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Abdominal X ray
This document provides an overview of how to approach and interpret abdominal x-rays. It describes normal bowel gas patterns and anatomy. Key signs of bowel obstruction, ileus, and free air are outlined. Specific radiographic findings that help localize or characterize abdominal pathologies are also reviewed, including thumbprinting, coffee bean sign, and pneumoperitoneum. Common causes and appearances of abdominal calcifications are summarized based on their location and morphology.
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Abdominal X ray
- 1. Abdominal X-ray RadiologicalSigns Suzanne O’Hagan
- 2. Lightbulb moment a momentof sudden inspiration, revelation, or recognition
- 3. Approach to AXR •Bowel gas pattern • Extraluminal air • Soft tissue masses • Calcifications
- 4. Normal AXR 11th rib Hepatic flexure Gasin stomach T12 Gas in caecum Iliac crest Femoral head SI joint Gas in sigmoid Transverse colon Splenic flexure Psoas margin Sacrum Left kidney Liver Bladder
- 5. Gas pattern • Stomach –Almost always air in stomach • Small bowel – Usually small amount of air in 2 or 3 loops • Large bowel – Almost always air in rectum and sigmoid – Varying amount of gas in rest of large bowel What is normal?
- 6. Normal fluid levels •Stomach – Always (upright, decub) • Small bowel – Two or three levels acceptable (upright, decub) • Large bowel – None normally (functions to remove fluid)
- 7. Large vs smallbowel • Large bowel – Peripheral (except RUQ occupied by liver) – Haustral markings don’t extend from wall to wall • Small bowel – Central – Valvulae conniventes extend across lumen and are spaced closer together
- 8. Radiographic principles Series offilms for acute abdomen • Obstruction series/ Acute abdominal series/ Complete abdominal series – Supine (almost always) – Upright or left decubitus (almost always) – Prone or lateral rectum (variable) – Chest, upright or supine (variable)
- 9. VIEW LOOK FOR SUPINEABDOMEN Bowel gas pattern Calcifications Masses PRONE ABDOMEN Gas in rectosigmoid Gas in ascending and descending colon UPRIGHT ABDOMEN Free air, air-fluid levels UPRIGHT CHEST Free air, lung pathology secondary to intraabdominal process Acute abdominal series What to look for Substitutes: Prone Lateral rectum Upright Left lateral decub Upright chest Supine chest
- 10. Obtaining views • Supine –Patient on back, x ray beam directed vertically downward, casette posterior, x-ray tube anterior (AP) • Prone – Patient on abdomen, x-ray beam directed vertically downward, cassette anterior, x-ray tube posterior (PA) • Upright – Patient stands or sits, x-ray beam directed horizontally, cassette posterior, x-ray tube anterior (AP) • Upright chest – Patient stands or sits, horizontal x-ray beam, cassette anterior, x-ray tube posterior (PA) 1900s X-Ray-based fluoroscopy machine in which radiation is shot directly through the patient and into the doctor’s face.
- 11. Abnormal Gas Patterns •Functional ileus – One or more bowel loops become aperistaltic usually due to local irritation or inflammation • Localised “sentinel loops” (one or two loops) • Generalised (all loops of large and small bowel) • Mechanical obstruction – Intraluminal or extraluminal • Small bowel obstruction • Large bowel obstruction
- 12. 3, 6, 9RULE Maximum Normal Diameter of bowel Small bowel 3cm Large bowel 6cm Caecum 9cm
- 13. Localised ileus Key features •One or two persistently dilated loops of small or large bowel (multiple views) • Often air-fluid levels in sentinel loops • Local irritation, ileus in same anatomical region as pathology • Gas in rectum or sigmoid • May resemble early SBO
- 14. Causes of LocalisedIleus by location SITE OF DILATED LOOPS CAUSE Right upper quadrant Cholecystitis Left upper quadrant Pancreatitis Right lower quadrant Appendicitis Left lower quadrant Diverticulitis Mid-abdomen Ulcer or kidney/ureteric calculi
- 15. Colon cut offsign Explanation: Inflammatory exudate in acute pancreatitis extends into the phrenicocolic ligament via lateral attachment of the transverse mesocolon Infiltration of the phrenicocolic ligament results in functional spasm and/or mechanical narrowing of the splenic flexure at the level where the colon returns to the retroperitoneum. Abrupt cutoff of colonic gas column at the splenic flexure (arrow). The colon is usually decompressed beyond this point.
