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.

695 results found
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Inevitable miscarriage

Inevitable miscarriage refers to the presence of an open internal os in the presence of bleeding in the first trimester of pregnancy. Most often the conception products are not expelled and intracervical contents are present at the time of examination. A sac may be seen low within the uterus and...
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Iniencephaly

Iniencephaly is a rare neural tube defect resulting in the following features 1-2: occipital bone defect partial or total absence (rachischisis)  of cervico-thoracic vertebrae  fixed fetal head retroflexion Epidemiology The estimated incidence is at ~0.1-10 per 10,000 live births 5. There i...
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Inter twin membrane

The inter twin membrane refers to a membraneous seperation between two fetuses in a twin pregnancy. Depending on the chorionicity and amnionicity, the membrane may have a number of layers di-chorionic di-amniotic (DCDA) pregnancy composed of two chorionic and two amniotic layers usually has ...
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Inter twin membrane folding

Inter twin membrane folding is an observation where the inter twin membrane in a twin pregnancy appears as being folded. It is sometimes used as a predictor for the development of twin to twin transfusion syndrome. It occurs as a result of amniotic fluid discordance. Some reports suggest that  ...
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Interocular distance

The interocular distance (IOD) is a measurement between the two medial canthi of each eye. It is often measured as an accessory biometric parameter on routine antenatal ultrasound scans on the axial images. As a rule of thumb, the interorbital distance should be roughly equal to the ocular diame...
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Interstitial ectopic pregnancy

Interstitial ectopic pregnancy (also known as an intramural) is an important type of ectopic pregnancy with higher risks of rupture and haemorrhage compared to usual tubal ectopic pregnancies.  Terminology The term interstitial pregnancy is sometimes interchangeably used with cornual pregnancy...
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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%).
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Intra-uterine contraceptive device

Intra-uterine contraceptive devices (IUCD) are one of the most frequently used methods of contraception throughout the world. It prevents pregnancy by: thinnning the endometrial lining preventing sperm motility preventing implantation There are two main types of IUCDs: non-hormonal metallic...
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Intracranial cystic lesions in the perinatal period

Intracranial cystic lesions in the perinatal period can carry a relatively wide differential which includes: Supratentorial cystic lesions cysts arachnoid cyst choroid plexus cyst connatal cyst holoprosencephaly multicystic encephalomalacia periventricular leukomalacia porencephalic cys...
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Intradecidual sac sign

Intradecidual sac sign (IDSS) is a useful feature in identifying an early intrauterine pregnancy (IUP) as early as 25 days of gestation 1. The threshold level (earliest one can see the sign) is 24 days of gestation and the discriminatory level (one should always see the sac) is 47 days. As per t...
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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...
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Intrauterine air

The presence of intrauterine air can sometimes be inferred by tiny internal echoes on ultrasound or foci of very low attenuation at computed tomography (CT). The term encompasses air within the uterine cavity as well as intramyometrial air. It can arise from a number of situations normal postp...
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Intrauterine blood clot

Intrauterine blood clot can result from a number of situations in gravid, non-gravid and postpartum states. It can mimic many other pathologies. Pathology Any condition that predisposes to an intrauterine haemorrhage can potentially result in an intrauterine blood clot. Radiographic features ...
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Intrauterine growth restriction

Intrauterine growth restriction (IUGR) is commonly defined as an estimated fetal weight (EFW) at one point in time during pregnancy being at or below the 10th percentile for gestational age 2. Some authors define the term IUGR when fetal biometric parameters fall under the 5th percentile or fal...
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Intrauterine membrane in pregnancy

An echogenic membrane might be seen within the uterus during pregnancy membrane of maternal origin uterine septum amniotic shelf intauterine synechiae membrane of fetal origin intertwin membrane amniotic band chorioamniotic separation chorioamniotic elevation fibrin strand
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Invasive mole

Invasive mole is a tumorous growth associated with gestation and falls under the spectrum of gestational trophoblastic disease. Due to their aggressive growth characteristics, invasive moles are considered locally invasive non-metastasising neoplasms. Epidemiology An invasive mole develops in ...
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Irregular gestational sac

An irregular gestational sac as the name suggests is a gestational sac which does not have the well defined, regular borders of a normal gestational sac. It is an imaging feature related to a non-viable pregnancy. See also irregular yolk sac anembryonic pregnancy
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Irregular yolk sac

