PLAIN X-RAY ABDOMEN
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PLAIN X-RAY ABDOMEN
INV-08
Shuja Tahir, FRCSEd
It is the radiological examination examination of abdomen and its contents. It is used as a screening investigation in various abdominal problems such as; 1. 2. 3. 4. 5. 6. 7.
Gast Gastro ro-i -int ntes estitina nall prob proble lems ms Inflam Inflammat mation ionss of abdo abdomin minal al visc viscera era Abdo Abdomi mina nall trau trauma ma Urin Urinar aryy tra tract ct prob proble lems ms Gyna Gynaec ecol olog ogic ical al proble problems ms.. Vasc Vascul ular ar prob proble lems ms Retr Retrop oper erito itone neal al proble problems ms..
The plain film is exposed with or without preparation. The abdominal abdominal x-ray is exposed exposed in appropriate position. The x-ray pictures are exposed in erect or standing position and supine or lying position. Occasionally the films are exposed in lateral position as well. Sometimes the patient is unfit to stand, then lateral decubitus film is exposed. It is a relatively poor alternate and does not provide enough information. The areas of lower chest and pelvis are also exposed to have complete visualization of the abdomen.
Plain x-ray abdomen (normal film) without preparation Plain x-ray abdomen (normal film) after preparation
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The clinical data is always critically examined before performing the radiological investigations. investigation s. It is inspected and interpreted in an organized and structured manner. OVER VIEW Whole of the exposed film is seen over an illuminater and never against sunlight or electric light to avoid wrong conclusions. Possible provisional diagnosis is made and objective interpretation is done. Large amount of gas is seen in stomach and colon. Stomach is identified because of its anatomical position and contents. contents. An air-fluid level is seen under the left hemidiaphragm normally. normally. The presence of gas in the bowel is seen on plain film.
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large intestine in small quantities. The gas is present as individual bubbles of gas scattered in the bowel. Peritoneal and extra-peritoneal contents of abdomen and pelvis are examined. Pancreas cannot be seen on plain film of abdomen. If a loop of bowel is seen filled with gas, it should not be longer longer than 5-8 cm and should not be distended under normal circumstances. The gas does not form a loop pattern in healthy persons. Gas shadows outside the intestine indicate intra-abdominal pathology.
always
Plain x-ray abdomen (normal) KUB film
Plain x-ray abdomen showing diverging psoas shadows
Gas is normally present in the stomach, small and 2
Multiple gas-fluid levels in the dilated loops of small or large gut indicate obstruction to the gastrointestinal flow. The level of obstruction is SURGERY-INVESTIGATIONS
PLAIN X-RAY ABDOMEN
usually looked for. The psoas shadows are visible as diverging lines on both sides of spine starting from first lumbar vertebra towards pelvis. The psoas shadows may be obliterated by inflammatory, neoplastic and hemorrhagic (traumatic) lesions of the organ in front and in the vicinity (pancreas, spleen, liver etc.) Ascities or presence of pus in the t he peritoneal cavity is identified by typical ground glass appearance. It offers valuable diagnostic information. Radio-opaque shadows and calcifications in the film are seen and their anatomical correlation is interpreted. Soft tissue shadows shadows of liver, spleen, spleen, kidneys, and psoas muscle are visible normaly. Outline of urinary bladder, if filled with urine may be seen on plain film.
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3. Psoa Psoass shad shadow ow obl oblite itera ratition on 4. Sent Sentiinel nel lo loops ops Trauma may be; a. Penetratin ting b. Blunt The penetrating injuries are usually visible on clinical examination. But the extent of injury may not be evaluated specifically on clinical examination. It presents with pneumoperiton pneumoperitoneum eum on radiological examination in the earlier part. Similarly blunt injuries of abdomen are diagnosed from clinical history and examination but extent of injury can only be assessed by various investigations and sometimes even laparoscopy or laparotomy may be required. PNEUMOPERITONEUM Normally no air is present in peritoneal cavity.
