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Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

777 results found
Article

Urinary tract dilatation classification

The urinary tract dilatation (UTD) classification system is a proposed unified classification of urinary tract dilatation for prenatal and postnatal care. This classification was formed with the collaborations from eight societies (American College of Radiology (ACR), American Institute of Ultra...
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Uterine artery

The uterine artery is seen bilaterally and is a branch of the anterior division of the internal iliac artery. Gross anatomy Course It runs medially in the pelvis, within the base of the broad ligament, to the outer surface of the uterus. From lateral to medial it has a descending, transverse ...
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Uterine artery embolization

Uterine artery embolization (UAE) is an interventional radiological technique to occlude the arterial supply to the uterus and is performed for various reasons. History Uterine artery embolization has been practised for more than 20 years for controlling hemorrhage following delivery/abortion,...
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Uterine artery embolization: MRI assessment

Uterine artery embolization (UAE) is used as an alternative to hysterectomy in selected patients and MRI assessment is key in allowing not only pre-procedure assessment but also assessing post-procedural outcome.   For a general discussion of the underlying condition refer to the article on ute...
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Uterine artery flow notching

Uterine artery flow notching refers to a phenomenon observed in uterine arterial Doppler ultrasound assessment. Pathology Associations The presence of notching after 22 weeks is associated with several other conditions including adverse pregnancy outcomes. These include pregnancy induced hyp...
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Uterine artery pseudoaneurysm

Uterine artery pseudoaneurysm (UAP) is a rare cause of secondary postpartum hemorrhage.  Clinical presentation UAP usually presents as delayed (secondary) postpartum hemorrhage, that is per vaginal bleeding which occurs more than 24 hours and up to 6 weeks postpartum. However, some reported ca...
Article

Uterine dehiscence

Uterine dehiscence is, usually, used to refer to the process of gradual myometrial rupture without a rupture of membranes. However, the term is used synonymously with uterine rupture by some authors. It is often described in the context of a C-section scar where it is also termed an incisional d...
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Uterine duplication anomalies

Uterine duplication anomalies are a group of Müllerian duct anomalies where fusion of the Müllerian duct associated structures fail to some degree: uterus didelphys: class III bicornuate uterus: class IV (second commonest duplication anomaly) septate uterus: class V (commonest duplication ano...
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Uterine enlargement (differential)

Uterine enlargement can occur in a number of situations from both diffuse and focal processes. These include:  gestation related events normal intrauterine pregnancy molar pregnancy - gestational trophoblastic disease  postpartum uterus - still larger than usual hormonal causes exogenous h...
Article

Uterine inversion

Uterine inversion is a rare condition in which the uterus is essentially turned inside out. There are two types: "puerperal" (within six weeks of childbirth) and "non-puerperal". The reason for uterine inversion is unclear. In the puerperal form, it is theorized that excessive traction on the um...
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Uterine perforation

Uterine perforation represents a serious complication that can occur as a result of any type of intrauterine procedure or implantation. Some authors use the term uterine rupture synonymously with the term uterine perforation. Pathology Causes IUCD insertion: IUCD related uterine perforation ...
Article

Uterine rupture

Uterine rupture is a rare but nevertheless potentially catastrophic complication that can occur in pregnancy.  Epidemiology The incidence rate in pregnancy is 0.05% 6.   Clinical presentation Uterine rupture is usually an acute presentation with hemodynamic instability and abdominal discomfo...
Article

Uteroplacental blood flow assessment

Uteroplacental blood flow assessment is an important part of fetal well-being assessment and evaluates Doppler flow in the uterine arteries and rarely the ovarian arteries. Pathology In a non-gravid state and at the very start of pregnancy the flow in the uterine artery is of high pulsatility ...
Article

Uterus

The uterus is an extraperitoneal hollow, thick-walled, muscular organ of the female reproductive tract that lies in the lesser pelvis. Gross anatomy The uterus has an inverted pear shape. It measures about 7.5 cm in length, 5 cm wide at its upper part, and nearly 2.5 cm in thickness in adults....
Article

VACTERL association

VACTERL is an acronym that describes a non-random constellation of congenital anomalies. It is not a true syndrome as such and is equivalent to the VATER anomaly. Epidemiology The estimated incidence is 1 in 10,000-40,000 births 3. Pathology The acronym VACTERL derives from: V: vertebral an...
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VACTERL-H association

The VACTERL-H association is a rare non-random association which bears the features of the standard VACTERL association with added fetal hydrocephalus. Unlike the standard VACTERL association which is sporadic, the VACTERL-H is hereditary with both X-linked 3 and autosomal recessive 2 inheritan...
Article