An irregular yolk sac or an abnormally shaped yolk sac is an imaging feature that can be observed in early pregnancy scanning. It may be seen in up to 17% of early pregnancy scans 1. In contrast to an irregular gestational sac, the observation of an irregular yolk sac in not thought to correlate...
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Isolated cleft palate

An isolated cleft palate is a type of facial cleft. This is a much rarer occurrence than a cleft lip +/- palate and is thought to represent a different pathological entity. Epidemiology The estimated incidence is at ~1 per 2000-2500 pregnancies 4-5. There may be a slight female predilection 4....
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Isthmic ectopic pregnancy

An isthmic ectopic pregnancy is a sub type of tubal ectopic pregnancy an accounts for ~ 12% of such cases. According to one study the rate of tubal wall disruption was higher than with an ampullary ectopic pregnancy, suggesting that in an isthmic ectopic pregnancy, the trophoblast penetrates the...
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IUCD related uterine perforation

IUCD related uterine perforations are one of the causes of uterine perforation. It is rare, but a serious complication of an IUCD insertion, and is often clinically silent.  Epidemiology The incidence rate is reported at ~2 in 1000 2. Clinical presentation Perforation at the time of insertio...
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Jarcho-Levin syndrome

The Jarcho-Levin syndrome (JLS) or spondylothoracic dysostosis is a rare autosomal recessive heterogeneous disorder which can occur to variable severity. Previously the condition spondylocostal dysostosis was also considered as part of the JLS spectrum but is now considered a distinct pathologic...
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Juberg-Hayward syndrome

Juberg-Hayward syndrome (JHS), also known as the oro-cranio-digital syndrome, is a rare autosomal recessive syndrome characterised by the association of the following:  growth retardation microcephaly cleft lip and palate minor vertebral and rib anomalies 4 horseshoe kidneys 4 thumb anomal...
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Kinked brainstem

Kinking of the brainstem is a rare finding in fetal or pediatric neuroimaging, invariably seen in association with other cerebral abnormalities.  It generally heralds a poor neurological outcome. Clinical presentation A kinked brainstem may be seen on fetal MRI, commonly after referral from ul...
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Lambda sign

There are a number of lambda signs: lambda sign of twin pregnancy lambda sign of sarcoidosis
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Large for dates uterus

A large for date uterus is a clinical observation based on uterine fundal height, which may result in referral for ultrasound assessment, usually in mid to late pregnancy.    Causes include : incorrect dates constitutionally large fetus multiple pregnancy fetal macrosomia polyhydramnios u...
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Large loop excision of the transformation zone

Large loop excision of the transformation zone (LLETZ) is a gynaecological procedure. It is currently one of the most commonly used approaches to treat high grade cervical dysplasia - cervical intraepithelial neoplasia.
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Large yolk sac

A large yolk sac is one measuring >5-6 mm in pregnancies between a gestational age of 5-10 weeks. One study had shown that a yolk sac diameter of >5 mm can be associated with an increased risk of spontaneous miscarriage although few other authors have mentioned the existence of a very large yolk...
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Larsen syndrome

Larsen syndrome (LS) is an extremely rare disorder, often classified as a type of osteochondrodysplasia. Epidemiology The estimated incidence is thought to be at ~ 1 in 100,000 people. There may be an increased female predilection. Clinical presentation It is characterised by many features i...
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Left ventricular outflow tract view (fetal echocardiogram)

The left ventricular outflow tract (LVOT) view (or five chamber view) is one of the standard views in a fetal echocardiogram. It is a long axis view of the heart, highlighting the path from the left ventricle into the ascending aorta (left ventricle outflow tract). In this view the right ventr...
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Lemon sign (cerebellum)

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%...
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Lethal multiple pterygium syndrome

Lethal multiple pterygium syndrome (LMPS) is a lethal sub type of the multiple pterygium syndrome. Pathology It is primarily characterised by the presence of pterygia (or wings) present in two or more body areas overlying predominantly the large joints. Accompanying joint contractures are almo...
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Lethal omphalocele-cleft palate syndrome

Lethal omphalocele-cleft palate syndrome is, as the name suggests, characterised by the association of omphalocele and cleft palate.  Prevalence is assumed to be <1 per 1,000,000. It has been postulated that this syndrome is likely to be an autosomal recessive condition 1. History and etymolog...
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Lethal skeletal dysplasias