- 16. Generalised ileus Key features •Entire bowel aperistaltic/hypoperistaltic • Dilated small bowel and large bowel to rectum (with LBO no gas in rectum/sigmoid) • Long air-fluid levels CAUSE REMARK *Postoperative Usually abdominal surgery Electrolyte imbalance Diabetic ketoacidosis * almost always
- 17. Generalised adynamic ileus Thelarge and small bowel are extensively airfilled but not dilated. The large and small bowel "look the same".
- 18. Mechanical SBO • Dilatedsmall bowel • Fighting loops (visible loops, lying transversely, with air-fluid levels at different levels) • Little gas in colon, especially rectum
- 19. SBO Erect SBOSupine Air fluid levels
- 20. Causes of MechanicalSBO * May be visible on AXR Adhesions Hernia* Malignancy Gallstone ileus* Intussesception Inflammatory bowel disease
- 21. Step ladder appearance •Loops arrange themselves from left upper to right lower quadrant in distal SBO
- 22.
- 23. String of pearlssign Considered diagnostic of obstruction (as opposed to ileus) and is caused by small bubbles of air trapped in the valvulae of the small bowel.
- 24. Stretch/slit sign Slit ofair caught in a valvulae, characteristic of SBO
- 25. Closed loop obstruction •Two points of same loop of bowel obstructed at a single location • Forms a C or a U shape – Term applies to small bowel, usually caused by adhesions – Large bowel, called a volvulus
- 26. Crescent Sign Caused by: LUQSoft tissue mass OR Head of intussusception in distal transverse colon
- 27. Double Bubble Sign DuodenalAtresia
- 28. Mechanical LBO • Colondilates from point of obstruction backwards • Little/no air fluid levels (colon reabsorbs water) • Little or no air in rectum/sigmoid
- 29. Large bowel obstruction Bowelloops tend not to overlap therefore possible to identify site of obstruction Little or no gas in small bowel if ileocaecal valve remains competent* * If incompetent, large bowel decompresses into small bowel, may look like SBO
- 30. Causes of MechanicalLBO TUMOUR VOLVULUS HERNIA DIVERTICULITIS INTUSSUSCEPTION
- 31. Note on volvulus •Sigmoid colon has its own mesentry therefore prone to twisting • Caecum usually retroperitoneal and not prone to twisting; 20% people have defect in peritoneum that covers the caecum resulting in a mobile caecum
- 32. Volvulus A volvulus alwaysextends away from the area of twist. Sigmoid volvulus can only move upwards and usually goes to the right upper quadrant. Caecal volvulus can go almost anywhere.
- 33. Coffee Bean Sign Sigmoidvolvulus Massively dilated sigmoid loop
- 34. Hernia Lateral decubitus ofvalue The advantage is that there may be a greater chance of air entering the herniated bowel because it is the least dependent part of the bowel in the supine position.
- 35. Apple core sign •Radiologic manifestation of a focal stricture of the bowel usually at contrast material enema examination. The stricture demonstrates shouldered margins and resembles the core of an apple that has been partially eaten. The most common cause is an annular carcinoma of the colon.
- 36. Thumbprinting The distance between loopsof bowel is increased due to thickening of the bowel wall. The haustral folds are very thick, leading to a sign known as 'thumbprinting.'
- 37. Lead pipe colon • Shorteningof colon secondary to fibrosis • Loss of haustration • Ulcerative colitis
- 38. Extraluminal air • TYPES –Pneumoperitoneum/free air/intraperitoneal air – Retroperintoneal air – Air in the bowel wall (pneumatosis intestinalis) – Air in the biliary system (pneumobilia)
- 39. Upright film best •The patient should be positioned sitting upright for 10-20 minutes prior to acquiring the erect chest X-ray image. • This allows any free intra-abdominal gas to rise up, forming a crescent beneath the diaphragm. It is said that as little as 1ml of gas can be detected in this way.
