2009: Neonatal and pediatric ultrasonography- part I Neonatal and pediatric ultrasonography- part I 1 T.W. Baker, A.P. Davidson 2 Department of Medicine and Epidemiology, School of Veterinary Medicine, University of 3 California, Davis, CA, USA 4 5 Introduction 6 Small animal patients are commonly presented to the veterinarian because of 7 signs referable to the abdominal cavity due to congenital anomalies, dietary indiscretion, 8 parasitic infestation and infectious or inflammatory disease. Abdominal ultrasound 9 provides valuable clinical information about the peritoneal cavity, great vessels, 10 abdominal viscera and lymph nodes obtained in a non invasive fashion, with no 11 confirmed adverse biologic effects, and usually not necessitating sedation or 12 anesthesia. This paper reviews the techniques for performing the pediatric abdominal 13 ultrasound scan. 14 Abdominal ultrasound provides useful data in a short period of time. The normal 15 paucity of intra-abdominal fat in pediatric patients results in less informative abdominal 16 radiography, but actually improves ultrasonographic imaging. (Abdominal fat attenuates 17 the ultrasound beam.)1 Image quality is improved with small patient size as a higher 18 frequency scanhead can be employed. Acquisition of special equipment for pediatric 19 ultrasonography is usually not necessary as scanheads selected for small animal 20 (especially feline) clinical use are appropriate for most pediatric cases. 21 Small animal patients are best evaluated using an ultrasound machine equipped 22 with a curvilinear variable frequency scanhead (6.0-8.0 MHz). Many portable machines 23 143 now have available a high frequency linear scanhead (8.0 -10.0 MHz) which will 24 improve quality and also allow evaluation of smaller regional anatomy (thyroid, 25 parathyroid, cryptorchid testes).2 26 Keywords: Ultrasound, pediatric, abdominal, neonatal 27 Preparation 28 The small animal patient is placed in dorsal recumbency within a padded V-29 trough, and is gently restrained by assistant(s) holding the forelimbs and hindlimbs. 30 Sedation is rarely required for the basic abdominal scan unless marked pain or 31 apprehension is present. Allowing the patient to become accustomed to this restraint 32 before clipping the hair or initiating the scanning process usually minimizes struggling 33 and the resulting aerophagia.3 34 To prepare the pediatric patient for abdominal ultrasonography, the cranioventral 35 abdominal hair is clipped using a No. 40 blade. Wetting the skin with water, tincture of 36 zephiran or 70% isopropyl alcohol, followed by a liberal application of ultrasound gel, 37 permits the best acoustic coupling of the scanhead to the patient and improves the 38 image obtained. Some pediatric patients have scant ventral haircoats that do not 39 require clipping. Care should be taken to avoid excessive chilling of pediatric patients. 40 Chilling can occur secondary to the application and evaporation of room-temperature 41 wetting agents. Electric warming devices (warm water blankets) may cause electronic 42 interference with the ultrasound equipment; warm water bottles or their equivalent are 43 superior.1 44 Patient preparation includes fasting as much as is safely possible given the 45 animal’s age and size. Fasting minimizes obscurement of the liver imaging by gastric 46 144 ingesta and of other abdominal viscera by gastrointestinal gas accumulation. Preventing 47 urination immediately prior to the examination allows urine to accumulate within the 48 urinary bladder lumen and permits better evaluation of this structure. 4 49 Serial evaluations can provide useful information when the clinical status of the 50 small animal patient has changed. Indications for serial ultrasonographic evaluation 51 include clinicopathologic deterioration, progressive lethargy or obtundation, acute pain, 52 changes in abdominal palpation findings and refractory vomiting or diarrhea. All warrant 53 repeat evaluation for signs indicating the development of intussusception, perforation 54 and/or peritonitis. 