The Urinary System Chapter 18 8 31 2012 online ed.

The Urinary System

Chapter 18

8 31 2012 online ed.

Urinary System

Also called “excretory system”

Consists of:– Two kidneys– Two ureters– One urinary bladder– One urethra

Kidneys

Kidney Function

• Remove waste products from blood

• Maintain fluid and electrolyte balance

• Secrete substances that affect blood pressure

• How much urine excreted per day?

1 - 2 liters

Kidneys (cont’d)

• Minor calyces unite to form major calyces

• Major calyces unite to form renal pelvis

• Renal pelvis drains into ureters

• Hilum - longitudinal slit in medial border for transmission of blood vessels, nerves, lymphatic vessels, and ureter

Kidneys (cont’d)

Each kidney has:

cortex

medulla

Medulla contains collecting system

Essential microscopic components of kidney called nephrons

Each kidney-contains how many nephrons?

about 1 million

Anatomy: Nephron

• Glomerulus - filter for blood, allows fine particles and water to pass into capsule

• Renal tubule is continuous with capsule– Proximal convoluted tubule– Nephron loop (loop of Henle)– Distal convoluted tubule

• Distal convoluted tubule opens into collecting ducts

• Collecting ducts drain into minor calyx

Adrenal Glands(Suprarenal)

Not part of urinary system

Cannot be seen on plain radiographs (need CT)

Regulate stress response through release of various hormones such as adrenaline

Ureters

• Two tubes 10 - 12 “ long

• Retroperitoneal

• Extend from renal pelvis

• Enter bladder at ureteral orifice

• How is urine moved through ureters?– peristalsis

Urinary Bladder

• Musculomembranous sac situated immediately posterior and superior to symphysis pubis of pelvis

• Serves as Urine reservoir

• How much fluid can bladder hold?– up to 500 mL

• Internal rethral orifice located in bladder neck

• Area between ureteral openings and urethral orifices is trigone

Urethra

• Carries urine from bladder to?– exterior of body

• How long is it in females? – About 1.5

• In males? – About 7 to 8

• Sphincter at neck of bladder

• Male urethra contains following parts:– Prostate– Membranous area– Spongy area

IVU- Intravenous Urogram !

Formerly erroneously known as IVP-Intravenous pyelogram!

pyelo refers to renal pelvis and calyces only

But study also shows ureters, bladder, and sometimes urethra

Indications For Urography

• Demonstrate physiologic function and structure of urinary system

• Evaluate abd. Masses, renal cysts and tumors• Urolithiasis (stones)

• Pyelonephritis (Inflammation of kidney)

• Hydronephrosis (distension of renal pelvis and calyces with urine)

• Trauma• Renal hypertension

• Pre-op evaluation

Contraindications

• Inability to filter contrast medium from blood

• Allergy to contrast

• Abnormal BUN and Creatinine levels

Preparation Of Pt

• Pt on low residue diet for 1-2 days prior to exam

• Laxative taken day prior to clean out bowel

• NPO after midnight

• Pts with multiple myeloma, high uric acid levels, or diabetes should be well hydrated before IVP exam

(Dehydration leads to increased risk of renal failure)

Contrast Media

• Used to visualize urinary tract adequately

• Iodinated, water-soluble contrast administered intravenously

• Antegrade filling

Contrast Media

Excretory urography (IVU) generally uses a 50 to 70% iodine solution

Lower concentrations required for bladder studies due to large amount required to fill bladder (30%)

Non-ionic contrast is generally usedMore expensive, but-Patients less likely to have reactions with nonionic

Contrast Media and Adverse Reactions

Do not leave pt. alone for first 5 minutes after injection!

Mild reactions:warmthflushinghives, Nausea/Vomiting, respiratory edema (accumulation of fluid in

lungs)

Severe reactions:Anaphylactic shock: sudden allergic response: sudden drop in blood

pressure and difficulty breathing

Death in a matter of minutes

IVU Procedure

Scout – KUB

Contrast injected

Timed sequence of films obtained until bladder begins to fill

Take Immediate image of kidneys5 minute image of abd. or kidneysThen apply Compression

(Take tomograms)

Ureteral Compression

• (Because of improvement of contrast agents, compression no longer generally used)

• Compression device centered at ASIS over distal ends of ureters

With as much compression as pt can tolerate!

