Untitled Quiz

• The urinary system includes the kidneys, ureters, urinary bladder, and urethra

Upper and Lower Urinary Tracts

• The upper urinary tract consists of the kidneys and ureters
• The lower urinary tract consists of the urinary bladder and the urethra

Kidney Functions

• Regulation of water balance (osmoregulation)
• Regulation of pH (acid-base balance) and inorganic ion balance (sodium, potassium, and calcium)
• Excretion of metabolic and nitrogenous waste products in urine
• Secretion of erythropoietin and renin-angiotensin system to control blood pressure
• Secretion of vitamin D active metabolite, calcitriol (1,25 dihydroxycholecalciferol)
• Gluconeogenesis, or the formation of glucose from amino acids and other precursors

Location and External Anatomy of Kidneys

• Paired reddish-brown, bean-shaped organs located retroperitoneally on the posterior abdominal wall, lateral to the vertebral column
• Kidneys extend from T12-L3 vertebrae
• Kidneys measure 12 cm tall, 6 cm wide, and 3 cm thick, weighing 130-150g
• Male kidneys are slightly larger than female kidneys
• The right kidney is slightly lower (1.2 cm) than the left due to the right lobe of the liver
• Left kidney is a little longer and narrower than the right
• Transpyloric plane passes through the superior part of the right hilum and the inferior part of the left hilum
• Kidney transplant sites are in the iliac fossa of the greater pelvis
• Each kidney has two surfaces (anterior and posterior), two borders (lateral convex and medial concave), and two poles (upper and lower)
• Kidneys move up and down (about 2 - 3 cm) in its fascial compartment during respiration, but not side to side
• Kidneys lie obliquely, with their upper pole nearer to the midline than its lower pole
• Only the lower poles are palpable in a normal individual
• The long axis of the kidneys runs parallel with the lateral border of the psoas major

Costovertebral Angle

• The costovertebral angle (CVA) is formed by the 12th rib and vertebral column
• It is clinically significant for detecting kidney problems
• Tenderness can indicate conditions like pyelonephritis or renal stones

Surgical Renal Access

• For surgical access, the posterior (flank) approach with an oblique incision is usually favored
• Incisions are made midway between the 12th rib and the iliac crest, extending laterally from the lateral border of the erector spinae
• In percutaneous renal biopsy, the biopsy needle is inserted 2.5 cm below the 12th rib
• This is to reach the lower pole of the kidney, with the patient holding their breath

Coverings

• Kidneys are enclosed in the following layers of fascia and fat:
• Fibrous renal capsule (true capsule): readily strips from the normal kidney surface and lines the renal sinus
• Perirenal (perinephric) fat lies between the fibrous capsule and renal fascia, surrounding both the kidney and suprarenal glands
• Renal fascia (false capsule): condensation of connective tissue outside the perirenal fat, surrounding the kidney, adrenal glands, ureter, and renal vessels
• The renal fascia is attached superiorly to the fascia of the diaphragm, medially to the aorta and IVC, and laterally to the transversalis fascia
• Limits the spread of infection or tumors from the kidney
• Pararenal (paranephric) fat lies external to the renal fascia and is continuous with the extraperitoneal (retroperitoneal) fat
• Pus from infection in the renal parenchyma is usually retained within the perirenal fascia, forming a perinephric abscess

Nephroptosis

• Nephroptosis is the downward displacement of the kidney (> 5 cm or about 2 vertebral bodies) and may result in hydronephrosis
• This results from inadequate support from the renal fascia, perirenal fat or the abdominal muscles
• Suprarenal glands occupy separate compartments in the renal fascia and are undisturbed during excessive mobility of the kidney

Renal structures

• Renal sinus: internal fat-filled lined by the fibrous capsule that houses the renal pelvis, calyces, blood vessels, lymphatic and nerves
• Hilus/hilum: external opening on the concave medial border where structures enter and exit

Hilum Transmission

• Ureter
• Renal vessels
• Nerves
• lymphatics
• The renal hilum is the entry into the renal sinus
• Renal pelvis: funnel-shaped and collects urine from the major calyces before directing it into the ureter
• Renal pelvis is formed by convergence of major calyces
• Total capacity of renal pelvis and calyces is about 8 ml
• Important when injecting the ureter with radiopaque substance

Variations in the Renal Pelvis:

• Buried within the renal parenchyma means that the pyelolithotomy will be difficult
• Protrudes outside the renal parenchyma means that a pyelolithotomy will be easy

Kidney Regions

• the kidneys consist of an outer cortex and an inner medulla
• Outer cortex
• The outer reddish-brown part
• Some parts project into the medulla as renal columns or columns of Bertin
• Inner medulla
• Lighter-coloured inner part
• contains renal pyramids (pyramids of Malpighi),
• The apex of the renal pyramid (renal papilla) fits into the cup-shaped minor calyx
• Papillary ducts (10 to 25 openings open into the minor calyx
• Minor calyces unite to form major calyces
• 2 to 3 major calyces, in turn, unite to form the renal pelvis