Lethal skeletal dysplasias form a heterogeneous group which are commonly characterised being non-survivable for prolonged periods ex-utero. They include: achondrogenesis atelosteogenesis campomelic dysplasia chondrodysplasia punctata: lethal variants  metatropic dysplasia: lethal variants 4...
Article

Limb body wall complex

The limb body wall complex (LBWC) is a rare variable group of congenital limb and body wall defects (involving mainly the chest and abdomen). They can include: abdominoschisis: usually large and left-sided 4, and almost always present thoracic wall defect / thoracoschisis ectopia cordis anom...
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Lithopaedion

Lithopaedions, also referred as stone babies, are a rare phenomenon which occurs most commonly when a fetus dies during an ectopic pregnancy. Epidemiology The estimated incidence is at ~ 1.5 to 1.8% of abdominal ectopic pregnancies 4. Pathology If the dead fetus is too large to be re-absorbe...
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Live ectopic pregnancy

A live ectopic pregnancy is an ectopic pregnancy where a live extrauterine fetus can be demonstrated.
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Loeys-Dietz syndrome

Loeys-Dietz syndrome (LDS) is an autosomal dominant genetic syndrome which has many features similar to Marfan syndrome. The syndrome features a classical triad of 1: arterial tortuosity and aneurysms hypertelorism bifid uvula or cleft palate Pathology It is caused by mutations in the gene...
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Long philtrum

A long philtrum is a clinical or imaging observation where the philtrum (middle part of the upper lip) is longer than normal.  Pathology Associations It can be associated with a number of anomalies which include Aarskog syndrome Cornelia de Lange syndrome  DiGeorge syndrome femoral hypo...
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Long umbilical cord

A long umbilical cord has been variably defined. Considering the mean length of the umbilical cord at ~50-70 cm 1, a long cord in absolute terms is usually taken as one that is over 70 cm in length at term 1-3.  Complications increased incidence of umbilical cord knots increased incidence of ...
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Low set ears

Low set ears is a descriptive term used to given a depressed or abnormally low positioning of the pinna by two or more standard deviations below the population average. Pathology Associations Low set ears can be associated with a number of anomalies which include aneuploidic / chromosomal sy...
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Low-lying placenta

Low-lying placenta occurs when the placenta extends into the lower uterine segment and its edge lies too close to the internal os of the cervix, without covering it. The term is usually applied when the placental edge is within 0.5-5.0 cm of the internal cervical os 1. Some alternatively give th...
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Lowe syndrome

Lowe syndrome (also known as the the oculocerebrorenal syndrome of Lowe) is a multi-system disorder characterised by anomalies primarily affecting the eyes, nervous system, and kidneys. Pathology It is an extremely rare, pan-ethnic, x-linked disease, with estimated prevalence in the general po...
Article

Lying down adrenal sign

The lying down adrenal sign is a feature seen usually associated with renal agenesis or renal ectopia. It is an important antenatal sonographic sign.  On an antenatal ultrasound scan, the adrenal of the affected side appears flattened ,elongated, and lying along the spine due to absence of the ...
Article

Macroglossia

Macroglossia means an enlarged tongue. It may be absolute (greater than the 95th centile) or relative (enlarged compared with oral cavity). Pathology Associations Recognised associations include: chromosomal anomalies Down syndrome tends to be a relative macroglossia may also have intermi...
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Marginal cord insertion

Marginal cord insertion is a type of abnormal cord insertion. Epidemiology The estimated incidence is at ~7% 1 of singleton pregnancies but ~25% of twin pregnancies. Hence, it is very important to locate the umbilical cord in all patients, particularly in high risk pregnancy. Pathology In th...
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Marginal placental abruption

Marginal placental abruption is the most common type of placental abruption wherein a haematoma is seen as the name suggests in the margin of the placenta and the blood collects below the chorionic membrane. It is most often seen in placentae that are partially implanted in the lower uterine seg...
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Marshall-Smith syndrome

Marshall-Smith syndrome (MSS) is a rare genetic syndrome primarily comprising of the triad of facial dysmorphism, failure to thrive and accelerated osseous maturation 5. Many cases however have wider clinical spectrum. Clinical spectrum general overgrowth - fetal macrosomia failure to thriv...
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Maternal hydronephrosis in pregnancy

