2009: Neonatal and pediatric ultrasonography-part II 1 Neonatal and pediatric ultrasonography-part II 2 3 A. P. Davidson, T. W. Baker 4 Department of Medicine and Epidemiology, School of Veterinary Medicine, University of 5 California, Davis, CA, USA 6 Introduction 7 Pediatric patients are commonly presented to the veterinarian because of signs 8 referable to the abdominal cavity. Presenting signs can be due to congenital anomalies, 9 dietary indiscretion, parasitic infestation and infectious disease. Abdominal ultrasound 10 examination is a particularly useful diagnostic tool in the pediatric patient because it is 11 noninvasive and can usually be performed without sedation or anesthesia. Ultrasonography 12 provides valuable clinical information about the peritoneal cavity, great vessels, abdominal 13 viscera and lymph nodes and thus greatly facilitates diagnostic differentiation between 14 congenital and acquired disorders.1 Ultrasonographic techniques will be described in this 15 paper. 16 Keywords: Ultrasound, neonatal, congenital, acquired, pediatric 17 Disorders of urogenital development 18 In the past, veterinary pediatric ultrasonography has been hampered by the small size of 19 neonatal organs. Recent advances in pediatric veterinary ultrasonography are encouraging. 20 Abdominal ultrasound can facilitate the diagnosis of congenital urogenital disorders because 21 ectopic, distended ureters and changes in renal architecture are usually readily imaged.2 The 22 presence and location of cryptorchid testes can often be detected with ultrasound.1 23 Ultrasonographic examination of the bladder disclosing urolithiasis can provide information 24 155 suggesting congenital hepatic vascular anomalies. Ammonium biurate urolithiasis is suggestive 25 of hyperammonemia, common with portosystemic shunt disorders (described below).3,4 26 The most common familial disorders in cats and dogs include renal agenesis, renal dysplasia, 27 polycystic kidneys, renal amyloidosis, basement membrane disorders, and tubular 28 dysfunction (Fanconi's syndrome).5 29 Renal agenesis 30 Congenital renal agenesis resulting in the absence of a kidney can be confirmed with 31 ultrasound. The contralateral kidney typically has normal internal anatomy, but is enlarged as 32 a consequence of obligatory hypertrophy. Renal function of the pediatric patient does not 33 equate that of the adult until 4-6 months of age, therefore compensatory renomegaly may not 34 be apparent until that time.3 35 Renal dysplasia 36 Until reliable genetic markers are marketed and thus available for the various breed 37 specific congenital renal dysplasias(i.e. Persian cats) , ultrasound provides the best method 38 of screening young dogs and cats for these likely heritable disorders. Early ultrasonographic 39 screening is possible in platycephalic breeds in which morphologic changes are grossly 40 evident (i.e., Cairn Terriers, German Shepherd Dogs).3,5 (fig1) 41 Ectopic ureter 42 Congenital ectopic placement of a distal ureter into the urethra, vestibule or vagina is 43 usually associated with ureteral dilation with or without renal pelvic dilation. Dilation of the 44 ureter improves the sensitivity of the ultrasound study; however, the diagnosis can be elusive. 45 Visualization of a nonvascular fluid filled structure with a hyperechoic wall passing dorsal to 46 the urinary bladder, or obvious insertion of the structure into the proximal urethra suggest the 47 diagnosis. Visualization of the ureteral jets in the bladder suggests normalcy, however some 48 156 ectopic ureters insert initially into the bladder and additionally tunnel distally to terminate in an 49 abnormal site. Visualization of the dilated ureter usually occurs near the urinary bladder. (fig 50 2) Visualization of the bladder neck and proximal urethra may be obscured by pubic bone, 51 making identification of such termination difficult.1,2 52 Hydronephrosis can eventually result from an uncorrected ectopic ureter due to flow 53 impedance at the abnormal site of insertion. (fig 3) Urinary tract infection is commonly 54 associated with ectopia, due to accompanying urethral sphincter mechanism anomalies. If 55 not detected and treated, urinary tract infection can progress to pyelonephritis and ureteritis. 