The urinary system is the organ system that produces, stores, and carries urine. In humans it includes two kidneys, two ureters, the urinary bladder, two sphincter muscles, and the urethra.
Kidneys-The kidney is one of the various organs (together with the lungs, intestine and skin) that participates in the elimination of the wastes of the organism. The kidneys are bean-shaped organs about the size of a human fist. They are near the middle of the spine, just below the ribcage.
Ureters-Urine is collected in the renal pelvis, which connects to the ureters, which carry urine to the bladder. The ureters are about 8 to 10 inches (200 to 250 mm) long. Smooth muscular tissue in the walls of the ureters peristaltically force the urine downward. Small amounts of urine are emptied into the bladder from the ureters about every 10 to 15 seconds.
Bladder-The urinary bladder is a hollow muscular organ shaped like a balloon. It is located in the pelvic fossa and held in place by ligaments attached to the pelvic bones.
The bladder stores urine; it swells into a round shape when it is full and gets smaller when empty. In the absence of bladder disease, it can hold up to 16 fluid ounces (500 ml) of urine comfortably for 2 to 5 hours.
Sphincters (circular muscles) regulate the flow of urine from the bladder. The bladder itself has a muscular layer (detrusor muscle) that, when contracted, increases pressure on the bladder and creates urinary flow.
Urination is a conscious process, generally initiated by stretch receptors in the bladder wall which signal to the brain that the bladder is full. This is felt as an urge to urinate. When urination is initiated, the sphincter relaxes and the detrusor muscle contracts, producing urinary flow.
Role in disease
Kidney diseases are normally investigated and treated by nephrologists, while the specialism of urology deals with problems in the other organs. Gynecologists may deal with problems of incontinence in women.
Diseases affecting the urinary system:
· There are numerous kidney diseases, many of which interfere with the normal production of urine. Renal failure may be acute or chronic, and may require medication and dialysis.
· Kidney stones may be painful and cause long-term kidney damage. Proteinuria is usually without symptoms but may indicate renal disease.
· Stenosis (blockage), reflux (backflow of urine into the kidney, causing damage)
· Urinary tract infections (UTIs), interstitial cystitis, incontinence (involuntary loss of urine), benign prostatic hyperplasia, prostatitis (inflammation of the prostate) and urinary retention (inability to pass urine).
· The term "uropathy" refers to a disease of the urinary tract, while "nephropathy" refers to a disease of the kidney.
· Urinalysis is a test that studies the content of urine for abnormal substances such as protein or signs of infection. This test involves urinating into a special container and leaving the sample to be studied.
· Urodynamic tests evaluate the storage of urine in the bladder and the flow of urine from the bladder through the urethra. It may be performed in cases of incontinence or neurological problems affecting the urinary tract.
· Ultrasound is commonly performed to investigate problems of the kidney and/or urinary tract. KUB is plain radiography of the urinary system, e.g. to identify kidney stones. An intravenous pyelogram studies the shape of the urinary system.
The kidneys are bean-shaped excretory organs in vertebrates. Part of the urinary system, the kidneys filter wastes (especially urea) from the blood and excrete them, along with water, as urine. The medical field that studies the kidneys and diseases affecting the kidney is called nephrology.
In humans, the kidneys are located in the posterior part of the abdomen. There is one on each side of the spine; the right kidney sits just below the liver, the left below the spleen. Above each kidney is an adrenal gland (also called the suprarenal gland).
Fig: Human kidneys viewed from behind with spine removed
The kidneys are retroperitoneal, which means they lie behind the peritoneum, the lining of the abdominal cavity. They are approximately at the vertebral level T12 to L3, and the right kidney usually lies slightly lower than the left in order to accommodate the liver.
The upper parts of the kidneys are partially protected by the eleventh and twelfth ribs, and each whole kidney is surrounded by two layers of fat (the perirenal fat and the pararenal fat) which help to cushion it.
In a normal human adult, each kidney is about 11 cm long and about 5 cm thick, weighing 150 grams. The kidneys are "bean-shaped" organs, and have a concave side facing inwards (medially). On this medial aspect of each kidney is an opening, called the hilum, which admits the renal artery, the renal vein, nerves, and the ureter.
The outermost portion of the kidney is called the renal cortex, which sits directly beneath the kidney's loose connective tissue capsule. Deep to the cortex lies the renal medulla, which is divided into 10-20 renal pyramids in humans. Each pyramid together with the associated overlying cortex forms a renal lobe. The tip of each pyramid (called a papilla) empties into a calyx, which empties into the renal pelvis. The pelvis transmits urine to the urinary bladder via the ureter.
Fig: Above each human kidney is one of the two adrenal glands.
The basic functional unit of the kidney is the nephron, of which there are more than a million in each normal adult human kidney. Nephrons regulate water and soluble matter (especially electrolytes) in the body by first filtering the blood, then reabsorbing some necessary fluid and molecules while secreting other, unneeded molecules. Reabsorption and secretion are accomplished with both cotransport and countertransport mechanisms established in the nephrons and associated collecting ducts.
Collecting duct system
Fluid flows from the nephron into the collecting duct system. This segment of the nephron is crucial to the process of water conservation by the organism. In the presence of antidiuretic hormone (ADH; also called vasopressin), these ducts become permeable to water and facilitate its reabsorption, thus concentrating the urine and reducing its volume. Failure of the organism to produce ADH (or inability of the collecting ducts to respond to it) may cause excessive urination, called diabetes insipidus. Conversely, when the organism must eliminate excess water, such as after excess fluid drinking, the production of ADH is decreased and the collecting tubule becomes less permeable to water, rendering urine dilute and abundant. Failure of the organism to decrease ADH production appropriately may lead to water retention and dangerous dilution of body fluids, which in turn may cause severe neurological damage. After being processed along the collecting tubules and ducts, the fluid, now called urine, is drained into the bladder via the ureter, to be finally excluded from the organism.