Maternal hydronephrosis in pregnancy often results as a physiological phenomenon due to the presence of the fetus.  Epidemiology It is estimated that up to 90 percent of women have some degree of asymptomatic dilatation of the renal calyces, the renal pelves and the upper two-thirds of the ure...
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McKusick Kaufman syndrome

McKusick Kaufman syndrome (MKS) is an autosomal recessive multiple malformation syndrome primarily characterised by hydrometrocolpos - vaginal atresia post-axial polydactyly congenital heart disease
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Mean sac diameter

Mean sac diameter (MSD) is a sonographic measurement of the gestational sac which is usually first seen at around 3 weeks after conception (5 weeks after the last menstrual period), when it measures 2-3 mm. MSD = (length + height + width)/3 Normal MSD (in mm) + 30 = days of pregnancy Role of ...
Article

Meckel-Gruber syndrome

Meckel-Gruber syndrome (MGS) is classically characterised by the triad of: renal cystic dysplasia: multiple renal cysts (present most cases) occipital encephalocoele / holoprosencephaly (~70%) postaxial polydactyly: usually hexadactyly (~65%) Additional hepatic developmental defects and hepa...
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Meconium pseudocyst

Meconium pseudocyst formation is a complication that can occur with meconium peritonitis. Pathology It occurs when the extruded meconium becomes walled off within the peritoneal space. Radiographic features Plain radiograph May be seen as a rim calcified mass within the abdomen. Antenetal ...
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Megacystis microcolon intestinal hypoperistalsis syndrome

Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) (also known as the Berdon syndrome) is a rare congenital disorder characterised by a dilated non-obstructive urinary bladder and hypoperistalsis of the gastrointestinal tract. Epidemiology There is recognised strong female predi...
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Megalencephaly

Megalencephaly (MEG) is a disorder characterised by an abnormally large brain. It is primarily a proliferative disorder of embryonic origin. It may involve all or part of the cerebral hemispheres and can be bilateral or unilateral. It is often associated with polymicrogyria or agyria.  Terminol...
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Mendelson syndrome

Mendelson syndrome or peptic pneumonia refers to acute chemical pneumonitis caused by the aspiration of stomach contents in patients under general anesthesia. Pathology The etiologic agents is believed to be aspiration of acidic stomach contents, other compounds, e.g. bile, may also play a rol...
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Mesoblastic nephroma

Mesoblastic nephroma, also sometimes known as a congenital mesoblastic nephroma (CMN) or fetal renal hamartoma, is, in general, a benign renal tumour that typically occurs in utero or in infancy. Epidemiology It is the commonest neonatal renal tumour. Diagnosis is usually made in the antenatal...
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Mesomelia

Mesomelia refers to a shortening of the middle (intermediate) portion of a limb.  Pathology Associations mesomelia-synostoses syndrome (MSS) or mesomelic dysplasia with acral synostoses1 Ellis van-Creveld syndrome 2 Robinow syndrome See also rhizomelia
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Metatropic dysplasia

Metatrophic dysplasia is a rare group of skeletal dysplasia. It is part of the wider category of rhizomelic dwarfism. Disorders in this group include: fibrochondrogenesis lethal metatropic dysplasia (type 2) or hyperchondrogenesis lethal hyperplastic metatropic dysplasia (type 1) Schneckenbe...
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Microcephaly

Microcephaly is a descriptive term meaning a small head and is associated with numerous disorders of diverse aetiology. It is usually associated with microencephaly (small brain). For the purpose of this article the two will be used interchangeably. Terminology As with most terms which describ...
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Microgenia

Microgenia is a term meaning a small chin. It is somewhat related to but let distinct from the term micrognathia which means a small mandible. Pathology Associations Microgenia can be isolated or be associated with a numer of anomalies which include camptomelic dysplasia 1 Hydrolethalus No...
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Micrognathia

The term micrognathia essentially means a small mandible. Pathology A small mandible occurs secondary to abnormalities of the first branchial arch which in turn are caused by deficient or insufficient migration of neural crest cells and usually occur around the 4th week of gestation. Associat...
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Microphthalmia

Microphthalmia essentially means small eyes. It is characterised by a small eye within a small orbit. It can be unilateral or bilateral. It is sometimes defined as a globe with a total axial length (TAL) that is at least two standard deviations below the mean for age. Pathology Microphthalmia ...
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Midfacial hypoplasia

