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.

756 results found
Article

Placental tumors

There are many tumors that can involve the placenta. These can be of  very different pathology and can include  placental chorioangioma (considered the most common primary tumor of the placenta 1) placental chorioangiomatosis placental teratoma placental metastases placental site trophobla...
Article

Placental venous lake

Placental venous lakes refer to a phenomenon of formation of hypoechoic cystic spaces centrally within the placenta. Finding placental lakes during a second trimester ultrasound scan is not associated with any uteroplacental complication or with an adverse pregnancy outcome. They can, however, b...
Article

Placenta membranacea

Placenta membranacea, also known as a placenta diffusa, is an extremely uncommon variation in placental morphology in which the placenta develops as a thin membranous structure occupying the entire periphery of the chorion. Epidemiology The estimated incidence is ~1:20,000-40,000 pregnancies 1...
Article

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 a serosal breach. It carries severe maternal as well as fetal risks. Epidemiol...
Article

Placenta previa

Placenta previa refers to an abnormally low lying placenta such that it lies close to, or covers the internal cervical os. It is a common cause of antepartum hemorrhage. Placenta previa is a potentially life-threatening condition for both mother and infant. As such, antenatal diagnosis is essen...
Article

Placentomegaly

Placentomegaly is a term applied to an abnormally enlarged placenta. Pathology Associations It can be associated with a number of maternal and fetal disorders which include: maternal maternal anemia(s) maternal diabetes chronic intrauterine infections alpha-thalassemia fetal umbilical ...
Article

Platyspondyly

Platyspondyly is a radiographic feature and refers to flattened vertebral bodies throughout the axial skeleton. Pathology Associations Platyspondyly can be feature of many conditions which include: severe Gaucher disease 1 metatrophic dysplasia Morquio syndrome osteogenesis imperfecta Ro...
Article

Polydactyly

Polydactyly (less commonly called hyperdactyly) refers to the situation where there are more than the usual number of digits (five) in a hand or foot. It can be broadly classified as: pre-axial polydactyly: extra digit(s) towards the thumb/hallux (radially) post-axial polydactyly: extra digit(...
Article

Polyhydramnios

Polyhydramnios refers to a situation where the amniotic fluid volume is more than expected for gestational age. It is generally defined as: amniotic fluid index (AFI) >25 cm largest fluid pocket depth (maximal vertical pocket (MVP)) greater than 8 cm 6: although some centers, particularly in ...
Article

Polysyndactyly

Polysyndactyly refers to the combined presence of polydactyly as well as syndactyly involving either the hands or feet. Polysyndactyly can be associated with a number of syndromes which includes: acrocephalopolysyndactylies (GCPS) type I: Noack syndrome type II: Carpenter syndrome (typically...
Article

Portal sinus

The portal sinus is an L-shaped venous confluence in the fetal circulation. It is located in the liver, between the left and right intrahepatic portal veins. The umbilical vein drains into the portal sinus at its medial aspect, near the left inferior intrahepatic portal vein 1,2. The ductus veno...
Article

Post-axial polydactyly

Post-axial polydactyly refers to polydactyly where the additional digit is on the ulnar margin of the hand, or lateral to the 5th toe. Epidemiology Post-axial polydactyly is more common than pre-axial polydactyly, with an estimated incidence of 1 in 3000 5. Pathology The majority of cases ar...
Article

Post dates fetus

Post dates fetus is when there is prolonged gestation when the fetus remains in-utero beyond 2 weeks beyond expected date of delivery (>42 weeks gestation). Epidemiology The reported frequency is at approximately 3-12% of pregnancies. Pathology Associations maternal obesity Complications ...
Article

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...
Article

Postpartum angiopathy

Postpartum angiopathy is a subset of reversible cerebral vasoconstriction syndrome (RCVS), although is has been described as a separate condition. It is also known as postpartum angiitis and puerperal vasospasm. Please refer to the main article on reversible cerebral vasoconstriction syndrome (R...
Article

Postpartum hemorrhage

Postpartum hemorrhage (PPH) refers to uterine bleeding after delivery and remains one of the major worldwide causes of maternal mortality. Pathology Classification A postpartum hemorrhage can be board classified as primary or secondary. Primary postpartum hemorrhage This is the most common ...
Article

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 f...
Article

Pre-eclampsia

Pre-eclampsia is a disorder of pregnancy involving new-onset hypertension (systolic BP ≥140 mmHg or diastolic BP ≥90 mmHg) and involvement of one or more other organ systems. Epidemiology Pre-eclampsia affects up to 8% of pregnancies 1. Risk factors diabetes mellitus 2 chronic hypertension ...
Article