55 The normal abdomen 56 Regardless of the clinical history, the abdomen should be evaluated methodically 57 with the animal in dorsal decumbency. Realize the sector image you are looking at on 58 the monitor screen is perpendicular to that ultrasound beam. You are viewing the 59 sagittal image from the side of the animal and the transverse image from the rear of the 60 animal. (fig 1a-c, fig 2a-c).1 61 Place the scanhead under the xyphoid with the beam in sagittal plane. 62 Visualization of the liver is achieved by fanning the beam from right to left. The gall 63 bladder is seen on the right; the left liver lobes are seen ventral and sometimes caudal to 64 the stomach. Turning the beam to transverse allows for visualization of the liver between 65 stomach and gall bladder. This view is useful for evaluation of the hepatic border, 66 echogenicity of hepatic parenchyma and portal architecture. The portal vessels have very 67 echogenic walls.5 (fig 3) 68 145 Resuming the sagittal plane, scan to the left of the dog past the stomach to the 69 spleen. The spleen will be visualized ventrally in the near field. Splenic border, 70 parenchyma and shape should be evaluated.6 (fig 4) Following the spleen transversely 71 down the left body wall, you will image the left kidney. (fig 5) 72 Once visualization of the kidney is achieved, turn the transducer to the sagittal 73 plane and evaluate the renal border, cortical echogenicity and pelvic architecture. 74 Dilatation of the renal pelvis is best seen in the transverse plane. Normal ureters are not 75 usually visible ultrasonographically.1,7 The left adrenal gland is located medial to the 76 cranial pole of the kidney. In a sagittal plane, maintaining strong hand pressure, scan 77 medially to visualize the linear aorta and the renal artery. The left adrenal is located cranial 78 to the left renal artery and caudal to the left cranial mesenteric artery. The left adrenal 79 gland is imaged as a bi-lobed structure with the phrenicoabdominal vein at its waist.1 (fig 6) 80 With the transducer in a transverse plane in the midabdomen, scan caudally to 81 image a large hypoechoic structure, the urinary bladder. Evaluate bladder wall and lumen 82 contents, and, dorsal to the bladder, the major vessels (caudal vena cava and aorta). 83 Sublumbar lymph nodes will be seen at the aortic bifurcation into the iliac arteries, 84 adjacent to the bladder wall. (fig 7) Sagittal scanning of the urinary bladder caudally will 85 allow visualization of the urethra (and prostate in the male).4 (fig 8) 86 Continuing in methodic fashion, the right kidney will be imaged at the edge of the 87 right ribcage adjacent to the renal fossa of the liver. The right kidney should be evaluated 88 as was the left with respect to renal border, cortical echogenicity and pelvic architecture. 89 By scanning sagittally between the right kidney and the caudal vena cava with a fanning 90 146 technique, the right adrenal gland is visualized just lateral to the caudal vena cava. In a 91 transverse plane, the duodenum is imaged lateral to the right kidney.1 (fig 9) 92 At the cranial end of the right kidney medial to the duodenum will be the right limb 93 of the pancreas. The right pancreatic limb is identified by visualizing the caudal 94 pancreaticoduodenal vein within the structure. (fig 10) Turning to the sagittal plane, follow 95 the pancreas, scanning medially to the angle of the body and left limb, or sagittally scan 96 the caudal border of the stomach. The pancreatic body is seen caudal to the stomach, 97 cranial to the splenic vein. The left pancreatic limb is found caudal to the splenic vein and 98 midline to the cranial pole of the left kidney.5 (fig 11) 99 Returning to the transverse plane in midabdomen at the mesenteric root, scan for 100 mesenteric lymph nodes and small bowel wall changes. Scanning in a uniform serpentine 101 fashion, 2-3 passes may be required to evaluate the entire bowel. Normally, the small 102 bowel appears sonographically