10/13/19

Case

Aorta and Renal Ultrasound • 62 year old male • CC severe left flank pain radiating to the left lower quadrant • HPI • The pain was insidious in onset and had an intensity of 10/10 • Emergency Ultrasound Course Constant pain, lasting 3 hours in duration, associated with two episodes of emesis since its onset Huntington Beach, CA • ROS November 8-10, 2019 • No chest pain, dyspnea, fever or bowel and bladder dysfunction Carolyn Chooljian, MD • PMHx • stones, left flank pain

Case Physical Examination DDx

• BP 110/60 P 100 , RR 24 T 36.7° C • Renal/Ureteral colic • Heart and Lung exam WNL • Diverticulitis • soft with diffuse tenderness which increased over the left • Aortic Dissection lower quadrant • AAA • Urinalysis specific gravity (1.030), hematuria (1+) and trace protein • Testicular torsion • Incarcerated inguinal hernia • Ectopic (female)

Aortic-Renal Ultrasound Abdominal Aortic (AAA)

• • Aneurysm---focal dilatation > 50% of vessel’s normal diameter • AAA • Aortic Dissection • AAA if diameter >3 cm • Kidney • Hydronephrosis • Stones

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AAA: Risk factors AAA statistics

• Age • Prevalence of AAA • Male:female 4:1 • Men aged 45-54 years 1.3% • Smoking (5x) • Men 75-84 years 12.5% • Family history • Women 0% in the youngest, to 5.2% in the oldest age groups

• Ruptured AAA causes ~ 9,000 deaths a year in US

AAA Statistics AAA

• Misdiagnosis of AAA is 30% to 60% • Most asymptomatic until rupture, may have normal vitals • > 80% of AAAs have not been previously diagnosed at the time of rupture • Physical exam poor sensitivity < 65% • Rupture rate by size • < 25% of patients present with the characteristic triad • 2%/year <4cm • Hypotension • 20-50% >7cm • Abdominal pain • Physical exam unreliable • Pulsatile abdominal mass • Mortality rate of ruptured AAA approaches 90% • Delays due to nonspecific clinical presentations that mimic AAA: • Rapid diagnosis/surgery + survival • Renal colic (Most frequently misdiagnosed as nephrolithiasis) • Large decrease in mortality in vascular surgery patients when AAAs were • Diverticulitis diagnosed and treated earlier • GI hemorrhage

AAA 1 year Rupture Risk by size Abdominal Aorta Aneurysm

• 5.0-5.9 cm 25% • AAA rupture high mortality total 80-90% • 6.0-6.9 cm 35% • Up to 70% die before reaching hospital • ≥ 7.0 cm 75% • Additional 15% die at hospital • Surgical patients have 50% survival

• ED bedside US • Accurate for ruling in/out AAA • Not accurate for distinguishing rupture

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AAA Bedside US Abdominal Aorta Anatomy

• Sensitivity: 94-100% • Retroperitoneal • Specificity: 98-100% • Enters the abdomen via the caudal to the xiphoid process • Rests anterior to the vertebral body • Limited by indeterminate studies and parallel to the IVC • Extends about 1 to 2 centimeters below the umbilicus • Divides into the common iliac at the level of L4 • Diminishes in size as it descends • Becomes more superficial

Abdominal Aorta Aneurysm Abdominal Aorta and its Arterial Branches

• Categories of AAA: fusiform and saccular • Celiac trunk • Majority are fusiform. Fusiform expand circumferentially. • Left gastric • • Saccular aneurysms are localized outpouchings, often secondary to an Hepatic artery infectious etiology. • Splenic artery • • 90% infrarenal Superior Mesenteric Artery • Scan to where the aorta bifurcates • Renal Arteries • 1 to 2 centimeters below the umbilicus • Inferior Mesenteric Artery • Divides into the common iliac arteries at the level of L4 • Bifurcation of the iliacs

