Ureteral Diverticulum
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The ureters are tubes composed of
smooth muscle Smooth muscle is one of the three major types of vertebrate muscle tissue, the others being skeletal and cardiac muscle. It can also be found in invertebrates and is controlled by the autonomic nervous system. It is non- striated, so-called bec ...
that transport
urine Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...
from the
kidney In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...
s to the urinary
bladder The bladder () is a hollow organ in humans and other vertebrates that stores urine from the kidneys. In placental mammals, urine enters the bladder via the ureters and exits via the urethra during urination. In humans, the bladder is a distens ...
. In an adult human, the ureters typically measure 20 to 30 centimeters in length and about 3 to 4 millimeters in diameter. They are lined with urothelial cells, a form of transitional
epithelium Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial ( mesothelial) tissues line the outer surfaces of man ...
, and feature an extra layer of smooth muscle in the lower third to aid in
peristalsis Peristalsis ( , ) is a type of intestinal motility, characterized by symmetry in biology#Radial symmetry, radially symmetrical contraction and relaxation of muscles that propagate in a wave down a tube, in an wikt:anterograde, anterograde dir ...
. The ureters can be affected by a number of diseases, including
urinary tract infections A urinary tract infection (UTI) is an infection that affects a part of the urinary tract. Lower urinary tract infections may involve the bladder (cystitis) or urethra ( urethritis) while upper urinary tract infections affect the kidney (pye ...
and
kidney stone Kidney stone disease (known as nephrolithiasis, renal calculus disease, or urolithiasis) is a crystallopathy and occurs when there are too many minerals in the urine and not enough liquid or hydration. This imbalance causes tiny pieces of cr ...
. is when a ureter is narrowed, due to for example chronic inflammation.
Congenital abnormalities A birth defect is an abnormal condition that is present at birth, regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth de ...
that affect the ureters can include the development of two ureters on the same side or abnormally placed ureters. Additionally, reflux of urine from the bladder back up the ureters is a condition commonly seen in children. The ureters have been identified for at least two thousand years, with the word "ureter" stemming from the stem relating to
urinating Urination is the release of urine from the bladder through the urethra in placental mammals, or through the cloaca in other vertebrates. It is the urinary system's form of excretion. It is also known medically as micturition, voiding, uresi ...
and seen in written records since at least the time of
Hippocrates Hippocrates of Kos (; ; ), also known as Hippocrates II, was a Greek physician and philosopher of the Classical Greece, classical period who is considered one of the most outstanding figures in the history of medicine. He is traditionally referr ...
. It is, however, only since the 1500s that the term "ureter" has been consistently used to refer to the modern structure, and only since the development of
medical imaging Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to revea ...
in the 1900s that techniques such as
X-ray An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...
, CT, and
ultrasound Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...
have been able to view the ureters. The ureters are also seen from the inside using a flexible camera, called
ureteroscopy Ureteroscopy is an examination of the upper urinary tract, usually performed with a ureteroscope that is passed through the urethra and the bladder, and then directly into the ureter. The procedure is useful in the diagnosis and treatment of dis ...
, which was first described in 1964.


