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.

697 results found
Article

Two diameter pocket method

The two diameter pocket (TDP) method is an alternative method of assessing amniotic fluid volumes on ultrasound. However, it is not thought to be good predictor of adverse neonatal outcome 2. Sonographic assessment According to this method 1-2: TDP <15 cm2: indicative of oligohydramnios TDP ...
Article

Umbilical arterial aneurysm

An umbilical arterial aneurysm (UAA) is an extremely rare but potentially lethal vascular anomaly which is usually detected in utero.  Pathology Location If tends to favour the placental end of the umbilical artery in the cord. Associations Concurrent associated anomalies are thought to be ...
Article

Umbilical arterial Doppler assessment

Umbilical arterial (UA) Doppler assessment is used in surveillance of fetal well-being in the third trimester of pregnancy. Abnormal umbilical artery Doppler is a marker of uteroplacental insufficiency and consequent intrauterine growth restriction (IUGR) or suspected pre-eclampsia.  Umbilical ...
Article

Umbilical cord

The umbilical cord is a fetal organ and connects the placenta to the uterus and is a vital passage for nutrients, oxygen and waste products to and from the fetus.  The umbilical cord inserts into the centre of the placental bulk and into the fetus at the umbilicus. Variations in insertion can o...
Article

Umbilical cord coiling index

Umbilical cord coiling index is defined as number of coils per one centimeter of length of the cord . Normal index is one coil for a length of five centimeters. If number of coils are more per centimeter it is called as hypercoiled and less than it is called as hypocoiled umbilical cord. This in...
Article

Umbilical cord cyst

Umbilical cord cysts can refer to any cystic lesion associated with the umbilical cord. They can be single (commoner) or multiple. Epidemiology They may be seen in ~3% of pregnancies in the first trimester 8. Pathology Umbilical cord cysts can represent either true or false cysts: true cyst...
Article

Umbilical cord entanglement

Umbilical cord entanglement is a feature which can mean either one of more loops of cord being encircled around any part of the any part of body 3 or two umbilical cord getting entangled with each other. In the latter situation it is a classical feature of a monochorionic-monoamniotic twin pregn...
Article

Umbilical cord haematoma

Umbilical cord haematoma is formation of a haematoma secondary to bleeding from the umbilical cord. Pathology The haematomas can be either spontaneous or iatrogenic. Spontaneous bleeding is very rare and documented to be around 0.02% of pregnancies. Majority of the cases are iatrogenic related...
Article

Umbilical cord knot

Umbilical cord knot is a term given to denote either true umbilical cord knot: often the term "umbilical cord knot" is used to describe this entity 1 or false umbilical cord knot: usually of no clinical significance See also umbilical cord entanglement
Article

Umbilical cord prolapse

Umbilical cord prolapse is a situation where the umbilical cord protrudes into the cervical canal. Epidemiology The estimated incidence is at  ~ 0.2-0.5% of all pregnancies 4,5.  Pathology Associations Recognised associations include multifetal pregnancy: twin gestation non cephalic/abnor...
Article

Umbilical cord pseudocyst

Umbilical cord pseudocysts are a type of cystic lesion occurring in relation to the umbilical cord. Epidemiology Although the true incidence not accurately known, they are comparatively much more common than true umbilical cord cysts. Pathology The pseudocyst basically comprises of mucoid de...
Article

Umbilical cord thrombosis

Umbilical cord thrombosis is a potentially fatal complication and can mean either a thrombosis of the umbilical vein or either or both the umbilical arteries. Umbilical vein thrombosis occurs more frequently than thrombosis of one or both umbilical arteries (umbilical arterial thrombosis) Epide...
Article

Umbilical vein varix

Umbilical vein varix (UVV) refers to a focal dilatation of the umbilical vein. Pathology Location It tends to favour the intra-abdominal portion of the cord (typically between the abdominal wall and the liver) which is then termed a fetal intra-abdominal umbilical vein varix (FIUVV) or the in...
Article

