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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.

763 results found

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...

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...


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 8-10 cm in length, extending posterosuperior from the vestibule through the urogenital diaphragm to th...

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...

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...

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...

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...

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...

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...

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

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...

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...

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...

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...

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...

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...

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...

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...

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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