· Excretion of waste products-The kidneys excrete a variety of waste products produced by metabolism, for example, urea (from protein catabolism) and uric acid (from nucleic acid metabolism).
· Homeostasis-The kidneys regulate the pH, mineral ion concentration, and water composition of the blood. By exchanging hydronium ions and hydroxyl ions, the blood plasma is maintained by the kidney at pH 7.4. Urine, on the other hand, becomes either acidic at pH 5 or alkaline at pH 8.
· Hormone secretion-The kidneys secrete a variety of hormones, including erythropoietin, renin, and vitamin D.
· Renal capsule: The membranous covering of the kidney.
· Cortex: The outer layer over the internal medulla. It contains blood vessels, glomeruli (which are the kidneys' "filters") and urine tubes and is supported by a fibrous matrix.
· Hilus: The opening in the middle of the concave medial border for nerves and blood vessels to pass into the renal sinus.
· Renal column: The structures, which support the cortex. They consist of lines of blood vessels and urinary tubes and a fibrous material.
· Renal sinus: The cavity, which houses the renal pyramids.
· Calyces: The recesses in the internal medulla, which hold the pyramids. They are used to subdivide the sections of the kidney. (singular-calyx)
· Papillae: The small conical projections along the wall of the renal sinus. They have openings through which urine passes into the calyces. (singular-papilla)
· Renal pyramids: The conical segments within the internal medulla. They contain the secreting apparatus and tubules and are also called Malpighian pyramids.
· Renal artery: Two renal arteries come from the aorta, each connecting to a kidney. The artery divides into five branches, each of which leads to a ball of capillaries. The arteries supply (unfiltered) blood to the kidneys. The left kidney receives about 60% of the renal blood flow.
· Renal vein: The filtered blood returns to circulation through the renal veins, which join into the inferior vena cava.
· Renal pelvis: Basically just a funnel, the renal pelvis accepts the urine and channels it out of the hilus into the ureter.
· Ureter: A narrow tube 40 cm long and 4 mm in diameter. Passing from the renal pelvis out of the hilus and down to the bladder. The ureter carries urine from the kidneys to the bladder by means of peristalsis.
· Medical terms related to the kidneys involve the prefixes renal- and nephro-.
· Nephrectomy-Surgical removal of the kidney is a nephrectomy, while a radical nephrectomy is removal of the kidney, its surrounding tissue, lymph nodes, and potentially the adrenal gland. A radical nephrectomy is performed for removal of cancers.
Diseases and disorders
· Polycystic kidney disease (PKD)-is a progressive, genetic disorder of the kidneys. PKD is characterized by the presence of multiple cysts (polycystic) in both kidneys. The disease can also damage the liver, pancreas and rarely the heart and brain.
- Autosomal dominant polycystic kidney disease (ADPKD) is generally a late onset disorder characterized by progressive cyst development and bilaterally enlarged kidneys with multiple cysts. Kidney manifestations in this disorder include renal function abnormalities, hypertension, renal pain, and renal insufficiency.
- Autosomal recessive polycystic kidney disease (ARPKD) is much rarer that ADPKD and is often lethal. The signs and symptoms of the condition are usually apparent at birth or in early infancy.
· Congenital hydronephrosis
· Renal dysplasia
· Congenital obstruction of urinary tract
· Horseshoe kidney- Horseshoe kidney is a congenital disorder, affecting about 1 in 500 children, in which a person's two kidneys fuse together to form a horseshoe-shape. This is the most common type of fusion anomaly in the kidneys.
· Duplicated ureter
· Renal failure-Acute renal failure & chronic renal failure
· Kidney stones are a relatively common and particularly painful disorder.
· Pyelonephritis is infection of the kidneys and is frequently caused by complication of a urinary tract infection.
· Azotemia is a toxic condition characterized by abnormal and dangerously high levels of urea, creatinine, various body waste compounds, and other nitrogen-rich compounds in the blood.
· Hydronephrosis is the enlargement of one or both of the kidneys caused by obstruction of the flow of urine.
· In nephrotic syndrome, the glomerulus has been damaged so that a large amount of protein in the blood enters the urine. Other frequent features of the nephrotic syndrome include swelling, low serum albumin, and high cholesterol.
· Kidney tumors
· Wilms tumor
· Renal cell carcinoma
· Glomerulonephritis-Glomerulonephritis is a primary or secondary autoimmune renal disease featuring inflammation of the glomeruli. It may be asymptomatic, or present with hematuria and/or proteinuria (blood resp. protein in the urine). There are many recognized types, divided in acute, subacute or chronic glomerulonephritis. Causes are infectious (bacterial, viral or parasitic pathogens), autoimmune or paraneoplastic.
· Diabetic nephropathy- Diabetic nephropathy, also known as Kimmelstiel-Wilson syndrome and intercapillary glomerulonephritis, is a progressive kidney disease caused by angiopathy of capillaries in the kidney glomeruli. It is characterized by nodular glomerulosclerosis. It is due to longstanding diabetes mellitus, and is a prime cause for dialysis in many Western countries.
· Lupus nephritis- Lupus nephritis is an inflammation of the kidney caused by systemic lupus erythematosus (SLE), a disease of the immune system. Apart from the kidneys, SLE can also damage the skin, joints and nervous system.
· Minimal change disease- Minimal change disease or nil disease (lipoid nephrosis) is a disease of the kidney which causes nephrotic syndrome and usually affects children (peak incidence at 2-3 years of age).
· Interstitial nephritis- Interstitial nephritis (or Tubulointerstitial nephritis) is a form of nephritis affecting the interstitium of the kidneys surrounding the tubules.
· Common causes include infection, or reaction to medication (such as an analgesic or antibiotics.)
Renal failure is the condition where the kidneys fail to function properly. Physiologically, renal failure is described as a decrease in the glomerular filtration rate. Clinically, this manifests in an elevated serum creatinine. It can broadly be divided into two categories: acute renal failure and chronic renal failure.
