"Flying-saucer in the pelvis" sign: An equivalent of "pelvic Mickey mouse" sign.

Isolated bilateral inguinal vesical hernia with urinary bladder as the only content is very rare. "Pelvic Mickey mouse" sign is a radiological sign described classically for bilateral inguinal vesical hernia on transverse axial imaging. Another imaging finding of a "Flying-saucer in the pelvis" sign seen on conventional intravenous urography is being presented.

INTRODUCTION

An inguinal hernia with urinary bladder as its only content is extremely rare. A bilateral inguinal vesical hernia is even a rarer finding. Bilateral inguinal vesical hernia can be seen on axial imaging as a “pelvic Mickey mouse” sign. However, this case reports an imaging finding of bilateral inguinal vesical hernia on conventional excretory urography (EU), which is being described for the first time as a “Flying-saucer in the pelvis” sign.

CASE REPORT

A 51-year-old man was incidentally detected to have left renal calculi during evaluation of choledocholithiasis. He had no urinary symptoms or flank pain. An EU revealed a peculiar shape of the urinary bladder [Figure 1a] that resembled the shape of a flying saucer [Figure 1b]. Magnetic resonance imaging that was done for workup of choledocholithiasis was reviewed. Bilateral inguinal hernia was noted with anterior wall of bladder as the only content [Figure 1c] and [d].

Figure 1

Imaging findings of a case of bilateral inguinal vesical hernia. (a) Conventional excretory urography bladder film, showing a peculiar flying-saucer shaped urinary bladder. (b) Artistic representation of a flying-saucer. Coronal (c) and axial (d) views of magnetic resonance imaging showing bilateral inguinal vesical hernia (arrows) and characteristic “pelvic Mickey mouse” sign

DISCUSSION

The urinary bladder is involved in 1%–4% of all inguinal hernias.[1] Bilateral involvement, especially with bladder as the only content, is extremely rare. Only two similar cases have been described.[23] Bilateral inguinal vesical hernias can be seen on transverse axial imaging as “pelvic Mickey mouse” sign [Figure 1d]. However, this entity may produce a “Flying-saucer in the pelvis” sign on anteroposterior images of any contrast imaging study including conventional EU. This particular radiologic finding has not been described before.

Inguinal vesical hernias are usually asymptomatic and do not need intervention.[4] Larger hernias may cause urinary symptoms and/or intermittent groin swelling. “Flying-saucer in the pelvis” sign being described for the first time on conventional EU suggests the diagnosis of bilateral vesical inguinal hernia.