Vagina

The vagina is a midline fibromuscular tubular organ positioned in the female perineum extending superiorly from the vulva, to the cervix and uterus in the pelvis.  Gross anatomy The vagina is 6-8 cm in length, extending posterosuperior from the vestibule through the urogenital diaphragm to the...
Article

Variation in cord insertion

There can be several variations with cord insertion into the placenta: central insertion (~90%): normal situation eccentric cord insertion: lateral insertion of the umbilical cord >2 cm from the placental margin term sometimes used synonymously with marginal cord insertion marginal cord inse...
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Variation in fetal presentation

There can be many variations in the fetal presentation which is determined by which part of the fetus is projecting towards the internal cervical os. This includes: cephalic presentation: fetal head presenting towards the internal cervical os, considered normal and occurs in the vast majority o...
Article

Variation in placental morphology

There can be several variations in placental morphology. These include: single lobed discoid placenta (single disc): most common scenario bilobed placenta: two near equal size lobes succenturiate lobe(s): one or more smaller accessory lobes circumvallate placenta: rolled placental edges with...
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Vasa previa

Vasa previa refers to a situation where there are aberrant fetal vessels crossing over or in close proximity to the internal cervical os, ahead of the fetal presenting part. These vessels are within the amniotic membranes, without the support of the placenta. Vasa previa is a rare but potentiall...
Article

Vein of Galen aneurysmal malformation

Vein of Galen aneurysmal malformations (VGAMs), probably better termed as median prosencephalic arteriovenous fistulas, are uncommon intracranial anomalies that tend to present dramatically during early childhood with features of a left-to-right shunt and high-output cardiac failure. Epidemiolo...
Article

Velamentous cord insertion

Velamentous cord insertion is a type of abnormal umbilical cord insertion into the placenta. Epidemiology The estimated incidence is ~1% in singleton and 9-15% in twin pregnancies, respectively 11. It is also more common in placenta previa than in normally located placentas. The prevalence may...
Article

Venous lake (disambiguation)

The term venous lakes may refer to: cutaneous venous lakes, often occurring on the lower lip 1 osseous venous lakes occurring in the skull 2 placental (venous) lakes 3
Article

Ventricular septal defect

Ventricular septal defects (VSD) represent defects in the interventricular septum that allow a hemodynamic communication between the right and left ventricles. It typically results in a left-to-right shunt. Epidemiology They represent one of the most common congenital cardiac anomalies and may...
Article

Vermian lobulation

Evaluation of vermian lobulation is essential in assessment of the vermian maturity. MRI is a useful tool in assessment of the fetal posterior fossa. Radiographic features Normal vermian lobulation by weeks 1: by 21 weeks: the prepyramidal fissure can be seen between the tuber and pyramis 21...
Article

Vermian maturity assessment (approach)

Radiological evaluation of the posterior fossa is an essential part of the routine fetal assessment, including vermian maturity assessment. Radiographic features Ultrasonography is a readily available diagnostic tool in the assessment of the fetal posterior fossa but is sometimes limited due t...
Article

Vitamin B9

Vitamin B9 (folate or folic acid) is a water-soluble vitamin, part of the vitamin B complex, vital for the synthesis of several amino acids, the purines adenosine and guanine and the pyrimidine thymine (three of the four nucleotide bases and hence critical for the synthesis of nucleic acids). T...
Article

Walker-Warburg syndrome

Walker-Warburg syndrome (WWS), sometimes known as HARDE syndrome, is an extremely rare lethal form of congenital muscular dystrophy. It is primarily characterized by: fetal hydrocephalus: almost always present neuronal migrational anomalies: agyria (cobblestone lissencephaly / lissencephaly ty...
Article

Wharton jelly

Wharton jelly refers to the gelatinous substance within the umbilical cord. Gross anatomy Wharton jelly is derived from extra-embryonic mesoderm and is largely made up of mucopolysaccharides (hyaluronic acid and chondroitin sulphate) while containing smaller amounts of fibroblasts and macropha...
Article

Wolf-Hirschhorn syndrome

Wolf-Hirschhorn syndrome (WHS) is an extremely rare chromosomal anomaly characterized by partial deletion of the p arm of chromosome 4 (4p16.3). Clinical presentation There is a large clinical spectrum: CNS agenesis of the corpus callosum hypertelorism coloboma seizures 4 craniofacial c...
Article

Yolk sac

Yolk sac is the first anatomical structure identified within the gestational sac. It plays a critical role in embryonal development by providing nutrients, serving as the site of initial hematopoiesis, providing endocrine, metabolic and immunological functions and contributing to the development...
Article

Zika virus infection

Zika virus infection is a zoonosis which is associated with congenital birth defects, with microcephaly the most widely known. Epidemiology Zika was once isolated to Africa and Asia, however, it spread to the Americas in the last decade 1. There were thousands of cases confirmed in the America...

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