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...
Article

Pregnancy of uncertain viability

Pregnancy of uncertain viability (PUV) is a term given to an intrauterine pregnancy in a situation where there are not enough criteria (usually on ultrasound grounds) to confidently categorize an intrauterine pregnancy as either viable or a failed pregnancy.  Radiographic features Ultrasound ...
Article

Pregnancy of unknown location

The term pregnancy of unknown location is assigned when neither an intrauterine pregnancy (IUP) or an ectopic pregnancy is identified on transvaginal ultrasound in the context of a positive pregnancy test. Clinical presentation pelvic pain, vaginal bleeding positive pregnancy test Pathology ...
Article

Pregnancy-related osteonecrosis

Pregnancy-related osteonecrosis, also known as pregnancy-related avascular necrosis, is a common cause of femoral head osteonecrosis. Since the femoral head is deficient in blood supply, it is particularly vulnerable to osteonecrosis. Pathology The pathophysiology is thought to be due to venou...
Article

Pregnancy with intrauterine contraceptive device

Pregnancy with intrauterine contraceptive device (IUCD) is uncommon and IUCD is a highly effective contraception method. Chances of pregnancy to occur is highest during the 1st year of IUCD usage and there are chances of adverse outcomes during pregnancy. Epidemiology Pregnancy with IUCD may o...
Article

Premature rupture of membranes

Premature rupture of membranes (PROM) refers to a rupture of the amniotic sac and chorion (membranes) occurring prior to the onset of uterine contractions. When this occurs prior to 37 weeks it is then termed a pre term premature rupture of membranes (PPROM). By this definition, PROM is classifi...
Article

Preplacental abruption

Preplacental abruption or hemorrhage 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 forms of placental abruptio...
Article

Pre-term labor

Pre-term labor 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: consi...
Article

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...
Article

Primary fetal hydrothorax

A primary fetal hydrothorax (PFHT) is a rare situation and refers to a primary accumulation of fetal pleural fluid without any underlying abnormality. It can present with a wide spectrum of severity and can be uni or bilateral. Epidemiology The estimated prevalence is at ~ 1:10,000-15,000 preg...
Article

Proboscis

Proboscis is a rare congenital anomaly where an anterior appendage-like structure is seen projecting from the midline fetal face/forehead. Depending on the exact location, this has further been classified into various subtypes (e.g. interorbital proboscis). Pathology Associations The presence...
Article

Prolonged rupture of membranes

Prolonged rupture of membranes refers to a rupture of membranes lasting longer than 18-24 hours (i.e. between time of rupture and time of delivery) 1-2. This situation can occur in either the term or pre-term newborns where in the latter case it is also termed prolonged preterm rupture of membra...
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, also known as a pseudosac or intra-cavitary fluid, is the concept 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 origi...
Article

Pseudo-omphalocele

Pseudo-omphalocele is a spurious sonographic appearance giving an impression of an anterior abdominal wall defect. Radiographic features Antenatal ultrasound Pseudo-omphalocele may be seen in: scanning errors where there is a deformation of the fetal abdomen by transducer pressure and the im...
Article

Pseudo-TORCH syndrome

Pseudo-TORCH syndrome is a term used to denote cases that clinically resemble congenital infection (see congenital TORCH infections) but where no organisms or serological, microbiological or immunological evidence of infection can be identified 1. It is now believed that pseudo-TORCH syndrome is...
Article

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 ruptu...
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...
Article

Pygopagus

Pygopagus twins are conjoined twins that are joined in the dorsal aspect, facing away from each other. They share the sacrococcygeal and perineal regions. Fusion of sacrum and coccyx frequently occurs. The dura and the spinal cords may be fused in as many as 1/3rd of the cases.The anus, rectum,...
Article

Rachipagus

Rachipagus twins are an extremely rare type of conjoined twins. They are joined in the dorsal aspect and face away from each other. Fusion of the occiput with varying segments of the vertebral column may occur, resulting in the sharing of the spinal cords. The fusion terminates above the sacrum...
Article

Rachischisis totalis

Rachischisis totalis, also known as complete spina bifida, refers to a severe form of spina bifida where there is a cleft through the entire spine. Pathology There is often a severe or complete defect of the neural tube involving the entire spine from the cervical region through to the sacrum....
Article

Radial ray anomaly

Radial ray anomalies comprise of a large spectrum of upper limb anomalies which range from partial (radial hypoplasia) to a complete (radial aplasia) deficiency of the radius with or without accompanying deficiency of the thumb bones. Pathology Associations They can be associated with a numbe...
Article