Chronic renal failure (CRF) develops slowly and gives few symptoms initially. It can be the complication of a large number of kidney diseases, such as IgA nephritis, glomerulonephritis, chronic pyelonephritis and urinary retention. End-stage renal failure (ESRF) is the ultimate consequence, in which case dialysis is generally required while a donor for renal transplant is found.
Acute renal failure (ARF) is, as the name implies, a rapidly progressive loss of renal function, generally characterized by oliguria (decreased urine production, quantified as less than 400 to 500 mL/day in adults, less than 0.5 mL/kg/h in children or less than 1 mL/kg/h in infants), body water and body fluids disturbances and electrolyte derangement. An underlying cause must be identified to arrest the progress, and dialysis may be necessary to bridge the time gap required for treating these underlying causes.
Wilms tumor is a neoplasm of the kidneys that typically occurs in children. It is eponymously named after Dr Max Wilms, a German surgeon (1867-1918). It is also known as a nephroblastoma.
Approximately 500 cases are diagnosed in the U.S. annually. Majority of them (75%) occur in otherwise normal children; a minority (25%) is associated with other developmental abnormalities. Wilms' tumor is a malignant tumor containing metanephric blastema, stromal and epithelial derivatives. Characteristic is the presence of abortive tubules and glomeruli surrounded by a spindled cell stroma. The stroma may include striated muscle, cartilage, bone, fat tissue, fibrous tissue. The tumor is compressing the normal kidney parenchyma. Wilms tumor may be separated into 2 prognostic groups based on pathologic characteristics:
· Favorable - Contains well developed components mentioned above
· Anaplastic - Contains diffuse anaplasia (poorly developed cells)
Wilms tumor can affect any child regardless of race, sex, country of origin, or parental occupation. The disease is mostly noticed around age three, but has been recorded in children as old as age sixteen. Most cases begin with experience of the following symptoms:
· Abdominal mass
· Blood in the urine
· Less frequent anorexia, vomiting, and malaise
· It can be associated with a WAGR complex. This complex includes Wilms' Tumor, aniridia, genitourinary malformation, and mental motor retardation.
Renal Cell Carcinoma
Renal cell carcinoma, also known by the eponym Grawitz tumor, is the most common form of kidney cancer arising from the renal tubule. It is the most common type of kidney cancer in adults. Initial therapy is with surgery. It is notoriously resistant to radiation therapy and chemotherapy, although some cases respond to immunotherapy.
Signs and symptoms
The classic triad is hematuria (blood in the urine), flank pain and an abdominal mass. This "classic triad" is infrequently present when the patient first presents for medical attention.
The characteristic appearance of renal cell carcinoma (RCC) is a solid renal lesion, which disturbs the renal contour. It will frequently have an irregular or lobulated margin. 85% of solid renal masses will be RCC. 10% of RCC will contain calcifications, and some contain macroscopic fat (likely due to invasion and encasement of the perirenal fat). Following intravenous contrast administration (computed tomography or magnetic resonance imaging), enhancement will be noted, and will increase the conspicuity of the tumor relative to normal renal parenchyma.
· If it is only in the kidneys, which is about 40% of cases, it can be cured roughly 90% of the time with surgery. If it has spread outside of the kidneys, often into the lymph nodes or the main vein of the kidney, then it must be treated with chemotherapy and other treatments.
· Surgical removal of all or part of the kidney (nephrectomy) is recommended. This may include removal of the adrenal gland, retroperitoneal lymph nodes, and possibly tissues involved by direct extension (invasion) of the tumor into the surrounding tissues.
· Percutaneous, image-guided therapies, usually managed by radiologists, are being offered to patients with localized tumor, but who are not good candidates for a surgical procedure. This sort of procedure involves placing a probe through the skin and into the tumor using real-time imaging of both the probe tip and the tumor by computed tomography, ultrasound, or even magnetic resonance imaging guidance, and then destroying the tumor with heat (radiofrequency ablation) or cold (cryotherapy).
· Radiation therapy is not commonly used for treatment of renal cell carcinoma because it is usually not successful. Radiation therapy may be used to palliate the symptoms of skeletal metastases.
· Medications such as alpha-interferon and interleukin-2 (IL-2) have been successful in reducing the growth of some renal cell carcinomas, including some with metastasis. IL-2 (Proleukin®) is presently the only therapy FDA-approved for the treatment of metastatic renal cell carcinoma (kidney cancer).
Urine and its Formation
Urine is liquid waste excreted by the kidneys and is produced by the process of filtration. This waste is eventually expelled from the body in a process known as urination. Most commonly the excretion of urine serves for flushing waste molecules collected from the blood by the kidneys, and for the homeostasis of the body liquids.
Urine is a transparent solution that is clear to amber in color, and usually is light yellow. It is the byproduct or waste fluid secreted by the kidneys, transported by the ureters to the urinary bladder where it is stored until it is voided through the urethra. Urine is made up of a watery solution of metabolic wastes (such as urea), dissolved salts and organic materials. Fluid and materials being filtered by the kidneys, destined to become urine, comes from the blood or interstitial fluid. The composition of urine is adjusted in the process of reabsorption when essential molecules needed by the body, such as glucose, are reabsorbed back into the blood stream via carrier molecules. The remaining fluid contains high concentrations of urea and other excess or potentially toxic substances that will be released from the body via urination. Urine flows through these structures: the kidney, ureter, bladder, and finally the urethra. Urine is produced by a process of filtration, reabsorption, and tubular secretion.
Urine contains large amounts of urea, an excellent source of nitrogen for plants. As such it is a useful accelerator for compost. Urea is 10,000 times less toxic than ammonia and is a byproduct of deamination (2 NH3 molecules) and cellular respiration's (1 CO2 molecule) products combining together. Other components include various inorganic salts such as sodium chloride (the discharge of sodium through urine is known as "natriuresis".)