Structure

The ureters are tubular structures, approximately in adults, that pass from the
pelvis The pelvis (: pelves or pelvises) is the lower part of an Anatomy, anatomical Trunk (anatomy), trunk, between the human abdomen, abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also c ...
of each kidney into the bladder. From the renal pelvis, they descend on top of the
psoas major The psoas major ( or ; from ) is a long fusiform muscle located in the lateral lumbar region between the vertebral column and the brim of the lesser pelvis. It joins the iliacus muscle to form the iliopsoas. In other animals, this muscle is e ...
muscle to reach the brim of the pelvis. Here, they cross in front of the
common iliac arteries The common iliac artery is a large artery of the abdomen paired on each side. It originates from the aortic bifurcation at the level of the 4th lumbar vertebra. It ends in front of the sacroiliac joint, one on either side, and each bifurcates in ...
. They then pass down along the sides of the pelvis and finally curve forward and enter the bladder from its left and right sides at the back of the bladder. The ureters are in diameter and surrounded by a layer of
smooth muscle Smooth muscle is one of the three major types of vertebrate muscle tissue, the others being skeletal and cardiac muscle. It can also be found in invertebrates and is controlled by the autonomic nervous system. It is non- striated, so-called bec ...
for near their ends just before they enter the bladder. The ureters enter the bladder from its back surface, traveling before opening into the bladder at an angle on its outer back surface at the slit-like ''ureteric orifices''. This location is also called the vesicoureteric junction. In the contracted bladder, they are about apart and about the same distance from the
internal urethral orifice The internal urethral orifice is the opening of the urinary bladder into the urethra. Anatomy It is usually somewhat crescent-shaped. Relations It is formed by the neck of the urinary bladder. It opens at the apex/inferior angle of the tri ...
; in the distended bladder, these measurements may be increased to about . A number of structures pass by, above, and around the ureters on their path down from the kidneys to the bladder. In its upper part, the ureter travels on the
psoas major muscle The psoas major ( or ; from ) is a long fusiform muscle located in the lateral lumbar region between the vertebral column and the brim of the lesser pelvis. It joins the iliacus muscle to form the iliopsoas. In other animals, this muscle is equ ...
and sits just behind the
peritoneum The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesotheli ...
. As it passes down the muscle, it travels over the
genitofemoral nerve The genitofemoral nerve is a mixed branch of the lumbar plexus derived from anterior rami of lumbar nerves L1–L2. It splits into a genital branch and a femoral branch. It provides sensory innervation to the upper anterior thigh, as well as t ...
. The
inferior vena cava The inferior vena cava is a large vein that carries the deoxygenated blood from the lower and middle body into the right atrium of the heart. It is formed by the joining of the right and the left common iliac veins, usually at the level of the ...
and the
abdominal aorta In human anatomy, the abdominal aorta is the largest artery in the abdominal cavity. As part of the aorta, it is a direct continuation of the descending aorta (of the thorax). Structure The abdominal aorta begins at the level of the diaphragm ...
sit to the midline of the right and left ureters, respectively. In the lower part of the abdomen, the right ureter sits behind the lower
mesentery In human anatomy, the mesentery is an Organ (anatomy), organ that attaches the intestines to the posterior abdominal wall, consisting of a double fold of the peritoneum. It helps (among other functions) in storing Adipose tissue, fat and allowi ...
and the
terminal ileum The ileum () is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine ma ...
, and the left ureter sits behind the
jejunum The jejunum is the second part of the small intestine in humans and most higher vertebrates, including mammals, reptiles, and birds. Its lining is specialized for the absorption by enterocytes of small nutrient molecules which have been pr ...
and the
sigmoid colon The sigmoid colon (or pelvic colon) is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about in length. The loop is typically shaped like a Greek letter sigma (ς) or Latin letter S (thus ''s ...
. As the ureters enter the pelvis, they are surrounded by connective tissue, and travel backward and outward, passing in front of the
internal iliac arteries The internal iliac artery (formerly known as the hypogastric artery) is the main artery of the pelvis. Structure The internal iliac artery supplies the walls and viscera of the pelvis, the buttock, the reproductive organs, and the medial compart ...
and
internal iliac veins The internal iliac vein (hypogastric vein) begins near the upper part of the greater sciatic foramen, passes upward behind and slightly medial to the internal iliac artery and, at the brim of the pelvis, joins with the external iliac vein to fo ...
. They then travel inward and forward, crossing the
umbilical Umbilical may refer to: Biology *Umbilical cord * Umbilical fold *Umbilical hernia *Umbilical notch *Umbilical vessels **Umbilical artery **Umbilical vein * Umbilical zone *Umbilical region Other * Umbilical cable, in engineering *The Umbi ...
, inferior vesical, and
middle rectal arteries The middle rectal artery is an artery in the pelvis that supplies blood to the rectum. Structure The middle rectal artery usually arises from the internal iliac artery. It is distributed to the rectum above the pectinate line. It anastomoses wit ...
. From here, in males, they cross under the vas deferens and in front of the
seminal vesicles The seminal vesicles (also called vesicular glands or seminal glands) are a pair of convoluted tubular accessory glands that lie behind the urinary bladder of male mammals. They secrete fluid that largely composes the semen. The vesicles are 5 ...
to enter the bladder near the trigone. In females, the ureters pass behind the
ovaries The ovary () is a gonad in the female reproductive system that produces ova; when released, an ovum travels through the fallopian tube/oviduct into the uterus. There is an ovary on the left and the right side of the body. The ovaries are endocr ...
and then travel in the lower midline section of the
broad ligament of the uterus The broad ligament of the uterus is the wide fold of peritoneum that connects the sides of the uterus to the walls and floor of the pelvis. Structure Subdivisions Contents The contents of the broad ligament include the following: * Reproduc ...
. For a short part, the
uterine arteries The uterine artery is an artery that supplies blood to the uterus in females. Structure The uterine artery usually arises from the anterior division of the internal iliac artery. It travels to the uterus, crossing the ureter anteriorly, to the ut ...
travel on top for a short () period. They then pass by the
cervix The cervix (: cervices) or cervix uteri is a dynamic fibromuscular sexual organ of the female reproductive system that connects the vagina with the uterine cavity. The human female cervix has been documented anatomically since at least the time ...
, traveling inward towards the bladder.


