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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...

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...

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...

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...

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 relatively deficient in blood supply, it is particularly vulnerable to osteonecrosis. Pathology The pathophysiology is thought to be d...

Patau syndrome

Patau syndrome (also known as trisomy 13) is considered the 3rd commonest autosomal trisomy. Patau syndrome, Down syndrome (trisomy 21), and Edwards syndrome (trisomy 18) are the only three trisomies compatible with extrauterine life. However, few infants with either Patau or Edwards syndrome l...

Omphalocele

Omphaloceles, also known as exomphalos (rare plural: exomphali), are congenital midline abdominal wall defects at the base of the umbilical cord insertion, with herniation of gut (or occasionally other structures) out of the fetal abdomen. Epidemiology The estimated occurrence can be up to 1:4...

Nuchal translucency

Nuchal translucency is the normal fluid-filled subcutaneous space identified at the back of the fetal neck during the late first trimester and early second trimester (11 weeks 3 days to 13 weeks 6 days). It should not be confused with the nuchal fold, which is seen in the second trimester. P...

Nuchal fold

The nuchal fold is a normal fold of skin seen at the back of the fetal neck during the second trimester of pregnancy. Increased thickness of the nuchal fold is a soft marker associated with multiple fetal anomalies, and is measured on a routine second trimester ultrasound. Terminology It shou...

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)

Twin pregnancy

Twin pregnancies are the most common multifetal pregnancies. Epidemiology Multifetal pregnancies account for ~1% of all pregnancies but are seen in much higher numbers in populations where in vitro fertilisation (IVF) is a common practice. Classification A twin pregnancy can be broadly cate...

Miscarriage

A miscarriage is the spontaneous termination of a pregnancy before 20 weeks of gestation. Fetal death after week 20 is termed fetal death in utero (FDIU). Terminology The term miscarriage is preferred by many over 'abortion' due to the use of the latter for therapeutic pregnancy termination, a...

Megalencephaly

Megalencephaly is a disorder characterized 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. Terminology ...

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. Measurement MSD = (length + height + width)/3 Normal MSD (in mm) + 30 = days of pregn...

Lithopedion

Lithopedions, also known 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 deceased fetus is too large to be re-absorbed...

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%...

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%).

Interstitial ectopic pregnancy

Interstitial ectopic pregnancy, also known as intramural ectopic pregnancy, is an important type of ectopic pregnancy which occurs in the proximal portion of the fallopian tube that lies within the muscle wall of the uterus. This is type of ectopic is associated with higher risks of rupture and ...

Holoprosencephaly

Holoprosencephaly (HPE) is a rare congenital brain malformation resulting from incomplete separation of the two hemispheres. Classically three subtypes have been recognized, however additional entities are now included in the spectrum of the disease. The three main subtypes, in order of decreas...

Gestational trophoblastic disease

Gestational trophoblastic disease (GTD) results from the abnormal proliferation of trophoblastic tissue and encompasses a wide spectrum of diseases, including 14: tumor-like lesions exaggerated placental site reaction placental site nodule and plaque abnormal (non-molar) villo...

Gestational sac

The gestational sac is the first sign of early pregnancy on ultrasound and can be seen with endovaginal ultrasound at approximately 3-5 weeks gestation when the mean sac diameter (MSD) would approximately measure 2-3 mm in diameter. A true gestational sac can be distinguished from a pseudogesta...

Fetal dosimetry

NB: Please consult original article(s) and discuss with your local radiology department/radiation physicist before making any clinical decision. Although radiation exposure to the gravid uterus is to be avoided whenever possible, and only deliberately performed after careful weighing up of the ...

Fallopian tube

The fallopian tube (TA: tuba uterina 8), also known as the uterine tube or, less commonly, the oviduct, is a paired hollow tube that bridges the ovary and uterus and functions to convey the mature ovum from the former to the latter. If conception occurs, it usually does so within the tube, which...

Hemimegalencephaly

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

Empty gestational sac

Empty gestational sacs can be due to a number of causes: anembryonic pregnancy (also known as "blighted ovum") early pregnancy (intrauterine): by 5.5 weeks gestational age, a yolk sac should be identifiable by transvaginal ultrasound pseudogestational sac with an ectopic pregnancy gestationa...