Midfacial hypoplasia is a type of congenital facial anomaly and can be feature of a number of congenital syndromic anomalies. These include: Antley-Bixler syndrome chromosome 1p36 deletion syndrome 2 chromosome 18q deletion syndrome Crouzon syndrome fetal alcohol syndrome fetal valproate s...
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Miller-Dieker syndrome

Miller-Dieker syndrome (MDS) or is a rare chromosomal anomaly and is one of the conditions considered part of lissencephaly type I (classic) 6.  Clinical presentation Features include: CNS neuronal migrational anomalies: lissencephaly type I prominent subarachnoid spaces widened cerebral v...
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Mirror syndrome

Mirror syndrome or triple oedema or Ballantyne syndrome is a rare disorder affecting pregnant women. It refers to the unusual association of fetal and placental hydrops with maternal pre-eclampsia and oedema. History and etymology It was first described in 1892 by John William Ballantyne.
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Miscarriage

A miscarriage is the spontaneous termination of a pregnancy before 20 weeks gestation.  Terminology The term miscarriage is preferred by many over 'abortion' due to the use of the latter for therapeutic pregnancy termination, and the perceived stigma attributed to it by some. Terminology vari...
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Missed miscarriage

A missed miscarriage, sometimes termed a missed abortion 3, is a situation when there is a non-viable fetus within the uterus, without symptoms of a miscarriage.   Radiographic features Ultrasound Ultrasound diagnosis of miscarriage should only be considered when either a mean gestation sac d...
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Mixed gonadal dysgenesis

Mixed gonadal dysgenesis (MGD) is a type of gonadal dysgenesis characterised by gonadal asymmetry, and/or sex chromosomal mosaicism, as well as retained Müllerian ducts. Pathology Depending on the chromosomal composition, patients may have testes and/or streak gonads. Genetics affected indiv...
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Mono nostril

A mono nostril falls under the midline facial defects which arise from cleavage anomalies. It can occur as part of many underlying conditions such as holoprosencephaly: particularly alobar holoprosencephaly trisomy 13 Pathology Associations Several other facial anomalies can be associated ...
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Monochorionic diamniotic twin pregnancy

A monochorionic diamniotic (MCDA) twin pregnancy is a subtype of monozygotic twin pregnancy. These fetuses share a single chorionic sac but have two amniotic sacs and two yolk sacs.  Epidemiology It accounts for the vast majority (~70-75%) of monozygotic twin pregnancies although only ~30% of ...
Article

Monochorionic monoamniotic twin pregnancy

A monochorionic monoamniotic (MCMA) twin pregnancy is a subtype of monozygotic twin pregnancy.  These fetuses share a single chorionic sac, a single amniotic sac and, in general, a single yolk sac.  Epidemiology It accounts for the minority (~5%) of monozygotic twin pregnancies and ~1-2% of al...
Article

Monochorionic twin pregnancy

A monochorionic twin pregnancy is a type of monozygotic twin pregnancy where the twins share a single chorion. Depending on the sharing of the amnion this can be divided into two types. monochorionic monoamniotic (MCMA) pregnancy: single amnion monochorionic diamniotic (MCDA) pregnancy: two am...
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Monozygotic twin pregnancy

A monozygotic (MZ) twin pregnancy results from division of single zygote following fertilisation and share similar genetic materials. These twins are therefore always of the same gender. Epidemiology MZ twins account for approximately 30% of all twin pregnancies 1. The estimated incidence is a...
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Müllerian duct anomalies

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...
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Multiple placental cysts

Multiple placental cystic spaces can be seen in many conditions: within the placenta venous lakes true placental cysts allantoic ducts cysts hydropic degeneration of placenta placental mesenchymal dysplasia adjacent the placenta subchorionic/retroplacental hematoma subamniotic hematomas...
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Multiple pterygium syndrome

The multiple pterygium syndrome(s) (MPS) refers to a group of disorders which are collectively characterised by multiple soft tissue webs (or pterygia) across the neck and various joints. They can be broadly classified into two main groups lethal multiple pterygium syndrome non lethal multipl...
Article

