Venous Abdominal Vasculature

Venous Abdominal Vasculature

• The IVC and Hepatic Veins’ flow pattern is called pulsatile and triphasic.
• The IVC and Hepatic Veins’ shape resembles an "W".
• The IVC and Hepatic Veins’ flow is above and below a baseline.
• Bidirectional flow is seen in the IVC and Hepatic Veins.
• An IVC diameter should measure no more than 2.5cm.

Hepatic Veins

• Flow in the Hepatic Veins is hepatofugal and moves away from the liver.

Portal Veins

• Flow in the Portal Veins is hepatopetal and moves towards the liver.
• Portal veins have thicker echogenic walls in sonographic images.
• Hepatic veins are anechoic structures with very thin walls.
• Portal veins have adjacent arteries in the liver.

IVC Abnormal

• Image "A" shows an IVC filter.
• Leg swelling will likely happen with IVC abnormality.
• The effects of an IVC abnormality can be remedied.
• Pulmonary Embolism happens when arteries in the lungs become blocked by a clot.

Portal Vein Resistance

• Portal hypertension develops when resistance to portal blood flow increases.
• The most common cause of portal hypertension is cirrhosis.

Kidney Anatomy

• Renal sinus is a collecting system and the most echogenic part of the kidney.
• The renal sinus consists of the pelvis, major and minor calyces, vessels, fatty tissue, and lymphatic channels.
• The renal parenchyma has 2 distinct areas, the cortex and the medulla (medullary pyramids).
• Cortical extensions between the medullary pyramids are called columns of Bertin.

Kidneys

• The gross anatomy of the kidney consists of the parenchyma and sinus.
• Kidneys are located in the retroperitoneum.
• The left kidney is a little higher and longer than the right kidney.

Bladder Facts

• Bladder wall thickness is typically 3 to 6 mm.
• Normal bladder volume is up to 500 ml; any more than that is considered excessive.
• Normal post-void residual volume is <50 ml.

Urinary System Junctions

• UPJ stands for the Ureteropelvic junction.
• UVJ stands for the Ureterovesical junction.
• VUJ stands for the Vesicoureteral junction.

UVJ Obstruction

• UVJ is the most common site of obstruction with a stone.
• Other potential etiologies are retroperitoneal fibrosis or tumor invasion and mechanical compression.

VUJ Obstruction

• VUJ obstruction may be present with Benign prostatic hypertrophy in older males.
• VUJ can be present with Posterior valve obstruction in fetus males.
• Bladder tumor invasion may cause VUJ obstruction.
• Pelvic organs tumor invasion may cause VUJ obstruction.

Bladder Ureteral Jet

• Only obtaining the left ureteral jet in a patient department for renal/bladder exam indicates a problem in the right kidney/ureter.
• Lack of ureteral jet in the right kidney/ureter.

PUV Obstruction

• Posterior urethral valves are obstructive membranes that develop in the urethra of male fetuses.
• Copum (Congenital Obstructing Posterior Urethral Membrane) is extra tissue in the distal urethra.
• PUV valves can obstruct or block the outflow of urine through the urethra.
• A bladder with a distinct appearance, massive bladder, bilateral hydro ureters, and bilateral hydronephrosis can be seen with PUV.

Horseshoe Kidney

• Horseshoe kidney, or renal fusion, is when two kidneys fuse or join together.
• The most common type involves fusion of the lower poles of the kidneys.
• The kidneys are joined by a midline area in the lower abdomen that lies over the great vessels; this connection is called the isthmus.
• Horseshoe kidney should be imaged with ultrasound to confirm the diagnosis.

Duplication

• Duplication of the Collecting System: 2 echogenic regions are separated by parenchymal tissue, creating 2 independent collecting systems in one kidney.
• The absence of an echogenic renal pelvis may be seen on mid transverse view.
• A duplicated ureter commonly has an ectopic insertion and stenotic opening into the bladder, forming a ureterocele.

Intrinsic Hydronephrosis Etiology

• Ureteral stricture stenosis causes hydronephrosis.
• Renal calculus located in the ureter or junctions can cause hydronephrosis..
• Bleeding or a blood clot located in the ureter or junctions can cause hydronephrosis.
• Ureterocele often appears as a site of stone lodging and can lead to hydronephrosis.
• Pyonephrosis can cause hydronephrosis.
• Tuberculosis of the genitourinary system can cause hydronephrosis.
• Hydronephrosis is caused from dilatation of the renal collecting system.