- 40. Free Air Causes • Ruptureof a hollow viscus – Perforated peptic ulcer – Trauma – Perforated diverticulitis (usually seals off) – Perforated carcinoma • Post-op 5-7 days normal, should get less with successive studies *NOT ruptured appendix (seals off)
- 41. Signs of freeair • Crescent sign • Chilaiditis sign • Riglers (and False Rigler’s) • Football sign • Falciform ligament sign • Triangle sign • Cupola sign • Lesser sac sign
- 42. Crescent Sign II Freeair under the diaphragm Best demonstrated on upright chest x rays or left lat decub Easier to see under right diaphragm
- 43. Chilaiditis sign • Maymimic air under the diaphragm • Look for haustral folds • Get left lat decub to confirm In patients who have cirrhosis or flattened diaphragms due to lung hyperinflation, a void is created within the upper abdomen above the liver. This space may be filled by bowel. If this bowel is air filled then it may mimic free gas.
- 44. Rigler’s Sign Bowel wallvisualised on both sides due to intra and extraluminal air Usually large amounts of free air May be confused with overlapping loops of bowel, confirm with upright view
- 45. False Rigler’s Sign •The Rigler sign can sometimes be simulated by contiguous loops of bowel, whereby intraluminal air in one loop of bowel may appear to outline the wall of an adjacent loop, which results in a misdiagnosis of free air. • Measure distance of interface if unsure
- 46. Football SIgn Seen withmassive pneumoperitoneum Most often in children with necrotising enterocolitis Paediatric Adult In supine position air collects anterior to abdominal viscera
- 47. Falciform ligament sign Normally invisible. Supinefilm, free air rises over anterior surface of liver
- 48. Other patterns ofair around liver Doge’s Cap Sign
- 49. Inverted V sign •On the supine radiograph, an inverted "V" may be seen over the pelvis in a patient with pneumoperitoneum. • While in infants this is produced by the umbilical arteries, in adults it appears to be created by the inferior epigastric vessels
- 50. Continuous diaphragm sign Sufficient freeair, left and right hemi- diaphragms appear continous
- 51. Lesser sac SignCupola Sign Lesser sac sign – (black arrows) The lesser sac is positioned posterior to the stomach and is usually a potential space. There is free connection between the lesser sac and the greater sac through the foramen of Winslow Cupola sign – (white arrows) Air superior to left lobe of liver Double Bubble Sign
- 52. Cupola Sign The termcupola comes from a dome such as this famous dome of the Duomo in Florence. Air beneath the central tendon of the diaphragm
- 53. Triangle Sign • Thetriangle sign refers to small triangles of free gas that can typically be positioned between the large bowel and the flank
- 54. Retroperitoneal Air • Recognisedby: – Streaky, linear appearance outlining retroperitoneal structures – Mottled, blotchy appearance – Relatively fixed position • May outline: – Psoas muscles – Kidneys, ureters, bladder – Aorta or IVC – Subphrenic spaces
- 55. Causes of retroperitonealair • Bowel perforation (appendix, ileum, colon) • Trauma (blunt or penetrating) • Iatrogenic • Foreign body • Gas producing infection
- 56. Pneumoretroperitoneum • This patienthas free air in the retroperitoneal space. The air is seen surrounding the lateral border of the right kidney (white arrow). There is other evidence of free gas including Rigler's sign. • If you are not confident that the appearance is pneumoretroperitoneum, you can try an erect and decubitus view to see if the gas moves. If the gas is seen to move, it's not in the retroperitoneum.