Blood and lymphatic supply

The arteries which supply the ureter vary along its course. The upper third of the ureter, closest to the kidney, is supplied by the
renal arteries The renal arteries are paired arteries that supply the kidneys with blood. Each is directed across the crus of the diaphragm, so as to form nearly a right angle. The renal arteries carry a large portion of total blood flow to the kidneys. Up to a ...
. The middle part of the ureter is supplied by the
common iliac arteries The common iliac artery is a large artery of the abdomen paired on each side. It originates from the aortic bifurcation at the level of the 4th lumbar vertebra. It ends in front of the sacroiliac joint, one on either side, and each bifurcates in ...
, direct branches from the
abdominal aorta In human anatomy, the abdominal aorta is the largest artery in the abdominal cavity. As part of the aorta, it is a direct continuation of the descending aorta (of the thorax). Structure The abdominal aorta begins at the level of the diaphragm ...
, and gonadal arteries; the gonadal arteries being the
testicular artery The testicular artery (the male gonadal artery, also called the internal spermatic arteries in older texts) is a branch of the abdominal aorta that supplies blood to the testicle. It is a paired artery, with one for each of the testicles. It ...
in men and the
ovarian artery The ovarian artery is an artery that supplies oxygenated blood to the ovary in females. It arises from the abdominal aorta below the renal artery. It can be found within the suspensory ligament of the ovary, anterior to the ovarian vein and urete ...
in women. The lower third of the ureter, closest to the bladder, is supplied by branches from the
internal iliac arteries The internal iliac artery (formerly known as the hypogastric artery) is the main artery of the pelvis. Structure The internal iliac artery supplies the walls and viscera of the pelvis, the buttock, the reproductive organs, and the medial compart ...
, mainly the
superior Superior may refer to: *Superior (hierarchy), something which is higher in a hierarchical structure of any kind Places * Superior (proposed U.S. state), an unsuccessful proposal for the Upper Peninsula of Michigan to form a separate state *Lak ...
and
inferior vesical arteries The inferior vesical artery (or inferior vesical artery) is an artery of the pelvis which arises from the internal iliac artery and supplies parts of the urinary bladder as well as other structures of the urinary system and structures of the male r ...
. The arterial supply can be variable, with arteries that contribute include the
middle rectal artery The middle rectal artery is an artery in the pelvis that supplies blood to the rectum. Structure The middle rectal artery usually arises from the internal iliac artery. It is distributed to the rectum above the pectinate line. It anastomoses wi ...
, branches directly from the aorta, and, in women, the uterine and vaginal arteries. The
arteries An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...
that supply the ureters end in a network of vessels within the
adventitia The adventitia ( ) is the outer layer of fibrous connective tissue surrounding an organ. The outer layer of connective tissue that surrounds an artery, or vein – the tunica externa, is also called the ''tunica adventitia''. To some degree, i ...
of the ureters. There are many connections () between the arteries of the ureter, particularly in the adventitia, which means damage to a single vessel does not compromise the blood supply of the ureter. Venous drainage mostly parallels that of the arterial supply; that is, it begins as a network of smaller veins in the adventitia; with the renal veins draining the upper ureters, and the vesicular and gonadal veins draining the lower ureters. Lymphatic drainage depends on the position of lymphatic vessels in the ureter.
Lymph Lymph () is the fluid that flows through the lymphatic system, a system composed of lymph vessels (channels) and intervening lymph nodes whose function, like the venous system, is to return fluid from the tissues to be recirculated. At the ori ...
collects in submucosal, intramuscular and adventitial
lymphatic vessels The lymphatic vessels (or lymph vessels or lymphatics) are thin-walled vessels (tubes), structured like blood vessels, that carry lymph. As part of the lymphatic system, lymph vessels are complementary to the cardiovascular system. Lymph vessel ...
. Those vessels closer to the kidney drain into renal collecting vessels, and from here into the lateral aortic nodes near the gonadal vessels. The middle part of the ureter drains into the right paracaval and interaortocaval nodes on the right, and the left paraaortic nodes on the left. In the lower ureter, lymph may drain into the
common iliac lymph node The common iliac lymph nodes, four to six in number, are grouped behind and on the sides of the common iliac artery, one or two being placed below the bifurcation of the aorta, in front of the fifth lumbar vertebra. They drain chiefly the hypog ...
s, or lower down in the pelvis to the
common Common may refer to: As an Irish surname, it is anglicised from Irish Gaelic surname Ó Comáin. Places * Common, a townland in County Tyrone, Northern Ireland * Boston Common, a central public park in Boston, Massachusetts * Cambridge Com ...
, external, or
internal iliac lymph nodes The internal iliac lymph nodes (or hypogastric) surround the internal iliac artery and its branches (the ''hypogastric vessels''), and receive the lymphatics corresponding to the distribution of the branches of it, i. e., they receive lymphatics f ...
.


Nerve supply

The ureters are richly supplied by nerves that form a network () of nerves, the
ureteric plexus The ureteric plexus (plexus: "braid") is a branching network of intersecting nerves (nerve plexus) covering and innervating the ureter. The plexus can be graduated into three parts, as the ureter itself can be divided: In the upper part of the uret ...
that lies in the adventitia of the ureters. This plexus is formed from a number of
nerve roots A nerve root () is the initial segment of a nerve leaving the central nervous system. Nerve roots can be classified as: * Cranial nerve roots: the initial or proximal segment of one of the twelve pairs of cranial nerves leaving the central nervous s ...
directly (T9–12, L1, and S2-4), as well as branches from other nerve plexuses and nerves; specifically, the upper third of the ureter receives nerve branches from the
renal plexus The renal plexus is a complex network of nerves formed by filaments from the celiac ganglia and plexus, aorticorenal ganglia, lower thoracic splanchnic nerves and first lumbar splanchnic nerve and aortic plexus. The nerves from these sourc ...
and aortic plexus, the middle part receives branches from the upper hypogastric plexus and
nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons). Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the Electrochemistry, electrochemical nerv ...
, and the lower ureter receives branches from the lower hypogastric plexus and nerve. The plexus is in the adventitia. These nerves travel in individual bundles and along small blood vessels to form the ureteric plexus. Sensation supplied is sparse close to the kidneys and increases closer to the bladder. Sensation to the ureters is provided by nerves that come from T11 – L2 segments of the
spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal c ...
. When pain is caused, for example by spasm of the ureters or by a stone, the pain may be referred to the
dermatome Dermatome may refer to: * Dermatome (anatomy), an area of skin that is supplied by a single pair of dorsal roots * Dermatome (embryology), the portion of the embryonic paraxial mesoderm, the somite, which gives rise to dermis * Dermatome (instrument ...
s of T11 – L2, namely the back and sides of the abdomen, the scrotum (males) or labia majora (females) and upper part of the front of the thigh.