Parapelvic Cyst vs. Hydronephrosis

• Parapelvic cysts originate from renal parenchyma and are seen in the renal hilum.
• Parapelvic cysts may present with hypertension.
• Parapelvic cysts follow the same criteria as simple cysts, but are located within the renal pelvis.
• Parapelvic cysts are solitary and large.
• Parapelvic cysts do not communicate with the collecting system like hydronephrosis does.
• An extrarenal pelvis, parapelvic cyst, or overdistended bladder could all be confused for hydronephrosis.

Mimic Hydronephrosis

• May mimic hydronephrosis with dilatation of the collecting system.
• Diuresis over distended bladder may mimic hydronephrosis.
• Parapelvic cyst or extrarenal pelvis congenital variant may mimic hydronephrosis.
• Reflux-vesicoureteral pediatric or diabetes insipidus excessive thirst may mimic hydronephrosis.
• Prominence of the renal vessel may mimic hydronephrosis.

Infantile Polycystic Kidney Disease

• IPKD is an autosomal recessive polycystic kidney disease (ARPKD) or Potter type I.
• It is the Least common and most fatal of the three cystic diseases, and more common in females (2:1).
• Hepatic fibrosis becomes a complication if a patient survives past infancy, with death resulting from hepatic failure and/or bleeding from esophageal varices.
• IPKD: presents as bilateral echogenic, enlarged kidneys with cysts and a loss of corticomedullary junction (the cysts classically are too small to be resolved).

Multicystic Dysplastic Kidney Disease

• MCDK or Potter Type II is the most common form of cystic disease in neonates.
• Patients present with renal failure.
• Small cysts in medullary portion of both kidneys with decreased definition between the cortical/medulla junctions.
• May be unilateral or bilateral.

Adult Polycystic Kidney Disease

• APKD is an autosomal dominant polycystic kidney disease (ADPKD) or Potter type III.
• It's an autosomal dominant disease and most common disorder, latent for years and might not manifest itself until the 4th decade.
• APKD presents with decreased renal function, hypertension, and flank pain, with cysts in the liver, pancreas, and spleen.
• APKD presents as bilateral large kidneys, randomly distributed cortical cysts of various sizes, and in the advanced stages, the kidneys lose the reniform shape.

Pyonephrosis

• Pyonephrosis happens in the dilated collecting system.
• It's a Complication of hydronephrosis, urinary stasis, or infection.
• It's a Common finding in patients with pyelonephritis.
• Typically associated with leukocytosis, fever, chills, and flank pain.
• The collecting system is dilated with debris, often shifting debris-urine level.

Nephrolithiasis

• With Nephrolithiasis, renal calculi appear as highly reflective echogenic foci with shadowing.
• The twinkle sign is a color artifact seen with urinary stones.
• Stones may be found in the renal sinus, ureter, junctions, and bladder.
• A calculus is large stone in the central portion of the kidney collecting system that takes the shape of the calyces and renal pelvis.

Medullary Sponge Kidney

• MSK is a developmental anomaly that occurs in the medullary pyramids.
• MSK consists of cystic or fusiform dilation of the distal collecting ducts (ducts of Bellini), causing stasis of urine and stone formation.
• MDK is associated with hypercalciuria.
• Nephrocalcinosis happens with diffused calcium depositions related to hypercalciuria and caused by the statis of urine.

Tuberous Sclerosis

• Tuberous Sclerosis is an autosomal dominant genetic disorder characterized by mental retardation, seizures, and adenoma sebaceous.
• Tuberous Sclerosis is associated with Von Hippel-Lindau syndrome.
• Multiple angiomyolipomas, renal cysts, and less commonly, oncocytomas can be found in the kidneys.

Emphysematous Pyelonephritis

• Morbid infection with gas formation within or around the kidneys
• It is a bacterial infection linked to renal ischemia.
• More commonly occurs in diabetics (87-97% of patients), immunosuppressed patients, and patients with urinary tract obstructions.
• Ultrasound findings: Anaerobic bacteria produce intrarenal gas causing reverberation, “comet tail," or dirty shadowing artifact.
• Nephrectomy is usually required to treat infection.

