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Rigler Sign
Definition/Introduction
The Rigler sign, or double-wall sign, is an indication of free air enclosed within the peritoneal cavity (pneumoperitoneum), imprinting a visible pattern on a plain radiographic image of the abdomen in the supine technique. This sign is present because of the separation between free air and intraluminal by the intestinal wall, marking the air radiolucency and radiopacity of the wall. Both serosal and luminal surfaces of the bowel are visible (see Image. Rigler Sign).[1]
In 1942, American radiologist Leo G Rigler (1896-1979) described this sign of pneumoperitoneum. He described the pattern in 4 cases reported in 1941. He observed this sign was present when large quantities of free air were in the peritoneal cavity.[2]
Issues of Concern
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Issues of Concern
In upright chest radiography or abdominal radiography, pneumoperitoneum is detectable under special conditions in small quantities as little as 1mL.[3] CT scan has greater sensitivity and specificity than conventional radiographic technique is more available and cheaper.[4] Because a large percentage of patients who require abdominal radiography for suspected pneumoperitoneum are ill and unable to stand or sit, the plain supine projection becomes an option. This modality has lower diagnostic accuracy for pneumoperitoneum (56%) compared with other projections (left lateral decubitus 96%, chest 85%, upright 60%).[5] Other studies sustain that radiography can detect pneumoperitoneum only in 69% to 89% of cases with visceral perforation.[6][7] Sensitivity and specificity for the detection of pneumoperitoneum by abdominal radiography are low compared with CT scans.[8][9] Dissemination of modern CT scan technology has made abdominal radiography less common in most developed health systems, and conventional abdominal radiology is omitted in the workup of most adult patients with acute abdominal pain.[10]
Clinical Significance
Rigler sign is the second most common sign of pneumoperitoneum, the first being the right upper quadrant subdiaphragmatic free air. Study cases report the incidence of Rigler sign with a lower prevalence then right upper quadrant subdiaphragmatic free air (46% vs. 32%).[11] For its presence, a large quantity of free air must be around 1000mL for clear recognition. Pseudo-Rigler sign occurs when 2 loops of gas-distended bowel make contact, enhancing the intestinal wall radiopacity image against the air-filled loops, misleading the diagnosis of pneumoperitoneum.[12] If the Rigler sign appears present, then abdomen/pelvis CT scanning and surgical consultation are warranted in the proper clinical context.[10]
Media
(Click Image to Enlarge)
Rigler Sign. Rigler sign and massive free air on chest as seen on radiograph after intubation.
Contributed by J Solano, MD
References
Ly JQ. The Rigler sign. Radiology. 2003 Sep:228(3):706-7 [PubMed PMID: 12954891]
Lewicki AM. The Rigler sign and Leo G. Rigler. Radiology. 2004 Oct:233(1):7-12 [PubMed PMID: 15333763]
Gans SL, Stoker J, Boermeester MA. Plain abdominal radiography in acute abdominal pain; past, present, and future. International journal of general medicine. 2012:5():525-33. doi: 10.2147/IJGM.S17410. Epub 2012 Jun 13 [PubMed PMID: 22807640]
Stapakis JC,Thickman D, Diagnosis of pneumoperitoneum: abdominal CT vs. upright chest film. Journal of computer assisted tomography. 1992 Sep-Oct; [PubMed PMID: 1522261]
Roh JJ, Thompson JS, Harned RK, Hodgson PE. Value of pneumoperitoneum in the diagnosis of visceral perforation. American journal of surgery. 1983 Dec:146(6):830-3 [PubMed PMID: 6650772]
Winek TG, Mosely HS, Grout G, Luallin D. Pneumoperitoneum and its association with ruptured abdominal viscus. Archives of surgery (Chicago, Ill. : 1960). 1988 Jun:123(6):709-12 [PubMed PMID: 3285808]
Level 2 (mid-level) evidenceBansal J, Jenaw RK, Rao J, Kankaria J, Agrawal NN. Effectiveness of plain radiography in diagnosing hollow viscus perforation: study of 1,723 patients of perforation peritonitis. Emergency radiology. 2012 Apr:19(2):115-9. doi: 10.1007/s10140-011-1007-y. Epub 2011 Dec 6 [PubMed PMID: 22143167]
Catalano O, [Computed tomography in the study of gastrointestinal perforation]. La Radiologia medica. 1996 Mar; [PubMed PMID: 8628938]
Level 2 (mid-level) evidenceLaméris W, van Randen A, van Es HW, van Heesewijk JP, van Ramshorst B, Bouma WH, ten Hove W, van Leeuwen MS, van Keulen EM, Dijkgraaf MG, Bossuyt PM, Boermeester MA, Stoker J, OPTIMA study group. Imaging strategies for detection of urgent conditions in patients with acute abdominal pain: diagnostic accuracy study. BMJ (Clinical research ed.). 2009 Jun 26:338():b2431. doi: 10.1136/bmj.b2431. Epub 2009 Jun 26 [PubMed PMID: 19561056]
Gans SL, Pols MA, Stoker J, Boermeester MA, expert steering group. Guideline for the diagnostic pathway in patients with acute abdominal pain. Digestive surgery. 2015:32(1):23-31. doi: 10.1159/000371583. Epub 2015 Jan 28 [PubMed PMID: 25659265]
Levine MS, Scheiner JD, Rubesin SE, Laufer I, Herlinger H. Diagnosis of pneumoperitoneum on supine abdominal radiographs. AJR. American journal of roentgenology. 1991 Apr:156(4):731-5 [PubMed PMID: 2003436]
Level 2 (mid-level) evidencede Lacey G, Bloomberg T, Wignall BK. Pneumoperitoneum: the misleading double wall sign. Clinical radiology. 1977 Jul:28(4):445-8 [PubMed PMID: 872511]