Ectopic pregnancy

Ectopic pregnancy refers to the implantation of a fertilised ovum outside of the uterine cavity. Epidemiology The overall incidence has increased over the last few decades and is currently thought to affect 1-2% of pregnancies. The risk is as high as 18% for first-trimester pregnancies with bl...

Edwards syndrome

Edwards syndrome, also known as trisomy 18, along with Down syndrome (trisomy 21) and Patau syndrome (trisomy 13), make up the only three autosomal trisomies to be compatible with extrauterine life in non-mosaic forms, albeit in the case of Edward syndrome only for a week or so. Epidemiology ...

Early pregnancy

Early pregnancy roughly spans the first ten weeks of the first trimester. Radiographic features Antenatal ultrasound 0-4.3 weeks: no ultrasound findings 4.3-5.0 weeks: possible small gestational sac possible double decidual sac sign (DDSS) possible intradecidual sac s...

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...

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) when the yolk sac or embryo is still not visualized. It consists of the decidua parietalis (lining the uterine cavity) and decidua capsularis (lining the gestati...

Cystic hygroma

Cystic hygroma, also known as cystic or nuchal lymphangioma, refers to the congenital macrocystic lymphatic malformations that most commonly occur in the cervicofacial regions, particularly at the posterior cervical triangle in infants. Terminology While these lesions are commonly known as cys...

Crown rump length

Crown rump length (CRL) is the length of the embryo or fetus from the top of its head to bottom of torso. It is the most accurate estimation of gestational age in early pregnancy, because there is little biological variability at that time. Measurement CRL is measured as the largest dimension ...

Congenital megaureter

A congenital (primary) megaureter encompasses causes of an enlarged ureter which are intrinsic to the ureter, rather than as a result of a more distal abnormality; e.g. bladder, urethra (see secondary megaureter). It includes: obstructed primary megaureter refluxing primary megaureter althoug...

Congenital pulmonary airway malformation

Congenital pulmonary airway malformations (CPAM) are multicystic masses of segmental lung tissue with abnormal bronchial proliferation. CPAMs are considered part of the spectrum of bronchopulmonary foregut malformations. Terminology Until recently, they were described as congenital cystic aden...

Cervical incompetence

Cervical incompetence refers to a painless spontaneous dilatation of the cervix and is a common cause of second trimester pregnancy failure. Epidemiology The estimated incidence varies geographically and generally thought to be around 1-1.5% of all pregnancies 1,15. Clinical presentation Typ...

Cervical ectopic pregnancy

Cervical ectopic pregnancy is a rare subtype of ectopic pregnancy, in which a gestational sac is seen at the endocervical canal below the closed internal os. Epidemiology It accounts for ~0.15-1% of all ectopic pregnancies. Pathology Implantation of the fertilized ovum occurs within the cer...

Cervical cancer (staging)

Staging of cervical cancer can either be based on the TNM or FIGO system. Classification Revised FIGO staging of cervical carcinoma (2018) FIGO no longer includes stage 0 (Tis) I: confined to cervix uteri (extension to the corpus should be disregarded) IA: invasive carcinoma only diagnosed ...

Cephalohematoma

Cephalohematomas are traumatic subperiosteal hematomas of the skull that are usually caused by birth injury. They are bound between the periosteum and cranium, and therefore cannot cross sutures. Being bound by a suture line distinguishes them from subgaleal hematoma, which can cross sutures. E...

Anembryonic pregnancy

Anembryonic pregnancy is a form of a failed early pregnancy, where a gestational sac develops, but the embryo does not form. Terminology The term blighted ovum is synonymous with this but is falling out of favor and is best avoided. Clinical presentation The patient may be asymptomatic, pr...

Banana sign (cerebellum)

The banana sign is one of the many notable fruit inspired signs. This sign is seen on axial imaging through the posterior fossa of fetuses with associated conditions such as Chiari II malformation and/or spina bifida. In Chiari II malformation, the banana sign describes the way the cerebellum...

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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