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.

52 results found
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AFP reduction

Human AFP (alpha-fetoprotein) reduction is seen in pregnancy where it can be associated with:  certain chromosomal anomalies Down syndrome Turner syndrome trisomy 13 trisomy 18 Cornelia de-Lange syndrome 2
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Hemimegalencephaly

Hemimegalencephaly is a rare congenital disorder of cortical formation with hamartomatous overgrowth all or a part of a cerebral hemisphere. This results from either increased proliferation or decreased apoptosis (or both) of developing neurons 2. Epidemiology Hemimegalencephaly is a cryptogen...
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Hydatidiform mole

Hydatidiform moles are one of the most common but benign forms of gestational trophoblastic disease.  Epidemiology It is a common complication of gestation, estimated to occur in one of every 1,000-2,000 pregnancies 3. These moles can occur in a pregnant woman of any age, but the rate of occur...
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Hydrops fetalis

Hydrops fetalis is excessive extravasation of fluid into the third space in a fetus which could be due to heart failure, volume overload, decreased oncotic pressure, or increased vascular permeability. Hydrops fetalis is defined as accumulation of fluid +/- oedema involving at least two fetal co...
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Incarcerated uterus

An incarcerated uterus or trapped uterus describes an extremely rare situation where a retroverted or retroflexed gravid uterus fails to ascend into the abdominal cavity. Epidemiology This is an uncommon presentation and is said to occur in 1 in 3000 pregnancies. Uncomplicated retroversion may...
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Incomplete miscarriage

Incomplete miscarriage is a term given to miscarriage where there are retained products of conception still within the uterus. Radiographic features Ultrasound Ultrasound appearance is variable, ranging from visible fetal parts to a mass of mixed echogenicity. The presence of a prominent vasc...
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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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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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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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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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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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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 ...
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Oesophageal atresia

An oesophageal atresia refers to an absence in contiguity of the oesophagus due to an inappropriate division of the primitive foregut into the trachea and oesophagus. This is the most common congenital anomaly of the oesophagus.  Epidemiology It is thought to occur in ~1:3000-4500 live births ...
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Omphalomesenteric duct cyst

An omphalomesenteric duct cyst is a type of true umbilical cord cyst. Pathology The omphalomesenteric duct serves as a communication between the midgut and yolk sac In early embryonic life and usually obliterates between the 9-18th week of gestation. The omphalomesenteric duct cyst is an embry...
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Ovarian ectopic pregnancy

Ovarian ectopic pregnancies are rare (1-3%) when compared to other types of ectopic pregnancy such as tubal ectopic.  Pathology Risk factors Risk factors include pelvic inflammatory disease, IUCD use and endometriosis. Pathogenesis is debated and lies between: fertilisation of the ovum in th...
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Partial hydatidiform mole

Partial hydatidiform mole (PHD) is a sub type of  hydatidiform mole which in turn falls under the spectrum of gestational trophoblastic disease.  Clinical presentation Clinical signs and symptoms such as abdominal pain, cramps of the lower abdomen and vaginal bleeding during pregnancy are non ...
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Parturition induced pelvic instability

Parturition-induced pelvic instability is a rare condition seen in women following vaginal delivery.  Epidemiology The incidence of symphyseal rupture after vaginal delivery ranges from one in 600 to one in 30,000 deliveries 1.  Predisposing factors include multiparity, complicated delivery, ...
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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...
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Placenta accreta

Placenta accreta (PA) is both the general term applied to abnormal placental adherence and also the condition seen at the milder end of the spectrum of abnormal placental adherence. This article focuses on the second, more specific definition. In a placenta accreta, the placental villi extend b...
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Placenta fenestrata

Placenta fenestrata is one of the variations in placental morphology, which is characterised by one or more areas of focal placental atrophy lacking villi and covered only by the chorion membrane. 
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Placenta increta

Placenta increta is an intermediate level in the spectrum of abnormal placental villous implantation and accounts for ~20% of such cases. The placental villi extend beyond the confines of the endometrium and invades the myometrium.  Epidemiology The estimated incidence is increasing (presumabl...
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Placental abruption

