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.

33 results found
Article

Abnormally eccentric gestational sac

An eccentrically located gestational sac towards the fundus of uterus is the normal sonographic appearance; however an abnormally eccentric gestational sac on ultrasound may be apparent due to a number of causes They include interstitial ectopic pregnancy 1 normally implanted pregnancy in a  ...
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Absent nasal bone

In fetal sonographic assessment, an absent nasal bone is a feature which can sometimes be used as an adjunctive marker for fetal aneuploidy. Radiographic assessment Antenatal ultrasound It is assessed on a midline sagittal view. In this section the nasal bone is often seen as a bright echogen...
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Apple-peel intestinal atresia

Apple-peel intestinal atresia, also known as type IIIb or Christmas tree intestinal atresia, is a rare form of small bowel atresia in which the duodenum or proximal jejunum ends in a blind pouch and the distal small bowel wraps around its vascular supply in a spiral resembling an apple peel. Oft...
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Banana sign

The banana sign is one of the many notable fruit inspired signs. It is seen on axial imaging through the posterior fossa of fetus and is associated with the Chiari II malformation. It describes the way the cerebellum is wrapped tightly around the brain stem as a result of spinal cord tethering ...
Article

Bunch of grapes sign

Bunch-of-grapes sign refers to the ultrasound appearance of multiple cystic spaces within the uterus as the result of hydropic swelling of trophoblastic villi within a hydatidiform mole. This sign is also described in bronchiectasis where on plain radiograph, the dilated bronchi in approximatio...
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Butterfly sign

Butterfly sign refers to the normal appearance of bilateral choroid plexuses on axial imaging of the fetal brain, commonly observed on the antenatal ultrasound. Its absence may suggest holoprosencephaly 1. In the CNS, the term should not be mistaken by butterfly glioma, which is a glioblastoma ...
Article

Chorionic bump

A chorionic bump is a finding that can be uncommonly seen in a first trimester scan (0.7% of pregnancies 1). It may represent a small haematoma bulging into the gestational sac or an anembryonic (failed) second pregnancy that is being resorbed. It is also seen in some patients undergoing inferti...
Article

Cloverleaf skull

A cloverleaf skull (also known as kleeblattschädel) refers to type of severe craniosynostosis which gives the skull a cloverleaf shape. It typically results from intrauterine premature closure of sagittal, coronal and lambdoid sutures. Pathology Associations thanatophoric dysplasia: classical...
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Double bleb sign

A double bleb sign is a sonographic feature where there is visualisation of a gestational sac containing a yolk sac and amniotic sac giving an appearence of two small bubbles 2. The embryonic disc is located between the two bubbles. It is an important feature of an intrauterine pregnancy and thu...
Article

Double decidual sac sign

The double decidual sac sign (DDSS) is a useful feature on early pregnancy ultrasound to confirm an early intrauterine pregnancy (IUP). It consists of the decidua parietalis (lining the uterine cavity) and decidua capsularis (lining the gestational sac) and is seen as two concentric rings surrou...
Article

Echogenic fetal bowel

Echogenic fetal bowel is an observation in antenatal ultrasound imaging, in which fetal bowel appears to be brighter than it is supposed to be. It is a soft marker for trisomy 21 and has several other associations. When observed, it needs to be interpreted in the context of other associated abno...
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Empty amnion sign

The empty amnion sign is a sonographic observation where there is visualization of an amniotic sac without concomitant visualization of an embryo. It is an indicator pregnancy failure regardless of the mean sac diameter and is considered to have a sufficiently high positive predictive value 2.  ...
Article

Expanded amnion sign

The expanded amnion sign has been described as a poor prognostic sign in early pregnancy, suspicious though not diagnostic of failed early pregnancy. An abnormal embryo will have an abnormally large amniotic cavity. Gestational sac diameter is usually found to be correct for age. See also empt...
Article

Fetal cardio thoracic circumference ratio

Fetal cardio-thoracic (C/T) circumference ratio is parameter than can be used in assessment of fetal cardiac and thoracic/chest wall anomalies. It is essentially the ratio of the cardiac circumference of the thoracic circumference and may be easily measured on ultrasound/fetal echocardiography. ...
Article

Fetal maceration

Fetal maceration is one of the signs of fetal death. It is a destructive aseptic process that appears between 12 to 24 hours after fetal death. It may not be seen in a pregnancy earlier than 6 months. In this a separation of the skin from head and trunk occurs giving a bubble like appearance.
Article

Floating head appearance

A floating head appearance refers to imaging features observed typically on antenatal ultrasound with certain skeletal dysplasias such as achondrogenesis.   Against the background of poorly mineralized spine, a normal ossified skull is seen giving an impression of a floating head.
Article

