Ian Donald (1910-1987) was a Scottish obstetrician who pioneered the diagnostic use of ultrasound in medicine.
Ian Donald was born in Cornwall, United Kingdom on 27th December 1910 6. His father was a general practitioner. In 1925 his family moved to South Africa where he attended C...
Congenital talipes equinovarus (CTEV) is considered the most common anomaly affecting the feet diagnosed on antenatal ultrasound.
While some use CTEV and clubfoot (CF) synonymously, in certain publications term clubfoot is considered a more general descriptive term that describes t...
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.
The estimated incidence is at 1:1000-2000 live births 2.
A constellation of fe...
Twin reversed arterial perfusion (TRAP) sequence is considered a severe variant of the twin to twin transfusion syndrome (TTTS). The hallmark of this condition which only happens in monochorionic pregnancies is the lack of placental perfusion of one of the twins (so-called acardiac twin), with a...
In utero Herpes simplex infection usually occurs from transplacental tramission of the Herpes simplex virus. Transplacental intrauterine infection with herpes simplex virus is an extremely rare complication of primary herpes simplex in pregnancy.
Fetal HSV infection much less comm...
Placental surface cysts are often related to cystic change in an area of subchorionic fibrin. They can be variable in size.
subchorionic cyst: commonest type 2
amniotic epithelial inclusion cyst
Most placental surface cysts are associated with a normal pregnancy outco...
An eccentrically-located gestational sac towards the fundus of the uterus is the normal sonographic appearance; however an abnormally eccentric gestational sac on ultrasound may be apparent due to a number of causes
interstitial ectopic pregnancy 1
normally implanted pregnancy in...
Threatened miscarriage (or threatened abortion) is mainly a clinical term, used when a pregnant woman in first 20 weeks of gestation presents with spotting, mild abdominal pain and contractions, with a closed cervical os.
It occurs in 20-25% of pregnancies and is associated with ...
Cephalocele refers to the outward herniation of CNS contents through a defect in the cranium. The vast majority are midline.
The estimated incidence is 0.8-4:10,000 live births 13 with a well recognised geographical variation between types; however, this has been speculated to be ...
Erb palsy, also known as brachial plexus birth palsy, is a form of obstetric brachial plexus injury as a result of complications during delivery.
The most common cause is due to excessive lateral traction or stretching of the fetal head and neck in opposite directions du...
Fetal toxoplasmosis is an in utero infection that results from transplacental transmission and subsequent infection with the organism Toxoplasma gondii. It falls in the TORCH group of infections.
Please refer on congenital cerebral toxoplasmosis for a specific discussion on this condition.
Placental thickness tends to gradually increase with gestational age in a linear fashion. Sonographically, this can be seen to be approximately 1 mm per week and the thickness of the placenta can be used to approximate gestational age:
approximate gestational age (in weeks) = placental thicknes...
Cardiac rhabdomyomas are a type of benign myocardial tumour and are considered the most common fetal cardiac tumour. They have a strong association with tuberous sclerosis.
Cardiac rhabdomyomas are often multiple and can represent up to 90% of cardiac tumours in the paediatric pop...
A telephone receiver deformity is a characteristic bowing of the shaft of the long bones, usually the humeri or femora, seen in thanatophoric dysplasia.
Thanatophoric dysplasia (TD) is a lethal skeletal dysplasia. It is the most common lethal skeletal dysplasia followed by osteogenesis imperfecta type II.
The estimated incidence is around 1:25,000-50,000 3.
It results from a mutation coding for the fibroblas...
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.
Unilateral renal agenesis affects approximately 1 in ...
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.
MDAs are estimated to occur...
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.
The overall prevalence is estimated at ~2 per 10,000 live births 3.
Congenital high airways obstruction syndrome (CHAOS) refers to a rare, often lethal, congenital laryngotracheal condition and is primarily characterised by obstruction to the fetal upper airway.
CHAOS can be of three possible types 2:
complete laryngeal atresia without an oesophagea...
Fetal pyelectasis refers to a prominence of the renal pelvis in utero that is a relatively common finding, which in the majority of cases resolves spontaneously.
Please refer to the article on fetal hydronephrosis for a continued discussion on this matter.
Although there is an ...
The rhombencephalon, or hindbrain is a primary vesicle of the neural tube.
During the fifth week of embryological development the rhombencephalon further subdivides into the secondary brain vesicles, the metencephalon and the myelencephalon 1.
The metencephalon goes on to form th...