Microanatomy

The ureter is lined by
urothelium Transitional epithelium is a type of stratified epithelium. Transitional epithelium is a type of tissue that changes shape in response to stretching (stretchable epithelium). The transitional epithelium usually appears cuboidal when relaxed and ...
, a type of
transitional epithelium Transitional epithelium is a type of stratified epithelium. Transitional epithelium is a type of tissue that changes shape in response to stretching (stretchable epithelium). The transitional epithelium usually appears cuboidal when relaxed and ...
that is capable of responding to stretches in the ureters. The transitional epithelium may appear as a layer of column-shaped cells when relaxed, and of flatter cells when distended. Below the epithelium sits the
lamina propria The lamina propria is a thin layer of connective tissue that forms part of the moist linings known as mucous membranes or mucosae, which line various tubes in the body, such as the respiratory tract, the gastrointestinal tract, and the urogenital ...
. The lamina propria is made up of loose connective tissue with many elastic fibers interspersed with blood vessels, veins and lymphatics. The ureter is surrounded by two muscular layers, an inner longitudinal layer of muscle, and an outer circular or spiral layer of muscle. The lower third of the ureter has a third muscular layer. Beyond these layers sits an
adventitia The adventitia ( ) is the outer layer of fibrous connective tissue surrounding an organ. The outer layer of connective tissue that surrounds an artery, or vein – the tunica externa, is also called the ''tunica adventitia''. To some degree, i ...
containing blood vessels, lymphatic vessels, and veins.


Development

The ureters develop from the
ureteric bud The ureteric bud, also known as the metanephric diverticulum, is a protrusion from the mesonephric duct during the development of the urinary and reproductive organs. It later develops into a conduit for urine drainage from the kidneys, which, in c ...
s, which are outpouchings from the
mesonephric duct The mesonephric duct, also known as the Wolffian duct, archinephric duct, Leydig's duct or nephric duct, is a paired organ that develops in the early stages of embryonic development in humans and other mammals. It is an important structure that pl ...
. This is a duct, derived from
mesoderm The mesoderm is the middle layer of the three germ layers that develops during gastrulation in the very early development of the embryo of most animals. The outer layer is the ectoderm, and the inner layer is the endoderm.Langman's Medical ...
, found in the early
embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...
. Over time, the buds elongate, moving into surrounding mesodermal tissue, dilate, and divide into left and right ureters. Eventually, successive divisions from these buds form not only the ureters, but also the pelvis, major and minor calyces, and collecting ducts of the kidneys. The mesonephric duct is connected with the
cloaca A cloaca ( ), : cloacae ( or ), or vent, is the rear orifice that serves as the only opening for the digestive (rectum), reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles, birds, cartilagin ...
, which over the course of development splits into a
urogenital sinus The urogenital sinus is a body part of a human or other Placentalia, placental only present in the development of the urinary system, development of the urinary and development of the reproductive organs, reproductive organs. It is the ventral p ...
and the
anorectal canal The anorectal canal is an embryonic structure in placental mammals that develops from the posterior portion of the cloaca, after it is divided by the urorectal septum in the 6th week of embryonic development. The anterior portion becomes the urogeni ...
. The urinary bladder forms from the urogenital sinus. Over time, as the bladder enlarges, it absorbs the surrounding parts of the primitive ureters. Finally, the entry points of the ureters into the bladder move upwards, owing to the upward migration of the kidneys in the developing embryo.


Function

The ureters are a component of the
urinary system The human urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, urinary bladder, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume ...
.
Urine Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...
, produced by the kidneys, travels along the ureters to the bladder. It does this through regular contractions called
peristalsis Peristalsis ( , ) is a type of intestinal motility, characterized by symmetry in biology#Radial symmetry, radially symmetrical contraction and relaxation of muscles that propagate in a wave down a tube, in an wikt:anterograde, anterograde dir ...
. File:Ultrasound_demonstration_of_ureteral_jet_effect_0301105703_1105300.gif,
Ultrasound Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...
showing a jet of urine entering the bladder (large black section) through the ureter