Hilum Relations

• Hilar relations anterior to posterior are Vein, Artery, then renal Pelvis/ureter (VAP)
• Hilar relations superior to inferior are Artery, Vein, then renal Pelvis/ureter (AVP)

Anterior Relations of the Kidneys

• Right kidney related to the suprarenal gland, right lobe of the liver, 2nd part of duodenum, hepatic flexure, and small intestine
• The suprarenal, duodenal, and colic areas are devoid of peritoneum
• The 2nd part of duodenum may be opened accidentally in performing a right nephrectomy
• Left kidney is related to suprarenal gland, stomach, spleen, pancreatic body and tail, jejunum, descending colon and/or splenic flexure
• This kidney, the suprarenal, pancreatic, and colic areas are devoid of peritoneum

Posterior Relations of the Kidneys

• Anterosuperiorly, related to the right adrenal (suprarenal) gland
• Posteriorly, related to the costodiaphragmatic recess of pleura, medial and lateral arcuate ligaments
• Posteriorly related to the muscle of the posterior abdominal wall (diaphragm, psoas major, quadratus lumborum, transversus abdominis)
• Posteriorly related to the subcostal, iliohypogastric and ilioinguinal nerves, subcostal vessels
• Posteriorly related to the 11th and 12th ribs (left kidney) and the 12th ribs (right kidney)

Blood Supply of the Kidney

• The kidneys receive 20-25% of the resting cardiac output and filter about 180 L of fluid each day
• Only 1-2 L of urine is produced
• Cortex has 90% to 95% of kidney related blood, while medulla receives only 5% to 10%
• The renal artery is a lateral branch of the abdominal aorta, below the origin of SMA, at L2
• The renal artery divides into anterior and posterior branches
• The anterior division supplies :apical, upper, middle, and lower segments
• The posterior division supplies the posterior segment of the kidney
• Branches supplying the segments are called segmental arteries
• The five segmental arteries and an important aspect of planning partial nephrectomy
• They are all end arteries

Renal Avascular Plane

• Avascular plane of the kidney (line of Brodel) is an imaginary avascular line along the lateral and slightly posterior aspect of the kidney
• Marks the boundary between the anterior and posterior blood supply
• Suitable site for both open and endoscopic surgical incision to access the inner kidney during nephrolithotomy

Each Renal Vein Drains into the IVC

• The left renal vein is 3x longer than the right, Passes anterior to the aorta (below the origin of the SMA), and receives the left gonadal, adrenal and lumbar vein
• Usually preferred for a live donor nephrectomy
• The right renal artery passes behind the IVC

Accessory Renal Arteries

• Accessory arteries occur in about 30% of individuals
• Usually arise from the abdominal aorta or the main renal artery
• Usually enter the kidney at the hilum or at one of its poles
• Aberrant (polar) arteries do not enter the kidney at the hilum
• The pelviureteric junction causes hydronephrosis
• Extrarenal branches include the:
  • Inferior suprarenal artery
  • Branches to the upper ureter, renal capsule
  • Perinephric fascia

Clinical Correlations

• Pelvic kidney
• Horseshoe kidney: liable to pelviureteric obstruction, infection and stone formation
• Nephrolithiasis/Renal calculus/Renal stone
• Percutaneous nephrolithotomy/Nephrolithotripsy
• Polycystic kidney disease
• Kidney transplantation
• Kidney Tumours- Wilm's tumor and renal cell carcinoma
• Renal artery stenosis
• Radiological – nephrogram
  • This study performs an intravenous pyelography (IVP) or intravenous urography (IVU) Renal angiography

Suprarenal Gland Details

• Yellowish retroperitoneal organs located in the upper pole of the kidneys
• Left suprarenal gland lies superiomedially, with its lower pole above the hilum
• Weighs 4-8 g (average 5 g, slightly larger in females), and measures about 4 × 3 × 1 cm
• Position varies laterally to each side of the vertebral column, deep to the 10th and 11th ribs
• Their position varies with respiration by approx. 3 cm with each movement of the diaphragm
• Surrounded by Gerota's fascia but separated from the kidneys by the perirenal fat
• Yellow cortex and a dark brown medulla, with an enlarged fetal cortex present at birth

Suprarenal Shape

• right gland is pyramidal, while the left gland is crescent-shaped
• The coeliac plexus is between the two glands
• Located near IVC and the liver

Location of Suprarenal Glands

• Located anterior to the left adrenal gland

Anatomical Relations of the Right Suprarenal Gland

• Anterior: Bare area of the liver for Superior and Medial, first part of the duodenum/peritoneum for Inferior
• Medial: Inferior vena cava
• Lateral : Right lobe of liver
• Posterior: Diaphragm for Superior to Inferior and Anteromedial aspect of right kidney for Inferior
• Medial:Right coeliac ganglion/inferior phrenic artery
• Lateral: Right lobe of liver