Terminal myelocystoceles are an uncommon form of spinal dysraphism representing marked dilatation of the central canal of the spinal cord, herniating posteriorly through a dorsal spinal defect. The result is a skin-covered mass in the lower lumbar region, consisting of an ependyma-lined sac.
Three-dimensional (3D) ultrasound is a technique that converts standard 2D grayscale ultrasound images into a volumetric dataset. The 3D image can then be reviewed retrospectively. The technique was developed for problem-solving (particularly in obstetric/gynaecologic exams) and to potentially r...
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.
Posterior urethral valves are congenital and only...
Hydranencephaly is a rare encephalopathy that occurs in-utero. It is characterised by destruction of the cerebral hemispheres which are transformed into a membranous sac containing cerebrospinal fluid and the remnants of cortex and white matter 1.
Porencephaly is considered a less severe degree...
The dorsal cyst of holoprosencephaly is a large cerebrospinal fluid cavity present in holoprosencephaly that occupies the area above the dorsocaudal aspect of the diencephalon. This communicates directly with the prosencephalic, telencephalic, or diencephalic ventricle. This cavity usually abuts...
A fetal arachnoid cyst is term given when an arachnoid cyst is diagnosed in utero. For a general discussion of arachnoid cysts refer to the parent article.
They can be classified as being primary or secondary 2.
primary (congenital) arachnoid cysts: result from a benign accumulation...
Ectopic pregnancy refers to the implantation of a fertilised ovum outside of the uterine cavity.
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...
The uterine tube, also known as the Fallopian tube or less commonly the oviduct, is a paired hollow tube that bridges between each ovary and the uterus and functions to convey the mature ovum from the former to the latter. If conception occurs, it normally does so within the tube. It can be affe...
The placenta is a fetal organ of pregnancy, responsible for providing nutrition and oxygen to the fetus as well as excretory functions.
Placenta is formed by fetal and maternal components 2:
maternal component: decidua placentalis is the inner portion of the placenta, which is for...
Fanconi anaemia (FA) is a rare disorder characterised by progressive bone marrow failure, various congenital abnormalities, and predisposition to malignancies (often acute myeloid leukaemia). It is considered the commonest type of inherited marrow failure syndrome 7.
Snake under the skull sign is a vascular anomaly seen in holoprosencephaly.
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...
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.
It typically occurs within the first 20 weeks of gest...
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)
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%).
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.
The true prevalence is not well known (1.4% of all births according to Knox et al. 13), but in cases of premature ruptu...
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 drug cl...
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...
The Potter sequence is a constellation of findings demonstrated postnatally as a consequence of severe, prolonged oligohydramnios in utero.
It consists of:
pulmonary hypoplasia: often severe and incompatible with life
growth restriction (IUGR)
abnormal facies (Potter f...
Pre-placental abruption or haemorrhage can be subamniotic or subchorionic in location.
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.
Pre-term labour refers to spontaneous delivery of the fetus prior to 37 weeks of gestation. This is regardless of estimated fetal weight.
shortened cervical length
presence of cervical funneling
dilatation or internal cervical os: cons...
Preterm premature rupture of membranes (PPROM) refers to rupture of membranes prior to 37 weeks of gestation.
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).
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 for both mother and infant, which may result in exsanguination. As such, antenatal diagnosis is essentia...
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.
The estimated incidence is ~1:20,000-40,000 pregnancies 1...
Placental insufficiency is a term given to a situation where the placenta cannot bring enough oxygen and nutrients to the growing fetus.
Fetuses may present with intra-uterine growth restriction (IUGR) (especially asymmetrical IUGR).
It can be primarily caused...
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.
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.
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.
commonest type of placental invasion (~75% of cases)
occurs in ~1 in 7,000...
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 invade the myometrium.
The estimated incidence is increasing (likely rel...
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.
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...
A persistent right umbilical vein (PRUV) is an uncommon vascular anomaly which is often detected in utero.
The estimated prevalence is ~2 per 1000 births 1,2.
In the normal situation, the right umbilical vein begins to obliterate in the ~4th week of gestation and disap...
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.
Nuchal translucency is the normal fluid filled subcutaneous space identified at the back of the fetal neck during in the late first trimester and early second trimester (11.3-13.6 weeks).
It should not be confused with the nuchal fold, which is seen in the second trimester.
Birth trauma relates to those conditions caused by both physical/mechanical and hypoxic injuries.
Birth trauma occurs in ~5 per 1000 births 2.
