Small Animal Abdominal Effusions Laura JE Crews DVM MS Radiology Resident University of Minnesota Modified from Dr DA Feeney Abdominal Radiography Survey radiographs 2 VIEWS Right lateral recumbency or left VD projection dorsal recumbency or DV Quality assessment Reasonable contrast differential penetration Entire abdomen well positioned Obscuring structures stool ingesta i e over the urinary bladder when looking for stones Normal Dog 1 Normal Cat Normal Abdominal Architecture Ingesta and Stool 2 Preparing for Abdominal Radiographs Not in an emergency not always Abdominal prep Withhold food 18 24 hours Cleansing enemas 1 2 hours before radiographs Advantages Can eliminate ingesta stool obscuring effects Looking for uroliths routine special procedures Disadvantages Disturbs the normal GI gas distribution Keys to abdominal radiographic interpretation Roentgen Signs Geometric Size Shape Position location Number Margination outline Opacity density Function AIR FAT SOFT TISSUE H20 MINERAL METAL Excretion integrity especially tubular organs motility patency Everything in moderation fat is our friend 3 Interpretive Background Poor Detail Ability to distinguish individual abdominal organs contrast is a function of adequate abdominal peritoneal retroperitoneal fat Very young animals lack fat and have excess brown fat poor contrast but normal Emaciated animals lack fat poor contrast but NOT normal concave abdominal contours Very obese animals may have a graying out of their abdominal contrast due to excess scatter radiation from too much fat Poor Abdominal Contrast Peritoneal Effusion Angry spastic or clumped SI loops Happy floating SI loops Poor Abdominal Contrast Emaciation or Very Young 4 Interpretive Background Abdominal Contrast Too Good BEWARE of abdominal contrast looking too good to be true This may indicate free peritoneal or retroperitoneal air Look for air between liver lobes around spleen or around bladder peritoneal air Look for air surrounding the kidneys or outlining the great vessels retroperitoneal air Use horizontal beam techniques to quantify and confirm Expect some free air for 7 14 days after laparotomy Pneumoperitoneum or retroperitoneum Surgical intervention is required Free air is not contained in bowel or any specific structure Penetrating abdominal wound Ruptured perforated alimentary structure Abdominal surgery Transfer from pneumothorax or pneumomediastinum very rare Free Peritoneal Air 5 Free Retro peritoneal Air Gas Patterns in the Abdomen from Lord Interpretive Background Abdomen Be sure to look for mineral opacities Renal ureteral bladder and urethral stones Bony material in the alimentary tract Dystrophic mineralization of parenchymal or vascular organs 6 Dystrophic Mineralization stomach Urethral calculus Interpretive Background Abdomen The amount of gut gas can influence the perception of peritoneal contrast Dogs Normal 30 60 of GI tract contains even distribution of gas with randomly varying bowel diameters Gasless small bowel can give the appearance of decreased peritoneal contrast Cats Normal little to no gas 30 in GI tract The bowel loop diameter should be distinguishable due to peritoneal contrast 7 Normal Gastrointestinal Gas Quantity Distribution Normal Dog Gasless dog Gassy dog Normal Gastrointestinal Gas Quantity Distribution Normal Cat Gassy Cat Interpretive Background Abdomen The amount of gut gas can indicate gut reaction to local regional stimuli Dyspnea resulting in aerophagia Local regional peritoneal inflammation causing adjacent bowel loops to dilate and fill with air e g peritonitis perforation with local peritonitis bile peritonitis etc Bowel ischemia e g thromboembolism segmental gut incarceration mesenteric volvulus resulting in excess gut gas Gut obstruction 8 Massive Gut Gas Accumulation Distal Small Intestinal Obstruction Interpretive Background Abdomen Peritoneal organs surrounded by peritoneum and obscured by peritoneal fluid Liver spleen pancreas alimentary organs urinary bladder uterus ovary prostate depending on location and mesenteric LNs Retroperitoneal organs only partially surrounded by peritoneum and NOT obscured by peritoneal fluid Great vessels kidneys adrenal glands ureters except very distal part urethra and retroperitoneal LNs Diffuse vs focal loss of peritoneal detail Transudate heart failure portal hypertension hypoalbuminemia Urine bladder distal ureteral or proximal urethral rupture Blood traumatic or spontaneous hemorrhage bleeding tumor Exudate FIP peritonitis Malignant effusion tumor seeding NOTE may be mistaken for transudate Chyle uncommon but not impossible 9 Poor Peritoneal Detail carcinomatosis Diffuse vs focal loss of retro peritoneal detail Transudate unlikely Urine distal urethral or proximal ureteral rupture Blood traumatic or spontaneous hemorrhage bleed tumor Exudate retroperitonitis Malignant effusion tumor seeding NOTE may be mistaken for transudate Chyle uncommon but not impossible Poor Retroperitoneal Detail 10 Additional Information from the Radiographs The uniformity of the peritoneal retroperitoneal contrast and the gas content in the regional bowel can provide clues Local variance may indicate localized inflammation or neoplasia and will require further diagnostics Local variance in peritoneal contrast Local loss of peritoneal contrast pancreatitis occult mass Focal peritonitis GI perforation bile leakage Local tumor invasion or seeding Local enhancement of peritoneal contrast Local free air from perforation or previous semiinvasive procedure Impact of peritoneal effusion on SI Freely floating happy SI loops Clumped irritated or angry SI loops Right sided heart failure Hypo albuminemia Hemorrhage Coagulopathy DIC Traumatic Peritonitis Bacterial GI perforation Bile Uroabdomen Neoplasia carcinomatosis Pancreatitis FIP Hints to help rank differentials not rules 11 Poor Local Peritoneal Contrast Pancreatitis Look at entire film cats with pancreatitis often have pleural effusion Interpretive Overview the 3 pass technique 1st pass 2nd pass Big masses fluid accumulation free air distended gut obvious foreign bodies Organ by organ or region by region can be done spiral vs reading a book vs on organ or system basis Don t neglect extra abdominal clues assess entire film s 3rd pass Age breed species related problems Abdominal Radiography 1st pass Any foci of obvious increased or decreased opacity e g bullets stones large gas accumulations Any obvious visceral displacement e g vertebral fractures