Pneumoretroperitoneum
Updates to Article Attributes
Body
was changed:
Pneumoretroperitoneum is by definition presence of gas within the retroperitoneal space.
Pathology
Pneumoretroperitoneum is always abnormal and has a relatively small differential:
- perforated retroperitoneal hollow viscus
-
duodenum
- peptic ulcer disease
- blunt or penetrating abdominal trauma
- endoscopy +/- biopsy (rare) 3
- ERCP: especially when a sphincterotomy is performed; incidence 0.5-2% 3
-
ascending/descending colon
- colorectal carcinoma (CRC)
- diverticulitis
- endoscopy +/- biopsy
- ischaemic colitis
-
rectum
- surgery, e.g. transanal excision of rectal carcinoma 2
- foreign body insertion
- endoscopy
- trauma
- rarely an intraperitoneal hollow viscus can perforate into the intramesenteric space and then track air to the retroperitoneal spaces
-
duodenum
- residual air from retroperitoneal surgery
- urological/adrenal 4
- spinal (anterolateral approach) 5
If localised, and especially in the presence of an air-fluid level, a retroperitoneal abscess should be suspected.
Radiographic features
Pneumoretroperitoneum is best appreciated by CT, however can also be detected by plain abdominal radiograph and even by transabdominal ultrasound (see veiled right kidney sign) 6,7
Ultrasound
Interfaces between free air and soft tissues appear as echogenic lines with posterior reverberation artifacts and the obscuration of far field structures. In pneumoretroperitoneum air will collect around the following structures 10;
-
right kidney
-
referred to as the veiled right kidney sign7
- will not change appearance with patient re-positioning, as opposed to the free air in pneumoperitoneum11
-
referred to as the veiled right kidney sign7
-
great vessels
- disappearance of the retroperitoneal inferior vena cava and abdominal aorta 9
- head of the pancreas
-
gallbladder
- retroperitoneal air will collect posteriorly
- duodenum
Differential diagnosis
On plain radiography, the differential is that of gas in other spaces which also projects over the abdomen. It thus includes:
CT has little difficulty in distinguishing these.
See also
-</ul><p>If localised, and especially in the presence of an air-fluid level, a retroperitoneal abscess should be suspected.</p><h4>Radiographic features</h4><p>Pneumoretroperitoneum is best appreciated by CT, however can also be detected by plain abdominal radiograph and even by transabdominal ultrasound (see <a href="/articles/veiled-right-kidney-sign">veiled right kidney sign</a>) <sup>6,7</sup>. Generally, air is most commonly seen surrounding the kidneys in the right and left upper quadrants of the abdomen <sup>6</sup>. There may also be a loss of the normal psoas muscle shadow <sup>6</sup>.</p><h4>Differential diagnosis</h4><p>On plain radiography, the differential is that of gas in other spaces which also projects over the abdomen. It thus includes:</p><ul>- +</ul><p>If localised, and especially in the presence of an air-fluid level, a retroperitoneal abscess should be suspected.</p><h4>Radiographic features</h4><p>Pneumoretroperitoneum is best appreciated by CT, however can also be detected by plain abdominal radiograph and even by transabdominal ultrasound. Generally, air is most commonly seen surrounding the kidneys in the right and left upper quadrants of the abdomen <sup>6</sup>. There may also be a loss of the normal psoas muscle shadow <sup>6</sup>.</p><h5>Ultrasound</h5><p>Interfaces between free air and soft tissues appear as echogenic lines with posterior <a title="Reverberation artifact" href="/articles/reverberation-artifact">reverberation artifacts</a> and the obscuration of far field structures. In pneumoretroperitoneum air will collect around the following structures <sup>10</sup>;</p><ul>
- +<li>right kidney<ul><li>referred to as the <a title="Veiled right kidney sign" href="/articles/veiled-right-kidney-sign">veiled right kidney sign</a> <sup>7</sup><ul><li>will not change appearance with patient re-positioning, as opposed to the free air in <a title="Pneumoperitoneum" href="/articles/pneumoperitoneum">pneumoperitoneum</a> <sup>11</sup>
- +</li></ul>
- +</li></ul>
- +</li>
- +<li>great vessels<ul><li>disappearance of the retroperitoneal inferior vena cava and abdominal aorta <sup>9</sup>
- +</li></ul>
- +</li>
- +<li>head of the pancreas</li>
- +<li>gallbladder<ul><li>retroperitoneal air will collect posteriorly </li></ul>
- +</li>
- +<li>duodenum</li>
- +</ul><h4>Differential diagnosis</h4><p>On plain radiography, the differential is that of gas in other spaces which also projects over the abdomen. It thus includes:</p><ul>
References changed:
- 8. Nürnberg D, Mauch M, Spengler J, Holle A, Pannwitz H, Seitz K. [Sonographical diagnosis of pneumoretroperitoneum as a result of retroperitoneal perforation]. (2007) Ultraschall in der Medizin (Stuttgart, Germany : 1980). 28 (6): 612-21. <a href="https://doi.org/10.1055/s-2007-963216">doi:10.1055/s-2007-963216</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/17703376">Pubmed</a> <span class="ref_v4"></span>
- 9. Oschatz E, Strasser G, Schober E, Janakiev D, Mostbeck G. ["Disappearance" of retroperitoneal vessels - a case report]. (2003) Ultraschall in der Medizin (Stuttgart, Germany : 1980). 24 (6): 410-2. <a href="https://doi.org/10.1055/s-2003-45219">doi:10.1055/s-2003-45219</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/14658085">Pubmed</a> <span class="ref_v4"></span>
- 10. Hoffmann B, Nürnberg D, Westergaard MC. Focus on abnormal air: diagnostic ultrasonography for the acute abdomen. (2012) European journal of emergency medicine : official journal of the European Society for Emergency Medicine. 19 (5): 284-91. <a href="https://doi.org/10.1097/MEJ.0b013e3283543cd3">doi:10.1097/MEJ.0b013e3283543cd3</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/22668809">Pubmed</a> <span class="ref_v4"></span>
- 11. Bob Jarman. Emergency Point-of-Care Ultrasound. (2017) ISBN: 9780470657577
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