MURCS association

MURCS association refers to the combination of: MU: Müllerian duct aplasia R: renal aplasia /renal agenesis CS: cervicothoracic somite dysplasia See also Mayer-Rokitansky-Kuster-Hauser syndrome
Article

Myelomeningocoele

Myelomeningocoele, also known as spina bifida cystica, is a complex congenital spinal anomaly that results in spinal cord malformation (myelodysplasia).  Epidemiology It is one of the commonest congenital CNS anomalies and thought to occur in approximately 1:500 of live births 5. There may be ...
Article

Naegele's formula

The Naegele's formula is simple arithmetic method for calculating the EDD (estimated date of delivery) based on the LMP (last menstrual period). To the date of the first day of the LMP (e.g. 22nd June 2008): add seven days (i.e 29th) subtract 3 months (i.e March) add one year (i.e 2009)
Article

Nager syndrome

The Nager syndrome (also known as acrofacial dysostosis) is a rare congenital syndrome primarily characterised by facial and skeletal features Pathology Genetics There may be agenetic defect localized to chromosome 9q32. Most cases are thought to be sporadic . Occasional autosomal recessive a...
Article

Narrow fetal thorax

A narrow fetal thorax on antenatal ultrasound can be present with a number of anomalies which include: achondrogenesis camptomelic dysplasia homozygous achondroplasia Jarcho-Levin syndrome Jeune syndrome - asphyxiating thoracic dysplasia Russell-Silver dwarfism short rib polydactyly syndr...
Article

Neu-Laxova syndrome

Neu-Laxova syndrome is a lethal autosomal recessive multiple malformation syndrome with a heterogeneous phenotype. Clinical features The clinical spectrum can be quite wide and includes: dermal / cutaneous severe skin restriction ichthyosis decreased fetal movement marked intrauterine gro...
Article

Neural tube defects

Neural tube defect (NTD) refers to the incomplete closure of the neural tube in very early pregnancy.  The neural tube comprises of a bundle of nerve sheath which closes to form brain at the anterior end and spinal cord at the posterior end. The closure should occur at around the 28th day of co...
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

Noack syndrome

The Noack syndrome is a type of acrocephalopolysyndactyly. It is now considered a variant of the Pfeiffer syndrome 2.
Article

Non gestational choriocarcinoma

Non-gestational choriocarcinoma is choriocarcinoma occurring in the absence of a preceding gestation.  As opposed to a gestational choriocarcinoma, this is a much rarer situation. Pathology In women they often tend to occur in ovary. Most ovarian non-gestational choriocarcinomas occur in mixed...
Article

Non visualisation of the fetal gallbladder

Non visualisation of the fetal gallbladder is often a transient finding and in most bases can be eventually detected. However it can be rarely associated with certain pathological conditions. Associations cystic fibrosis aneuploidy agenesis of the gallbladder biliary atresia See also dif...
Article

Non-invasive perinatal testing (NIPT)

Non-invasive perinatal testing (NIPT) is an antenatal screening technique which has relatively recently come into practice.  It relies on the detection of small amounts of cell free fetal DNA to be detected in the maternal bloodstream, hence allowing prenatal genetic diagnosis to occur by way of...
Article

Noonan syndrome

Noonan syndrome (NS) is a genetically and phenotypically heterogenous non aneuploidic congenital RASopathy. Affected individuals can bear some clinical features similar to that of Turner syndrome.  Epidemiology The estimated incidence is at ~1 in 1000-2500 11. As individuals have normal number...
Article

Noonan syndrome with multiple lentigines

Noonan syndrome with multiple lentigines, previously known as LEOPARD syndrome (LS), is a rare autosomal dominant RASopathy that has many similarities to Noonan syndrome. Clinical presentation Despite a change in formal name, the 'LEOPARD' acronym is still useful to summarise the clinical feat...
Article

Nuchal cord

A nuchal cord (NC) is a term given to situation where there are one or more loops of umbilical cord wrapped around the fetal neck for ≥360°. Epidemiology The prevalence is dependent on the extent of coiling and range from ~25% for a single loop to 2.5% for a double loop to ~0.5% for more than ...
Article

Nuchal fold thickness

Nuchal fold thickness is a parameter that is measured in a second-trimester scan (at ~18-22 weeks) and should not be confused with nuchal translucency (which is measured in the first trimester). Pathology The proposed aetiology of increased nuchal thickness is the result of congenital heart di...

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