Gas pattern Basic Interpretations of What is normal? Abdominal Radiographs (2) z Stomach z Almost always air in stomach ဎ೽YӀТ୷ҁղ᠐໪ޕ! z Small bowel z Usually small amount of air in 2 or 3 loops ୯ੀᆕӝᙴଣܫ৔ጕࣽ! z Large bowel !஭҉மᙴৣ! z Almost always air in rectum 3128022029! and sigmoid z Varying amount of gas in rest of large bowel 1 2 Normal air-fluid levels Large vs small bowel z Stomach z Always (upright, decub) z Large bowel z Peripheral (except RUQ occupied by liver) z Small bowel z Haustral markings don’t extend from wall to z Two or three levels wall acceptable (upright, decub) z Small bowel z Large bowel z Central z None normally z Valvulae conniventes extend across lumen (functions to remove fluid) and are spaced closer together 3 4 Abnormal Gas Patterns Localized ileus Key features z Functional ileus z One or two persistently z One or more bowel loops become aperistaltic dilated loops of small or usually due to local irritation or inflammation large bowel (multiple views) z Localized “sentinel loops” (one or two loops) z Generalized (all loops of large and small bowel) z Often air-fluid levels in sentinel loops z Mechanical obstruction z Local irritation, ileus in same z Intraluminal or extraluminal anatomical region as z Small bowel obstruction pathology z Large bowel obstruction z Gas in rectum or sigmoid z May resemble early SBO 5 6 Generalized adynamic ileus Causes of Localized Ileus by location The large and small bowel are extensively air-filled SITE OF DILATED CAUSE but not dilated. LOOPS Right upper quadrant Cholecystitis The large and Left upper quadrant Pancreatitis small bowel "look Right lower quadrant Appendicitis the same". Left lower quadrant Diverticulitis Mid-abdomen Ulcer or kidney/ureteric calculi 7 8 Generalized ileus Key features Mechanical small bowel obstruction (SBO) z Entire bowel aperistaltic/hypoperistaltic z Dilated small bowel and large bowel to z Dilated small bowel rectum (with LBO no gas in z Fighting loops (visible loops, lying rectum/sigmoid) transversely, with air-fluid levels at z Long air-fluid levels different levels) CAUSE REMARK z Little gas in colon, especially rectum *Postoperative Usually abdominal surgery Electrolyte imbalance Diabetic ketoacidosis * almost always 9 10 Double Bubble Sign SBO Erect SBO Supine Air fluid levels 11 Duodenal Atresia 12 M/68. Step ladder appearance At ER z Loops arrange themselves SBO from left upper to right lower quadrant in distal SBO 13 14 Closed loop obstruction Crescent Sign (versus Open loop obstruction) z Two points of same loop of bowel obstructed at a single location Caused by: z Forms a C or a U shape LUQ Soft tissue mass z Term applies to small bowel, usually caused by adhesions OR z Large bowel, called a volvulus Head of intussusception in distal transverse colon 15 16 F/01. KUB (2015-09-11) at ER Mechanical ileus of small F/01. CT (2015-09-14) bowel at ER Ileocolic intussusception with intestinal obstruction 1717 1818 M/29. Plain standing abdomen X-ray (2015-09-22): Multiple air-flluid levels in the small bowel Æ Mechanical ileus M/29. Abd CT (2015-09-22): Mechnical ileus due to ileal polyposis Æ Surgically and pathologically proved. 1919 2020 M/74. Abdominal pain. KUB (2015-05-16) Status post appendectomy Æ Mechanical ileus M/74. CT (2015-05-16): Mechanical & adhesion ileus with incomplete obstruction 2121 2222 Mechanical LBO Causes of Mechanical LBO z Colon dilates from point of obstruction backwards TUMOR VOLVULUS z Little/no air fluid levels HERNIA (colon reabsorbs water) DIVERTICULITIS INTUSSUSCEPTION z Little or no air in rectum/sigmoid 23 24 Crescent Sign M/78. KUB (2013-01-17) Caused by: LUQ Soft tissue mass Left inguinal hernia of OR bowel Head of intussusception in distal transverse colon 25 2626 Volvulus M/88. KUB (2012-08-27) Volvulus of sigmoid colon 27 2828 Coffee Bean Sign F/59 Sigmoid volvulus Massively dilated sigmoid loop Standing abdomen X-ray (2015-10-22): “Stepladder sign” 29 Æ mechanial ileus of bowel 3030 F/59 F/59 CT (2015-09-16): Sigmoid colon CA with open loop obstruction of colon bowel and CT (2015-09-16): Sigmoid colon CA with open loop obstruction of colon bowel, regional lymphadenopathy regional lymphadenopathy and distant mets to liver and lungs 3131 3232 F/59 F/59 Crescent Sign CT (2015-09-16): Sigmoid colon CA with open loop obstruction of colon bowel, regional lymphadenopathy and distant mets to liver and lungs 3333 34 Abnormal gas collections and abdominal fluid Extraluminal air z TYPES z Pneumoperitoneum/free air/intraperitoneal air z Intraperitoneal z