56 Infection and its associated inflammation in the tract can further alter the ultrasonographic 57 appearance of the kidneys, bladder, ureters and urethra.1 58 Contrast enhanced computed tomography is the most sensitive and specific modality 59 for the diagnosis of ectopia, but, like double contrast radiography, requires anesthesia, 60 making initial evaluation with ultrasound desirable when ectopia is suspected clinically. The 61 condition is thought to be heritable (mode not known), and is more commonly symptomatic in 62 females due to the greater strength of the male urethral sphincter and longer length of the 63 urethra.5 64 Ureterocele 65 A ureterocele is an uncommon congenital dilation of the ureter near the bladder, 66 appearing as a cystic structure within the bladder lumen or wall. (fig 4) The ureterocele 67 occurs most commonly in association with an ectopic ureter. Diagnosis can be made by 68 scanning the urinary bladder in the transverse plane and watching for strong peristalsis of the 69 adjacent ureter.1 70 Patent urachus 71 157 The urachus permits the flow of urine from the bladder into the allantoic sac of the 72 fetus, and normally atrophies at birth. A patent urachus in the neonate is characterized 73 clinically by urine dribbling from the umbilicus. The fluid filled urachus can be identified 74 ultrasonographically, extending cranially from the cranioventral bladder wall. If an 75 incompletely patent urachus is present in the neonate, a urachal diverticulum may result, 76 seen as a divot in the apex of the bladder. (fig 5) Urachal diverticula can predispose the 77 bladder to recurrent infection because of abnormal bladder flow in the region, surgical 78 excision can be indicated.1 79 Cryptorchidism 80 Ultrasound identification of cryptorchid testis(es) can confirm cryptorchidism in 81 pediatric patients with bilateral involvement whose neutering status is unknown. 82 Ultrasonographic localization of undescended testes can assist the surgeon in planning the 83 approach (i.e., inguinal vs. cranial abdominal). A retained testis can be positioned anywhere 84 between the ipsilateral kidney and the scrotum. A systematic evaluation of the region from 85 the caudal renal pole to the inguinal canal can identify an oval, homogenously echogenic 86 structure with a mildly hyperechoic border representing the parietal and visceral tunics. The 87 epididymis is usually distinctly less echoic than the testicular parenchyma, as in the scrotal 88 testis. The cryptorchid testis will maintain the anatomic structure, the median testes (a 89 hyperechoic slash), and normal testicular echogenicity despite being reduced in size as 90 compared to a scrotal testis.1 (fig 6) 91 Ultrasonography is also the procedure of choice to detect undescended testicles in 92 pediatric or adult dogs and cats. Clinical evaluation via serum LH concentration or 93 testosterone stimulation tests can increase support the diagnosis. An ultrasound examination 94 158 may also detect nonpalpable scrotal testicular tumors and neoplastic transformation in 95 abdominal testes.1 (fig 7) 96 Disorders of digestive system development 97 Hernia 98 Congenital peritoneopericardial diaphragmatic hernias occur in both the dog and cat; 99 ultrasonography provides an additional modality for their diagnosis. As with other 100 diaphragmatic hernias, careful evaluation for continuity of the echogenic diaphragm 101 differentiates a true hernia from mirror image artifacts. Evaluation of the pericardial contents 102 can be made from the subcostal (across the liver) or intercostal (using the heart as an 103 acoustic window) approach. Abnormal pericardial contents can include falciform fat, liver, gall 104 bladder and/or intestines. Congenital inguinal and scrotal hernias can similarly be confirmed 105 by ultrasonographic identification of intestines in the subcutaneous space of the affected 106 groin. This can be a dynamic finding. Mesenteric fat may alternatively be entrapped through 107 the hernia.1,6 (fig 8) 108 Congenital hiatal hernias are more difficult to confirm with ultrasound because of the 109 inherent difficulty imaging the gas filled stomach and the intermittent nature of the disorder. 