Urinary Bladder Pathology Quiz

Lower Urinary System

• The lower urinary system is composed of the ureters, bladder, and urethra.
• Kidneys are part of the superior urinary system.
• The ureters, bladder, and urethra work together to transport, store, and eliminate urine.
• The pelvic ureter and urethra are conduits in the elimination process.
• The urinary bladder is located between the ureters and urethra and acts as a reservoir for urine storage.

Embryological Development

• During early embryology of the urogenital system, kidneys develop in three successive waves from cranial to caudal.
• The first wave is the pronephros, which occurs early in the fourth week of embryonic development.
• The second wave of development is the mesonephros, present late in the fourth week.
• The third and final wave is the metanephros, occurring in the fifth week, and these ultimately develop into the permanent kidneys.
• The caudal end of the hindgut has cloaca, a dilated chamber, in close contact with the ectoderm forming the cloacal membrane.
• An extension from the cloaca into the umbilical cord is the allantois.
• The intermediate mesoderm of the gastrula bulges into the dorsal aspect of the intraembryonic coelom to form a urogenital ridge.
• The urogenital ridge develops into two ridges: the medial genital (gonadal) ridge, and the lateral nephrogenic ridge.
• Mesonephric (Wolffian) duct and paramesonephric (Müllerian) duct form in the nephrogenic ridge or cord.
• Approximately in the seventh gestational week, the urorectal septum fuses with the cloacal membrane to divide into ventral (anterior) urogenital sinus and the dorsal (posterior) rectum.

Anatomy & Organogenesis (Urinary bladder)

• The urinary bladder develops into a hollow, smooth, musculomembranous, collapsible sac that acts as a reservoir for urine.
• It is located in the retroperitoneum on the pelvic floor, posterior to the pubic symphysis.
• Its size, position, and relationship to other organs vary depending on the amount of fluid it contains.
• The bladder lining contains mucosal membrane of transitional epithelium, allowing for expansion.
• The mucous membrane lining contains rugae or folds when the bladder is empty, which appear folded or wrinkled when empty.
• The mucous membrane is loosely attached to the underlying muscle coat, except at the trigone region where it is firmly attached.
• The bladder is capable of considerable distention.
• The normal adult bladder is generally moderately full at 500 mL but may hold nearly double when necessary.
• The bladder, in a normal empty state, has a round-edged tetrahedron shape with a superior, posterior, and two inferior surfaces.
• The superior surface has two regions: the fundus-located posteriorly, and the apex-located anteriorly.
• Two ureteral orifices are located in the body on the posteroinferior portion.
• The urethral orifice is located in the neck of the bladder and is the most inferior region.
• Normally, the anterior surface of the bladder lies just behind and rarely superior to the symphysis in both males and females.

Pelvic Anatomy

• The fibrous medial umbilical ligament (obliterated urachus) extends from the apex upward as a blunt cone and attaches to the umbilicus in the midline of the abdominal wall.
• When distended with urine, the bladder can rise approximately 16 cm above the symphysis pubis, ascending into the abdominal cavity and contacting the lower anterior abdominal wall.
• When fully distended, the bladder can be readily palpated or percussed.
• As the bladder enlarges, it loses its ovoid or spherical configuration and becomes more globular.
• The small intestine coils lie adjacent to the upper surface of the bladder and are displaced posteriorly as the bladder enlarges.
• In females, the relative empty bladder fundal region lies in contact with the anterior wall of the vagina and cervix.
• The uterus and vagina are interposed between the bladder and rectum.
• When empty, the uterus rests on the bladder's superior surface.
• The pelvic muscular anatomy is greatly enhanced by a full bladder technique

Male Pelvic Anatomy

• In males, the bladder fundus and body relate to the rectum, separated by the rectovesical pouch of peritoneum.
• Inferolaterally, on each side, the ductus deferens and seminal vesicle are present.
• The prostate is a fibromuscular and glandular organ that lies just inferior to the bladder.
• The greater part of the caudal surface is directly continuous with the bladder wall.
• The normal prostate encircles the prostatic urethra and prostate gland secretions enter the prostatic urethra via several ducts.
• Seminal vesicles are approximately 6 cm long and quite soft, and they join their corresponding vas deferens to form ejaculatory ducts, located cephalad to the prostate underneath the base of the bladder.

