Items tagged “variant”

A duplex collecting system, or duplicated collecting system, is one of the most common congenital renal tract abnormalities. It is characterized by an incomplete fusion of upper and lower pole moieties resulting in a variety of complete or incomplete duplications of the collecting system. While ...

Intracranial arterial fenestration refers to segmental duplication of the intracranial arteries. They may be contrasted to arterial duplication, which consists of two distinct vessels with separate origins and no downstream convergence. They are rare anomalies, felt to result from incomplete fus...

The artery of Percheron is a variant of the posterior cerebral circulation characterized by a solitary arterial trunk that supplies blood to the paramedian thalami and the rostral midbrain bilaterally. From the original classification of arterial patterns at the origin of the paramedian arteries...

Persistent fetal lobulation is a normal variant seen occasionally in adult kidneys. It occurs when there is incomplete fusion of the developing renal lobules. Embryologically, the kidneys originate as distinct lobules that fuse as they develop and grow. Radiographic features It is often seen o...

An azygos anterior cerebral artery (sometimes spelled azygous) is a rare variant of the circle of Willis where the two A1 segments of the anterior cerebral artery (ACA) join to form a single trunk. As a result, there is no anterior communicating artery. This organization is similar to that seen ...

A septate uterus is the most common type of congenital uterine anomaly, and may lead to an increased rate of pregnancy loss. The main imaging differential diagnoses are arcuate uterus and bicornuate uterus. Epidemiology It is considered the most common uterine anomaly (accounts for ~55% of suc...

An arcuate uterus is a mildly variant shape of the uterus. It is technically one of the Müllerian duct anomalies, but is often classified as a normal variant. It is the uterine anomaly that is least commonly associated with reproductive failure. Arcuate uterus can be characterized with ultrasoun...

A unicornuate uterus or unicornis unicollis is a type of Müllerian duct anomaly (class II). It is also known as a banana-shaped uterus6,7, because of the shape the single horn assumes, and it usually drains into a single fallopian tube. Epidemiology This type can account for ~10% (range 6-13%)...

Müllerian duct anomalies (MDAs) are congenital abnormalities that occur when the Müllerian ducts (paramesonephric ducts) do not develop correctly. This may be as a result of complete agenesis, defective vertical or lateral fusion, or resorption failure. Epidemiology MDAs are estimated to occur...

Splenunculi, also known as supernumerary spleens, accessory spleens, or splenules, are small nodules of spleen that are separate from the rest of the organ.  Epidemiology They are common, seen in up to 16% of CTs of the abdomen and up to 30% of autopsies 2.  Pathology Accessory spleens are c...

Total anomalous pulmonary venous return (TAPVR) is a cyanotic congenital heart anomaly with abnormal drainage anatomy of the entire pulmonary venous system. This contrasts with partial anomalous pulmonary venous return (PAPVR) where only part of the pulmonary venous anatomy is abnormal. In TAPV...

Heterotaxy syndromes refer to abnormal left/right distribution of thoracic and abdominal organs that is neither situs solitus nor situs inversus. They are frequently associated with congenital heart disease and other visceral abnormalities. Terminology Isomerism implies mirrored organs, and ca...

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 ...

Uterine agenesis is the extreme of Mullerian duct anomalies (Class I) where there is a complete absence of uterine tissue above the vagina.  Epidemiology The uterine agenesis-hypoplasia spectrum accounts for ~10-15% of all Müllerian duct anomalies. Clinical presentation Clinical presentation...

Incomplete hippocampal inversion describes the situation where the normal inversion of the hippocampus fails to happen during development. Terminology Incomplete hippocampal inversion is the most correct description of this finding. Hippocampal malrotation is a term used by some authors 1 alth...

A cardiac bronchus, sometimes termed accessory cardiac bronchus, is a rare anatomic variant of the tracheobronchial tree, arising from the medial aspect of the bronchus intermedius. Epidemiology This anomaly is rare and is reported in ~0.3% (range 0.09-0.5%) of individuals 3-5. There may be a ...

Aberrant left pulmonary artery, also known as pulmonary sling, represents an anatomical variant characterized by the left pulmonary artery arising from the right pulmonary artery and passing above the right main bronchus and in between the trachea and esophagus to reach the left lung. It may lea...