The plain x-ray film of the abdomen showing complete urinary system is called KUB film (Kidney, Ureter, Bladder film). ABDOMINAL TRAUMA The injuries of abdomen show various radiological features depending upon the type, time and site of injury. The common features seen on plain x-ray abdomen after various type of trauma are: 1. Pneu Pneumo mope peri rito tone neum um 2. Grou Ground nd gla glass ss appe appeara aranc ncee
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X-ray chest showing air under the diaphragm (pneumoperitoneum)
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PLAIN X-RAY ABDOMEN
Pneumoperitoneum is the presence of free air in the peritoneal cavity. The most common site is usually under the right dome of diaphragm. The penetrating injuries of abdomen present with wit h free air in the peritoneal cavity. (Pneumoperitoneum) The free air may be either due to perforation of the hollow viscus or the air entering from the exterior. The free gas appears about 1-2 hours after the perforation of bowel.
GROUND GLASS APPEARANCE This is a typical feature seen on x-ray abdomen. It is visible due to presence of fluid, pus or blood in the peritoneal cavity. The presence of fluid gives this appearance on plain x-ray abdomen. This is seen within few hours after penetrating injuries of abdomen when the peritonitis has already set in. The blunt injury of abdomen may lead to injury to the hollow viscera leading to leakage of gastrointestinal contents into the peritoneal cavity and similar radiological features.
Absence of free gas in the peritoneal cavity does not necessarily exclude presence of perforation as it is absent in approximately 25 % cases of perforated duodenal ulcer. It is very rare in acute appendicitis even if it is perforated. It is seen in following conditions; 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.
Perf Perfor orate atedd duod duoden enal al ulc ulcer er Perf Perfor orate atedd gas gastri tricc ulc ulcer er Perfora Per forated ted gastric gastric carci carcino noma ma Perfora Per forated ted coloni colonicc carci carcinom nomaa Perfora Per forated ted coloni colonicc dive diverti rticul culum um Trau Trauma matiticc gast gastric ric rupt ruptur uree Trau Trauma matiticc smal smalll gut gut rupt ruptur uree Trau Trauma matiticc colo colonic nic rup ruptu ture re Typh Typhoi oidd perfo perfora ratition on Diagnostic Diagnostic pneumope pneumoperitone ritoneum um Post laparotomy laparotomy pneumope pneumoperiton ritoneum eum Post laparoscopy laparoscopy pneumoperi pneumoperitoneu toneum. m. Penetrating Penetrating intraperito intraperitoneal neal injuries injuries Diagnostic Diagnostic fallopian fallopian tube insufflat insufflation ion Gas gangrene gangrene of intra peritoneal peritoneal viscera. viscera. Septic peritonitis with gas forming forming organi organisms sms
Plain x-ray abdomen showing ground glass appearance due to presence of fluid or pus in the peritoneal cavity
PSOAS SHADOW OBLITERATION The hematomas hemato mas are formed which may obliterate
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the psoas shadow in case of injury to the solid organs. This feature is seen seen in hepatic, splenic splenic and renal trauma. It is also seen in pancreatic injuries or infections. SENTINEL LOOPS An isolated distended loop of bowel is seen near the site of injured viscus or inflamed organ. This loop is called a "sentinel loop". It is a feature due to body's efforts to localize traumatic or inflammatory lesions. The local distention of intestinal loop is due to local paralysis and accumulation of gas in the intestinal loop.
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Indo-Pak subcontinent the incidence of typhoid perforation is higher. These conditions can be diagnosed reasonably well by looking at the plain x-ray of the abdomen. It shows free gas under the diaphragm specially on right side in most of the cases. Ileal Il eal perforation due to typhoid presents in this manner.