Urination is the primary method for excreting chemicals and drugs from the body. These chemicals can be detected and analyzed by urinalysis.
In cases of kidney or urinary tract infection (UTI) the urine will contain bacteria, but otherwise urine is virtually sterile and nearly odorless when it leaves the body. However, after that, bacteria that contaminate the urine will convert chemicals in the urine into smelling chemicals that are responsible for the distinctive odor of stale urine; in particular, ammonia is produced from urea.
Urine therapy-Urine therapy is a specialized branch of alternative medicine. Any sort of oral or external application of human urine for medicinal purposes falls into this category. Promoters of urine therapy believe urine to have many curative powers. Some cultures, especially Indian, have traditionally used urine as a medicine.
Urolagnia (also known as urophilia) is a paraphilia involving sexual attraction to urine. People with urolagnia often like to urinate in public, or urinate on, or be urinated on by other people, and may drink the urine. The consumption of urine is urophagia. Some like to watch others doing these things. These activities are often described by the euphemisms "golden showers" or "watersports" (which should not be confused with water sports). Urolagnia is sometimes associated with, or confused with, a sexual attraction to someone experiencing the discomfort or pain of a full bladder, a sadomasochistic inclination.
Drinking urine-A healthy individual's urine is sterile. However, if an individual has a bacterial infection of the urethra, there can be some transmittance of the infection to a person who drinks the urine. It has been suggested that when a person is in desert survival or surrounded by water and devoid of drinking water that the person must resort to drinking his own urine if it is the only liquid available. This technique has been said to extend life from one to two extra days but evidence remains sparse.
Contrary to that notion is that drinking urine may actually increase the speed of dehydration because of certain bodily toxins and salinity in the urine.
The ureters are the ducts that carry urine from the kidneys to the urinary bladder. The ureters are muscular tubes that can propel urine along by the motions of peristalsis. In the adult, the ureters are usually 25 to 35cm long.
The ureters enter the bladder posteriorly, running within the wall of the bladder for a few centimeters. There are no valves in the ureters, backflow being prevented by pressure from the filling of the bladder, as well as the tone of the muscle in the bladder wall.
The ureter has a diameter of about 3 millimeters, and the lumen is star-shaped. Like the bladder, it is lined with transitional epithelium, and contains layers of smooth muscle.
The epithelial cells of the ureter are stratified (in many layers), are normally round in shape but become squamous (flat) when stretched. The lamina propria is thick and elastic (as it is important that it is impermeable).
There are two spiral layers of smooth muscle in the ureter wall, an inner loose spiral, and an outer tight spiral. The inner loose spiral is sometimes described as longitudinal, and the outer as circular, (this is opposite to the situation in the gastrointestinal tract).
The adventitia of the ureter, like elsewhere is composed of fibrous connective tissue, that binds it to adjacent tissues.
Diseases and disorders
Medical problems that can affect the ureter include:
· Cancer of the ureter
· Passage of kidney stones
Megaureter is a descriptive term aptly applied to the ureter that is dilated out of proportion to the rest of the urinary tract. The term implies a congenital disorder, and since the neonatal ureter contains a large amount of elastic fibers, it can become enormously wide. Congenital ureteral dilatation may be caused by vesicoureteral reflux, obstructive disease, high urine flow from non?concentrating kidneys, and maldevelopment of ureteral musculature.
A ureterocele is a congenital abnormality found in the urinary bladder. In this condition called ureteroceles, the distal ureter balloons at its opening into the bladder, forming a sac-like pouch. It is most often associated with a double collector system, where two ureters drain their respective kidney instead of one. Ureteroceles strikes only one in 4,000 individuals, atleast four fifths of whom are female. Since the advent of the ultrasound, most ureteroceles is diagnosed prenatally. The pediatric and adult conditions are often found only through diagnostic imaging performed for reasons other than suspicious ureteroceles.
Kidney stones, also known as nephrolithiases, urolithiases or renal calculi, are solid accretions (crystals) of dissolved minerals in urine found inside the kidneys or ureters. They vary in size from as small as a grain of sand to as large as a golf ball. Kidney stones typically leave the body in the urine stream; if they grow relatively large before passing (on the order of millimeters), obstruction of a ureter and distention with urine can cause severe pain most commonly felt in the flank, lower abdomen and groin.
Conventional wisdom has held that consumption of too much calcium can aggravate the development of kidney stones, since the most common type of stone is calcium oxalate. However, strong evidence has accumulated demonstrating that low-calcium diets are associated with higher stone risk and vice-versa for the typical stone former.
Other examples of kidney stones include struvite (magnesium, ammonium and phosphate), uric acid, calcium phosphate, or cystine (the amino acid found only in people suffering from cystinuria). The formation of struvite stones is associated with the presence of urease splitting bacteria (Klebsiella, Serratia, Proteus, Providencia species) which can split urea into ammonia, most commonly Proteus mirabilis.
Types of Stones:
· Calcium - most common type
· Struvite - infection stone
· Uric acid stone
· Cystine stone
Kidney stones are usually idiopathic and asymptomatic until they obstruct the flow of urine. Symptoms can include acute flank pain (renal colic), nausea and vomiting, restlessness, dull pain, hematuria, and possibly fever if infection is present. Acute renal colic is described as one of the worst types of pain that a patient can suffer from.
Diagnosis & Investigation
Diagnosis is usually made on the basis of the location and severity of the pain, which is typically colic in nature (comes and goes in spasmodic waves). Radiological imaging is used to confirm the diagnosis and a number of other tests can be undertaken to help establish both the possible cause and consequences of the stone.
The relatively dense calcium renders these stones radio-opaque and they can be detected by a traditional X-ray of the abdomen that includes Kidneys, Ureters and Bladder—KUB. This may be followed by an IVP (Intravenous Pyelogram) which requires roughly about 50ml of a special dye to be injected into the bloodstream that goes straight to the kidneys and helps outline any stone on a repeated X-ray. Computed tomography, a specialized X-ray, is by far the most accurate diagnostic test for the detection of kidney stones.