Funneling of the internal cervical os

Cervical funneling is a sign of cervical incompetence and represents the dilatation of the internal part of the cervical canal and reduction of the cervical length. Greater than 50% funneling before 25 weeks is associated with approximately 80% risk of preterm delivery. Radiographic assessment...
Article

Hanging noose sign

Hanging noose sign in obstretric imaging is a rarely described but classical finding of a true umbilical cord knot. It demonstrates a transverse section of the umbilical cord surrounded by a loop of umbilical cord and changes in the pressure of the knot can be demonstrated with the fetus movemen...
Article

Interstitial line sign

The interstitial line sign is an ultrasound finding in interstitial ectopic pregnancy. It is an echogenic line from the mass to the endometrial echo complex. Reportedly it has high sensitivity (80%) and specificity (98%).
Article

Intradecidual sac sign

Intradecidual sac sign (IDSS) is a useful feature in identifying an early intrauterine pregnancy as early as 25 days of gestation 1. As per this sign, site of implantation is seen as an early gestational sac or an intrauterine fluid collection or an echogenic area in a markedly thickened decidua...
Article

Lambda sign

There are a number of lambda signs: lambda sign of twin pregnancy lambda sign of sarcoidosis
Article

Lemon sign

The lemon sign, noted on antenatal imaging, is one of the many notable fruit inspired signs. It is a feature when there appears to be an indentation of the frontal bone (depicting that of a lemon). It is classically seen as a sign of a Chiari II malformation and also seen in the majority (90-98%...
Article

Pseudo-omphalocoele

Pseudo-omphalocoele is the spurious sonological appearance giving an impression of an anterior abdominal wall defect. Radiographic features Ultrasound Pseudo-omphalocoele may be seen in: scanning errors where there is a deformation of fetal abdomen by transducer pressure and the image is bei...
Article

Pseudodysraphism

A pseudodysraphism refers to the splayed  appearance of a normal spine created due to excessive craniocaudal angulation during sonographic evaluation. This can erroneously lead to the diagnosis of a spinal neural tube defect.
Article

Pseudogestational sac

A pseudogestational sac is the idea that a small amount of intrauterine fluid in the setting of a positive pregnancy test and abdominal pain could be erroneously interpreted as a true gestational sac in ectopic pregnancy. The sign was originally reported before the use of endovaginal ultrasound...
Article

Robert sign

Robert sign refers to the presence of a gas shadow within the heart or the greater vessels, in cases of fetal death in utero. It is a rare sign caused by postmortem blood degeneration, usually seen 1-2 days after death; and may be seen as early as 12 hours. Related articles fetal death in utero
Article

Shortening of the cervical canal

Shortening of the uterine cervical canal as the name implies refers to a abnormal shortening of the uterine cervical length. It is considered a sign of cervical incompetence in pregnancy and can lead to premature delivery. Pathology Aetiology primary (i.e. congenital/idiopathic) secondary m...
Article

Snowstorm sign: complete hydatiform mole

Snowstorm sign in obstetric imaging is classically seen in complete hydatiform mole. It is characterised by the presence of multiple hydropic villi which gives the ultrasonographic appearance of a central heterogeneous mass having a solid, hyper echoic area and interspersed with multitude of cys...
Article

Spalding sign

The Spalding sign refers the overlapping of the fetal skull bones caused by collapse of the fetal brain.  It appears usually a week or more after fetal death in utero.  This finding was originally described on abdominal radiographs and is indicative of fetal demise.
Article

Strawberry skull

Strawberry skull refers to the shape of the head on an antenatal ultrasound. Epidemiology Associations In general, strawberry skull is considered one of the nonspecific 'soft markers' for abnormal fetal development. It is considered more closely associated with trisomy 18 (Edward syndrome). ...
Article

T sign

The "T sign" is really the absence of a twin-peak sign (or lambda sign) and is used in ultrasound assessment of a mulifetal pregnancy. It refers to the lack of chorion extending between the layers of the intertwin membrane, denoting a monochorionic pregnancy. The intertwin membrane co...
Article

Tubal ring sign

Tubal ring sign is one of the ultrasound signs of a tubal ectopic. It comprises of an echogenic ring which surrounds an unruptured ectopic pregnancy. It is said to have a 95% positive predictive value (PPV) for ectopic pregnancy. Differential diagnosis It can be mimicked by a normal corpus lut...
Article

Twin-peak sign

The twin peak sign (also known as the lambda (λ) sign) is a triangular appearance of the chorion insinuating between the layers of the inter twin membrane and strongly suggests a dichorionic twin pregnancy. It is best seen in the first trimester (between 10-14 weeks). 5 While the presence of a t...

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