Anatomical Relations of the Left Suprarenal Gland

• Anteriorly Stomach/peritoneum for superior, tail of pancreas for inferior
• Medial : Left coeliac ganglion/inferior phrenic artery
• Lateral: Superomedial aspect of the Spleen
• Kidney is diaphragm, medial to the tail of Pancreas
• Medial: Left crus of diaphragm.
• Lateral: Medial aspect of the left

Suprarenal Vascular Supply

• As endocrine organs, adrenal glands receive arteries from 3 sources:
  • the inferior phrenic provides superior suprarenal artery
  • the middle suprarenal artery provides the adrenal aorta,
• the inferior suprarenal artery from the renal artery supplies the area of the rear

Lymph and Venous Suprarenal Drainage

• Suprarenal vein empties into the IVC on the right and the renal vein on the left
• Lymph drains to lateral aortic nodes

Ureter Features

• Fibromuscular tubes connecting the renal pelvis to the urinary bladder in the pelvis
• Retroperitoneal structure that is approximately 25 to 30 cm
• Distinguished from vessels and nerves in the living body by its: whitish, non-pulsatile and peristaltic activity when gently pinched with forceps- Kelly's sign
• Parts include the abdominal, pelvic and intravesical/intramural
• The pelvic ureter is enveloped in a fibromuscular sheath (Waldeyer sheath)
• Waldeyer sheath aids in fixing the ureter to the bladder
• Intravesical ureter passes obliquely through the bladder wall to prevent reflux of urine during urinary bladder contraction

Relations of the right Ureter

• Anterior: 2nd part of duodenum, terminal part of ileum, right colic and ileocolic vessels, gonadal vessels, and the root of mesentery of small intestine
• Posterior: right psoas muscle, separating it from the lumbar transverse processes and the bifurcation of the right common iliac artery

Relations of the left Ureter

• Anterior: sigmoid colon & mesocolon containing sigmoidal arteries, left colic vessels, and gonadal vessels
• Posterior: left psoas muscle separating it from the lumbar transverse processes, bifurcation of the left common iliac artery
• Medial: Inferior mesenteric vein

Pelvic Ureter in Males

• Lies above the seminal vesicle near its termination
• Crossed superficially by the vas deferens

Pelvic Ureter in Females

• Passes posterior to the ovary at the ovarian fossa to reach the base of the broad ligament adjacent to the lateral fornix of the vagina
• Subsequently crossed by the uterine artery (water under the bridge) before entering the bladder
• Ureters at risk of injury during pelvic surgery and hysterectomy
• Stones impacted in the lower ureter can be felt during exams through the lateral fornices

Constriction Sites

• Anatomical constriction sites of the ureter include:
  • Pelviureteric junction (PUJ), where the renal pelvis joins the ureter
  • At the pelvic brim/inlet, where the ureter crosses the bifurcation of the common iliac artery
  • Ureterovesical junction (VUJ), which is the narrowest of all, is where the ureter enters the wall of the bladder
• Ureteric calculus can lodge at these constrictions
• Lodge formation can lead to hydroureter and hydronephrosis
• Ureter lies across the lumbar vertebrae
• This crosses in front of the sacro-iliac joint, swinging out to the ischial spine, then passes medially toward the bladder on an x-ray plain screen

Blood Supply Locations

• Received from ureter across the following courses:
  • Proximal third: ureteric branches from renal artery
  • Middle third is abdominal aorta, gonadal, common and internal iliac arteries, lateral to the ureter
  • Distal third: superior and inferior vesical, and uterine arteries originating medially, toward that vessel
  • Pelvic regions should be approached towards the the pelvic ureter, instead of laterally

Blood Supply & Lymphatics

• Vessels anastomose in the adventitia of the ureter forming longitudinal channels
• Arterial supply is where the venous drain originates
• The ureter can safely transected at any level intraoperatively
• Perform a uretero-ureterostomy, without comprising their function
• upper abdominal ureter drains into nodes lateral to the aorta
• lower abdominal ureter drains into the common iliac nodes
• The pelvic ureter drains into the common, external, or internal iliac nodes

Innervation of the kidneys & Suprarenal Glands:

• The kidney & suprarenal glands arise from the renal & celiac plexus
• They arise out of the abdominopelvic splanchnic nerves with the least amount of aorticorenal ganglion
• Sympathetic preganglionic fibers from T10-L1 (via the lesser & least splanchnic nerves) travel to the renal & celiac plexuses
• These Synapse in the aorticorenal ganglion
• Postganglionic fibers vasoconstrict the renal blood vessels
• Stimulate Renin cells and juxtaglomerular
• Parasympathetic fibers connect to G.I tract

Suprarenal Gland Innervation

• Preganglionic sympathetic fibers pass from the preganglionic chain
• The fibers then cross the celiac ganglion via greater splanchnic nerves
• Epinephrine and norepinephrine are released into the sympathetic chain
• The medulla lacks parasympathetic stimulation

Ureters Innervation

• Is provided via the renal, aortic, superior and/or inferior hypogastric plexus
• Originates from the spinal cord
• The Vagus nerves innervate the upper ureter area
• Parasympathetic is S4
• The fibers go out to the aorta and hypogastric plexus