Umbilical venous dilatation

Umbilical venous dilatation is a rare entity and often tends to occur as an isolated finding 4. It can arise from a number of patholgies umbilical venous varix (UVV): particularly if focal fetal hydrops: a focal dilatation due to an umbilical venous varix with an ensuing thrombosis can also ...
Article

Umbilical venous flow assessment

Umbilical venous flow in the physiological situation comprises of a monophasic non-pulsatile flow pattern with a mean velocity of 10-15 cm/s. The presence of pulsatility implies a pathological state unless in the following situations: early in pregnancy: up to ~13 weeks gestation  the presence...
Article

Urethral agenesis

Urethral agenesis (or urethral atresia) refers to a situation where there is a congenital absence of the urethra.  It can be a cause of fetal obstructive uropathy. Pathology Associations prune belly syndrome 5 bladder agenesis 2 Radiographic features Antenatal ultrasound May show a dilate...
Article

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 ...
Article

Uterine artery embolisation

Uterine artery embolisation (UAE) is an interventional radiological technique to occlude the arterial supply to the uterus and is performed for various reasons. History Uterine artery embolisation has been practised for more than 20 years for controlling haemorrhage following delivery / aborti...
Article

Uterine artery embolisation: MRI assessment

Uterine artery embolisation (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...
Article

Uterine artery flow notching

Uterine artery flow notching refers to 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 hyper...
Article

Uterine artery pseudoaneurysm

Uterine artery pseudoaneurysm (UAP) is a rare cause of secondary postpartum haemorrhage.  Clinical presentation UAP usually presents as delayed (secondary) postpartum haemorrhage, that is per vaginal bleeding which occurs more than 24 hours and up to 6 weeks postpartum. However, some reported ...
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 C-section scar where it is also termed an incisional deh...
Article

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...
Article

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 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 at 0.05% 6.   Clinical presentation Uterine rupture is usually an acute presentation with haemodynamic instability and abdominal disc...
Article

Uterine tube

The uterine tube, also known as the fallopian tube, is a paired structure that bridges between each ovary and the uterus and functions to convey the mature ovum from the former to the latter. If conception occurs, it normally does so within the tube. It can be affected by a wide range of patholo...
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

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...
Article

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 structure positioned in the female perineum extending superiorly to the cervix and uterus in the pelvis.  Gross anatomy The vagina is 8-10 cm in length, extending posterosuperior from the vestibule through the urogenital diaphragm to the uterus. Th...
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...
Article

Variation in fetal presentation

There can be many  variations in 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 of b...
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 of more smaller accessory lobes circumvallate placenta: rolled placental edges with...
Article

Vasa praevia

Vasa praevia is a term given when there are abnormal fetal vessels within the amniotic membranes that either cross or run in extremely close proximity to the internal cervical os. Pathology Vasa previa can be of two types type I (present in ~ 90% of cases with vasa praevia 3): abnormal fetal ...
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 one of the types 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 prev...
Article

Ventricular septal defect

Ventricular septal defects (VSD) represent defects in the interventricular septum that allow a haemodynamic 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 ma...
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. Normal Vermian lobulation by weeks 1: By 21 weeks - Prepyramidal fissure can be seen between the tuber and pyramis. 21 to 22 weeks - Preculmina...
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 that is 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.) The antimicrobial group s...
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 characterised 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

Widow's peak hair anomaly

Widow's peak hair anomaly refers to a frontal hairline projection. Clinical features Prominent V shaped hairline projection. Ocular hypertelorism might be noted. On examination a bony prominence may be present. Pathology It is purported that the periorbital fields of hairless region or hairg...
Article

Wolf-Hirschhorn syndrome

Wolf-Hirschhorn syndrome (WHS) is an extremely rare chromosomal anomaly characterised by partial deletion of the p arm of chromosome 4 (4p16.3). Clinicopathological spectrum CNS agenesis of the corpus callosum hypertelorism coloboma craniofacial calvarial asymmetry cleft lip + / - palate...
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 haematopoiesis, providing endocrine, metabolic and immunological functions and contributing to the developmen...

Updating… Please wait.
Loadinganimation

Alert accept

Error Unable to process the form. Check for errors and try again.

Alert accept Thank you for updating your details.