Proximal Aorta Aortic US Celiac Axis “Seagull Sign” • Ultrasound Aorta from subxiphoid to bifurcation • Transverse • Sagitally • Measurements aorta from outer wall to outer wall • Aneurysms will often contain a thrombus • Don’t mistake the inner rim of the thrombus for the aortic wall

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SMA Sagittal Aorta

Aorta Exam Aorta vs. IVC Transverse Approach • Vena cava to right of aorta, intrahepatic proximally

• Aorta is thicker, not compressible

• IVC is compressible

• Both are pulsatile

• IVC diameter > Aorta

• Normal aorta tapers distally

• IVC gets larger as it approaches renal vessels

Normal Aorta AAA

• ≤ 3 cm external diameter even at the level of the diaphragm • Loss of the normal proximal-to-distal taper (earliest sign)

• Often 1-1.5 cm diameter • Diameter > 3 cm

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Aortic Dissection Assessing the Aorta

• All measurements are from the outer wall to outer wall

• Significant aneurysms are ≥ 5cm

• True dissections sometimes occur with AAA and a flap can sometimes be visualized by US

• Thrombus and arteriosclerotic changes in the wall are common

Bedside renal ultrasonography Indications/Goals

• Flank pain • Bladder distention/postvoid residual • Abdominal pain with hematuria • Decreased urinary output Renal Ultrasound • Hydronephrosis/hydroureter • Foley • Nephrolithiasis • Cysts/Polycystic • Renal failure

Nephrolithiasis/Ureterolithiasis Renal Ultrasound

• X-ray 50-60% sensitive • Normal adult kidneys are 9-12 cm long; 2.5-3.5 cm thick; 4-5 cm wide. • CT 94-97% sensitive and 96-100% specific • US Stone: Sensitive: 45%, Specificity: 94% • The kidneys have two distinct areas: • US Hydronephrosis: Sens 85-90%, Spec 85% Sinus () Parenchyma Outer cortex Inner medulla Consists of 8-18 renal pyramids that pass urine to the minor calyces.

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Renal Anatomy Right Kidney

• Right kidney is more caudal than the left kidney

Left Kidney Hydronephrosis

• Obstruction to flow causes rise in intrarenal pressure

• Renal pelvis and calyces dilate first

• Renal parenchyma becomes compressed causing thinning of the pyramids

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Hydronephrosis Renal US: Hydronephrosis Mimics

• Gravid uterus • Renal cysts • May compress right and cause right renal hydronephrosis • Typically single • Located at periphery of the kidney • AAA • Can be multiple as in polycystic kidney disease • May compress left ureter and cause left renal hydronephrosis • Extrarenal pelvis • A collecting system located outside the kidney

• Can mimic early hydronephrosis but is a normal developmental variant • Overhydrated patient may have mild bilateral hydronephrosis without obstruction

Renal Cysts Hydronephrosis vs. Polycystic Kidney

The fluid filled areas of hydronephrosis communicate Polycystic cysts do not communicate

Renal Ultrasound findings Renal Ultrasound: Ureter

• Pyelonephritis: • Normal ureter is not ordinarily seen • Sonographic appearance is most commonly normal, but you may find hypoechoic cortex and loss of demarcation between the outer cortex and middle pyramids and columns of Bertin. • Dilated ureter is sometimes seen • Renal mass:

• May have any echotexture (hyperechoic, anechoic etc.) and appear anywhere within the kidney

• Chronic renal failure:

• Kidneys appear small and hyperechoic.

• Ureteral stents:

• Have a characteristic appearance but can be difficult to visualize due to size and position.

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Renal and Ureteral Stones Intrarenal Stones

• Renal stones • May be seen on ultrasonography • Look for bright objects that cast a shadow within the kidney.

• Ureteral stones • Unlikely to be visualized, though may be seen at uretero-vesicular junction (UVJ)

UV Junction Stone Bladder Mass

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