Role of radiology and imaging in the daignosis of ... - Orion Group

Review ArticleRole of radiology and imaging in the daignosisof acute abdominal conditionsMiah MAYIntroductionIn our day to day practice we have to facemany of the acute abdominal conditions. Aswe know acute abdomen means the patientcomplaints of an acute attack of pain inabdomen which may occur suddenly or for aperiod of several hours and graduallybecoming worse and demands an urgentdiagnosis, treatment and even surgicalintervention. Early accurate diagnosis isessential for proper management. A carefulhistory and examination findings are veryvery essential for the radiologists also to givea comment about the cause of the disease.Though not all, many of the cases may bediagnosed without the help of any diagnostictool. Some cases may be problematic. In thosecases Radiology and Imaging can help a lot indetermining the proper diagnosis.Usual radiological tools we use are1. Plain film of abdomen and Chest P.A inerectposture2. U.S 3. C.T.Scan (Occasionally) 4.MRI(Rarely)What we see in plain radiography(a) In most acute abdominal conditions theradiological diagnosis depends on gas patternse.g. distribution of gases in dilated & nondilatedbowel, presence of gas inside oroutside the bowel lumen.(b) Radiopaque shadows (c) Fluid and gaslevels.What are the radiographic techniques1.Supine abdomen: We can see thedistribution of gas and calibre of the boweland may show displacement of bowel gasesby a mass.Dr. Md. Abu Yusuf Miah, MBBS,DMRD,Asst. Prof. of Radiology and Imaging, DMCH,DhakaThe ORION Vol. 9, May 20012.Erect abdomen:To see fluid levels and freegases. Usually 3 or more small bowel fluidlevels longer than 2.5 cm are abnormal.3.Left lateral decubitus: Patients lying ontheir left side and the X-ray beam ishorizontal. Patients who are unfit to sit orstand for an erect film, it is the projection ofchoice to show a small pneumoperitonium. Inthis projection free gas may be trappedbetween the edge of the liver and the lateralabdominal wall, or sometimes in the pelviswhere it is the highest point specially in caseoffemale.4.Chest X-ray: Why?(a) Erect chest film is the best film to showthe presence of a small pneumoperitonium.(b) A number of chest conditions which maymimic acute abdomen:1. Lower lobar pneumonia 2. Myocardialinfarction3. Pulmonary infarction 4. C.C.F 5.Pericarditis6. Leaking or dissecting thoracic aorticaneurysm 7. Pneumothorax(c) Acute abdominal conditions may becomplicated by chest pathology: e.g. pleuraleffusion frequently complicate acutepancreatitis, following prolong vomiting inelderly patients in intestinal obstruction, theremay be pneumonia or heart failure.Abdomen may be compared with a pandora'smagic box. There are many causes of acuteabdomen of which some are common whichwe face at our day to day practice. I want toshow some of the radiological findingssystemwise.Common acute abdominal conditionsfound in relation with-G.I.Tract(A)Acute appendicitis: Commonest acutesurgical condition in the developed world. Norole of radiography. But can be done toexclude other causes.Direct visualisation by HRSG Puylaert JBwww.orion-group.net/journals

Review Articlegraded compression technique.The fat and the bowel loops are displaced bycompression. Inflamed appendix appears tobe a thick walled incompressible sausage liketube with concentric layers in transverseplane . Perifocal oedema is also present. Fluidis also seen in the lumen of appendix. It iselongated tube with one end blind. When wallthickness exceeds 6 mm it is suggestive ofinflammation.Fig. no.4- -Abdomensupine -A triangularcollection of free gas inthe sub -hepatic regionFig. no.5--A band ofcurvilinear pulmonarycollapse with acrescent of normal lungbeneath it- simulatingPseudo -pneumoperitoniumFig. no.l-Shows inflamedappendix in transverse plane.The ORION Vol. 9, May 2001Fig. no.2-Showsinflamed appendix inlong axis.(B)Pneumoperitonium: Demonstration ofsmall pneumoperitonium is very essential.Most of the cases the cause of thepneumoperitonium will require emergencysurgery.Fig. no.3-(a) Erect chest film- Free gasseen under both domes ofdiaphragm.(b) Abdomen erect ,free gas under tIledomes 6(diaphragm.(C) Pseudopneumoperitonium: A number ofconditions which simulate pneumoperitoneume.g.-1. Chilaiditis syndrome -Distended bowelbetween liver and right. dome of diaphragm2. Sub diaphragmatic fat-omental fat3. Curvilinear pulmonary collapse(D)lntestinal obstruction: Dilation of boweloccursin1. Mechanical intestinal obstruction 2.Pseudoobstruction 3. Paralytic ileus 4. Airswallowing5. Several other conditions.Radiological differentiation depends mainlyon the size, mucosal appearance and thedistribution of loops of bowel. The diagnosisof intestinal obstruction depends on thedemonstration of dilated loops of bowelproximally with non-dilated or collapsedbowel distal to the presumed point ofobstruction.(A)Acute gastric dilatation:Dilatation of the stomach can be caused by 4main groups of conditions--(I)Mechanical gastric outlet obstruction maybe a sequel of peptic ulcer or a carcinoma ofthe antrum.(II)Paralytic ileus- This group of conditions isfrequently referred to as acute gastricdilatation.(III)Volvulus and air swallowing are usuallyuncommonconditions.(B)Small bowel obstruction:Usual causes are the bands,adhesions andstrangulations. Complete obstructionof the small bowel usually causes small boweldilatation with accumulation of both gas andfluid and a reduction in calibre of the largebowel. Plain film changes in small bowelobstruction may appear after 3-5 hours ifwww.orion-group.net/journals

