Abdominal Vasculature and Spleen

Venous Abdominal Vasculature

• In the IVC and Hepatic Veins, the pattern of flow is called pulsatile and triphasic.
• The flow shape resembles the letter "W".
• Flow goes above and below the baseline.
• The maximum IVC diameter should measure no more than 2.5 cm.
• In the hepatic veins, flow is hepatofugal, it moves away from the liver.
• In the portal veins, flow is hepatopetal, moving towards the liver.
• Portal veins have thicker echogenic walls on sonographic images.
• Hepatic veins are anechoic structures with thinner walls.
• Portal veins have arteries adjacent to them in the liver.

What do we see here?

• 1: Portal Vein
• 2: Superior Mesenteric Artery
• 3: Inferior Vena Cava (IVC)
• 4: Right Renal Artery
• 5: Left Renal Artery
• 6: Abdominal Aorta
• 7: Left Renal Vein
• 8: Splenic Vein

Spleen

• Functions of the spleen include recycling/filtration of RBCs, and production of lymphocytes, plasma cells and antibodies (all defense mechanisms)
• Further functions include storage of iron and other metabolites
• Splenomegaly, enlarged spleen ,is the most common abnormality.
• The upper limit of adult splenic length is 13 cm, but can be more in taller males.
• White and red pulp make up the spleen.
• Lymphoid tissue and numerous lymphocytes make up the white pulp.
• Connective tissue that forms cords and venous sinuses make up red pulp.
• Macrophages make up the cords which act as a secondary filter for infections.
• There exists no solid walls in venous sinuses. RBC's can pass through specialized slots.
• Splenic appearance can be homogeneous with mild-gray echoes.
• It appears hyperechoic relative to the liver.
• Splenic tissue separated from the spleen near the splenic hilum or tail of the pancreas is called an accessory spleen, which is the most common congenital anomaly.
• Wandering spleen is a spleen in an ectopic location, usually in the pelvis.
• Hemangioma is the most common benign tumor of the spleen.
• It is typically found as an isolated echogenic mass with multiple small hypoechoic areas.
• A large hemangioma may rupture.
• Appearance is variable, can be well-defined echogenic solid mass to a complex mixed patterned; infarction with coagulated blood is seen in larger lesions.
• Congestive splenomegaly can be acute (bloodborne etiology, acute infection) or chronic (cardiovascular congestion).
• Songraphic appearance is enlarged to a mild-moderate degree.
• Portal hypertension, congestive heart failure (CHF) and Budd-Chiari are all characteristics.
• It may be complicated by splenic vein thrombosis.
• Splenic Granulomatosis is a reactive hyperplasia from a previous acute or chronic infection.
• Histoplasmosis, sarcoidosis, splenitis sarcoid and tuberculosis are included as causes.
• Songraphic appearance includes hypoechoic spleen and echogenic lesions throughout the parenchyma.
• Splenic infarction is generally caused by an embolus coming from the heart.
• It appears as a peripheral wedge-shaped hypoechoic lesion showing diminished flow on Doppler interrogation.

Urinary System Anatomy

• The renal sinus is a collecting system and the most echogenic part of the kidney.
• It consists of the pelvis, major and minor calyces, vessels, fatty tissue, and lymphatic channels.
• An image is transverse to the ATL.
• The renal parenchyma has two distinct areas: the cortex and the medulla, or medullary pyramids.
• Cortical extensions between the medullary pyramids are columns that project toward the renal sinus.
• Gross anatomy of the kidney consists of the parenchyma and sinus.
• Kidneys are located in the retroperitoneum.
• The left kidney is typically higher and longer than the right kidney.
• Normal ureters join the bladder at the posterior-inferior portion.
• UPJ is Ureteropelvic junction
• UVJ is Ureterovesical junction
• VUJ is Vesicoureteral junction
• Bladder wall thickness is typically 3 to 6 mm.
• Normal bladder volume is up to 500 ml, anything more is excessive volume.
• Normal post-void residual volume is 50 ml.