Anatomy & Organogenesis (Ureters)

• Ureters are slender tubes that convey urine from the kidneys to the bladder.
• Each ureter is a continuation of the renal pelvis.
• Descending in the retroperitoneum, ureters course obliquely through the posterior bladder wall.
• The average ureter length is 30 cm, and the diameter is 6 mm.
• Ureters are constricted in three locations: at the ureteropelvic junction, as they cross iliac vessels, and at the junction with the bladder.
• As the bladder fills, pressure increases, causing the upper and lower walls of the terminal portions of the ureter to meet and act as valves, preventing urine regurgitation from the bladder.
• When the bladder is distended, the openings of the ureters are about 5 cm apart, and the distance between them is diminished by half when the bladder is empty and contracted.

Anatomy & Organogenesis (Urethra)

• The urethra is a thin-walled fibromuscular tube that drains urine from the bladder and conveys it outside the body.
• The urethra represents the terminal portion of the urinary tract.
• At the bladder-urethral junction, the thickening of the detrusor smooth muscle of the bladder wall forms the internal urethral sphincter.
• The detrusor muscle is involuntary and keeps the urethra closed to prevent leakage between voiding events.
• The sphincter is unique in that contraction opens and relaxation closes it.
• The external urethral sphincter surrounds the urethra as it passes through the urogenital diaphragm, is a skeletal muscle, and is controlled voluntarily.
• In females, the urethra is 3 to 4 cm long and conveys urine from the body, specifically located directly posterior to the symphysis pubis and anterior to the vagina.
• The external urethral orifice is the external opening of the urethra, located anterior to the vaginal opening and posterior to the clitoris.
• The urethral opening to the exterior is referred to as the urinary meatus.
• In males, the urethra serves a double function: as a conduit for eliminating urine and as the terminal portion of the reproductive system for ejaculate passage.

Normal Ureteral Jet Phenomenon

• The ureteral jet phenomenon occurs during sonography in the urinary tract.
• The ureteral jets are visualized as echoes that appear to enter the bladder from the trigone.
• These jets have a brief duration of 5 to 20 seconds and originate at the level of ureteral orifices.
• Ureteral jets often appear simultaneously, although they are more commonly separated.
• Such jets usually extend up to 3 cm and often broaden.
• The echoes eventually lose intensity after a few seconds, becoming distributed in the bladder until they are no longer differentiable.
• Color Doppler is more sensitive than the Ureteral Jet Phenomenon in demonstrating ureteral jets, with evaluation aiding in determining the degree of ureteral obstruction.

Three Dimensional Imaging

• Multiplanar reconstruction demonstrates a small bladder tumor, simultaneously seen in the sagittal, transverse, and coronal planes, along with the bladder lining.
• Intersecting lines on each image represent the same anatomic position in all three planes.

Bladder Diverticulum

• The diverticulum is a pouch-like eversion of the bladder wall.
• Diverticula are produced by mucosal herniation through defects in the muscle wall, arising as congenital defects or acquired lesions.
• Careful scanning may reveal a narrow communication between the diverticulum and bladder, leading to diagnosis.
• Intradiverticular tumors or stones are also possible.
• Diverticula may not empty completely and possibly increase in size post voiding.

Posterior Urethral Valves

• Posterior urethral valves usually consist of a mucosal flap originating from the verumontanum.
• This valve syndrome is commonly the cause of urinary obstruction during the early stages of infants' life and is more likely to be found during the first year of life, rarely presenting in older children or adults.
• About 40% of affected patients will have associated vesicoureteral reflux, often as a result of periureteral diverticulum.
• Sonographic recognition of a dilated and elongated prostatic urethra supports diagnosis from neurogenic bladder dysfunction.
• The bladder wall with these valves will often appear thickened, along with hydrouretors with dilation of the upper urinary tract.