Review Articlethere is complete small bowel obstruction andsuch changes are usually marked after 12hours. In incomplete obstruction early filmsmay be normal.This slide shows the feature of gall stone ileus.Here you see multiple dilated loops of smallbowel with a band of gas within the CBD.Gallstone ileus is a mechanical obstruction causedby the impaction of one or more gall stones inthe intestine, usually in the terminal ileum andrarely in the duodenum.Fig, No.9-Gall stoneileus.Slide no.6-Shows acutegastric dilatationThe ORION Vol. 9, May 2001Slide no. 7-ShowsSmall bowelobstruction: Multipledilated loops and airfluid level. A verysmall amount of gasesare noted in the largebowel.Differentiating points between a small andlarge bowel obstruction:String of beads sign:What is that: In dilated small bowel which isalmost completely filled with fluid. Smallbubbles of gas may be trapped in rowsbetween the Volvulae connivanties onhorizontal ray films- this is known as Stringof beads sign. This sign if present is virtuallydiagnostic of small bowel obstruction.Fig. No.8- -Anotherslide of small bowelobstruction showingString of beads sign.Signs of gallstone ileusa) Gas within the bile duct b)Features of smallbowel obstruction c)Abnormallocation ofgallstone d)Other previous findings whichcoincides biliary stone.What are the other causes of gas in the biliarytree:a)Physiological if the sphincter is laxed.b)Following biliary surgery c)Malignantfistula d)Perforated peptic ulcer into the bileduct.Its a case of intussusception is seenin children under 2 years of age. In children itusually commences in the ileum as the resultof inflammation of the lymphoid tissue andtends to be associated with mesentericadenitis. The enlarged lymphatic patches areforced into the ileum by peristaltic movementand acting as a tumour. So one part of theileum is pushed into the other and causingintussusception. In adults intussusception isinvariably caused by a tumour of bowel. Abarium enema examination is frequentlyrequired to establish a definite diagnosis andsometimes also relieves the patient.Fig. no. 10(a)--Multiple gas filledloops of dilated smallbowel there is a softtissue mass in the rightiliac fossa,Contrast enema examination of large gut of ababy shows the intussusception producing awww.orion-group.net/journals

Review Articleconcave defect in the head of the contrastcolumn. Sometimes contrast medium maypass beyond this, causing the well knowncoiled spring appearance.obstruction, the radiographic appearance maybe identical to those of a paralytic ileus.Paralytic ileus causes when intestinalperistalsis ceases and as a result fluid and gasaccumulates in the dilated bowel. It isfrequently found in cases of peritonitis and inthe post operative cases. Along with theradiological findings, history and clinicalsigns are helpful in differentiating betweenlarge bowel obstruction & paralytic ileus.Fig. no.10 (b)(iii) Large bowel obstruction:Usual causes are thea) Carcinoma -60% is situated in the sigmoidcolonb) Diverticular disease c)Volvulus of thecolon.Key to the radiological appearance of thelarge bowel obstructiondepends on the state of the competence of theIleocaecal valve. The obstructed coloninvariably contains large amounts of air andcan usually be identified by its location andby the presenc of haustral markings.When both small and large bowel dilatationare present in a case of large bowelThe ORION Vol. 9, May 2001Fig. no.10 (c)Fig. no.11. Shows hugelydilated large gut. Its a caseof sigmoid volvulus. Ahaustral loop of sigmoid isseen rising out the pelvis inthe shape of an inverted 'U'Dilated haustral colons arepresent on the two sides ofthe volvulus.Fig.no.12--Th/s filmshowsgeneralised dilatatlon of both small andlarge bowel and its acase of paralytic ileus.Acute pacreatitis: Clinical diagnosis may bedifficult in the initial stage .Other acuteabdominal conditions such as perforation,acute cholecystitis, acute peptic ulcer have tobe included in the differential diagnosis. Alarge number of radiological signs have beendescribed, most of them are non-specific.USGand CT are the diagnostic modality.Fig. no. 13- -Shows the transverse scan ofnormal pancreas and its duct.The normal pancreas has about the sameechogenecity as that of liver but itsechogenecity increase with age. When wescan the pancreas we usually identify thefollowing anatomical landmarks:1.Aorta2. Superior mesenteric artery3. Superior mesenteric vein4. Liver etc.Average diameter of the head of the pancreasis 2.8 cm. body 2 cm and tail 2.5cm, ductdiameter less than 2mm.In acute pancreatitis pancreas is diffuselyenlarged and oedematous which ishypoechogenic in comparison with the liverparenchyma. Diffusely enlarged irregularlyhypoechogenic pancreas may also seen inwww.orion-group.net/journals

Review Articleacute pancreatitis when it is superimposed onchronic pancreatitis. C. T. is the investigationof choice for such cases.Fig. no. 14- -Showsdiffusely enlargedand oedematousPancreasThe ORION Vol. 9, May 2001www.orion-group.net/journals

Review ArticleThe ORION Vol. 9, May 2001www.orion-group.net/journals