Urinary System Pathology

• Hydronephrosis develops when resistance to portal blood flow increases.
• Common cause is cirrhosis.
• UVJ is the most common site of obstruction with a stone.
• Other potential etiologies include retroperitoneal fibrosis or tumor invasion, mechanical compression.
• VUJ obstruction may be present with benign prostatic hypertrophy (older males).
• It may also occur with posterior valve obstruction (fetus males), bladder tumor invasion, and pelvic organs tumor invasion.
• 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.
• Bladder has a distinct appearance with PUV obstruction and massive bladder, bilateral hydroureters, and bilateral hydronephrosis.
• Horseshoe kidney, or renal fusion, is when two kidneys are fused or joined together.
• The most common type involves fusion of the inferior poles.
• Kidney's join in the midline area in the lower abdomen that lies over the great vessels.
• A renal ultrasound should be done to confirm diagnosis.
• Duplication of the collecting system occurs when 2 echogenic sections are separated by parenchymal tissue. This creates 2 independent collecting systems in one kidney.
• No echogenic renal pelvis seen on mid transverse view.
• The duplicated ureter commonly has an ectopic insertion and stenotic opening into the bladder, forming a ureterocele.
• Intrinsic hydronephrosis is caused by ureteral stricture, renal calculus in ureter or junctions, bleeding or blood clot, ureterocele and/or pyonephrosis.
• Additionally, tuberculosis of the genitourinary system can cause hydronephrosis.
• Parapelvic cysts originate from renal parenchyma and seen in the renal hilum; may present with hypertension and are large and solitary.
• Does not communicate when the collecting system as hydronephrosis does.
• Extrarenal pelvis, parapelvic cyst, or overdistended bladder could all be confused for hydronephrosis.
• May mimic hydronephrosis such as with diuresis, overdistended bladder, parapelvic cyst and extrarenal pelvis.
• Reflux-vesicoureteral (pediatric), diabetes insipidus (excessive thirst) and renal vessel prominence can also mimic hydronephrosis.
• IPKD (Infantile Polycystic Kidney Disease) is an autosomal recessive polycystic disease (ARPKD), or Potter type I
• It is the least common and most fatal of these cystic diseases.
• Autosomal recessive and more common in females (2:1).
• If survive past infancy, hepatic fibrosis becomes a complication, with death from hepatic failure and/or bleeding from esophageal varices.
• Bilateral echogenic, enlarged kidneys with cysts, loss of corticomedullary junction (cysts classically are too small to be resolved)
• Potter Type II is most common form of cystic disease in neonates.
• Patients will generally present with renal failure.
• Small cysts in medullary portion of both kidneys are typical with decreased definition between the cortical/medulla junctions. It could be unilateral or bilateral.
• APKD (Adult Polycystic Kidney Disease) is an autosomal dominant polycystic kidney disease (ADPKD) or Potter type III
• It is also autosomal dominant and the most common disorder.
• There can be a latency for years before manifesting in the fourth decade.
• Decreased renal function, hypertension, and flank pain are typical symptoms.
• Cysts appear in the liver, pancreas, and spleen.
• Kidneys are bilaterally large, with randomly distributed cortical cysts of various sizes.
• In advanced stages, kidneys lose the reniform shape.
• Pyonephrosis will present in the dilated collecting system.
• This is a complication of hydronephrosis, urinary stasis, or infection
• It is a common finding in patients with pyelonephritis.
• It is typically associated with leukocytosis, fever, chills, and flank pain, but some patients may be asymptomatic.
• A collecting system dilates with debris, often shifting debris-urine level.
• Renal calculi appear as highly reflective echogenic foci with shadowing.
• Stones may be found in the renal sinus, ureter, junctions, and bladder.
• Calculus: large stone in central portion of the kidney collecting system that has the shape of the calyces and renal pelvis.
• Medullary Sponge Kidney (MSK) is a developmental anomaly that occurs in the medullary pyramids.
• It consists of cystic or fusiform dilation of the distal collecting ducts (ducts of Bellini), causing stasis of urine and stone formation.
• It is generally associated with hypercalciuria.
• Nephrocalcinosis: diffused calcium depositions related to hypercalciuria and by statis of urine.
• Tuberous Sclerosis is an autosomal dominant genetic disorder characterized by mental retardation, seizures, and adenoma sebaceous.
• It is associated with Von Hippel-Lindau syndrome.
• In TSC, renal pathologies include multiple angiomyolipomas, renal cysts, and less commonly, oncocytomas.
• Differentiation from APKD (Adult Polycystic Kidney Disease) can be difficult.
• Emphysematous Pyelonephritis is a morbid infection with gas formation within or around the kidneys.
• There is a bacterial infection linked to renal ischemia.
• Morbid infection with gas formation within or around the kidneys. Includes bacterial infection linked to renal ischemia.
• 87-97% occurs in diabetics, 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 done to treat infection.
• Renal Angiomyolipoma, a common benign tumor, is typical in women (2:1)
• Symptoms include flank pain, hematuria, and hypertension
• Highly echogenic mass found in the cortex. Posterior shadowing is appreciated in larger masses.
• Wilms Tumor/Nephroblastoma is the most common primary renal malignancy in children.
• Symptoms can include abdominal mass, hypertension, nausea, and hematuria
• Early on mass is encapsulated, later it may extend into the perirenal area
• Varied sonographic appearance depending upon the amount of necrosis and hemorrhage
• Renal Cell Carcinoma (RCC) is also known as Hypernephroma, Adenocarcinoma, and Grawitz tumor, and affects males more after 50.
• Hematuria and hypertension are primary symptoms.
• Hyperperfusion is seen on angiogram
• Metastases to bone, heart, vessels, and brain -Unilateral, solitary, encapsulated
• Sonographically, varied echogenicity, from hypoechoic to hyperechoic
• Look for metastatic renal vein/vena cava invasion and thrombosis
• Renin vein thrombosis and lymph node may be seen. Also look for the invasion of the contralateral side, ureter, peritoneum, spleen.
• Acute Pyelonephritis is the most common disease of the urinary tract caused by Bacteria ascending from bladder or adjacent lymph nodes to the kidney.
• Infection is in the parenchymal, caliceal, and pelvic.
• Bacteriuria is typically a symptom.
• Inability to filter metabolites from blood, resulting in renal dysfunction and hypertension.
• There will be increased BUN and creatinine levels.
• Acutely, kidneys may be normal size or enlarged.
• There may be depleted definitions between the medullary/cortical junctions.
• There will be increasing echogenicity if chronic.
• Small echogenic kidneys are difficult to visualize, representing the end-stage.
• Hypertension is the primary clinical symptom observed in patients with renal disease.
• Bladder Diverticulum (plural: diverticula) is an outpouching from the bladder wall and can be congenital or acquired.
• Can be congenital or acquired. Can be solitary or multiple in nature and size can vary considerably.
• Cystitis is infection or inflammation of the bladder. The wall will be thickened and debris may be seen.
• Transitional cell carcinoma (TCC) occurs 95% of the time while squamous cell carcinoma 5% in bladder tumors.
• Can affect urothelium and is found anywhere in the urinary system, and may be detected late stage.
• They are invasive tumors and 40% will metastasize into the prostate and pelvic organs
• Symptoms are Hematuria, dysuria, anuria, urinary frequency.
• Symptoms are hematuria, dysuria, anuria, urinary frequency.
• TCC can affects the urothelium and an be found anywhere in the urinary system.
• May be asymptomatic or have pain, palpable mass, and hematuria.
• Renal hypertension occurs if arteries in the kidneys become blocked or narrowed.
• Arteries in kidneys become blocked or narrowed causing high blood pressure (Also referred to as renal artery stenosis (RAS)
• Etiology includes renovascular disease,renal parenchymal disease, renal tumors and transplantation and complications.
• Atherosclerosis affects the proximal segment/origin of the main renal artery.
• Fibromuscular dysplasia (FMD) affects mid and distal portions of the MRA often.