110 Stomach wall with characteristic rugal folds can be imaged crossing the diaphragm into the 111 thoracic cavity. Fluoroscopic evaluation can be more informative in these cases. 112 A developmental anomaly resulting in extrusion of a portion of the gastrointestinal tract 113 outside of the body wall, occurring within the umbilical canal (omphalocele) or lateral to the 114 umbilical canal (gastroschisis), has been reported in humans and occurs in both dogs and 115 cats. The condition is usually hopeless in small pediatric patients presented to the 116 veterinarian hours after birth; however, a 30-70% survival rate is reported in humans with 117 immediate post partum surgical intervention. Diagnosis is made pre partum with abdominal 118 159 ultrasound, based on the recognition of fetal gastric wall (rugal) structures or intestinal 119 contents in an abnormal location. Earlier surgical intervention before inevitable septic 120 contamination occurs may improve the prognosis in veterinary patients.1,5 121 Enteric anomalies 122 Pyloric stenosis secondary to hypertrophic gastritis has been reported in a pediatric 123 dog. Focal circumferential thickening of the pylorus primarily involving the muscularis is 124 typical. 125 Enteric duplication or agenesis can be confirmed ultrasonographically in pediatric 126 patients. Duplication is rare, can occur anywhere in the intestinal tract and the clinical signs 127 may be nonspecific. A fluid filled juxtaintestinal formation with variable peristalsis and 128 contents can be seen. Enteric agenesis usually results in severe clinical signs in the neonatal 129 period. Ultrasonographic findings usually include marked fluid and gas distention of bowel 130 proximal to the defect.5 131 Several breeds of dogs have a reported genetic predilection to small intestinal 132 disease. Normally, the small bowel appears sonographically as four distinct layers. The 133 bowel lumen is hyperechoic, as gas and ingesta are compressed. The layer just outside the 134 lumen is the mucosa; it is hypoechoic and normally the thickest appearing section. Outside 135 the mucosa is the submucosa, it is hyperechoic to the mucosa and about one third the 136 thickness. The muscularis, the bowel muscle layer, is outside of the submucosa and appears 137 as a very thin hypoechoic black line. (fig 9, 10) 138 An immunoproliferative enteropathy is seen in the Basenji breed which is 139 characterized by lymphangectasia, intermittent diarrhea, weight loss, hypoalbuminemia and 140 hyperglobulinemia, and lymphoplasmacytic mucosal infiltrates throughout the GI tract. 141 Histopathology is diagnostic, however abdominal ultrasonography can identify bowel in which 142 160 disruption of the normal layering has occurred. Chinese Sharpei dogs have been identified 143 with a lymphoplasmacytic-eosinophilic infiltrative enteropathy that is characterized by poor 144 weight gain, weight loss, or intermittent diarrhea episodes, with onset of signs typically 145 between 2 to 6 months of age. Infiltrative enteropathies can be characterized 146 ultrasonographically as having changes in the normal bowel wall layering.5 147 Portosystemic shunt 148 Portosystemic shunts (PSS) are congenital malformations of the hepatic portal venous 149 drainage system and can have either a familial, i.e. genetic, or random occurrence. 