Renal Angiomyolipoma

• Renal Angiomyolipoma is a more common benign tumor in women (2:1).
• Symptoms are flank pain, hematuria, and hypertension.
• A discrete highly echogenic mass was found in the cortex.
• Posterior shadowing is appreciated in larger masses.

Wilm's Tumor/Nephroblastoma

• Wilm's Tumor/Nephroblastoma is the primary renal malignancy in children.
• Abdominal mass, hypertension, and nausea hematuria may occur.
• During sonographic findings, mass is encapsulated.
• Varied sonographic appearance depending upon the amount of necrosis and hemorrhage.

Renal Cell Carcinoma

• Renal Cell Carcinoma is also known as RCC, Hypernephroma, Adenocarcinoma, and Grawitz tumor.
• Renal Cell Carcinoma affects males more after 50.
• Hematuria and hypertension can occur along with hyperperfusion.
• Metastases to bone, heart, vessels, and the brain cause renal cell carcinoma.
• Sonographic Findings: Unilateral, solitary, encapsulated.
• Varied echogenicity, from hypoechoic to hyperechoic
• Metastatic renal vein/vena cava invasion and thrombosis can happen with renal cell carcinoma.
• Look for the invasion to the contralateral side, ureter, peritoneum, and spleen.
• Renal vein thrombosis may be seen.

Acute Pyelonephritis

• Infection is the most common disease of the urinary tract.
• Parenchymal, caliceal, and pelvic inflammation occur.
• Bacteria ascending from the bladder or adjacent lymph nodes to the kidney is its usual cause.
• Bacteriuria is a symptom.

Renal Failure

• Renal failure is the inability to filter metabolites from blood, resulting in decreased renal function and hypertension.
• Increased BUN and creatinine levels
• Acute: the kidney may be normal-sized or enlarged.
• There may be decreased definition between the medullary/cortical junctions
• Chronic: increased echogenicity in small echogenic kidneys is difficult to visualize
• Hypertension is the primary clinical symptom observed in patients with renal disease.

Bladder Diverticulum

• A bladder diverticulum (plural: diverticula) is an outpouching from the bladder wall.
• Bladder diverticulum may be solitary or multiple in nature and vary considerably in size.
• Bladder diverticulum can be congenital or acquired.

Cystitis

• Cystitis is an Infection or inflammation of the bladder.
• During Cystitis, the wall will be thick and debris may be seen.

Bladder Tumors

• Primary malignant bladder tumors consist of 95% transitional cell carcinoma (TCC) and 5% squamous cell carcinoma.
• TCC affects the urothelium and may be found anywhere in the urinary system.
• Bladder tumors are invasive tumors and 40% will metastasize into the prostate and pelvic organs.
• Bladder tumors are usually detected late stage.
• Patients with bladder tumors have symptoms with hematuria, dysuria, anuria, and urinary frequency.

Transitional Cell Carcinoma

• TCC can affect the urothelium and can be found anywhere in the urinary system.
• Patients with TCC may be asymptomatic or have pain, a palpable mass, and hematuria.

Renal Hypertension

• Renal hypertension is when the arteries in the kidneys become blocked or narrowed, causing high blood pressure.
• Narrowing of the main renal artery is also called renal artery stenosis (RAS).
• Etiology: Renovascular disease, renal parenchymal disease (reflux nephropathy, glomerulopathies, renal dysplasia, polycystic disease, renal parenchymal damage, acute/chronic failure), renal tumors, transplantation and complications.
• Hypertension is the primary clinical symptom commonly observed in patients with renal disease.
• Doppler ultrasound allows diagnosis and grading of renal artery stenosis (RAS).
• 2 common causes of RAS are atherosclerosis and fibromuscular dysplasia.
• Atherosclerosis affects the proximal segment and origin of the main renal artery.
• FMD affects mid and distal portions of the MRA.
• FMD is more often the cause of RAS in young people because they would not have developed atherosclerosis yet.

Adrenal Glands

• Adrenal Glands are located in the suprarenal space, medial, and enclosed with the kidney by Gerota's fascia

Adrenal Cortex

• The cortex produces the steroid hormones: aldosterone, cortisol, and gonadocorticoids.
• Aldosterone regulates electrolyte metabolism and blood pressure.
• Cortisol is an antistress and anti-inflammatory hormone that protects the body.
• Gonadocorticoids regulates secretion of androgens and estrogens, aka the sex hormones.