Adrenal Glands

• The adrenal glands are located in the suprarenal space, they are medial and enclosed with kidney by Gerota's fascia.
• The cortex secretes steroid hormones: aldosterone, cortisol, and gonadocorticoids.
• Aldosterone regulates electrolyte metabolism and blood pressure.
• Cortisol is an antistress and anti-inflammatory hormone
• Gonadocorticoids regulate secretion of androgens and estrogens, the sex hormones.
• Epinephrine dilates coronary vessels, constricts the skin and kidney vessels, increases coronary output, raises oxygen consumption, causes hyperglycemia.
• Norepinephrine constricts all arterial vessels except coronary arteries (which dilate), essential regulator of blood pressure
• Cortical Syndrome: Cushing's is an Adrenocortical Hyperfunction
• CORTISOL is elevated and adrenal androgens
• Symptoms include diabetes, large abdomen, loss of tissue's elasticity, cardiomegaly, edema, hirsutism, amenorrhea
• Causes masculating effects in women.
• Cortical Syndrome: Conn's involves Adrenocortical Hyperfunction
• ALDOSTERONE is elevated. Associated with sodium retention = hypertension, and increased thirst/urination.
• Cortical Syndrome: Addison's involves Adrenocortical Hypofunction
• Production of CORTISOL is decreased and aldosterone is decreased.
• Autoimmune accounts for (80%)
• Adenoma is the most common benign tumor of the adrenal glands and may be functional and non-functional.
• Functional adenoma alters production of hormones. Associated with Cushing's and Conn's syndromes (hyperproduction of hormones).
• Nonfunctional type is asymptomatic. Round or oval in shape mass, usually larger than 1 cm, hypoechoic lesion.
• Pheochromocytoma is a rate vascular tumor; most common medullary tumor
• Excessive production of the epinephrine /norepinephrine
• Symptoms such as Uncontrollable hypertension, angina, cardiac arrhythmias, tachycardia, anxiety, vomiting, headaches, sweating are indicative.
• Affecting people 30-50 years and results in a Well-defined large, bulky, highly vascular, cystic or solid

Peritoneum

• Serous membrane lining the cavity of the abdomen (peritoneum) and covering the abdominal organs.
• It pads/insulates organs, holds in place and secrets lubricating fluid to reduce friction when they rub against each other.
• Retroperitoneum is the area between the posterior portion of the parietal peritoneum and the posterior abdominal wall.
• Space is posterior to the peritoneal cavity and extends from the diaphragm to the pelvis. Subject to infection, bleeding, inflammation, and tumors.
• Retroperitoneal hematoma presents with with a complex mass within the psoas muscle. There will be a drop in hematocrit as well.
• Subphrenic Abscess is Associated with a bacterial spill into the peritoneum caused by a surgical procedure, bowel rupture, peptic ulcer perforation, or trauma.
• Fluid collection superior to the liver or spleen, inferior to the diaphragm; transmission variable; gas (dirty shadowing)
• Retroperitoneal Fibrosis are thick sheets of connective tissue extend from the perirenal space to the dome of the bladder and is often 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.
• Great vessels may be potentially occluded