Clinical significance


Ureteral stones

A
kidney stone Kidney stone disease (known as nephrolithiasis, renal calculus disease, or urolithiasis) is a crystallopathy and occurs when there are too many minerals in the urine and not enough liquid or hydration. This imbalance causes tiny pieces of cr ...
can move from the
kidney In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...
and become lodged inside the ureter, which can block the flow of urine, as well as cause a sharp
cramp A cramp is a sudden, involuntary, painful skeletal muscle contraction or overshortening associated with electrical activity. While generally temporary and non-damaging, they can cause significant pain and a paralysis-like immobility of the aff ...
in the back, side, or lower
abdomen The abdomen (colloquially called the gut, belly, tummy, midriff, tucky, or stomach) is the front part of the torso between the thorax (chest) and pelvis in humans and in other vertebrates. The area occupied by the abdomen is called the abdominal ...
. Pain often comes in waves lasting up to two hours, then subsides, called
renal colic Renal colic (literally, kidney pain), also known as ureteric colic (literally, pain in the ureters), is characterized by severe abdominal pain that is spasmodic in nature. This pain is primarily caused by an obstruction of one or both ureters fr ...
. The affected kidney could then develop
hydronephrosis Hydronephrosis is the hydrostatic dilation of the renal pelvis and Renal calyx, calyces as a result of obstruction to urine flow downstream. Alternatively, hydroureter describes the dilation of the ureter, and hydronephroureter describes the dila ...
, should a part of the kidney become
swollen Edema (American English), also spelled oedema (British English), and also known as fluid retention, swelling, dropsy and hydropsy, is the build-up of fluid in the body's tissue. Most commonly, the legs or arms are affected. Symptoms may inclu ...
due to blocked flow of urine. It is classically described that there are three sites in the ureter where a kidney stone will commonly become stuck: where the ureter meets the renal pelvis; where the iliac blood vessels cross the ureters; and where the ureters enter the urinary bladder, however a
retrospective A retrospective (from Latin ', "look back"), generally, is a look back at events that took place, or works that were produced, in the past. As a noun, ''retrospective'' has specific meanings in software development, popular culture, and the arts. ...
case study A case study is an in-depth, detailed examination of a particular case (or cases) within a real-world context. For example, case studies in medicine may focus on an individual patient or ailment; case studies in business might cover a particular f ...
, which is a
primary source In the study of history as an academic discipline, a primary source (also called an original source) is an Artifact (archaeology), artifact, document, diary, manuscript, autobiography, recording, or any other source of information that was cre ...
, of where stones lodged based on
medical imaging Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to revea ...
did not show many stones at the place where the iliac blood vessels cross. Most stones are compounds containing
calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...
such as
calcium oxalate Calcium oxalate (in archaic terminology, oxalate of lime) is a calcium salt of oxalic acid with the chemical formula or . It forms hydrates , where ''n'' varies from 1 to 3. Anhydrous and all hydrated forms are colorless or white. The monohydr ...
and
calcium phosphate The term calcium phosphate refers to a family of materials and minerals containing calcium ions (Ca2+) together with inorganic phosphate anions. Some so-called calcium phosphates contain oxide and hydroxide as well. Calcium phosphates are white ...
. The first recommended investigation is a CT scan of the abdomen because it can detect almost all stones. Management includes
analgesia Pain management is an aspect of medicine and health care involving relief of pain (pain relief, analgesia, pain control) in various dimensions, from acute and simple to chronic and challenging. Most physicians and other health professionals ...
, often with nonsteroidal antiinflammatories. Small stones (< 4mm) may pass themselves; larger stones may require
lithotripsy Lithotripsy is a procedure involving the physical destruction of hardened masses like kidney stones, bezoars or gallstones, which may be done non-invasively. The term is derived from the Greek words meaning "breaking (or pulverizing) stones" ( lit ...
, and those with complications such as hydronephrosis or infection may require surgery to remove.


Reflux

Vesicoureteral reflux Vesicoureteral reflux (VUR), also known as vesicoureteric reflux, is a condition in which urine flows retrograde, or backward, from the urinary bladder, bladder into one or both ureters and then to the renal calyx or kidneys. Urine normally trave ...
refers to the reflux of fluid from the bladder into the ureters. This condition can be associated with
urinary tract infection A urinary tract infection (UTI) is an infection that affects a part of the urinary tract. Lower urinary tract infections may involve the bladder (cystitis) or urethra (urethritis) while upper urinary tract infections affect the kidney (pyel ...
s, particularly in children, and is present in up to 28–36% of children to some degree. A number of forms of medical imaging are available for diagnosis of the condition, with modalities including
doppler The Doppler effect (also Doppler shift) is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave. The ''Doppler effect'' is named after the physicist Christian Doppler, who described ...
urinary tract ultrasound Ultrasound of the urinary tract involves the use of an ultrasound probe to image parts of the urinary tract. The urinary tract is the path that urine follows after it is formed within the kidneys, and involves a left and right ureter, the Urinary ...
.Factors that affect which of these are selected depends if a child is able to receive a
urinary catheter The human urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pr ...
, and whether a child is toilet trained. Whether these investigations are performed at the first time a child has an illness, or later and depending on other factors (such as if the causal bacteria is '' E. coli'') differ between US, EU and UK guidelines. Management is also variable, with differences between international guidelines on issues such as whether
prophylactic antibiotic Antibiotic prophylaxis refers to, for humans, the prevention of infection complications using antimicrobial therapy (most commonly antibiotics). Antibiotic prophylaxis in domestic animal feed mixes has been employed in America since at least 1970. ...
s should be used, and whether surgery is recommended. One reason is most instances of vesicoureteral reflux improve by themselves. If surgery is considered, it generally involves reattaching the ureters to a different spot on the bladder, and extending the part of the ureter that it is within the wall of the bladder, with the most common surgical option being Cohen's cross-trigonal reimplantation.