Radiation effects on embryonic and fetal development

Radiation effects on embryonic and fetal development are generally considered low risk compared to the normal risks of pregnancy. Most diagnostic x-ray and nuclear medicine examinations are <50 mSv and have not been demonstrated to produce any significant impact on fetal growth and development. ...
Article

Redating pregnancy (ultrasound)

Redating a pregnancy may occur when there is a discrepancy between the estimated due date (EDD) calculated by last menstrual period (LMP) and that by ultrasound. Care should be taken when redating a pregnancy, especially in the third trimester, as there may be other reasons for a fetus to be sma...
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 ...
Article

Renal dysgenesis

Renal dysgenesis is a very broad term which can include any form underdevelopment of the kidneys. The spectrum includes: renal agenesis: complete lack of formation renal hypoplasia: partial lack of formation Some authors also classify any form of renal maldevelopment affecting size, shape of ...
Article

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 RPOC complicate ~1-5% of all routine vaginal deliveries 12. According to one prospective study, RPOC was ...
Article

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 visualized post 20 weeks of gestation seen as an echo-poor, subplacental region...
Article

Retroplacental hemorrhage

Retroplacental hemorrhage occurs when there is perigestational hemorrhage that is confined to the retroplacental space. Pathology This type of hemorrhage occurs behind the placenta. The hematoma, therefore, separates the placenta from the uterine wall. The source of bleeding is probably from s...
Article

Reversal of umbilical arterial end diastolic flow

Reversal of umbilical artery end-diastolic flow (REDF) or velocity is often an ominous finding if detected after 16 weeks. It is classified as Class III in severity in abnormal umbilical arterial Dopplers 6. Epidemiology The estimated incidence is at ~0.5% of all pregnancies with a much higher...
Article

Rhizomelic dwarfism

Rhizomelic dwarfism is a type of dwarfism where the dominant feature is proximal (i.e. femoral, humeral) limb shortening. Pathology The following conditions fall under the heading of rhizomelic dwarfism 3 metatropic dysplasia achondrogenesis rhizomelic chondrodysplasia punctata achondropla...
Article

Rhombencephalon

The rhombencephalon (plural: rhombencephalons or rhombencephala), 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 myelenceph...
Article

Right ventricular outflow tract

The right ventricular outflow tract (RVOT) refers to the region of blood outlfow from the right ventricle between the supraventricular crest and the pulmonary valve. It is comprised of the conus arteriosus (infundibulum), ventricular septum and right ventricular free wall. It is commonly assesse...
Article

Right ventricular outflow tract view (fetal echocardiogram)

The right ventricular outflow tract (RVOT) view (or three vessel view/3VV) is one of the standard views in a fetal echocardiogram. It principally assesses the right ventricular outflow tract. It is a long axis view of the heart, highlighting the path from the right ventricle into the pulmonary t...
Article

Roberts sign (fetal demise)

Roberts 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. History and etymology First describ...
Article

Roberts syndrome

Roberts syndrome, also known as Roberts-SC phocomelia syndrome, pseudothalidomide syndrome, or Appelt-Gerken-Lenz syndrome, is a rare congenital malformation syndrome. Clinical presentation general intrauterine growth restriction postnatal growth retardation failure to thrive thrombocytope...
Article

Robinow syndrome

Robinow syndrome is a rare heterogeneous genetic disorder with at least two distinct forms. Clinical spectrum The syndrome can affect several systems, including: mesomelic limb shortening: mesomelia hemivertebrae characteristic facies anomalies fetal facies hypertelorism 3 frontal bossin...
Article

Rocker bottom foot

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

Rothmund-Thomson syndrome

Rothmund-Thomson syndrome (RTS) is an extremely rare autosomal recessive disorder with heterogeneous clinical features. Clinical presentation It is characterized by many features which include: poikiloderma: characteristic rash, typically develops in infancy sparse hair, eyelashes, and/or ey...
Article

Rubinstein-Taybi syndrome

Rubinstein-Taybi syndrome (RTS) is a very rare genetic multi-system disorder primarily characterized by intellectual disability, broad and often angulated thumbs and halluces, and distinctive facial features. Epidemiology The estimated incidence is 1 in 100,000-125,000 live births 5. Clinical...
Article

Ruptured omphalocele

Ruptured omphalocele occurs when there is rupture of the outer membrane of an omphalocele. When this happens the eviscerated fetal bowel looks free floating and distinction from gastroschisis becomes difficult. However, with a ruptured omphalocele, the abdominal defect generally tends to be larg...
Article

