Rigler sign: Radiographic sign of pneumoperitoneum. Air in the peritoneum and air within the intraluminal spaces outline the luminal and serosal surfaces of the bowel wall.

Rigler sign may be seen in up to 32% of patients with pneumoperitoneum demonstrated by supine abdominal radiographs



Supine pneumoperitoneum 1924
Fig. 2. X-ray plate of patient in supine position showing A, level of fluid in free abdominal cavity; B, free air in abdominal cavity above the fluid level; C, anterior abdominal wall; D, loop of bowel containing air. Vaughn 1924

1941Leo George Rigler (1896-1979) described the pneumoperitoneum sign and emphasized that it would only be observed when large quantities of free gas were present.

A roentgenologic sign of pneumoperitoneum hitherto not reported or clearly defined is described. I t consists of the demonstration of the outer as well as the inner bowel wall due to the accumulation of gas between the loops of bowel. It is of value because it can be observed in roentgenograms of the abdomen made in the supine position.

This sign may be the first evidence of the presence of pneumoperitoneum in cases in which such a condition is entirely unsuspected. Routine roentgenograms of the abdomen should be made at frequent intervals in all cases of obstruction of the gastro-intestinal tract which are being treated conservatively. Such films should always be examined for evidences of pneumoperitoneum because of the possibility of supervention of perforation without obvious clinical signs.

Rigler, Radiology 1941
Rigler 1941 pneumoperitoneum supine 2 and 3
Fig. 2. Roentgenogram (supine position) after perforation of the cecum. The outer margins of the bowel loops (arrow) may now be seen owing to the presence of gas about them, producing contrast. The diagnosis of pneumoperitoneum can be made from this film without the use of the upright or lateral decubitus position.
Fig. 3. Case of perforation of the colon with pneumoperitoneum; roentgenogram of abdomen, supine position. Note the distended loops of small bowel, both their inner and outer contours (arrows) being readily visible. Rigler 1941


Diagnosis of Pneumoperitoneum on Supine Abdominal Radiographs 1991
Summary of Radiographic Findings in 44 Cases of Pneumopentoneum and 87 Controls. Levine et al 1991
Rigler Double wall sign-labelled
Rigler sign on supine abdominal film with pneumoperitoneum

Pseudo-Rigler sign

Form of pseudopneumoperitoneum, and mimic of the classic Rigler sign, which can be encountered on normal abdominal X-rays.

Caused by omental / mesenteric fat; oral contrast media outlining the bowel loops; or overlapping gas-filled bowel loops making the wall contours appear more prominent.

In such cases further examination with erect or lateral decubitus views, or CT are required to rule in or out the presence of free gas.

Associated Persons

Alternative names
  • Rigler’s sign
  • Double-Wall Sign, double-lumen sign
  • bas-relief sign


Original references

Review articles


Andrew Warnock LITFL Author 2

Third year M.D. student at the University of Notre Dame Fremantle. Passionate about emergency and retrieval medicine, rural practice and clinical research

BA MA (Oxon) MBChB (Edin) FACEM FFSEM. Emergency physician, Sir Charles Gairdner Hospital.  Passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |

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