150 Congenital PSS can be either intrahepatic or extrahepatic; breed predilections for 151 extrahepatic shunts include Yorkshire terrier, Maltese, Poodle, Miniature Schnauzer, 152 Dachshund, Lhasa Apso, Pekingese, Pug, and Shih Tzu, whereas intrahepatic shunts are 153 more commonly identified in large breed dogs such as Golden Retrievers, German 154 Shepherds, Irish Wolfhounds, Irish Setters, and Samoyeds. PSS are uncommon in cats. 155 Ultrasonography provides a rapid and noninvasive method for screening patients 156 suspected to have congenital PSS. Although scintigraphy (transcolonic portal scintigraphy or 157 transplenic portography) is considered the most reliable noninvasive method of documenting 158 a PSS, its availability is limited to specialty and university practices, and its use dictates 159 special handling of the radioactive patient for at least 12 hours. Mesenteric portography, 160 although more invasive and requiring general anesthesia, is a highly reliable method of 161 confirming and localizing PSS.1,7 162 Abdominal ultrasonography is a useful diagnostic tool and is routinely done when a 163 PSS is suspected. (fig 11,12) It is non-invasive and requires no anesthesia however 164 diagnostic accuracy is highly operator dependent, and the PSS will be confirmed in only 165 approximately 60-80% of cases. The liver may be small and difficult to image in patients with 166 161 congenital portosystemic shunts. Imaging the liver from the standard ventral approach can be 167 improved in some cases by using the left ventral intercostal and right dorsal intercostal 168 approaches. The presence of ascites can facilitate the study, as can adding fluid to the 169 stomach, and positioning the patient to shift gas away from the scanhead and shift abdominal 170 organs caudally.(fig 13) Ultrasound evaluation of portosystemic anomalies can be facilitated 171 by positive pressure ventilation under anesthesia for the same reason. Cystic calculi, most 172 commonly ammonium biurate, should increase the clinical suspicion of PSS. Urinary bladder 173 calculi (radiolucent and radiopaque) produce a strong acoustic shadow when viewed 174 ultrasongraphically.1 (fig 14) 175 Post operatively, ultrasound can be used to evaluate portal blood flow following 176 surgical banding or coil embolization. Extrahepatic shunts most commonly arise from the 177 portal vein, splenic vein or left gastric vein in the dog, and from the left gastric vein in the cat. 178 (fig 15) Identification of a shunting vessel emptying into the caudal vena cava is difficult but 179 confirmatory. Intrahepatic shunts can be more difficult to identify because of patient size, 180 bowel gas and liver size. Clipping the hair coat intercostally on the right can allow for 181 transverse vessel stacking (of the aorta, vena cava and portal vein) and allow visualization of 182 ductal shunts. There can be right and left shunting of the ductus.1,7 183 References 184 1. Baker TW: Baker TW: Find your friends: location and appearance of normal 185 abdominal viscera, liver, spleen, kidney and urinary bladder. In: What’s that? A 186 beginner’s guide to veterinary abdominal ultrasound. Lakewood, CO: AAHA Press, 187 2009. 188 189 162 2. Lamb CR: Ultrasonography of the ureters. Vet Clin North Am Sm Anim Pract 190 1998;28:823-848. 191 192 3. Nyland TG, Mattoon JS, Herrgesell EJ, et al: Urinary tract. In: Nyland TG, Mattoon JS, 193 editors. Small animal diagnostic ultrasound, 2nd ed. Philadelphia: WB Saunders; 194 2002. p.158-195. 195 196 4. Nyland TG, Hager DA: Sonography of the liver, gallbladder, and spleen. Vet Clin 197 North Am Sm Anim Pract 1985;15:1123-1148. 198 199 5. Gough A: Disease summaries. In: Breed predispositions to disease in dogs and cats. 200 Gough A, Thomas A, editors. Oxford: Blackwell Publishing; 2004. p. 179-229. 201 202 6. Suter PF, Lord PF: Abnormalities of the diaphragm. In: Suter PF, editor. Thoracic 203 radiography: a text atlas of thoracic disease in the dog and cat. Wettswil, Switzerland: 204 PF Suter; 1984. p. 180-204. 