Rupture of fetal membranes

A rupture of membranes (ROM) or amniorrhexis is a term used during pregnancy to describe a rupture of the amniotic sac. This can occur as part of normal birth (or "spontaneously")  if it occurs at full term at the onset of, or during, labor. It is also  colloquially known as "breaking water." S...
Article

Russell-Silver dwarfism

Russell-Silver dwarfism is a very rare syndrome characterized by: intrauterine growth restriction: tends to give an asymmetrical IUGR postnatal growth restriction relatively large calvarium: pseudohydrocephalus clinodactyly/clinobrachydactyly of the small finger a typical triangular type fa...
Article

Sacrococcygeal teratoma

Sacrococcygeal teratoma (SCT) refers to a teratoma arising in the sacrococcygeal region. The coccyx is almost always involved 6. Epidemiology It is the commonest congenital tumor in the fetus 11 and neonate 3. The incidence is estimated at ~1:35000-40000. There is recognized female predilectio...
Article

SADDAN syndrome

SADDAN syndrome is an acronym for severe achondroplasia with developmental delay and acanthosis nigricans. It is an extremely rare condition, and as the name states, comprises a combination of skeletal, brain and cutaneous anomalies. Pathology Genetics The syndrome results from a mutation in ...
Article

Sakati-Nyhan syndrome

The Sakati-Nyhan syndrome, also known as Sakati-Nyhan-Tisdale syndrome or acrocephalosyndactly type III, is an extremely rare type of acrocephalopolysyndactyly. Its main features include: craniofacial defects congenital limb abnormalities congenital heart defects History and etymology It w...
Article

Sandal gap deformity

A sandal gap deformity, also known as hallux varus, is an imaging observation in antenatal ultrasound (typically second trimester) where there is an expanded first interspace, i.e. the gap between the great toe of the foot from the rest of the toes (likened to the gap caused by a sandal).  Whil...
Article

Scar endometriosis

Scar endometriosis is a term given to endometriosis occurring in a Cesarian section scar. It can be located in the skin, subcutaneous tissue, rectus muscle/sheath, intraperitoneally, or in the uterine myometrium (within uterine scar). Epidemiology The reported incidence of abdominal scar endom...
Article

Schizencephaly

Schizencephaly is a rare cortical malformation that manifests as a grey matter lined cleft extending from the ependyma to the pia mater. Terminology Some authors do not use the term schizencephaly, preferring to group these disorders under the blanket term of porencephaly. For the purpose of t...
Article

Seckel syndrome

Seckel syndrome is an autosomal recessive congenital dwarfing disorder. Epidemiology The estimated incidence is ~1:10,000. There is no recognized gender predilection. Clinical presentation It is clinically characterized by many features including: intrauterine growth restriction postnatal ...
Article

Second trimester ultrasound scan

The second trimester scan is a routine ultrasound examination in many countries that is primarily used to assess fetal anatomy and detect the presence of any fetal anomalies.  The second trimester extends from 13 weeks and 0 days to 27 weeks and 6 days of gestation although the majority of thes...
Article

Semilobar holoprosencephaly

Semilobar holoprosencephaly is a subtype of holoprosencephaly characterized by incomplete forebrain division. It is intermediate in severity, being worse than lobar holoprosencephaly and better than alobar holoprosencephaly. Epidemiology Please refer to the general article of holoprosencephaly...
Article

Shortened fetal femoral length

Shorted fetal femur is a morphological descriptor and is usually defined when the femoral length falls below the 5th centile for gestational age (some define it when it is under the 2.5th centile 5) or less than 0.91 predicted by the bi-parietal diameter. It can occur in isolated or in associati...
Article

Shortened fetal humerus

Shortened fetal humerus is a morphological description and is usually defined when the humeral length falls below the 5th percentile or less than 0.9 as predicted by the biparietal diameter (BPD). It can occur in isolation or in association with a number of other anomalies. The humeral length i...
Article

Shortened fetal long bones

Shortened fetal long bones (SFLB) can involve either the upper limb and/or the lower limb. It is a broad descriptive entity which can include short fetal femur short fetal humerus short fetal tibia-fibula short fetal radius - ulna Pathology Associations the presence of shorted fetal long ...
Article

Shortening of the cervical canal

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

Short maxillary length

A short maxillary length can result from many congenital and acquired causes. If seen in an antenatal ultrasound scan, it is often considered to have a high association with trisomy 21 1.  Congenital conditions Many conditions that can cause midfacial hypoplasia will result in a short maxillar...
Article