Investigations typically carried out include:
· Culture of a urine sample to exclude urine infection (either as a differential cause of the patient's pain, or secondary to the presence of a stone)
· Blood tests: Full blood count for the presence of a raised white cell count, (Neutrophilia) suggestive of infection, a check of renal function and if raised blood calcium blood levels (hypercalcemia).
· 24 hour urine collection to measure total daily urinary calcium, oxalate and phosphate.
Stones less than 5 mm in size usually will pass spontaneously, with diclofenac usually proving effective pain management. However the majority of stones greater than 6 mm will require some form of intervention, especially so if the stone is stuck causing obstruction and infection of the urinary tract.
In many cases non-invasive Extracorporeal Shock Wave Lithotripsy may be used. Otherwise some form of invasive procedure is required; with approaches including retrograde ureteral, percutaneous nephrolithotomy or open surgery, and using laser, ultrasonic and mechanical (pneumatic, shock-wave) forms of energy to fragment stones.
· Preventive strategies include dietary modifications and sometimes also taking drugs with the goal of reducing excretory load on the kidneys.
· Drinking enough water to make 2 to 2.5 liters of urine per day.
· A diet low in protein, nitrogen and sodium intake.
· Restriction of oxalate-rich foods and maintaining an adequate intake of dietary calcium is recommended. There is no convincing evidence that calcium supplements increase the risk of stone formation.
· Taking drugs such as thiazides, potassium citrate and allopurinol depending on the cause of stone formation.
Extracorporeal Shock Wave Lithotripsy (ESWL)
A lithotriptor is a medical device used in the non-invasive treatment of kidney stones (urinary calculosis) and biliary calculi (stones in the gallbladder or in the liver). The scientific name of this procedure is Extracorporeal Shock Wave Lithotripsy (ESWL). Lithotripsy was developed in the early 1980s.
Lithotripsy attempts to break up the stones with minimal collateral damage by using an externally applied, focused high-intensity acoustic pulse. The sedated or anesthestized patient lies down in the apparatus' bed, with his back supported by a water-filled coupling device placed at the level of kidneys, for instance. A fluoroscopic x-ray imaging system or an ultrasound imaging system is used to locate the stone and aim the treatment head such that the F1 of the shock wave is focused upon the offending stone. The treatment usually starts at the equipment's lowest power level, with a long gap between pulses, in order to accustom the patient to the sensation. The frequency of pulses & power level will then be gradually increased, in order to break up the stone more effectively. The successive shock wave pressure pulses result in direct shearing forces, as well as cavitation bubbles surrounding the stone, which fragment the stones in smaller pieces, which then can pass easily through the ureters or the cystic duct. Extracorporeal lithotripsy works best with stones between 4 mm and 2 cm in diameter that are still located in the kidney. It can be used to break up stones, which are located in a ureter, too, but with less success.
ESWL is the least invasive of the commonplace modalities for definitive stone treatment, but provides a lower stone-free rate than other more invasive treatment methods, such as ureteroscopic manipulation with laser lithotripsy or percutaneous nephrolithotomy (PCNL).
ESWL is not without risks. The shock waves themselves, as well as cavitation bubbles formed by the agitation of the urine medium can lead to capillary damage, renal parenchymal or subcapsular hemorrhage. This can lead to long-term consequences such as renal failure and hypertension. Overall complication rates of ESWL range from 5-20%.
Percutaneous nephrolithotomy is a technique that may be used to remove stones from the kidney or upper ureter. It avoids the morbidity of an open procedure.
A needle is passed through the skin into the renal pelvis under ultrasound or radiological guidance. A guide-wire is then threaded through the needle into the kidney to create a track. Using graduated dilators, the track is then enlarged to a diameter of approximately 30 mm. The stone may then be removed immediately or following drainage for 48 hours with a nephrostomy tube.
Small stones can be removed through the nephrostomy track under direct vision using special nephroscope and a variety of grasping instruments. Stones larger than the tract must be fragmented prior to removal, either with ultrasound or electrohydraulic probes.
Urinary Bladder and Pathology
The urinary bladder is the organ that collects urine excreted by the kidneys prior to disposal by urination. Urine enters the bladder via the ureters and exits via the urethra.
The urinary bladder is a hollow, muscular and distensible organ that sits on the pelvic floor (superior to the prostate in males). On its anterior border lies the pubic symphysis and, on it’s posterior border, the vagina (in females) and rectum (in males). The urinary bladder is normally capable of storing 1.1-1.3 liters of urine, but because it is made up of transitional epithelium it is able to stretch to volumes of even several liters.
The ureters enter the bladder diagonally from its dorsolateral floor in an area called the trigone. The trigone is a triangular shaped area on the posteroinferior wall of the bladder. The urethra exits at the lowest point of the triangle of the trigone
The detrusor muscle is a layer of the urinary bladder wall, made up of smooth muscle fibers arranged in inner and outer longitudinal layers and a middle circular layer. Contraction of the detrusor muscle causes the bladder to expel urine through the urethra. Problems with this muscle can lead to incontinence.
Diseases of the bladder
· Bladder sphincter dyssynergia, a condition where the sufferer cannot coordinate relaxation of the urethra sphincter with the contraction of the bladder muscles
· Cystitis-Cystitis is the inflammation of the bladder. The condition primarily affects women, but can affect all age groups from either sex. There are several types of cystitis:
Bacterial cystitis (most common)
Interstitial cystitis, which is rare, difficult to diagnose, and does not involve foreign organisms
The main cause of bacterial cystitis (or urinary tract infection) is coliform bacteria. These bacteria commonly occupy the bowel, and may become transferred to the urethra, then the bladder, and cause cystitis. An antibiotic is the initial treatment for bacterial cystitis and drinking lots of water.