- 57. Air in thebowel wall • Signs – Best seen in profile producing a linear lucency that parallels the bowel – Air en face has a mottled appearance resembling gas mixed with faeculent material
- 58. Causes of airin bowel wall • Primary Pneumatosis cystoides intestinalis (rare) – usually affects left colon – Produces cyst-like collections of air in the submucosa or serosa • Secondary – Diseases with bowel wall necrosis – Obstructing lesions of the bowel that raise intraluminal pressure • Complications – Rupture into peritoneal cavity – Dissection of air into portal venous system
- 59. Pneumatosis intestinalis • Intramuralair, best appreciated in profile
- 60. Air in thebiliary tree • One or two tube-like branching lucencies in the RUQ, conform to location of major bile ducts
- 61. Causes • “Normal” ifSphincter of Oddi incompetence • Previous surgery including sphincterotomy or transplantation of CBD • Pathology (uncommon) – Gallstone ileus: gallstone erodes through wall of GB into the duodenum producing a fistula between the bowel and the biliary system. – Stone impacts in small bowel = mechanical SBO. “ileus” misnomer
- 62. Biliary vs PortalVenous Air • Portal venous air usually associated with bowel necrosis • Air is peripheral rather than central • Numerous branching structures
- 63. Soft tissue masses •Organomegaly – Know normal landmarks 2 ways to identify soft tissue masses/organs: – Direct visualisation of edges of structure – Indirect by displacement of bowel CT, US and MRI have essentially replaced conventional radiography in the assessment of organomegaly and soft tissue masses
- 64.
- 65. First exclude artefact KimKardashian’s butt – real or artefact?
- 66. Location • Vascular • Liver •Gallbladder • Spleen • Pancreas • Lymph nodes • Adrenals • Kidneys • Ureters • Bladder • Prostate
- 67. Rim-like • Calcification thathas occurred in the wall of a hollow viscus – Cysts • renal, splenic, hepatic – Aneurysms • aortic, splenic, renal artery – Saccular organs • Gallbladder • Urinary bladder Calcified hydatid cysts
- 68. Linear/Track • Calcification inwalls of tubular structures – Arteries – Fallopian tubes – Vas deferens – Ureter Aortoiliac calcification
- 69. Chinese Dragon Sign Calcifiedsplenic artery
- 70.
- 71. Floccular, Amorphous, Popcorn •Formed in solid organ or tumour – Pancreas (chronic pancreatitis) – Leiomyomas of uterus – Ovarian cystadenomas – Lymph nodes – Adenocarcinomas of stomach, ovary, colon – Metastases – Soft tissue (previous trauma, crystal deposition)
- 72. Calcified enteric lymph nodes Calcifiedfibroids Calcified pancreas Floccular
- 73. Lamellar or laminar •Formed around a nidus inside hollow lumen • Concentric layers due to prolonged movement of stone inside hollow viscus – Renal stones – Gallstones – Bladder stones
- 74.
- 75.
- 76. Staghorn Calcification Renal stonesare often small, but if large can fill the renal pelvis or a calyx, taking on its shape which is likened to a staghorn.Tubular
- 77. Nephrocalcinosis Uncommonly the renal parenchymacan become calcified. This is known as nephrocalcinosis, a condition found in disease entities such as medullary sponge kidney or hyperparathyroidism. Renal calculi Parenchymal calcification Flocculent
- 78. Putty Kidney • "Puttykidney" – sacs of casseous, necrotic material (TB) • Autonephrectomy – small, shrunken kidney with dystrophic calcification Flocculent
- 79.
- 80. Conclusion • Approach toAXR should include gas pattern, extraluminal air, soft tissue and calcifications • Named radiological signs are a useful way of remembering, identifying and reporting on films
- 81. References • Herring, W.Learning Radiology 2nd Ed, 2012 • Begg, J. Abdominal X-rays Made Easy, 1999 • http://www.wikiradiography.com • http://www.radiopaedia.org • http://www.imagingconsult.com • Roche, C et al. Radiographics: Selections from the buffet of food signs in Radiology. Nov 2002, RG, 22, 1369-1384 • Young, L. Radiology Cases in Paediatric Emergency Medicine. Vol 1 Ca 2. The Target, Crescent and Absent Liver Edge Signs. • Raymond, B et al. Radiographics: Classic signs in uroradiology. RSN 2004 • http://www.swansea-radiology.co.uk Radiology Teaching Site. Introduction to abdominal radiography • Mussin, R. Postgrad Med J 2011: 87:274-287. Gas patterns on plain abdominal radiographs • http://www.radiologymasterclass.co.uk/tutorials/abdo/abdo_x-ray_abnormalities • Mettler: Essentials of Radiology, 2nd Ed, 2005 • http://www.learningradiology.com/radsigns • Muharram Food signs in radiology. International Journal of Health Sciences Vol 1 No 1. Jan 2007.
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