In acute pancreatitis, the sentinel loop is usually seen in left hypochondrium while in acute appendicitis, appendici tis, the sentinel sentinel loop is seen in right iliac ilia c fossa. The sentinel loop is seen in right hypochondrium in acute cholecystitis. Other radiological features of peritonitis are also seen in late cases of blunt injuries of abdomen, when peritonitis has developed (Ground glass appearance and pneumoperitoneum). INFLAMMATORY & MISCELLANEOUS LESIONS OF ABDOMEN There are many inflammatory lesions of peritoneal perit oneal viscera. The history of illness is present for some period. The acute symptoms of intestinal perforation and resulting peritonitis are seen as pneumoperitoneum, ground glass appearance and Psoas shadow obliteration. The duodenal ulcer ulcer and gastric ulcer perforations perforat ions used to be one of the most common surgical emergencies emergenc ies during previous decades. decades. Now in our
Plain x-ray abdomen (supine film) showing dilated jejunal loops due to small gut obstruction
Perforations of other intra peritoneal hollow viscera also present similarly. Perforation of appendix is rarely associated with pneumoperitoneum. INTESTINAL OBSTRUCTION OBSTRUCTION The obstruction to the flow of contents of
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gastrointestinal tract can be;
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distension of intestinal loops and gas fluid levels inside the intestine.
MECHANICAL Acute Subacute Chronic
The gas shadows are better seen in supine or lying position film. More Mor e than two fluid levels seen in small gut are abnormal and pathological.
PARALYTIC Adynamic ileus
The gas filled loops of gut show increase in their diameter due to distension.
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The fluid levels are seen in erect or standing films or lateral decubitus films. SMALL INTESTINAL OBSTRUCTION The small gut distended loops are recognized by the following features;
Plain x-ray abdomen (erect film) showing multiple air fluid levels in the loops of jejunum due to small gut obstruction.
The causes of intestinal obstruction may be external external or internal hernias, adhesions, neoplasia, volvulous, stenotic lesions, lesi ons, inflammatory lesions, meconeum and gallstones. After 3-5 hours of acute intestinal obstruction, enough gas and fluid accumulates to show 6
1. The caecum caecum is not not diste distende ndedd in cases cases of small intestinal obstruction. 2. The The location location of of disten distended ded loop loopss or air air fluid fluid level is central. 3. Fine Fine serrat serration ionss along along the marg margins ins forme formedd by mucosal folds are complete along the transverse axis in case of jejunum. 4. These These fine fine serra serratio tions ns are are very very close close to each each other. 5 Featu Featurel reles esss gut gut ((wit withh serr serrati ations ons)) is seen seen in ileal obstruction. 6 Step Step ladder ladder patter patternn of air fluid fluid shado shadows ws is also seen some times. COLONIC OBSTRUCTION The colon is distended from caecum to the obstructive lesion where the distension ends abruptly. Haustrations are deeper and these are not
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continuous along the transverse axis of colon. These are in fact alternating type. If caecum gets distended more than 9-10 cm it is likely to perforate.
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4. The serr serrati ations ons are are partia partiall and incom incomple plete. te. These look like indentations into the transverse diameter of the colon. These are not opposite each other but are alternating. VOLVULUS OF COLON
Colonic obstruction presents with following features on x-ray abdomen; 1. The caecu caecum m and and colon colon are disten distended ded
In cases of volvulus of sigmoid colon, an inverted U shaped distended loop of colon is seen in the pelvis and abdomen. Double fluid levels may be seen.
2. The dist distend ended ed colon colonic ic loops loops are are prese present nt at the periphery in the abdomen.
Plain x-ray abdomen showing marked dilatation of the large gut from caecum to splenic flexure due to large gut obstruction.
3. The gas gas fluid fluid lev levels els are are seen seen and and these these are are more than those normally seen in a single x-ray view.
