Mickey mouse sign

Excerpt

The pelvic “Mickey Mouse” sign is created when bilateral inguinal hernias that contain portions of the bladder as isolated content are seen at imaging (Figs. 1, 2) [1]. Bladder participation in inguinal hernias is seen in about 4% of cases, with isolated bladder herniation considered a rare occurrence [2]. Urinary bladder hernias are more commonly seen in older, obese males. Bladder herniation may be asymptomatic or they may present with lower urinary tract symptoms, depending on the degree of bladder involvement [2]. Bladder herniation may present with inguinoscrotal swelling that becomes smaller after voiding. Inguinal hernias containing urinary bladder may also present with Mery’s syndrome, which is described as double micturition with second voiding done by external compression of the swelling [2]. Scrotal pressure for voiding in patients over 50 years is a specific sign of urinary bladder in the hernia [3]. Transient protrusions of the lateral aspect of the bladder base (the so-called “bladder ears”) seen in infants should not be incorrectly diagnosed as bladder herniation [4, 5]. Computed tomography and magnetic resonance imaging are comprehensive tools for diagnosis and detection of complications of bladder herniation [2, 3]. Awareness of this unusual condition and its specific imaging appearance is important to avoid injury to the bladder during hernia repair.

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