Ureterocele

• Ureterocele is a cyst-like enlargement of the lower end of the ureter.
• Problems arise due to stenosis of the ureteral opening in the sac wall, often causing hydroureter, hydronephrosis, and infection proximal to the ureterocele.
• The ureterocele sac itself may obstruct the bladder outlet or even prolapse through the urethra.
• An ectopic ureterocele is formed when an ectopic ureter is obstructed where it enters the bladder, causing its anterior wall to balloon into the bladder.
• Sonographic diagnosis should include the complete scanning of kidneys to ensure both ectopic ureters and ureteroceles are considered.
• Duplex kidneys may show the presence of two ureters arising within the kidney and frequently, ectopic ureters are characterized by being massively dilated and tortuous in the distal portion, while mildly dilated proximally.
• Large ureteroceles may be confused with multiseptate, cystic abdominal masses, as the ectopic ureteroceles dynamically change shape and size based on intravesical pressure.
• Simple ureteroceles are easily seen during sonography, generally as incidental findings located at the expected position of the distal ureteral orifice.
• They are oval- or round-shaped, thin-walled cystic structures on the posterior bladder wall of a distended bladder.

Urachal Variants

• In the fetus, the bladder is positioned at the umbilicus and communicates with the allantoic canal, an extension of the cloaca/urogenital sinus, and the umbilical cord.
• The urachus is an embryonic tract that forms as the bladder descends into the true pelvis, thus creating a fibromuscular appendage that surrounds the allantoic canal and measures approximately 5 cm in length.
• This appendage is usually obliterated by birth; failure to close the urachus leads to an open channel between the bladder and umbilicus.
• Four types of urachal anomalies include: a patent urachus/fistula, urachal sinus, urachal cyst, and urachal diverticulum.
• In 50% of cases, a patent urachus/fistula is identified, and urine is often draining constantly from the umbilicus.
• The urachal sinus is present in about 15% of cases, where the urachus closes at the bladder but opens at the umbilicus.
• Urachal cysts develop when both ends of the urachus close, trapping some urine within, seen in about 30% of cases.
• Urachal diverticulum is the least common type, occurring in 5% of cases and forming when the urachus closes at the umbilicus but remains open at the bladder.

Bladder Wall Abnormalities

• Bladder wall thickening is among the most common sonographically observed abnormalities of the bladder.
• This thickening often results from outlet obstruction.
• Other causes include neurogenic bladder, cystitis, edema from adjacent inflammatory processes, and primary or secondary neoplasms.

Trauma/Rupture

• Bladder rupture often occurs in response to severe blunt lower abdominal or pelvic trauma, or penetrating abdominal or perineal injury occurring when the bladder is full.
• Rupture is more likely with pelvic crush injuries that occur with a percentage ranging from 1% to 15% of the cases.
• Bladder rupture is usually extraperitoneal, and it happens in 80% of cases.
• An urinoma is when a bladder tear leads to an accumulation of urine in the surrounding tissues, presenting as an anechoic mass with enhanced through-transmission.
• Irregular borders and internal septations/debris are common findings for urinoma.
• A clinical history of leukocytosis and a dropping hematocrit suggests an infected hematoma, while a dropping hematocrit alone suggests a hematoma.

Trauma/Blood Clots

• Blood clots may occur either due to a pathologic process or from trauma.
• These clots can adhere to the bladder wall.
• Clots appear as irregular patterns on the bladder mucosal surface; they can move with changes in the patient’s position.

Bladder Neoplasms

• Bladder tumors are frequently observed in urogenital and renal sonography.
• These tumors are almost always epithelial or uroepithelial in origin.
• Painless hematuria is a common symptom, aside from dysuria, urinary frequency, and urgency.
• Tumors cause an irregularity in the 3 to 5 mm thickness of the bladder wall.
• Bladder neoplasms are often found using cystoscopy, which involves inserting a cystoscope into the urethra and into the bladder.

Stress Incontinence

• Stress incontinence is an issue resulting from a poorly supported bladder neck and/or section between the bladder and urethra.
• When a patient coughs, strains, or bears down, the bladder neck moves inferiorly, the urethra opens, and urine is pushed out.