Adrenal Medulla

• The medulla produces Epinephrine and Norepinephrine.
• Epinephrine (adrenalin) dilates coronary vessels, constricts the skin and kidney vessels, increases coronary output, raises oxygen consumption, and causes hyperglycemia.
• Norepinephrine constricts all arterial vessels except coronary arteries (which dilate), is an essential regulator of blood pressure
• Cortical Syndrome: Cushing's with Adrenocortical Hyperfunction and CORTISOL ↑ and adrenal androgens
• Cortical Syndrome: Conn’s with Adrenocortical Hyperfunction & ALDOSTERONE ↑
• Cortical Syndrome: Addison’s with Adrenocortical Hypofunction, production of CORTISOL↓ and aldosterone↓↓

Adrenal Gland

• Adenoma is the most common benign tumor of the adrenal glands and may be functional and non-functional.
• Functional adenoma alters the production of hormones, is associated with Cushing's and Conn's syndromes (hyper-production of hormones)
• Nonfunctional type is asymptomatic
• Round or oval shape mass, usually larger than 1 cm, hypoechoic lesion

Adrenal Medullary Tumor

• Pheochromocytoma is a rare vascular tumor and the most common medullary tumor.
• Causes excessive production of the epinephrine /norepinephrine
• Causes Uncontrollable hypertension, angina, cardiac arrhythmias, tachycardia, anxiety, vomiting, headaches, sweating
• Affecting people 30-50 years

Spleen Functions

• Functions of the spleen: recycling/filtration of RBCs, production of lymphocytes (WBC) and plasma cells (defense mechanism), and production of antibodies (defense mechanism).
• The spleen also stores iron and metabolites.
• Splenomegaly is the most common abnormality.
• The upper limit of adult splenic length is 13 cm, but lengths upwards of 14 cm can be seen in normal, taller males.
• The spleen anatomy consists of white and red PULP.
• White pulp consists of lymphoid tissue and a large number of lymphocytes.
• Red pulp consists of connective tissue that forms CORDS and VENOUS SINUSES.
• Cords-clusters of macrophages are a secondary filter for infections.
• Venous sinuses have no solid walls and let RBCs through special slots.

Spleen

• The spleen appearance is homogeneous.
• The spleen has Mild-gray echoes.
• The spleen is Hyperechoic relative to the liver.

Splenic Congenital Anomalies

• Splenic tissue separated from the spleen, usually found near the splenic hilum or adjacent to the tail of the pancreas, is called an accessory spleen
• A wandering spleen is a spleen in an ectopic location usually found in the pelvis; patients usually present with abdominal or pelvic mass and intermittent pain, and may have splenic torsion.

Splenic Hemangioma

• Splenic Hemangioma is the Most common primary benign tumor of the spleen.
• It is Typically found as an isolated echogenic mass with multiple small hypoechoic areas; large hemangioma may rupture the spleen.
• The Splenic Hemangioma's appearance is variable, from a well-defined echogenic solid mass to a complex mixed patterned; infarction with coagulated blood is seen in larger lesions.

Congestive Splenomegaly

• Acute: bloodborne etiology, acute infection
• Chronic: cardiovascular congestion
• Sonographic Appearance: Diffuse mild to moderate enlargement, portal hypertension, CHF, Budd-Chiari may be complicated by Splenic vein thrombosis.

Splenic Granulomatosis

• Features Reactive hyperplasia resulting from previous acute or chronic infection such as histoplasmosis, sarcoidosis, splenitis sarcoid, or tuberculosis.
• Causes hypoechoic spleen and Echogenic lesions throughout the parenchyma (intrasplenic calcifications).

Splenic Infarction

• Most common cause of focal splenic lesions resulting from splenic artery/branches occlusion.
• Sonographic appearance of an acute splenic infarct is a peripheral wedge-shaped hypoechoic lesion showing diminished flow on Doppler interrogation.
• Embolus typically comes from the heart.

