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.

32 results found
Article

Amnion

Amnion refers to a membranous structure which covers and protects the embryo. It forms inside the chorion. The amnion usually fuses with the outer chorion by around 14 weeks of gestation. Radiographic features Ultrasound The amnion can be visualised in most pregnancies before the 12th week of...
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Anatomy curriculum

The anatomy curriculum is one of our curriculum articles and aims to be a collection of articles that represent the core anatomy knowledge for radiologists and imaging specialists. General anatomy Neuroanatomy Head and neck anatomy Thoracic anatomy Abdominal and pelvic anatomy Spinal anat...
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Basal plate

The basal plate is a synonym for the maternal side of the placenta. The fetal side of the placenta is termed the chorionic plate. Some pathologies and processes are localized to the basal plate, and evaluation of the basal plate is a part of placental grading.
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Broad ligament

The broad ligament(s) are the lateral folds of the parietal peritoneum which reflect over the upper genital tract. Gross anatomy The broad ligament extends from the lateral aspect of the uterus to the lateral pelvic wall and can be divided into three main components - the mesosalpinx, mesovari...
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Cervical incompetence morphological changes of the internal os (mnemonic)

Sequential morphological ultrasound changes of the endocervical canal with cervical incompetence can be remembered using the mnemonic: Trust Your Vaginal Ultrasound Mnemonic T-shaped (normal internal cervical os) Y-shaped V-shaped  U-shaped Related article cervical incompetence funnelin...
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Chorion

The chorion is one of the embryonic membranous structures than encloses both the fetus as well as the amnion. The chorion begins to form chorionic villi towards its outer surface, which initially serves to provide nutrition to the developing embryo.  Part of the chorionic villi arborize more ex...
Article

Chorionic plate

The chorionic plate is a synonym for the fetal side of the placenta. The maternal side of the placenta is termed the basal plate. Some pathologies and processes are localized to the chorionic plate, and evaluation of the chorionic plate is a part of placental grading.
Article

Congenital utero-vaginal anomalies

There are many classification systems for congenital utero-vaginal anomalies. These include: Buttram and Gibbons classification 2 American Fertility Society (AFS) classification Modified Rock and Adam - AFS classification Modified Rock and Adam - AFS classification This classification divid...
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Corpus luteum

The corpus luteum is a temporary endocrine structure involved in ovulation and early pregnancy. During ovulation, the primary follicle forms the secondary follicle and subsequently the mature vesicular follicle. At ovulation the follicle ruptures expelling the ovum into the fallopian tube. The...
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Dominant ovarian follicle

A dominant ovarian follicle refers to the follicle that enlarges to release an ovum during a menstural cycle. Usually approximately 10 Graafian follicles begin to mature where one becomes a dominant follicle and the rest become atretic ovarian follicles. After release of the ovum the remainder o...
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Ductus arteriosus

The ductus arteriosum (or arteriosus) is the thick short conduit for blood to bypass the non-ventilated lungs in the fetus. It is located between and connects the proximal left pulmonary artery and the undersurface of the aortic arch distal to the origin of the last branch of the arch, at the ao...
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Fetal circulation

Fetal circulation differs from the adult circulation due to the presence of certain vessels and shunts.  These shunts will close after birth, and most of these fetal vessels will be seen as remnants in the adult circulation. The function of these shunts is to direct oxygen-rich venous blood to ...
Article

Foramen ovale (cardiac)

The foramen ovale (or ovalis) is the opening in the interatrial septum in the fetal heart that allows blood to bypass the right ventricle and non-ventilated lungs, shunted from the right atrium to the left atrium. Specifically it represents the opening between the upper and lower portions of the...
Article

Hemivertebra

Hemivertebra is a type of vertebral anomaly and results from a lack of formation of one half of a vertebral body. It can be a common cause of a congenital scoliosis.  Epidemiology The estimated incidence is at ~0.3 per 1000 live births 2. Pathology It falls under the spectrum of segmentation...
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Intramembranous ossification

Intramembranous ossification describes the process of ossification from mesenchymal cells (stem cells) without a cartilaginous template and is involved in the healing process of fractures. The stages of intramembranous ossification osteogenesis are as follows: mesenchymal cells differentiate in...
Article

Neurenteric canal of Kovalevsky

The neurenteric canal or canal of Kovalevsky is the transient communication of the amnion through notochordal canal to the yolk sac during notochordal formation at day 16-17. Abnormalities during this stage produce the neurenteric cyst spectrum.
Article

Ovarian artery

The ovarian artery is a paired structure and is the main gonadal artery in females. Gross anatomy Origin The ovarian artery arises anterolaterally from the aorta just inferior to the renal arteries and superior to the inferior mesenteric artery. Course Descends caudally in the retroperitone...
Article

Persistent right umbilical vein

A persistent right umbilical vein (PRUV) is an uncommon vascular anomaly which is often detected in utero. Epidemiology The estimated prevalence is at ~2 per 1000 births 1-2. Pathology In the normal situation, the right umbilical vein begins to obliterate in the ~4th week of gestation and di...
Article

Placenta

The placenta is a fetal organ of pregnancy, responsible for providing nutrition and oxygen to the fetus as well as excretory functions. Ultrasound is the first-line modality for imaging the placenta, but MRI may be indicated if an abnormality is suspected.  Embryology Placenta is formed by fet...
Article

Placental shelf

A placental shelf refers to a ridge of placental tissue freely abutting the margin. It may represent part of a circumvallate placenta, although an early second-trimester placental shelf can be a common, benign and transient finding 1. Placental shelves detected in early second-trimester are tho...
Article

Renal agenesis

Renal agenesis refers to a congenital absence of one or both kidneys. If bilateral (traditionally known as the classic Potter syndrome) the condition is fatal, whereas if unilateral, patients can have a normal life expectancy.  Epidemiology Unilateral renal agenesis affects approximately 1 in ...
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Retroplacental complex

Retroplacental complex (RPC) is the region behind the placenta and is composed of decidua basalis and portions of myometrium including the maternal veins which drain the placenta. Radiographic features Ultrasound visualised post 20 weeks of gestation seen as an echo-poor, subplacental region...
Article

Rhombencephalon

The rhombencephalon, or hindbrain is a primary vesicle of the neural tube. Development During the fifth week of embryological development the rhombencephalon further subdivides into the secondary brain vesicles, the metencephalon and the myelencephalon 1.  The metencephalon goes on to form th...
Article

Straight umbilical cord

Straight umbilical cord implies, as the name suggests, an umbilical cord with no coils. Epidemiology The reported incidence of a straight cord is about 3.7-5% of all pregnancies. Radiographic features Ultrasound the entire length of the umbilical cord shows no evidence of coiling Complicat...
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

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 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 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

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...
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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

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

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...

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