· Cancer of the urinary bladder: bladder cancer
· Hematuria-is the presence of blood in the urine. It is a sign of a large number of diseases of the kidneys and the urinary tract, ranging from trivial to lethal. Occasionally "hemoglobinuria" is used synonymously, although more precisely it only refers to hemoglobin in the urine. Red discoloration of the urine can have various causes:
· Microscopic hematuria (small amounts of blood, can only be seen on urinalysis or light microscopy)
· Macroscopic (or "frank" or "gross") hematuria
· Hemoglobin (only the red pigment, not the red blood cells)
· Other pigments (e.g. porphyrins in porphyria)
· Interstitial cystitis-Interstitial cystitis (commonly abbreviated to "IC") is a urinary bladder disease of unknown cause characterized by pelvic and intense bladder pain, urinary frequency (as often as every 10 minutes), pain with sexual intercourse, and often pain with urination. It is not unusual for patients to experience nocturia and pain with sexual intercourse. IC is also known as painful bladder syndrome (PBS), particularly outside of the USA.
· Urinary bladder dysfunction
· Urinary incontinence
Urinary incontinence is the involuntary excretion of urine from one's body. It is often temporary, and it almost always results from an underlying medical condition. Women experience incontinence twice as often as men. Pregnancy and childbirth, menopause, and the structure of the female urinary tract account for this difference. But both women and men can become incontinent from neurologic injury, birth defects, strokes, multiple sclerosis, and physical problems associated with aging. While urinary incontinence affects older women more often than younger women. Incontinence is treatable and often curable at all ages.
Types of incontinence
Stress incontinence is incontinence that is caused by actions such as coughing, laughing, sneezing, exercising or other movements that increase intraabdominal pressure and thus increase pressure on the bladder. Physical changes resulting from pregnancy, childbirth, and menopause often cause stress incontinence. It is the most common form of incontinence in women and is treatable.
Urge incontinence is involuntary loss of urine occurring for no apparent reason while suddenly feeling the need or urge to urinate. The most common cause of urge incontinence is inappropriate bladder contractions. Medical professionals describe such a bladder as "unstable," "spastic," or "overactive." It may also be called "reflex incontinence" if it results from overactive nerves controlling the bladder. Involuntary actions of bladder muscles can occur because of damage to the nerves of the bladder, to the nervous system (spinal cord and brain), or to the muscles themselves. Multiple sclerosis, Parkinson's disease, Alzheimer's disease, stroke, and injury--including injury that occurs during surgery--all can harm bladder nerves or muscles.
People with functional incontinence may have problems thinking, moving, or communicating that prevent them from reaching a toilet.
Overflow incontinence occurs when the patient's bladder is always full so that it frequently leaks urine. Weak bladder muscles or a blocked urethra can cause this type of incontinence.
Other types of incontinence
Stress and urge incontinence often occur together in women. Combinations of incontinence - and this combination in particular - are sometimes referred to as "mixed incontinence."
"Transient incontinence" is a temporary version of incontinence. It can be triggered by medications, urinary tract infections, mental impairment, restricted mobility, and stool impaction (severe constipation), which can push against the urinary tract and obstruct outflow.
Diagnosis of incontinence
A careful history taking is essential especially in the pattern of voiding and urine leakage as it suggests the type of incontinence faced. Other important points include straining and discomfort, use of drugs, recent surgery, and illness. The test often performed is the measurement of bladder capacity and residual urine for evidence of poorly functioning bladder muscles.
Other tests include:
Stress test - the patient relaxes, then coughs vigorously as the doctor watches for loss of urine.
Urinalysis - urine is tested for evidence of infection, urinary stones, or other contributing causes.
Blood tests - blood is taken, sent to a laboratory, and examined for substances related to causes of incontinence.
Ultrasound - sound waves are used to "see" the kidneys, ureters, bladder, and urethra.
Cystoscopy - a thin tube with a tiny camera is inserted in the urethra and used to see the inside of the urethra and bladder.
Urodynamics - various techniques measure pressure in the bladder and the flow of urine.
Treatment of incontinence
Kegel’s exercises to strengthen or retrain pelvic floor muscles and sphincter muscles can reduce or cure stress leakage.
Brief doses of electrical stimulation can strengthen muscles in the lower pelvis in a way similar to exercising the muscles. Electrodes are temporarily placed in the vagina or rectum to stimulate nearby muscles. This will stabilize overactive muscles and stimulate contraction of urethral muscles. Electrical stimulation can be used to reduce both stress incontinence and urge incontinence.
Biofeedback uses measuring devices to help you become aware of your body's functioning. By using electronic devices or diaries to track when your bladder and urethral muscles contract, you can gain control over these muscles.
Timed voiding or bladder training
Timed voiding (urinating) and bladder training are techniques that use biofeedback. In timed voiding, you fill in a chart of voiding and leaking. From the patterns that appear in your chart, you can plan to empty your bladder before you would otherwise leak.
Medications can reduce many types of leakage. Some drugs inhibit contractions of an overactive bladder. Others relax muscles, leading to more complete bladder emptying during urination. Some drugs tighten muscles at the bladder neck and urethra, preventing leakage. And some, especially hormones such as estrogen, are believed to cause muscles involved in urination to function normally.
A pessary is a medical device that is inserted into the vagina. The most common kind is ring shaped, and is typically recommended to correct vaginal prolapse. The pessary compresses the urethra against the symphysis pubis and elevates the bladder neck. For some women this may reduce stress leakage.
Implants are substances injected into tissues around the urethra. The implant adds bulk and helps to close the urethra to reduce stress incontinence.
Doctors usually suggest surgery to alleviate incontinence only after other treatments have been tried. Many surgical options have high rates of success.
