Herniation of the urinary bladder is a relatively uncommon but not a rare condition. It occurs when the urinary bladder or ureter herniates into the inguinal canal, scrotal sac or femoral canal. Herniations through ischiorectal, obturator, or abdominal wall openings have also been described. Bladder herniation into the scrotum has also been called scrotal cystocele.
It is important to be aware of this condition in any males older than 50 years with an inguinal hernia, as unknowingly, bladder injury during herniorrhaphy can lead to infection, sepsis, or death.
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Epidemiology
Herniation of the bladder is seen in 1-3% of inguinal hernias. It is seen in 10% of men older than 50 years. Femoral hernias are more common in women. These hernias have a predilection for the right side 1.
Clinical presentation
Most are asymptomatic and are discovered incidentally during radiological evaluation of inguinal hernias. However, symptoms such as dysuria, frequency, urgency, nocturia, and hematuria are also common. A typical symptom will be a reduction of hernia size after passing urine, and the ability to pass urine after pressing the hernia sac 1.
Pathology
Etiology
Many factors can lead to bladder herniation:
chronic bladder distension (e.g. prostatism) and its contact with the inguinal canal
loss of bladder tone
pericystitis
perivesical fat protrusion
large pelvic mass lesions
Classification
paraperitoneal hernia: most frequent type, in which the extraperitoneal portion of the hernia lies along the medial wall of the sac
intraperitoneal hernia: herniated bladder is thus completely covered by peritoneum
extraperitoneal hernia: the bladder is not covered by the peritoneum at all
However, anatomical classification of inguinal hernias (direct and indirect) can also be applied.
Radiographic features
Excretory urography
A wide-mouthed rounded protrusion of the bladder wall directed downwards is seen.
Indirect signs are:
small asymmetric bladder
incomplete visualization of the bladder base
lateral displacement of the lower ureter
One important technical consideration is the positioning of the patient - In typical supine radiographs, they are usually missed. Prone position can improve the detection, while erect radiographs can detect 100% of such hernias.
Retrograde cystography
It is the best technique to image a bladder hernia. However, bladder herniation is still visible during voiding.
Ultrasound
Usually, only large scrotal lesions can be well visualized in sonography. A fluid-filled sac in continuity with the urinary bladder is seen. Sometimes, this continuity is difficult to demonstrate, where it is seen as a beaked appearance of fluid-filled scrotal sac cranially 1.
CT
CT is indicated when the patient is a male and obese, aged ≥50 years, and presents with inguinal swelling and lower urinary tract symptoms 8. Pointing of the bladder toward the side of the hernia, i.e. angulation of the bladder base anteroinferiorly, is the CT sign of bladder herniation. A prone position can enhance its visualization. CT can also reveal herniation through uncommon sites like the obturator foramen.
MRI
Findings are similar to CT features of bladder hernia, however coronal and sagittal planes can clarify the issue. Also, relations to adjacent vascular landmarks can be well-identified 1.
Differential diagnosis
General imaging differential considerations include
bladder ears: in young infants, normal protrusion of the lateral aspect of the bladder into the inguinal canal
cystocele: are usually triangular and along the midline, whereas bladder hernias are projected laterally
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