Abdominal Compartments

• Intraperitoneal, Retroperitoneal and Subperitoneal Peritoneum: The serous membrane lining the cavity of the abdomen and covering the abdominal organs.
• Pads and insulates organs, helps hold them in place, and secretes a lubricating fluid to reduce friction when they rub against each other.

Intraperitoneal Organs

• Liver
• Gallbladder
• Spleen
• Stomach
• Jejunum, ileum
• Cecum
• Transverse and sigmoid colon

Retroperitoneal Organs

• Kidneys and adrenal glands
• Pancreas
• Duodenum
• Ascending and descending colon
• IVC and Aorta
• Ureters

Retroperitoneum

• The retroperitoneum is the area between the posterior portion of the parietal peritoneum and the posterior abdominal wall.
• This is the space posterior to the peritoneal cavity that extends from the diaphragm to the pelvis.
• The retroperitoneal area is subject to infection, bleeding, inflammation, and tumors.

Conditions of the Retroperitoneum

• Psoas muscle abscess is variable, complex, solid or cystic lesion with septa, debris, and scattered echoes and has clinical findings such as fever, pain, dysuria, and leukocytosis.
• Retroperitoneal hematoma presents with a drop in hematocrit and a complex mass within the psoas muscle.
• Subphrenic Abscess is associated with a bacterial spill into the peritoneum caused by a surgical procedure, bowel rupture, peptic ulcer perforation, or trauma.
• Location: fluid collection superior to the liver or spleen, inferior to the diaphragm; transmission variable; gas (dirty shadowing)

Retroperitoneal Fibrosis

• Characterized by the formation of thick sheets of connective tissue extending from the perirenal space to the dome of the bladder.
• Condition linked to inflammatory AAA (periaortitis). Fibrosis encases the great vessels, ureters, and lymph channels, causing hydro and obstruction of the renal collecting system
• Does NOT distend bladder.
• The great vessels can potentially become occluded in the presence of retroperitoneal fibrosis. Male prevalence
• The etiology is usually idiopathic and may be associated with aortic aneurysms inflammation medications

Lymphatic System

• Direction of the flow: lymphatic capillaries, lymph vessels, lymphatic nodes, thoracic ducts, Subclavian veins, and SVC then right heart

Lymphadenopathy

• Characterized by Swelling of lymph nodes which can be secondary to bacterial, viral, or fungal infections, autoimmune disease, or malignancy.
• Primary criteria for differentiating malignant from a benign node size greater than 2 cm includes shape round and absence of an echogenic central portion includes presence of an echogenic hilum

Crura

• Diaphragmatic crura: right and left fibromuscular bundles that attach the diaphragm to the lumbar vertebra.
• Left crus can be visualized anterior to the aorta above the level of the celiac artery (2)
• Right crus is visualized posterior to the caudate lobe and IVC (cr)

Pseudomyxoma Peritonei

• PMP is a rare cancer that affects the peritoneal cavity and is caused by cancerous cells that produce mucin, a jelly-like substance, inside the abdominal cavity, gelatinous ascites.
• The condition originates from a perforated appendiceal epithelial tumor

Most Common Diagnoses

• Most common pediatric tumor: Nephroblastoma or Wilm's tumor
• Most common neonatal cystic abdominal mass: Multicystic Dysplastic kidney disease or Potter II
• Most lethal neonatal or pediatric congenital condition: Infantile Recessive Polycystic Kidney disease or Potter I
• Most common adult cystic disease: Adult Polycystic dominant kidney disease or Potter III
• Most common benign renal mass: Angiomyolipoma
• Most common renal malignancy: RCC or Grawitz tumor
• Most common bladder malignancy: Transitional Cell carcinoma
• Most common cortical benign tumor: Adenoma
• Most common medullary benign tumor: Pheochromocytoma
• Most common pathology of the spleen: Splenomegaly
• Most common splenic anomaly: Accessory spleen, splenula
• Most common benign splenic tumor: Hemangioma
• Most common splenic malignancy: Lymphoma

Echogenicity of Normal Abdominal Organs

• Liver/spleen comparison
• Kidneys and other Abd organs
• From Darkest to brightest:
• Kidney Medulla → Renal Cortex→ Liver → Spleen → Pancreas → Perivertebral fat/diaphragm -Anechoic - Hypoechoic- level, echoes-high- Echogenic Course.hyperechoic