometimes helpful.
In males , foreskin is retracted and catheter is introduced .
The catheter should be lubricated with anaesthetic jelly
and inserted slowly and gently into the urthera holding the
penis is vertical position .
The normal bladder capacity in children is estimated to be
1 ounce ie 29 cc .
For newborns -30 to 35 cc can be instilled.
• For upto 3 yrs – 200 to 250 cc
Adequate capacity is reached when the child becomes
uncomfortable and begins voiding around the catheter.
Bladder capacity (in milliliters) is variable but can often be
predicted with the previous mentioned formula
50. Filming
In children : upto 2 yrs of age bladder is filled by hand
injection . For older children contrast medium is instilled from
a bottle elevated one metre above the examination table.
During filming , fluroscopic screening is performed at short
intervals to see any vu reflux ,diverticuli .
The child is turned oblique on both sides to ensure that
minimal reflux is not overlooked.
In infants : voiding starts the moment catheter is removed. At
the end of voiding ,frontal film is taken which includes entire
abdomen including the kidney region to prevent overlooking
the vu reflux which is apparent only on termination of voiding
and may reach upper collecting system.
51. In adult male : bladder is filled in the usual
way as in older child and voiding filming is
done in both oblique projection views.
The voiding study in male adults can be
modified by getting the patient to void against
resistance i.e. by compression of distal part of
penis thus enhancing the visualization of
urethra by artificial distention .
52. ALTERNATE TECHNIQUES
1) SUPRAPUBIC BLADDER PUNCTURE.
Sometimes in PUV & pelvic trauma – not possible to catheterize.
2) URETHROCYSTOGRAPHY
Contrast medium introduced into the bladder during RGU.
3) EXCRETION MCU ( MCU followed by IVU )
Advantage – avoid catheterization and related risk of infection.
Disadvantage - VUR can not be visualized properly .
takes longer time.
53. Excretion MCU : (MCU followed by
IVP)
• This method makes use of contrast media accumulated
in the urinary bladdder during ivp
• Advantages : avoidance of physical and psychological
trauma of catherization
• Avoidance of infection
• More physiological procedure hence more reliable.
• Disadvatanges : visualization is not usually adequate
• Takes longer time
• Vu reflux visualised poorly.
54. COMPICATIONS
Contrast reaction.
Contrast induced cystitis.
UTI.
Catheter trauma.
Bladder perforation – overfilling.
Retention of a foley catheter.
Catheterisation of vagina / ectopic ureter.
Radiation exposure
Autonomic dysreflexia- in paraplegic patients due
to spinal cord injury at or above t6 level, forceful
injection of contrast causes severe headache
,sweating ,hypertension with bradycardia due to
forceful opening of bladder neck
56. Posterior urethral valves
Congenital thick folds of mucous membrane located in the posterior urethra
(prostatic + membranous) distal to the verumontanum.
Most common cause of severe obstructive uropathy in children.
Almost exclusively in males.
Leading cause of end stage renal disease in boys.
Now rare for them to present with severe UTI and septicaemia -diagnosis is
generally made in early infancy and antenatal period.
57. Micturiting cystourethrography
Procedure of choice for defining the valves.
Indication -Thick walled bladder & dilated ureters on USG.
Combination of ultrasound and MCU allows both urologist and
nephrologist to plan immediate management.
Repeated 3 months after ablation.
60. Posterior urethral valve -image shows a
dilated posterior urethra with an abrupt
transition to a normal-calibre anterior urethra
with bladder neck hypertrophy, the irregular
trabeculated bladder wall, and the left-sided
grade III vesicoureteric reflux.
61. Grading of VUR
• Grade 1 : reflux limited to ureter
• Grade 2 : reflux into renal pelvis
• Grade 3 : mild dilatation of ureter
and pelvicalyceal system.
• Grade 4 : tortuous ureter with
moderate dilatation, blunting of
fornicies but preserved papillary
impressions.
• Grade 5 : tortuous ureter with
severe dilatation of ureter and
pelvicalyceal system, loss of
fornicies and papillary impressions
62.
63. • Congenital megalourethra
• This is a rare congenital anomaly resulting
from the faulty development of the corpora
cavernosa and corpus spongiosum.
64. megalourethra in an infant. Lateral mcu image
reveals an extensively dilated anterior and
posterior urethra
65. Urachal diverticulum :
• persistence of a segment of the urachus,
present as a protrusion at the vertex of the
bladder. It may predispose to urolith
formation.
67. Prostatic utricle
• The prostatic utricle is a small, blind-ending
midline pouch arising from the prostatic
urethra at the level of the verumontanum
• A large prostatic utricle may be associated
with urinary retention, stasis, and infection
68. MCU image shows a diverticulum resulting from spontaneous
opacification of a prostatic utricle
70. Take home message
• Verumontanum acts as a normal filling defect
on the RGU
• Rule out acute UTI prior to urethrogram
• Always stretch the penis during RGU
• RGU usually underestimates the length of
stricture.