Placental abruption refers to a premature separation of the normally implanted placenta after the 20th week of gestation and before the 3rd stage of labour. It is a potentially fatal complication of pregnancy and is a significant cause of third-trimester bleeding / antepartum haemorrhage. Epide...
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Placental insufficiency

Placental insufficiency is a term given to a situation where the placenta cannot bring enough oxygen and nutrients to the growing fetus. Clinical presentation Fetuses may present with intra-uterine growth restriction (IUGR) (especially asymmetrical IUGR). Pathology It can be primarily caused...
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Placental mesenchymal dysplasia

Placental mesenchymal dysplasia (PMD) is a rare, benign condition that is characterised by enlargement of the placenta with multiple bunch of grape-like vesicles that can resemble a molar pregnancy by ultrasound and gross pathologic examination.  Epidemiology This is an often underdiagnosed an...
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Placental septal cyst

A placental septal cyst is a placental cyst typically located in a mid placenta. It forms between the cotyledons of the placenta. The cysts contain gelatinous material and are usually 5-10 mm in diameter. They may be present in 10-20% of placentas from full term uncomplicated pregnancies. See a...
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Placental site trophoblastic tumour

Placental site trophoblastic tumour (PSTT) is a rare and one of the least common (~ 0.2% 7) forms of gestational trophoblastic disease (GTD). Epidemiology PSTT typically occurs in women of reproductive age with the average age around 30. It may occur after a normal pregnancy, molar pregnancy o...
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Placenta membranacea

Placenta membranacea, also known as a placenta diffusa, is an extremely uncommon variation in placental morphology in which placenta develops as a thin membranous structure occupying the entire periphery of the chorion. Epidemiology The estimated incidence is at ~1:20000-40000 pregnancies 1. ...
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Placenta percreta

Placenta percreta is a term given to the most severe but least common form of the spectrum of abnormal placental villous adherence, where there is a transmural extension of placental tissue across the myometrium with serosal breach. It carries severe maternal as well as fetal risks. Epidemiolog...
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Placenta praevia

Placenta praevia is a term given to an abnormally low position of the placenta such that it lies close to, or covers the internal cervical os.  It is a potentially life-threatening condition to both mother and infant, which may result in exsanguination. As such, antenatal diagnosis is essential...
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Posterior urethral valves

Posterior urethral valves (PUVs), also referred as congenital obstructing posterior urethral membranes (COPUM), are the most common congenital obstructive lesion of the urethra and a common cause of obstructive uropathy in infancy. Epidemiology Posterior urethral valves are congenital and only...
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Potter sequence

The Potter sequence is a constellation of findings demonstrated postnatally as a consequence of severe, prolonged oligohydramnios in utero. Clinical presentation It consists of pulmonary hypoplasia: often severe and incompatible with life growth restriction (IUGR) abnormal facies (Potter fa...
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Pregnancy-associated plasma protein-A

Pregnancy-associated plasma protein-A (PAPP-A) is a protein found in the maternal circulation and is produced by the placenta. The PAPP-A gene has been assigned to human chromosome 9q33.1 and contains 22 exons 5. PAPP-A values tend to rise exponentially during pregnancy and the reference range d...
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Preplacental abruption

Pre-placental abruption or haemorrhage can be subamniotic or subchorionic in location. Clinical presentation vaginal bleeding most often painless Symptoms may be similar to placental abruption in other locations; however, it may not have as poor a prognosis as other placental abruption.  Tr...
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Pre-term labour

Pre-term labour refers to spontaneous delivery of the fetus prior to 37 weeks of gestation. This is regardless of estimated fetal weight. Radiographic assessment Ultrasound Sonographic markers shortened cervical length presence of cervical funneling dilatation or internal cervical os: cons...
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Preterm premature rupture of membranes

Preterm premature rupture of membranes (PPROM) refers to rupture of membranes prior to 37 weeks of gestation. Epidemiology It is thought to occur in 0.4-2% of all pregnancies. It however may account for up to one-third of all preterm births (particularly in the United States 5). Pathology PP...
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Pulmonary hypoplasia

Pulmonary hypoplasia (PH) refers to deficient or incomplete development of parts of the lung. It can develop as a result of a number of other in-utero anomalies. Epidemiology The true prevalence is not well known (1.4% of all births according to Knox et.al 13), but in cases of premature ruptur...
Article

