the unveiling…

the case.

a 64 year old female presents to your Emergency Department at midnight with acute severe abdominal pain.

She has a past medical history of rectal cancer which had been treated with resection & a defunctioning colostomy. This had been successfully reversed 4 years ago.

Our patient reports three days of colicky abdominal pain & reduced bowel motions, however developed sudden, severe abdominal pain at precisely 8pm tonight & just ‘cannot get comfortable now’ !! There is associated nausea and vomiting (without haematemesis) as well as severe pain in her right shoulder. Despite 20mg of intravenous morphine, she is crying in pain & unable to settle in the bed.

On examination; she has frank peritonism & a palpable (exquisitely tender) hernia in her right lower quadrant, adjacent to an old surgical scar.

Amongst the usual work-up (demonstrating acute kidney injury & a white count > 18,000) she undergoes plain x-rays of the abdomen….

[DDET Here are her initial plain x-rays…]

Supine AXR with an unusual pattern of free-gas extending from right psoas muscle, along the vertebral column involving the perisplenic & perinephric spaces.
Supine AXR with an unusual pattern of extraluminal gas extending from right psoas muscle, along the vertebral column involving the perisplenic & perinephric spaces; suggestive of retroperitoneal perforation (pneumoretroperitoneum).
Erect AXR with an unusual pattern of free-gas. Localised gaseous bowel distension (right side) with air-fluid levels.
Erect AXR with an unusual pattern of free-gas. Localised gaseous bowel distension (right side) with an air-fluid level.

Given the above findings, we arrange for a CT of her abdomen. IV contrast is withheld given the new renal impairment.


[DDET Here is the CT…]



[DDET The diagnosis…]

A right incisional hernia containing distended loops of ascending & proximal transverse colon resulting in a closed-loop obstruction of the hepatic flexure. Extensive extra-peritoneal gas, consistent with perforation of the obstructed hepatic flexure.

Retroperitoneal perforation.

Results in pneumoretroperitoneum – the presence of gas within the retroperitoneal space.
Typically the air outlines structures like the kidneys, psoas muscles and retroperitoneal portions of the bowel

The hallmark of this is the “veiled kidney sign”.

Veiled Kidney
“Veiled kidney sign”

Recall the structures that reside in the retroperitoneal space.



Causes of pneumoperitoneum.

  • Duodenum.
  • Rectum.
    • Malignancy
    • Foreign body insertion
    • Pelvic trauma
    • Complication of endoscopy
    • Contrast enema
  • Colon (ascending & descending).
    • Diverticulitis
    • Appendicitis
    • Ischaemic colitis
    • Malignancy
    • Complication of endoscopy / polypectomy.
  • Genitourinary.
    • Post-operative residual air
    • Infective
    • Spontaneous (renal transplant / immunosuppressed)


[DDET Case conclusion…]

With the above diagnosis; she receives ongoing analgesia, volume replacement, electrolyte correction, nasogastric tube & in-dwelling catheter.

At sunrise she is taken to theatres for a laparotomy which reveals that her ascending colon & part of the hepatic flexure was incarcerated in the incisional hernia with a focal area of necrosis (the point of perforation). She undergoes a right hemicolectomy.

There is a rocky post-operative course with multiple sub-diaphragmatic abscesses requiring drainage however she is finally discharged 26 days after her initial presentation to ED.


[DDET References.]

  1. Yagan N, Auh YH, Fisher A. Extension of air into the right perirenal space after duodenal perforation: CT findings.Radiology. 2009 Mar;250(3):740-8
  2. Wang, HP & Su, WC. Veiled Right Kidney Sign in a Patient with Valentino’s Syndrome. N Engl J Med 2006; 354:e9
  3. Yildirim, M et al. Retroperitoneal perforation of the rectum during double-contrast barium-enema examination: a life-threatening complication. Radiol Oncol 2009; 43(1): 26-9.
  4. Pneumoretroperitoneum @ Radiopaedia.org


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