This document discusses various radiographic signs that can indicate the presence of free air or pneumoperitoneum within the peritoneal cavity. It begins by explaining that pneumoperitoneum is most commonly caused by a perforation of the abdominal viscus, usually the stomach or bowel. It then presents 15 different named radiographic signs visible on abdominal x-rays that suggest pneumoperitoneum, such as the anterior subhepatic space free air sign and Rigler's sign. Each sign is accompanied by an illustrative image and brief explanation. Additional less common signs are also listed. References for further information are provided.

1. Ext. จริยาภรณ์ พัฒนกุลเลิศ

2. “ within the peritoneal cavity”
The most common cause is a perforation of the
abdominal viscus
– most commonly, a
Soto JA, Lucey BC. (2009). Emergency Radiology: The Requisites. Pg 305
Khan AN. (2014). Pneumoperitoneum Imaging. Medscape.

3. 1-3) RUQ/Liver signs on supine AXR:
• Anterior Subhepatic Space Free Air
• Doges Cap Sign
• Air Anterior to Ventral Surface of Liver
4) Rigler’s Sign
5) Decubitus Abdomen Sign
6) Falciform Ligament Sign
7) Football Sign
8) Continuous Diaphragm Sign
9) Double Bubble Sign
10) Cupola Sign
11) Lesser Sac Gas
12) Triangle Sign
13) Abscess Gas
14) Pneumoretroperitoneum
15) Others

4. • Supine; RUQ/Liver sign 1
• Linear shape
Index

5. • Supine; RUQ/Liver sign 2
shaped
lateral
corner
border
outlining the medial
border of the liver
4. Positioned inferior to
the 11thrib
5. Positioned superior to
the right kidney
Morrison’s pouch =
a potential space between
the right kidney & the liver
Index

6. • Supine; RUQ/ Liver sign 3
• Uneven density in
Index

7. • Supine
• Bowel wall
(extraluminal = free
peritoneal gas)
of bowel wall
can be seen
(red arrows)
Index

8. • Left lateral
decubitus
• Air-fluid level
between
the abdominal
wall and the liver
in the
peritoneum
Index

9. • Supine
• Falciform ligament
– connects the anterior
abdominal wall to the
liver
– extends inferiorly
beyond the liver →
becomes round ligament
– becomes
in a patient with free
abdominal gas
Index

10. • massively air-filled
peritoneum
Index

11. • massive
pneumoperitoneum
→ sufficient air
beneath the
diaphragm
• left & right
hemidiaphragms
contrasted by the
free gas appear as a
Index

12. • subdiaphragmatic gas
under the left
hemidiaphragm
– subdiaphragmatic free
gas (under black arrow)
– normal gas within the
fundus of the stomach
(under white arrow)
Index

13. • Air accumulation
beneath the central
tendon of the
diaphragm
Index

14. • The lesser sac
– positioned posterior to
the stomach
– usually a potential space
Note:
White arrow = Cupola sign
Index

15. • small triangles of free
gas positioned between
the large bowel and the
flank
Index

16. • arrowed
NOT clearly contained
within normal hollow
abdominal viscus
– NOT aligned in a linear
fashion nor outline
normal haustral features
Index

17. • Air seen surrounding
the lateral border of the
kidney (retroperitoneal
organs)
• If the gas is seen to
move in an erect and
decubitus view, it's
in the retroperitoneum
Index

18. Urachus Sign
Inverted V
Sign
Leaping
Dolphins Sign
Ligamentum
Teres Sign
Index

19. • Air contrasted urachus
• Vertical line between
bladder and umbilicus
• Outline of medial
umbilical ligament
Index

20. • Supine
• Free air outlining the
, coursing
inferiorly and laterally
from the umbilicus
– Infants: umbilical
arteries
– Adults: inferior epigastric
vessels
http://dx.doi.org/10.1148/radiology.151.1.6230689
Index

21. • Air under
hemidiaphragm and
diaphragmatic muscle
slips visible
Index

22. • Extraluminal air in the
fissure for the
Ligamentum Teres
• Linear density running
along the inferior edge of
the falciform ligament
Emerg Med J 2011;28:728
doi:10.1136/emj.2010.098699
Picture: DOI: 10.1056/NEJMicm0904627
Index

23. More Signs:
• Coronary Ligament Outlined by Air
– The coronary ligament sited anterior to the liver
• Pneumo-gall bladder
– Air in the gall bladder fossa outlining the gall
bladder
Index

24. • Soto JA, Lucey BC. (2009). Emergency Radiology: The Requisites. Pg 305.
• Khan AN. (2014). Pneumoperitoneum Imaging. Medscape.
• Fuller MJ. (2011, May 27). Pneumoperitoneum. WikiRadiography.
Website: http://www.wikiradiography.com/page/Pneumoperitoneum
• Menuck L, Siemers PI. (1976). Pneumoperitoneum: Importance of Right
Upper Quadrant Features. Am J Roentgeno. 127:753-756.
• Weiner CI, Diaconis JN, Dennis JM. (1973, April). The “Inverted V”: A New
Sign of Pneumoperitoneum. RSNA. Vol. 107, Issue 1.
• Bray JF. (1984, April). The “inverted V” sign of pneumoperitoneum. RSNA.
Vol. 151, Issue 1: 45-46.
• Lee CH. (2010, June 24). Radiologic Signs of Pneumoperitoneum. N Engl J
Med 2010; 362:2410.
• Images in emergency medicine. Emerg Med J 2011;28:728
doi:10.1136/emj.2010.098699