Pulmonary sequestration

Pulmonary sequestration, also called accessory lung, refers to the aberrant formation of segmental lung tissue that has no connection with the bronchial tree or pulmonary arteries. It is a bronchopulmonary foregut malformation (BPFM). There are two types: intralobar sequestration (ILS) extral...
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Retained products of conception

Retained products of conception (RPOC) refer to the persistence of placental and/or fetal tissue in the uterus following delivery, termination of pregnancy or a miscarriage.  Epidemiology Retained products of conception complicate ~1-5% of all pregnancies (routine vaginal deliveries 12).  Acc...
Article

Retroplacental haemorrhage

Retroplacental haemorrhage (RPH) occurs when there is perigestational haemorrhage that is confined to the retroplacental space. Pathology This type of haemorrhage occurs behind the placenta. The haematoma therefore separates the placenta from the uterine wall. The source of bleeding is probabl...
Article

Rocker bottom foot

A rocker bottom foot (also known as a congenital vertical talus) is a congenital anomaly of the foot. It is characterised by a prominent calcaneus/heel and a convex rounded sole. Pathology It results from a dorsal and lateral dislocation of the talonavicular joint. Associations aneuploidic s...
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Ruptured omphalocoele

Ruptured omphalocoele occurs when there is rupture of the outer membrane of an omphalocoele. When this happens the eviscerated fetal bowel looks free floating and distinction from gastroschisis becomes difficult. However the abdominal defect generally tends to be larger and may contain liver wit...
Article

Single umbilical artery

Single umbilical artery (SUA) results when there is a congenital absence of either the right or left umbilical artery. In the usual situation, there are paired umbilical arteries. For some unknown reason, the absence of the left umbilical artery is much more common (~70%). Epidemiology The est...
Article

Snake under the skull sign

Snake under the skull sign is a vascular anomaly seen in holoprosencephaly. Pathology Due to the defect in the cleavage of the two hemispheres there is a fusion of the frontal lobes. This band of abnormal cortical tissue causes forward displacement of the anterior cerebral artery, so that it l...
Article

Spectrum of abnormal placental villous adherence

The spectrum of abnormal placental villous adherence describes the degree to which there is an invasion of chorionic villi into the myometrium because of a defect in the decidua basalis. Pathology Placental villous adherence is classified on the basis of depth of myometrial invasion: placenta...
Article

Spina bifida

Spina bifida is a type of neural tube defect/spinal dysraphism which can occur to varying degrees of severity. It is often considered the most common congenital CNS malformation. Epidemiology The estimated incidence is at 1:1000-2000 live births 2. Clinical presentation A constellation of fe...
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Subchorionic haemorrhage

Subchorionic haemorrhage (SCH) occurs when there is perigestational haemorrhage and blood collects between the uterine wall and the chorionic membrane in pregnancy. It is a frequent cause of first and second trimester bleeding. Epidemiology It typically occurs within the first 20 weeks of gest...
Article

Subgaleal haematoma

Subgaleal haematoma describes scalp bleeding in the potential space between the periosteum and the galea aponeurosis. It most commonly occurs after vacuum assisted delivery, but may also be seen following head trauma. In patients with intracranial haemorrhage or skull fractures, the incidence o...
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Succenturiate lobe

A succenturiate lobe is a variation in placental morphology and refers to a smaller accessory placental lobe that is separate to the main disc of the placenta. There can be more than one succenturiate lobe. Epidemiology The estimated incidence is ~2 per 1000 pregnancies. Radiographic features...
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Symmetrical intrauterine growth restriction

Symmetrical intrauterine growth restriction is a type of intrauterine growth restriction (IUGR) where all fetal biometric parameters tend to be less than expected (below the 10th percentile) for the given gestational age. Both length and weight parameters are reduced. Please, refer to the artic...
Article

Triploidy

Triploidy is a rare lethal chromosomal (aneupliodic) abnormality caused by the presence of an entire extra chromosomal set.  Epidemiology It is considered the 3rd commonest fatal chromosomal anomaly 7. While it is thought to affect as much as 1-2% of conceptions, the vast majority are thought ...
Article

Vitamin B9

Vitamin B9 (folate or folic acid) is a water soluble vitamin that is 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.) The antimicrobial group s...

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