Anatomical and surgical abnormalities

Blockage, or obstruction of the ureter can occur, as a result of narrowing within the ureter, or compression or fibrosis of structures around the ureter. Narrowing can result of ureteric stones, masses associated with cancer, and other lesions such as
endometriosis Endometriosis is a disease in which Tissue (biology), tissue similar to the endometrium, the lining of the uterus, grows in other places in the body, outside the uterus. It occurs in women and a limited number of other female mammals. Endomet ...
tuberculosis Tuberculosis (TB), also known colloquially as the "white death", or historically as consumption, is a contagious disease usually caused by ''Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can al ...
and
schistosomiasis Schistosomiasis, also known as snail fever, bilharzia, and Katayama fever is a neglected tropical helminthiasis, disease caused by parasitism, parasitic Schistosoma, flatworms called schistosomes. It affects both humans and animals. It affects ...
. Things outside the ureters such as
constipation Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The Human feces, stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the ...
and
retroperitoneal fibrosis Retroperitoneal fibrosis or Ormond's disease is a disease featuring the proliferation of fibrous tissue (fibrosis) in the retroperitoneum, the compartment of the body containing the kidneys, aorta, renal tract, and various other structures. It m ...
can also compress them. Some
congenital abnormalities A birth defect is an abnormal condition that is present at birth, regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth de ...
can also result in narrowing or the ureters. Congenital disorders of the ureter and
urinary tract The human urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressu ...
affect 10% of infants. These include partial or total duplication of the ureter (a duplex ureter), or the formation of a second irregularly placed () ureter; or where the junction with the bladder is malformed or a ureterocoele develops (usually in that location). If the ureters have been resited as a result of surgery, for example due to a
kidney transplant Kidney transplant or renal transplant is the organ transplant of a kidney into a patient with end-stage kidney disease (ESRD). Kidney transplant is typically classified as deceased-donor (formerly known as cadaveric) or living-donor transplantat ...
or due to past surgery for vesicoureteric reflux, that site may also become narrowed. A narrowed ureter may lead to ureteric enlargement () and cause swelling of the kidneys (
hydronephrosis Hydronephrosis is the hydrostatic dilation of the renal pelvis and Renal calyx, calyces as a result of obstruction to urine flow downstream. Alternatively, hydroureter describes the dilation of the ureter, and hydronephroureter describes the dila ...
). Associated symptoms may include recurrent infections, pain or
blood in the urine Hematuria or haematuria is defined as the presence of blood or red blood cells in the urine. "Gross hematuria" occurs when urine appears red, brown, or tea-colored due to the presence of blood. Hematuria may also be subtle and only detectable with ...
; and when tested,
kidney function Assessment of kidney function occurs in different ways, using the presence of symptoms and medical sign, signs, as well as measurements using urine tests, blood tests, and medical imaging. Renal physiology, Functions of a healthy kidney include ...
might be seen to decrease. These are considered situations when surgery is needed. Medical imaging, including urinary tract ultrasound, CT or
nuclear medicine Nuclear medicine (nuclear radiology, nucleology), is a medical specialty involving the application of radioactivity, radioactive substances in the diagnosis and treatment of disease. Nuclear imaging is, in a sense, ''radiology done inside out'', ...
imaging is conducted to investigate many causes. This may involve reinserting the ureters into a new place on the bladder (reimplantion), or widening of the ureter. A
ureteric stent A ureteral stent (pronounced you-REE-ter-ul), or ureteric stent, is a thin tube inserted into the ureter to prevent or treat obstruction of the urine flow from the kidney. The length of the stents used in adult patients varies between 24 and 3 ...
may be inserted to relieve an obstruction. If the cause cannot be removed, a
nephrostomy A nephrostomy or percutaneous nephrostomy is an artificial opening created between the kidney and the skin which allows for the urinary diversion directly from the upper part of the urinary system ( renal pelvis). It is an interventional radiolo ...
may be required, which is the insertion of a tube connected to the renal pelvis which directly drains urine into a
stoma bag An ostomy pouching system is a prosthetic medical device that provides a means for the collection of waste from a surgically diverted biological system (Colon (anatomy), colon, ileum, urinary bladder, bladder) and the creation of a stoma (medici ...
.


Cancer

Cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...
of the ureters is known as
ureteral cancer Ureteral cancer is cancer of the ureters, muscular tubes that propel urine from the kidneys to the urinary bladder. It is also known as ureter cancer,smoking Smoking is a practice in which a substance is combusted, and the resulting smoke is typically inhaled to be tasted and absorbed into the bloodstream of a person. Most commonly, the substance used is the dried leaves of the tobacco plant, whi ...
and exposure to
dye Juan de Guillebon, better known by his stage name DyE, is a French musician. He is known for the music video of the single "Fantasy Fantasy is a genre of speculative fiction that involves supernatural or Magic (supernatural), magical ele ...
s such as
aromatic amine In organic chemistry, an aromatic amine is an organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be a ...
s and
aldehydes In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...
. When cancer is present, the most common symptom is blood in the urine; it may not cause symptoms, and a physical
medical examination In a physical examination, medical examination, clinical examination, or medical checkup, a medical practitioner examines a patient for any possible medical signs or symptoms of a Disease, medical condition. It generally consists of a series of ...
may be otherwise normal, except in late disease. Ureteral cancer is most often due to cancer of the cells lining the ureter, called
transitional cell carcinoma Transitional cell carcinoma is a type of cancer that arises from the transitional epithelium, a tissue lining the inner surface of these hollow organs. It typically occurs in the urothelium of the urinary system; in that case, it is also called ...
, although it can more rarely occur as a
squamous cell carcinoma Squamous-cell carcinoma (SCC), also known as epidermoid carcinoma, comprises a number of different types of cancer that begin in squamous cells. These cells form on the surface of the skin, on the lining of hollow organs in the body, and on the ...
if the type of cells lining the urethra have changed due to chronic inflammation, such as due to stones or schistosomiasis. Investigations performed usually include collecting a sample of urine for an inspection for malignant cells under a microscope, called
cytology Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living an ...
, as well as medical imaging by a CT urogram or
ultrasound Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...
. If a concerning lesion is seen, a flexible camera may be inserted into the ureters, called
ureteroscopy Ureteroscopy is an examination of the upper urinary tract, usually performed with a ureteroscope that is passed through the urethra and the bladder, and then directly into the ureter. The procedure is useful in the diagnosis and treatment of dis ...
, in order to view the lesion and take a
biopsy A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, an interventional radiologist, or an interventional cardiology, interventional cardiologist. The process involves the extraction of sampling (medicine), sample ...
, and a
CT scan A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or ...
will be performed of other body parts (a CT scan of the chest, abdomen and pelvis) to look for additional lesions. After the cancer is
staged ''Staged'' is a British television comedy series. Set and filmed during the COVID-19 pandemic in the United Kingdom, primarily using video-conferencing technology, the series stars actors Michael Sheen and David Tennant as fictionalised versions ...
, treatment may involve
open surgery Minimally invasive procedures (also known as minimally invasive surgeries) encompass surgical techniques that limit the size of incisions needed, thereby reducing wound healing time, associated pain, and risk of infection. Surgery by definitio ...
to remove the affected ureter and kidney if it is involved; or, if the lesion is small, it may be removed via ureteroscopy. Prognosis can vary markedly depending on the
tumour grade In pathology, grading is a measure of the cell appearance in tumors and other neoplasms. Some pathology grading systems apply only to malignant neoplasms (cancer); others apply also to benign neoplasms. The neoplastic grading is a measure of cell ...
, with a worse prognosis associated with an ulcerating lesion.