Short rib polydactyly syndrome

Short rib polydactyly syndrome(s) (SRPS) comprise a rare group of severe osteochondrodysplasias. There are four major recognized types present: type I: Saldino-Noonan type type II:: Majewski type type III: Verma-Naumoff type type IV: Beemer-Langer type There may also be other very rare type...
Article

SHORT syndrome

SHORT syndrome refers to an acronym which primarily comprises of the following features: S: short stature H: hyperextensibility of joints and/or inguinal hernia O: ocular depression R: Rieger anomaly T: teething delay In a addition to these there can be numerous associated minor features w...
Article

Short umbilical cord

Short umbilical cord has been variably defined. Considering the mean length of the umbilical cord is 50-70 cm 1-2, a short cord in absolute terms is usually taken as one that is under 35-40 cm in length at term 1-2.  Pathology Associations Recognized associations include chromosomal anomalie...
Article

Simple hydropic degeneration of the placenta

Simple hydropic degeneration of the placenta is a form of hydropic degeneration of the placenta that can occur in a first trimester pregnancy loss. In this situation, the serum beta HCG will tend to be low and tend to show a decline with repeat testing. The overall sonographic appearance can va...
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 unknown reasons, the absence of the left umbilical artery is much more common (~70%). Epidemiology The estimat...
Article

Sirenomelia

Sirenomelia (also known as the mermaid syndrome) is a rare congenital malformation characterized by the fusion of lower limb structures. Epidemiology The estimated incidence is at ~1 in 60,000-70,000 of pregnancies 9. There may be greater male predilection (somewhat paradoxical given the usage...
Article

Skeletal dysplasia

Skeletal dysplasia (also known as osteochondrodysplasia) refers to any abnormality in bone formation. There is a very wide clinicopathological spectrum and any part of the skeleton can be affected. Epidemiology The overall prevalence is estimated at ~2 per 10,000 live births 3. Pathology Typ...
Article

Small for date fetus

A small for dates fetus can result from a number of factors Fetal factors aneuploidy trisomy triploidy skeletal dysplasia(s) structural anomalies (syndromes) Maternal factors Common hypertension medication(s): fetal Warfarin syndrome hydantoin embryopathy (Dilantin TM) cytotoxic dru...
Article

Small gestational sac

A small gestational sac in early first trimester is considered a poor prognostic factor. Some authors use the mean sac diameter to crown rump length difference of 5 mm or greater to be normal 1.   The smaller than expected sac diameter in pregnancies 36-42 days from the last menstrual period ha...
Article

Small placenta

A small placenta if observed on antenatal ultrasound can arise from a number of situations. They include: variation in placental morphology: where only part of the placenta is seen bilobed placenta: with only one lobe seen succenturiate lobe: with either main lobe or succenturiate lobe not se...
Article

Small placenta (mnemonic)

A mnemonic to remember the causes of small placenta is: PCI 2 It can be read as percutaneous coronary intervention i.e. PCI 2 Mnemonic P: pre-eclampsia C: chromosomal anomaly e.g. Down syndrome I: intrauterine infection I: intrauterine growth retardation
Article

Small yolk sac

A small yolk sac is considered a non-specific feature and, at the time of writing, there are not many publications about the clinical importance of small yolk sacs. According to some publications, a very small yolk sac may be a normal finding during early periods of normal embryologic developme...
Article

Smith-Lemli-Opitz syndrome

Smith-Lemli-Opitz syndrome (SLOS) also known as 7-dehydrocholesterol reductase deficiency is an inborn error of cholesterol synthesis.  Epidemiology The estimated incidence is at 1:20000-40000 live births. Prevalence may be greater in Nordic countries. Clinical presentation There are many wh...
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

Snowstorm sign (complete hydatiform mole)

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

Snowstorm sign (disambiguation)

Snowstorm sign may refer to: snowstorm sign: complete hydatiform mole (ultrasound) snowstorm sign: extracapsular breast implant rupture (ultrasound) snowstorm sign: thyroid pulmonary metastases (chest radiograph)
Article

Sonographic values in obstetrics and gynecology

Obstetric and gynecological ultrasound is rampant with numerous cut off values. Some of these get revised over the years. The following list is a useful aid to refer to and revise. 1 mm rate of increase of a mean sac diameter per day in early pregnancy 2 mm generally accepted value for a thi...
Article

Spalding sign (fetal demise)

The Spalding sign refers to 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 by Alfred Baker Spalding (1874-1942), an American obstetrician 2, on abdominal radiogr...