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Plain x-ray abdomen showing dilatation of large gut due to twisted and obstructed caecum and ascending colon due to volvulus of caecum
In cases of peritonitis, the signs of free fluid present in the peritoneal cavity, sentinel loop or a localized distended loop of bowel is seen adjacent to the lesion. 7
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COLONIC CARCINOMA Most often these are not diagnosed from presence of soft tissue shadows. When these lesions are causing partial or complete obstruction or perforation, these can be detected indirectly from; 1. Radiol Radiologi ogical cal featur features es of intestin intestinal al obstruc obstruction tion 2. feature featuress of of intes intestin tinal al perf perfora oratio tionn 3. featur features es of of genera generaliz lized ed peri periton toniti itiss
PLAIN X-RAY ABDOMEN
Presence of air fluid level under the diaphragm is highly suspicious of subphrenic collection. Ultrasound examination helps to confirm the diagnosis. GALL STONE ILEUS In cases of gall stone ileus when the gall stone has ulcerated into the duodenum and descended along the small intestine, it causes small gut obstruction. It presents with following features;
ACUTE MESENTERIC OCCLUSION It shows the features of peritonitis and may be detected by plain x-ray abdomen. INTRA ABDOMINAL ABSCESSES These can not be seen on plain x-ray film directly.
Plain x-ray abdomen showing air fluid level under the right dome of diaphragm due to presence of gas in the right subphrenic abscess
1. All the feature featuress of small small intestin intestinal al obstru obstruction ction are present. 2. It is diag diagnos nosed ed by pres presenc encee of stone stone whic whichh is usually radio-opaque. 3. Gas shado shadow w is seen seen in the bili biliary ary tree tree (common bile duct, common hepatic duct and hepatic ducts).
Plain x-ray abdomen showing gas in the biliary passages and gall bladder due to gall stone ileus
Various features such as presence of sentinel loops, abnormal diaphragmatic shadows and ground glass appearance may help in suspecting the lesion. 8
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4. The gall gall bladde bladderr may may also also be be filled filled by by the gas. gas. Gas shadow is seen in biliary tree in following conditions; 1. Colo-biliar Colo-biliaryy fistul fistulaa due due to gall stone erosion. erosion. 2. Duoden Duodeno-b o-bilia iliary ry fistu fistula la due due to gall gall stone stone erosion or duodenal ulcer penetration. 3. Sphinteroto Sphinterotomy my or sphint sphintero eropla plasty sty of sphin sphinter ter of oddi 4. Choled Choledoch ocho-d o-duod uodena enall anast anastomo omosis sis 5. Acute Acute chol cholecy ecysti stitis tis with with gas gas formi forming ng organisms.
Plain x-ray abdomen showing calcification in the large uterine fibroid
CYSTS Soft tissue shadows of larger cysts may
GYNECOLOGICAL PROBLEMS FIBROID UTERUS In women, uterine shadow may also be seen specially if the patient is not fat or the fibroid is calcified. It is easily seen on plain film x-ray of the pelvic area. OVARIAN TUMOURS Normally these are not picked up on plain film at an early stage. Teratomas may be detected because of radiopaque radiopa que structures present in these these tumours (cartilage, teeth etc) RENAL TUMOURS Soft tissue renal shadow is usually seen in properly prepared patients and occasionally renal lesion may be detected on plain x-ray abdomen.
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Plain x-ray abdomen showing multiple radioopaque shadows in the upper part (multiple biliary and bilateral renal stones)
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occasionally be out lined on plain film. But most often these are undetected undetect ed and require ultrasound examination or urography for proper detection.
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Foreign bodies may be in ingested gested accidently. These usually pass through the gastro intestinal tract easily if small and not pointed. pointed. Even Even needles needles may pass without causing perforation.
CALCULUS DISEASE Stones in the gall bladder and stones in the urinary system are seen as radio-opaque shadows in the relevant area. These cases are diagnosed if the stones are radio-opaque otherwise ultrasonography, cholecystography or urography is required. FOREIGN BODIES
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The plain x-ray of abdomen helps in finding the t he site and type of foreign body if it is radio-opaque. If the foreign body is obstructed at some place, it may be removed surgically. REFERENCES 1.
P e t e r A rm st st r o n g . M ar ar t in L . W as as titi e . Plain Abdomen: In Diagnostic Imaging. 4th Edition Blackwell Scientific publications London. pp 133-143, 1998
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