Injury

Injuries to the ureter can occur after penetrating abdominal injuries, and injuries at high speeds followed by an abrupt stop (such as a high speed car accident). The ureter can be injured during surgery to nearby structures. It is injured in 2 per 10,000 cases of vaginal
hysterectomies Hysterectomy is the surgical removal of the uterus and cervix. Supracervical hysterectomy refers to removal of the uterus while the cervix is spared. These procedures may also involve removal of the ovaries (oophorectomy), fallopian tubes (salpin ...
and 13 per 10,000 cases of abdominal hysterectomies, usually near the
suspensory ligament of the ovary The suspensory ligament of the ovary, also infundibulopelvic ligament (commonly abbreviated IP ligament or simply IP), is a fold of peritoneum that extends out from the ovary to the wall of the pelvis. Some sources consider it a part of the broad ...
or near the
cardinal ligament The cardinal ligament (also transverse cervical ligament, lateral cervical ligament, or Mackenrodt's ligament) is a major ligament of the uterus formed as a thickening of connective tissue of the base of the broad ligament of the uterus. It exten ...
, where the ureter runs close to the blood vessels of the uterus.


Imaging

Several forms of medical imaging are used to view the ureters and urinary tract. Ultrasound may be able to show evidence of blockage because of hydronephrosis of the kidneys and renal pelvis. CT scans, including ones where
contrast media A contrast agent (or contrast medium) is a substance used to increase the contrast of structures or fluids within the body in medical imaging. Contrast agents absorb or alter external electromagnetism or ultrasound, which is different from radio ...
is injected
intravenous Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutr ...
ly to better show the ureters, and with contrast to better show lesions, and to differentiate benign from malignant lesions. Dye may also be injected directly into the ureters or renal tract; an antegrade pyelogram is when contrast is injected directly into the renal pelvis, and a
retrograde pyelogram Pyelogram (or pyelography or urography) is a form of imaging of the renal pelvis and ureter. Types include: * Intravenous pyelogram – In which a contrast solution is introduced through a vein into the circulatory system. * Retrograde pyelogra ...
is where dye is injected into the urinary tract via a catheter, and flows backwards into the ureters. More invasive forms of imaging include ureteroscopy, which is the insertion of a flexible
endoscope An endoscope is an inspection instrument composed of image sensor, optical lens, light source and mechanical device, which is used to look deep into the body by way of openings such as the mouth or anus. A typical endoscope applies several modern ...
into the urinary tract to view the ureters. Ureteroscopy is most commonly used for medium to large-sized stones when less invasive methods of removal cannot be used.


Other animals

All
vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...
s have two kidneys located behind the abdomen that produce urine, and have a way of excreting it, so that waste products within the urine can be removed from the body. The structure specifically called the ureter is present in
amniote Amniotes are tetrapod vertebrate animals belonging to the clade Amniota, a large group that comprises the vast majority of living terrestrial animal, terrestrial and semiaquatic vertebrates. Amniotes evolution, evolved from amphibious Stem tet ...
s, meaning
mammals A mammal () is a vertebrate animal of the class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle e ...
,
birds Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...
and
reptiles Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocepha ...
. These animals possess an adult kidney derived from the
metanephros Kidney development, or nephrogenesis, describes the embryologic origins of the kidney, a major organ in the urinary system. This article covers a 3 part developmental process that is observed in most reptiles, birds and mammals, including humans. ...
. The duct that connects the kidney to excrete urine in these animals is the ureter. In
placental mammals Placental mammals ( infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguish ...
, it connects to the
urinary bladder The bladder () is a hollow organ in humans and other vertebrates that stores urine from the Kidney (vertebrates), kidneys. In placental mammals, urine enters the bladder via the ureters and exits via the urethra during urination. In humans, the ...
, whence urine leaves via the
urethra The urethra (: urethras or urethrae) is the tube that connects the urinary bladder to the urinary meatus, through which Placentalia, placental mammals Urination, urinate and Ejaculation, ejaculate. The external urethral sphincter is a striated ...
. In
monotremes Monotremes () are mammals of the order Monotremata. They are the only group of living mammals that lay eggs, rather than bearing live young. The extant monotreme species are the platypus and the four species of echidnas. Monotremes are typified ...
, urine flows from the ureters into the
cloaca A cloaca ( ), : cloacae ( or ), or vent, is the rear orifice that serves as the only opening for the digestive (rectum), reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles, birds, cartilagin ...
. The ureters are
ventral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
to the
vasa deferentia The vas deferens (: vasa deferentia), ductus deferens (: ductūs deferentes), or sperm duct is part of the male reproductive system of many vertebrates. In mammals, spermatozoa are produced in the seminiferous tubules and flow into the epididyma ...
in male placental mammals, but dorsal to the vasa deferentia in
marsupial Marsupials are a diverse group of mammals belonging to the infraclass Marsupialia. They are natively found in Australasia, Wallacea, and the Americas. One of marsupials' unique features is their reproductive strategy: the young are born in a r ...
s. In female marsupials, the ureters pass between the median and lateral vaginae.