205 206 7. Penninck DG: Gastrointestinal tract. In: Nyland TG, Mattoon JS, editors. Small animal 207 diagnostic ultrasound, 2nd ed. Philadelphia: WB Saunders; 2002. p. 207-230. 208 163 Button24: Button25: Button26: Button27: Button28: Button29: Button30: Button31: Button32: Button33: Button34: Button35: Button36: Button37: Button38: Button39: Button40: Button41: << /ASCII85EncodePages false /AllowTransparency false /AutoPositionEPSFiles true /AutoRotatePages /All /Binding /Left /CalGrayProfile (Dot Gain 20%) /CalRGBProfile (sRGB IEC61966-2.1) /CalCMYKProfile (U.S. Web Coated \050SWOP\051 v2) /sRGBProfile (sRGB IEC61966-2.1) /CannotEmbedFontPolicy /Warning /CompatibilityLevel 1.4 /CompressObjects /Tags /CompressPages false /ConvertImagesToIndexed true /PassThroughJPEGImages true /CreateJobTicket false /DefaultRenderingIntent /Default /DetectBlends true /DetectCurves 0.0000 /ColorConversionStrategy /CMYK /DoThumbnails false /EmbedAllFonts true /EmbedOpenType false /ParseICCProfilesInComments true /EmbedJobOptions true /DSCReportingLevel 0 /EmitDSCWarnings false /EndPage -1 /ImageMemory 1048576 /LockDistillerParams false /MaxSubsetPct 100 /Optimize true /OPM 1 /ParseDSCComments true /ParseDSCCommentsForDocInfo true /PreserveCopyPage true /PreserveDICMYKValues true /PreserveEPSInfo true /PreserveFlatness false /PreserveHalftoneInfo false /PreserveOPIComments false /PreserveOverprintSettings true /StartPage 1 /SubsetFonts true /TransferFunctionInfo /Apply /UCRandBGInfo /Preserve /UsePrologue false /ColorSettingsFile () /AlwaysEmbed [ true ] /NeverEmbed [ true ] /AntiAliasColorImages false /CropColorImages false /ColorImageMinResolution 300 /ColorImageMinResolutionPolicy /OK /DownsampleColorImages false /ColorImageDownsampleType /Average /ColorImageResolution 300 /ColorImageDepth -1 /ColorImageMinDownsampleDepth 1 /ColorImageDownsampleThreshold 1.50000 /EncodeColorImages false /ColorImageFilter /DCTEncode /AutoFilterColorImages true /ColorImageAutoFilterStrategy /JPEG /ColorACSImageDict << /QFactor 0.76 /HSamples [2 1 1 2] /VSamples [2 1 1 2] >> /ColorImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /JPEG2000ColorACSImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /JPEG2000ColorImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /AntiAliasGrayImages false /CropGrayImages false /GrayImageMinResolution 300 /GrayImageMinResolutionPolicy /OK /DownsampleGrayImages false /GrayImageDownsampleType /Average /GrayImageResolution 300 /GrayImageDepth -1 /GrayImageMinDownsampleDepth 2 /GrayImageDownsampleThreshold 1.50000 /EncodeGrayImages false /GrayImageFilter /DCTEncode /AutoFilterGrayImages true /GrayImageAutoFilterStrategy /JPEG /GrayACSImageDict << /QFactor 0.76 /HSamples [2 1 1 2] /VSamples [2 1 1 2] >> /GrayImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /JPEG2000GrayACSImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /JPEG2000GrayImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /AntiAliasMonoImages false /CropMonoImages false /MonoImageMinResolution 1200 /MonoImageMinResolutionPolicy /OK /DownsampleMonoImages false /MonoImageDownsampleType /Average /MonoImageResolution 300 /MonoImageDepth -1 /MonoImageDownsampleThreshold 1.50000 /EncodeMonoImages false /MonoImageFilter /FlateEncode /MonoImageDict << /K -1 >> /AllowPSXObjects false /CheckCompliance [ /None ] /PDFX1aCheck false /PDFX3Check false /PDFXCompliantPDFOnly false /PDFXNoTrimBoxError true /PDFXTrimBoxToMediaBoxOffset [ 0.00000 0.00000 0.00000 0.00000 ] /PDFXSetBleedBoxToMediaBox true /PDFXBleedBoxToTrimBoxOffset [ 0.00000 0.00000 0.00000 0.00000 ] /PDFXOutputIntentProfile () /PDFXOutputConditionIdentifier () /PDFXOutputCondition () /PDFXRegistryName () /PDFXTrapped /False /CreateJDFFile false /Description << /ENU ([Based on 'No Compression'] [Based on 'No Compression wbleeed'] [Based on '[High Quality Print]'] Use these settings to create Adobe PDF documents for quality printing on desktop printers and proofers. 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