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.
Herniation of 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.
Most are asymptomatic and are discovered incidentally during radiological evaluation of inguinal hernias. However, symptoms such as dysuria, frequency, urgency, nocturia, and haematuria 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.
Many factors can lead to bladder herniation:
- chronic bladder distension (e.g. prostatism) and its contact with inguinal canal
- loss of bladder tone
- perivesical fat protrusion
- large pelvic mass lesions
- 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 peritoneum at all
However, anatomical classification of inguinal hernias (direct and indirect) can also be applied.
A wide-mouthed rounded protrusion of bladder wall directed downwards is seen.
Indirect signs are:
- small asymmetric bladder
- incomplete visualization of bladder base
- lateral displacement of the lower ureter
One important technical consideration is positioning of patient - In typical supine radiographs, they are usually missed. Prone position can improve the detection, while erect radiographs can detect 100% of such hernias.
It is the best technique to image bladder hernia. However, bladder herniation is still visible during voiding.
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. Prone position can enhance its visualization. CT can also reveal herniations through uncommon sites like the obturator foramen.
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.
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.
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
- urinary bladder diverticulum 3
- ureteral hernia
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