History

The word "ureter" comes from the
Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...
noun , , meaning "urine", and the first use of the word is seen during the era of
Hippocrates Hippocrates of Kos (; ; ), also known as Hippocrates II, was a Greek physician and philosopher of the Classical Greece, classical period who is considered one of the most outstanding figures in the history of medicine. He is traditionally referr ...
to refer to the
urethra The urethra (: urethras or urethrae) is the tube that connects the urinary bladder to the urinary meatus, through which Placentalia, placental mammals Urination, urinate and Ejaculation, ejaculate. The external urethral sphincter is a striated ...
. The anatomical structure of the ureter was noted by 40 AD. However, the terms "ureter" and "urethra" were variably used to refer to each other thereafter for more than a millennium. It was only in the 1550s that anatomists such as
Bartolomeo Eustachi Bartolomeo Eustachi (27 August 1574), also known as Eustachio or by his Latin name of Bartholomaeus Eustachius (), was an Italian anatomist and one of the founders of the science of human anatomy. Biography Bartolomeo was born in San Severi ...
and
Jacques Dubois Jacques Dubois ( Latinised as Jacobus Sylvius; 1478 – 14 January 1555) was a French anatomist. Dubois was the first to describe venous valves, although their function was later discovered by William Harvey. He was the brother of Franciscus Sy ...
began to use the terms to specifically and consistently refer to what are in modern English called the ureter and the urethra. Following this, in the 19th and 20th centuries, multiple terms relating to the structures such as ureteritis and ureterography, were coined. Kidney stones have been identified and recorded about as long as written historical records exist. The urinary tract including the ureters, as well as their function to drain urine from the kidneys, has been described by
Galen Aelius Galenus or Claudius Galenus (; September 129 – AD), often Anglicization, anglicized as Galen () or Galen of Pergamon, was a Ancient Rome, Roman and Greeks, Greek physician, surgeon, and Philosophy, philosopher. Considered to be one o ...
in the second century AD. The first to examine the ureter through an internal approach, called ureteroscopy, rather than surgery was
Hampton Young Hampton may refer to: Places Australia *Hampton bioregion, an IBRA biogeographic region in Western Australia *Hampton, New South Wales *Hampton, Queensland, a town in the Toowoomba Region *Hampton, Victoria **Hampton railway station, Melbourne ...
in 1929. This was improved on by
VF Marshall Vf or VF may stand for: Arts and entertainment *''Virtua Fighter'', a series of fighting games by Sega * Variable fighter, in the ''Macross'' manga series Businesses and organizations * AJet, a Turkish airline, IATA code VF * VF Corporation, a ...
who is the first published use of a flexible endoscope based on
fiber optics An optical fiber, or optical fibre, is a flexible glass or plastic fiber that can transmit light from one end to the other. Such fibers find wide usage in fiber-optic communications, where they permit transmission over longer distances and at ...
, which occurred in 1964. The insertion of a drainage tube into the renal pelvis, bypassing the ureters and urinary tract, called nephrostomy, was first described in 1941. Such an approach differed greatly from the open surgical approaches within the urinary system employed during the preceding two millennia. The first
radiological imaging Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to revea ...
of the ureters was by
X-ray An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...
s, although this was made more difficult by the thick abdomen, which the low power of the original X-rays could not penetrate enough to produce clear images. More useful images were able to be produced when Edwin Hurry Fenwick in 1908 pioneered the use of tubes covered in material visible to X-rays inserted into the ureters, and in the early 20th century when contrasts were injected externally into the urinary tract (retrograde pyelograms). Unfortunately, much of the earlier retrograde pyelograms were complicated by significant damage to the kidneys as a result of contrast based on
silver Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. ...
or
sodium iodide Sodium iodide (chemical formula NaI) is an ionic compound formed from the chemical reaction of sodium metal and iodine. Under standard conditions, it is a white, water-soluble solid comprising a 1:1 mix of sodium cations (Na+) and iodide anions ...
. Hryntshalk in 1929 pioneered the development of the
intravenous urogram Pyelogram (or pyelography or urography) is a form of imaging of the renal pelvis and ureter. Types include: * Intravenous pyelogram – In which a contrast solution is introduced through a vein into the circulatory system. * Retrograde pyelogram ...
, in which contrast is injected into a vein and highlights the kidney and, when excreted, the urinary tract. Things improved with the development by
Moses Swick In Abrahamic religions, Moses was the Hebrew prophet who led the Israelites out of slavery in the Exodus from Egypt. He is considered the most important prophet in Judaism and Samaritanism, and one of the most important prophets in Christiani ...
and Leopold Lichtwitz in the late 1920s of relatively nontoxic contrast media, with controversy surrounding publication as to who was the primary discoverer. Side-effects associated with imaging improved even more when Tosten Almen published a ground-breaking thesis in 1969 based on the less toxic low-osmolar contrast media, developed based on swimming experiences in lakes with different salinity.


References

{{Authority control Abdomen Urinary system Kidney