Extraperitoneal z Retroperintoneal air z Inflammation or infection z Ascites z Air in the bowel wall (pneumatosis intestinalis) z Air in the biliary system (pneumobilia) 3535 36 Upright film best Intraperitoneal Free Air Causes z The patient should be positioned sitting upright for 10-20 minutes prior to acquiring z Rupture of a hollow viscus the erect chest X-ray image. z Perforated peptic ulcer z Trauma z Perforated diverticulitis (usually seals off) z This allows any free intra-abdominal gas z Perforated carcinoma to rise up, forming a crescent beneath the diaphragm. It is said that as little as 1ml of z Post-op 5-7 days normal, should get less with gas can be detected in this way. successive studies *NOT ruptured appendix (seals off) 37 38 Signs of intraperitoneal free air z Crescent sign M/21 Abdominal pain z Chilaiditis sign z Riglers (and False Rigler’s) z Football sign z Falciform ligament sign z Triangle sign z Cupola sign z Lesser sac sign 39 4040 F/54. Abdominal pain, Standing CXR M/21 (2015-10-08) Abdominal pain Minimal amount of right subphrenic free air Subphrenic free air ÆPerforation of hollow organ 4141 4242 Crescent Sign F/54. Abdominal pain Free air under the diaphragm Best demonstrated on upright chest x rays or left lat decub Easier to see under right diaphragm Abdomen radiograph in left decubitus view (2015-10-08) Æ Pneumoperitoneum Æ Intraperitoneal hollow organ perforation Æ Perforation of duodenal ulcer 4343 44 Rigler’s Sign M/80. Acute abdominal pain Bowel wall visualised 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 Pneumoperitoneum 4545 46 Football SIgn Falciform ligament sign Seen with massive pneumoperitoneum Normally invisible. Most often in children with necrotising Supine film, free enterocolitis air rises over anterior surface of liver In supine position air collects anterior to abdominal viscera Pediatric Adult 47 48 Continuous diaphragm sign Triangle Sign z The triangle sign refers to small Sufficient free air, left triangles of free and right hemi- gas that can diaphragms typically be appear continuous positioned between the large bowel and the flank 49 50 Retroperitoneal Air Causes of retroperitoneal air z Recognized by: z Streaky, linear appearance outlining z Bowel perforation (appendix, ileum, colon) retroperitoneal structures z Trauma (blunt or penetrating) z Mottled, blotchy appearance z Iatrogenic z Relatively fixed position z Foreign body z May outline: z Gas producing infection z Psoas muscles z Kidneys, ureters, bladder z Aorta or IVC z Subphrenic spaces 51 52 M/46. Pneumoretroperitoneum Right flank pain. KUB (2014-01-18). z This patient has 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. z 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 CT (2014-02-04) seen to move, it's not in Rt perirenal abscess the retroperitoneum. 53 5454 Causes of air in bowel wall Air in the bowel wall z Primary Pneumatosis cystoides intestinalis (rare) z Signs z usually affects left colon z Produces cyst-like collections of air in the submucosa or serosa z Best seen in profile producing a linear lucency that parallels the bowel z Secondary z Diseases with bowel wall necrosis z Obstructing lesions of the bowel that raise intraluminal z Air en face has a mottled appearance pressure resembling gas mixed with feculent material z Complications z Rupture into peritoneal cavity 55 56 z Dissection of air into portal venous system Pneumatosis intestinalis Air in the biliary tree z Intramural air, z One or two tube-like branching lucencies best appreciated in the RUQ, conform to location of major in profile bile ducts 57 58 Biliary vs Portal Venous Air z Portal venous air usually associated with bowel necrosis z Air is peripheral rather than central z Numerous branching CT (2015-03-03): structures Liver abscess wih gas formation Æ Percutaneous catheter drainage F/71. Abdominal pain and fever. 59 CXR including upper abdomen (2015-03-03) 6060 F/74, abdominal discomfort Massive ascites. M/69 Centralization of small bowel Massive ascites. Centralization of small bowel 6161 6262 F/57. KUB (2015-09-16) Abdominal masses and Pleomorphic Foreign bodies Calcifications 6363 6464 F/57. F/78. KUB F/53. KUB CT (2015-09-28): Renal cell carcinoma with pleomorphic Calcifications. Calcified uterine myomas 6565 6666 F/04. M/47. KUB Chondrosaercoma at the right retroperitonum Miss-swallowing of a coin passing through the stomach. 6767 KUB (2015-10-08). 6868 F/034, physical exam. F/45, KUB Abdominal pain Pregnancy with a fetus Gossypiboma 6969 7070 Thank for your attention! 7171 .