• Inhibits flow of urine into bladder

• Distends renal pelvis and calyces

Contraindications for Compression

Should not be applied when pt has:

Kidney stones

abdominal mass or aneurysm

colostomy

suprapubic catheter

recent abd. surgery or trauma

Radiation Protection

Gonadal shield - if it does not interfere with exam

Shield males for all urinary studies, except when urethra is of primary interest

Shield females when IR centered over kidneys

Close collimation

Avoid repeat exposures

Rule out chance of pregnancy before examination(Emergency cases may not allow time)

Radiographic Positions IVU

AP Projection-IVU

• Patient supine

• Typical Abdomen positioning

• Use shielding

• (All exposures at end of expiration for any urinary system study)

AP Projection- IVU (cont’d)

Must include entire KUB region

Should include prostatic region on older males

Time Delay - IVU

3 minute6 minutes

Time delay- IVU

9 minutesWith compression

AP Projection Variations

Trendelenberg:

Lower head 15 - 20 degrees

Helps demonstrate lower ureters

Upright:Must lower CR - organs change position

ProneDemonstrates ureteropelvic region

Fills obstructed ureter in cases of hydronephrosis (distension of renal pelvis and calyces with urine)

AP Oblique Projections - RPO/LPO

• Pt. supine

Rotated 30 degrees

• Typical Abdomen oblique position

AP Oblique Projections (cont’d)

• Elevated kidney will be parallel to cassette

• Kidney closest to cassette will be perpendicular

• Entire KUB region must be included

Nephrotomography

• Best method for visualizing renal parenchyma (neprons and collecting tubules)

• To visualize kidneys free of intestinal content superimposition

Tomogram Procedure cont’d

• Tomograms are obtained once bladder is filled

– Pt is measured, divide number by 3, cuts begin there

• Pt. measures 30cm, beginning cuts at 10cm

• Release compression slowly

• Have pt void, and obtain post-void film

Retrograde Urography

What does retrograde mean?

Requires catheterization of ureters

Contrast injected directly through cathethers

Provides improved opacification of renal collecting system

Opposite normal flow

Retrograde Urography (cont’d)

• Contrast does not enter blood stream

• Used for patients with renal insufficiency or contrast sensitivity

• Ureters, and collecting systems can be selectively imaged and sampled

• Little physiologic information provided

Retrograde Urography cont’d

• Considered an operative procedure

• Pt may be under general anesthesia

• Sterile technique

• Nurse responsible for set-up of exam and pt. care

Cystography

• Radiologic exam of urinary bladder

• Contrast administration usually performed retrograde (against normal flow of urine)

Indications for Cystography

Vesicoureteral reflux (backward flow of urine into ureters)

Recurrent lower urinary tract infection

Neurogenic bladder: (dysfunction due to disease of central nervous system or peripheral nerves)

Bladder trauma

Prostate enlargement

Lower urinary tract fistulae

Urethral stricture

Posterior urethral valves (obstructive congenital defect of the male urethra)

Contraindications for Cystography

Anything related to catheterization of urethra!

Cystography Procedure

• Contrast drip-infused via a catheter

• Bladder filled to capacity

• Fluoro-spot and overhead images obtained

Scout

Filled AP or PA (axial)

Both obliques

Lateral

Post-void

Routine Cystography Series

AP Axial Bladder (similar to coccyx projection)

CR:

Angle 10 to 15 degrees caudad

Enters 2 above upper border of pubic symphysis

Can be done PA

AP Oblique Bladder

Pt position:

40- to 60-deg. rotation

RPO or LPO depending on physician preference

Lateral Bladder

Demonstrates:

anterior/posterior bladder walls

– Base of bladder

– Any vesicovaginal or vesicorectal fistulae

Male Cystourethrography

• Images obtained as contrast injected by urethral syringe

• Entire urethra must be visualized

• Bladder can be filled to obtain antegrade voiding study

• Why is this antegrade if its injected into urethra?

AP Oblique Projection - RPO/LPO

Female Cystourethrography

• Retrograde

• AP Projection (maybe obliques)

• Bladder can be filled and pt. voids for antegrade studies

Voiding Cystourethrogram

X-ray images of bladder and urethra during urination

Follows cystogram - urinary catheter removed

Pt. urinates into special radiolucent urinal as images taken

.

Voiding Cystourethrogram cont’d

• Shows size and shape of bladder under stress caused by urination

• Demonstrates urethra functioning

• Most commonly used for young girls with history of recurrent bladder infections

Metallic Bead Chain Cystourethrography

• To evaluate stress incontinence in females only

• Beaded chain inserted in Urethra

• Shows anatomic changes in shape and position of anatomic floor

• Valsalva tech. applied for comparison

Summation of exams of Urinary System

IVU- entire urinary system

Retrograde Urogram- same as IVU but performed through catheter starting at urethra

Nephrotomography- slices of kidneys

Cystogram- for bladderVoiding Cytogram

Cystourethrogram- for urethraVoiding Cystourethrogram