Most stress incontinence results from the bladder dropping down toward the vagina. Therefore, common surgery for stress incontinence involves pulling the bladder up to a more normal position. Working through an incision in the vagina or abdomen, the surgeon raises the bladder and secures it with a string attached to muscle, ligament, or bone.
If you are incontinent because your bladder never empties completely (overflow incontinence) or your bladder cannot empty because of poor muscle tone, past surgery, or spinal cord injury, you might use a catheter to empty your bladder. A catheter is a tube that you can learn to insert through the urethra into the bladder to drain urine. Catheters may be used once in a while or on a constant basis, in which case the tube connects to a bag that you can attach to your leg.
Bladder cancer refers to any of several types of malignant growths of the urinary bladder. It is a disease in which abnormal cells multiply without control in the bladder. The bladder is a hollow, muscular organ that stores urine; it is located in the lower abdomen. The most common type of bladder cancer begins in cells lining the inside of the bladder (epithelial cells) and is called transitional cell carcinoma (TCC).
The greatest risk factor for bladder cancer is a genetic predisposition; it is also associated with smoking and occupational exposure to aniline-based dyes (such as in textile factories), as well as with petrol and other chemicals.
Signs and symptoms-Bladder cancer may cause blood in the urine, pain during urination, frequent urination, or feeling the need to urinate without results.
The treatment of bladder cancer depends on how deep the tumor invades into the bladder wall. Superficial tumors (those not entering the muscle layer) can be "shaved off" using an electrocautery device. Tumors which infiltrate the bladder require more radical surgery where part or all of the bladder is removed and the urinary stream is diverted. Radiation can also be used to treat this disease.
Immunotherapy in the form of BCG instillation is also used to treat and prevent the recurrence of superficial tumors.
The FGFR3, HRAS, RB1 and TP53 genes are associated with bladder cancer. As with most cancers, the exact causes of bladder cancer are not known; however, many risk factors are associated with this disease. Chief among them are smoking and exposure to industrial chemicals.
Urethra and Urinary tract Infections
The flow of urine from the urinary bladder is controlled by a group of muscles collectively called the urethral sphincter, named for their proximity to the urethra. Both sexes have at least two areas of muscle: the internal sphincter, or bladder neck; and the external, or distal, sphincter.
In males the internal and external urethral sphincters are more powerful, able to retain urine for twice as long as females, and are furthermore backed up by the tertiary rings of urethral sphincters along the length of the penis.
Both sexes can use the levator ani, the voluntary muscle of the pelvic floor, to control urination. In females this muscle is more important because of the weakness of the urethral sphincters. Kegel exercises are a form of exercise intended to strengthen the pelvic floor muscles.
Urinary incontinence is the inability to control urination, and is more common in women than men.
The urethra is a tube, which connects the urinary bladder to the outside of the body. The urethra has an excretory function in both sexes, to pass urine to the outside, and also a reproductive function in the male, as a passage for sperm.
The external urethral sphincter is a smooth muscle that allows voluntary control over urination.
Men have a longer urethra than women. This means that women tend to be more susceptible to infections of the bladder (cystitis) and the urinary tract. The length of a male's urethra, and the fact it contains a number of bends makes catheterization more difficult.
In the human female, the urethra is about 1-1.5 inches (2.5-4 cm) long and opens in the vulva between the clitoris and the vaginal opening. In the human male, the urethra is about 8 inches (20 cm) long and opens at the end of the penis.
The urethra is divided into three parts in men, named after the location:
· The prostatic urethra crosses through the prostate gland. There is a small opening where the vas deferens enters.
· The membranous urethra is a small (1 or 2 cm) portion passing through the external urethral sphincter. This is the narrowest part of the urethra.
· The spongy (or penile) urethra runs along the length of the penis on its ventral (underneath) surface. It is about 15-16 cm in length, and travels through the corpus spongiosum.
The epithelium of the urethra starts off as transitional cells as it exits the bladder. Further along the urethra there are stratified columnar cells, then stratified squamous cells near the external meatus (exit hole). There are small mucus secreting urethral glands.
Medical problems of the urethra
· Hypospadias and epispadias are forms of abnormal development of the urethra in the male, where the opening is not quite where it should be (it occurs lower than normal with hypospadias, and higher with epispadias). A chordee is when the urethra develops between the penis and the scrotum.
· Infection of the urethra is urethritis, said to be more common in females than males. Urethritis is a common cause of dysuria (pain when urinating).
· Related to urethritis is so called urethral syndrome.
· Passage of kidney stones through the urethra can be painful and subsequently it can lead to urethral strictures
· Endoscopy of the bladder via the urethra is called cystoscopy.
· Urethral Stricture-A urethral stricture is internal damage to the urethra caused by injury or disease such as urinary tract infections or other forms of urethritis.
The Gräfenberg spot' or G-spot is named after German gynecologist Ernst Gräfenberg. It is a small area in the genital area of women behind the pubic bone and surrounding the urethra. It is the same as, or part of, the urethral sponge, the site of Skene's glands.
Stimulation of the G-spot (through the front wall of the vagina) is said to promote a more vigorous and satisfying orgasm, and is possibly the cause of female ejaculation from the Skene's glands, contained in the urethral sponge. Such stimulation requires a somewhat opposite thrust to that required to obtain maximal clitoral stimulation via the penis, called "riding high". The stimulation of the G-spot is thought to be more intense for women beyond their thirties, because of changes in tissue structure inside the vagina allowing easier access to the G-spot. Some women believe their thirties are their sexual peak because of this reason.
Sounding or urethral sounding is a medical activity using probes called sounds to increase the inner diameter of the urethra and to locate obstructions in the urethra. Sounds are usually made of stainless steel and come in two main types: the Van Buren (named after its inventor, William Holme Van Buren), which has a J-shaped curve at one end, and the Dittle, which is straight. The curved variety may inhibit the ability to gain an erection. A urethral sound may be connected to a special electrical device for use in erotic electrostimulation.