as four distinct layers. (fig 12, 13) The bowel lumen is 103 hyperechoic, as gas and ingesta are compressed. The layer just outside the lumen is 104 the mucosa; it is hypoechoic and normally the thickest appearing section. Outside the 105 mucosa is the submucosa, it is hyperechoic to the mucosa and about one third the 106 thickness. The muscularis, the bowel muscle layer, is outside of the submucosa and 107 appears as a very thin hypoechoic black line. The outermost serosal layer is 108 hyperechoic.1 (fig 14) 109 References 110 111 147 1. Baker TW: Find your friends: location and appearance of normal abdominal 112 viscera, liver, spleen, kidney and urinary bladder. In: What’s that? A beginner’s 113 guide to veterinary abdominal ultrasound. Lakewood, CO: AAHA Press, 2009. 114 115 2. Nyland TG, Mattoon JS, Herrgesell EJ, et al: Physical principles, instrumentation, 116 and safety of diagnostic ultrasound. In: Nyland TG, Mattoon JS, editors. Small 117 animal diagnostic ultrasound, 2nd ed. Philadelphia: WB Saunders; 2002. p. 1-118 18. 119 120 3. Penninck DG: Artifacts. In: Nyland TG, Mattoon JS, editors. Small animal 121 diagnostic ultrasound, 2nd ed. Philadelphia: WB Saunders; 2002. p. 19-29. 122 123 4. Nyland TG, Mattoon JS, Herrgesell EJ, et al: Urinary tract. In: Nyland TG, 124 Mattoon JS, editors. Small animal diagnostic ultrasound, 2nd ed. Philadelphia: 125 WB Saunders; 2002. p.158-195. 126 127 5. Penninck DG: Gastrointestinal tract. In: Nyland TG, Mattoon JS, editors. Small 128 animal diagnostic ultrasound, 2nd ed. Philadelphia: WB Saunders; 2002, p.207-230. 129 130 6. Nyland TG, Hager DA: Sonography of the liver, gallbladder, and spleen. Vet Clin 131 North Am Sm Anim Pract 1985;15:1123-1148. 132 133 148 7. Lamb CR: Ultrasonography of the ureters. Vet Clin North Am Sm Anim Pract 134 1998; 28:823-848. 135 149 Fig 1a The correct sagittal scanhead placement: Button2: Button4: Button5: Button6: Button7: Button8: Button9: Button10: Button11: Button12: Button13: Button15: Button16: Button17: Button18: Button19: Button20: Button21: Button22: Button23: << /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. Created PDF documents can be opened with Acrobat and Adobe Reader 5.0 and later.) >> /Namespace [ (Adobe) (Common) (1.0) ] /OtherNamespaces [ << /AsReaderSpreads false /CropImagesToFrames false /ErrorControl /WarnAndContinue /FlattenerIgnoreSpreadOverrides false /IncludeGuidesGrids false /IncludeNonPrinting false /IncludeSlug false /Namespace [ (Adobe) (InDesign) (4.0) ] /OmitPlacedBitmaps false /OmitPlacedEPS false /OmitPlacedPDF false /SimulateOverprint /Legacy >> << /AddBleedMarks false /AddColorBars false /AddCropMarks false /AddPageInfo false /AddRegMarks false /BleedOffset [ 0 0 0 0 ] /ConvertColors /NoConversion /DestinationProfileName () /DestinationProfileSelector /NA /Downsample16BitImages true /FlattenerPreset << /PresetSelector /MediumResolution >> /FormElements false /GenerateStructure true /IncludeBookmarks false /IncludeHyperlinks false /IncludeInteractive false /IncludeLayers false /IncludeProfiles true /MarksOffset 6 /MarksWeight 0.250000 /MultimediaHandling /UseObjectSettings /Namespace [ (Adobe) (CreativeSuite) (2.0) ] /PDFXOutputIntentProfileSelector /NA /PageMarksFile /RomanDefault /PreserveEditing true /UntaggedCMYKHandling /LeaveUntagged /UntaggedRGBHandling /LeaveUntagged /UseDocumentBleed false >> << /AllowImageBreaks true /AllowTableBreaks true /ExpandPage false /HonorBaseURL true /HonorRolloverEffect false /IgnoreHTMLPageBreaks false /IncludeHeaderFooter false /MarginOffset [ 0 0 0 0 ] /MetadataAuthor () /MetadataKeywords () /MetadataSubject () /MetadataTitle () /MetricPageSize [ 0 0 ] /MetricUnit /inch /MobileCompatible 0 /Namespace [ (Adobe) (GoLive) (8.0) ] /OpenZoomToHTMLFontSize false /PageOrientation /Portrait /RemoveBackground false /ShrinkContent true /TreatColorsAs /MainMonitorColors /UseEmbeddedProfiles false /UseHTMLTitleAsMetadata true >> ] >> setdistillerparams << /HWResolution [2400 2400] /PageSize [612.000 792.000] >> setpagedevice