The use of urethral sounding in this way can potentially be damaging to the urethra. The dangers include tearing or cutting of the urethra and the possibility of urinary tract infection.
Urinary Tract Infection
A urinary tract infection (UTI) is an infection of the urinary tract. An infection anywhere from the kidneys to the ureters to the bladder to the urethra qualifies as a urinary tract infection.
Symptoms & Signs
· Urethritis: discomfort or pain at the urethral meatus or a burning sensation throughout the urethra with micturition (dysuria).
· Cystitis: pain in the midline suprapubic region and/or frequent urination
· Hematuria (bloody urine)
· Cloudy and foul-smelling urine
Common organisms that cause UTIs include Escherichia coli and Staphylococcus saprophyticus. Less common organisms include Proteus mirabilis, Klebsiella pneumoniae, and Enterococcus spp.
UTIs are most common in sexually active women, and increased in diabetics and people with sickle-cell disease or anatomical malformations of the urinary tract.
Most uncomplicated UTIs can be treated with oral antibiotics such as trimethoprim, cephalosporins, Macrodantin, or a fluoroquinolone (e.g. ciprofloxacin, levofloxacin). Patients with recurrent UTIs may need further investigation. This may include ultrasound scans of the kidneys and bladder or intravenous urography (X-rays of the urological system following intravenous injection of iodinated contrast material).
Some Common pathological conditions of Digestive System:
Laboratory tests, clinical procedures and abbreviations
Some important Abbreviations
ADH Antidiuretic hormone, called also vasopressin.
ARF Acute renal failure.
BUN Blood urea nitrogen.
CAPD Continuous ambulatory peritoneal dialysis.
CRF Case report form.
cysto Cystoscopic exam.
ESRD End stage renal disease.
ESWL Extracorporeal shock wave lithotripsy.
IVP Intravenous pyelogram.
KUB Kidneys, ureters, and bladder.
pH Hydrogen-ion concentration - acid / alkaline
UTI Urinary tract infection.
VCUG Voiding cystourethrogram.
CORTEX: the outermost or superficial layer of an organ
CREATININE: Creatinine is a breakdown product of creatine phosphate in muscle, and is usually produced at a fairly constant rate by the body (depending on muscle mass).
GLOMERULUS: A glomerulus is a capillary tuft surrounded by Bowman's capsule in nephrons of the vertebrate kidney. It receives its blood supply from an afferent arteriole of the renal circulation, and empties into an efferent arteriole. The resistance of the arterioles results in high pressure in the glomerulus aiding the process of ultrafiltration where fluids and soluble materials in the blood are forced out of the capillaries and into Bowman's capsule.
HILUM: A hilum (formerly called a hilus) is a depression or pit at the part of an organ where structures such as blood vessels and nerves enter.
MEATUS: In anatomy, a meatus is a natural body opening or canal
MEDULLA: Medulla in general means the inner part, and derives from the Latin word for 'marrow'. In medicine it is contrasted to the cortex
RENAL ARTERY: The renal arteries normally arise off the abdominal aorta and supply the kidneys with blood. The arterial supply of the kidneys is variable and there may be one or more renal arteries supplying each kidney
RENIN: Renin, also known as angiotensinogenase, is a circulating enzyme released mainly by juxtaglomerular cells in the JGA of the kidneys in response to low blood volume or low body NaCl content, mediated through the rapid release of prostaglandins. Although it has hormone-like actions, it cleaves a protein precursor in the circulation rather than working on a cellular target.
UREA: Urea is also known as carbamide, especially in the recommended International Non-proprietary Names (rINN) in use in Europe
URETER: In human anatomy, the ureters are the ducts that carry urine from the kidneys to the urinary bladder. The ureters are muscular tubes that can propel urine along by the motions of peristalsis. In the adult, the ureters are usually 25 to 35cm long.
URETHRA: In anatomy, the urethra is a tube which connects the urinary bladder to the outside of the body. The urethra has an excretory function in both sexes to pass urine to the outside, and also a reproductive function in the male, as a passage for sperm.
URIC ACID: Purine precursors include xanthine and hypoxanthine, which are converted to uric acid by xanthine oxidase. In humans and higher primates, uric acid is the final oxidation product of purine metabolism. In most other mammals, uric acid is further oxidized to allantoin by the enzyme uricase
ADNEXA: In anatomy, adnexa refers to the appendages of an organ.
AMNION: The amnion is a membranous sac which surrounds and protects the embryo. It is developed in reptiles, birds, and mammals, which are hence called “Amniota”; but not in amphibia and fish, which are consequently termed “Anamnia”.
AREOLA: is used to describe any small circular area such as the colored skin surrounding the nipple. While it is most commonly used to describe the pigmented ring around the human nipple, it can also be used to describe other small circular areas such as the inflamed area surrounding a pimple.
Blood urea nitrogen
The blood urea nitrogen (BUN) test is a measure of the amount of nitrogen in the blood that comes from urea. Urea is a substance secreted by the liver, and removed from the blood by the kidneys.
An intravenous pyelogram (also known as IVP, pyelography, intravenous urogram or IVU) is a radiological procedure used to visualise disturbances of the urinary system, including the kidneys, ureters, and bladder. Among other uses, IVP can detect kidney stones.
Angiography or arteriography is a medical imaging technique in which an X-ray picture is taken to visualize the inner opening of blood filled structures, including arteries, veins and the heart chambers. Its name comes from the Greek words angeion, "vessel", and graphien, "to write or record". The X-ray film or image of the blood vessels is called an angiograph, or more commonly, an angiogram.
Retrograde Pyelogram is a urologic procedure where the physician injects contrast into the ureter in order to visualize the ureter and kidney. The flow of contrast (up from the bladder to the kidney) is opposite the usual flow of urine, hence the retrograde name.
In urology, a voiding cystourethrogram, also VCUG, is a test used to visualize the urethra and urinary bladder that takes place during micturition (voiding).