Placental site trophoblastic tumour (PSTT) is a rare and one of the least common (~ 0.2% 7) forms of gestational trophoblastic disease (GTD).
PSTT typically occurs in women of reproductive age with the average age around 30. It may occur after a normal pregnancy, molar pregnancy o...
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...
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.
This is an often underdiagnosed an...
A placental septal cyst is a placental cyst typically located in the 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.
Lithopaedions, also referred as stone babies, are a rare phenomenon which occurs most commonly when a fetus dies during an ectopic pregnancy.
The estimated incidence is at ~ 1.5 to 1.8% of abdominal ectopic pregnancies 4.
If the deceased fetus is too large to be re-abs...
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.
The estimated incidence is ~2 per 1000 pregnancies.
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...
Parturition-induced pelvic instability is a rare condition seen in women following vaginal delivery.
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, ...
Partial hydatidiform mole is a type of hydatidiform mole, which in turn falls under the spectrum of gestational trophoblastic disease.
Clinical signs and symptoms such as abdominal pain, cramps of the lower abdomen and vaginal bleeding during pregnancy are common but non...
Ovarian ectopic pregnancies are rare (1-3%) when compared to other types of ectopic pregnancy such as tubal ectopic.
Risk factors include pelvic inflammatory disease, IUCD use and endometriosis. Pathogenesis is debated and lies between:
fertilisation of the ovum in th...
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...
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...
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.
It results from a dorsal and lateral dislocation of the talonavicular joint.
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.
Retained products of conception complicate ~1-5% of all pregnancies (routine vaginal deliveries 12).
Triploidy is a rare lethal chromosomal (aneupliodic) abnormality caused by the presence of an entire extra chromosomal set.
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 ...
Retroplacental haemorrhage occurs when there is perigestational haemorrhage that is confined to the retroplacental space.
This type of haemorrhage occurs behind the placenta. The haematoma therefore separates the placenta from the uterine wall. The source of bleeding is probably from...
Thrombocytopenia with absent radius (TAR) syndrome is primarily characterised by the following two features:
absent fetal radii (bilaterally) with the presence of both thumbs
The condition is extremely rare with an estimated incidence of 0.4 per 100,000 bi...
Fetal thrombocytopenia refers to an abnormally low platelet count in the fetus. The acceptable normal range for a fetal platelet count is similar to adults and do not vary significantly with gestation age. The lower limit for cut off is therefore usually taken as:
150,000/uL for thrombocytopeni...
Isolated inferior vermian hypoplasia (IIVH), also referred as part of Dandy-Walker variant (DWV), is a congenital malformation characterised by partial absence of the inferior portion of the cerebellar vermis.
The term Dandy-Walker variant was created to include those malformations...
Interstitial ectopic pregnancy (also known as intramural ectopic pregnancy) is an important type of ectopic pregnancy with higher risks of rupture and haemorrhage compared to usual tubal ectopic pregnancies.
The term interstitial pregnancy is sometimes interchangeably used with co...
An omphalomesenteric duct cyst is a type of true umbilical cord cyst.
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...
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...
Incomplete miscarriage is a term given to miscarriage where there are retained products of conception still within the uterus.
Ultrasound appearance is variable, ranging from visible fetal parts to a mass of mixed echogenicity. The presence of a prominent vasc...
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.
This is an uncommon presentation and is said to occur in 1 in 3000 pregnancies. Uncomplicated retroversion may...
An oesophageal atresia refers to an absence in the 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.
It is thought to occur in ~1:3000-4500 live bir...
The uterus is a hollow, thick-walled, muscular organ of the female reproductive tract that lies in the lesser pelvis.
The uterus has an inverted pear shape. In the adult, it measures about 7.5 cm in length, 5 cm wide at its upper part, and nearly 2.5 cm in thickness. It weighs ...
Myelomeningocoele, also known as spina bifida cystica, is a complex congenital spinal anomaly that results in spinal cord malformation (myelodysplasia).
It is one of the commonest congenital CNS anomalies and thought to occur in approximately 1:500 of live births 5. There may be ...
Ovarian vein thrombosis (actually most often a thrombophlebitis) occurs most commonly in postpartum patients and can result in pulmonary emboli. A presentation is usually with acute pelvic pain in the postpartum period, then termed puerperal ovarian vein thrombosis or postpartum ovarian vein th...
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.
Depending on the chromosomal composition, patients may have testes and/or streak gonads.
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.
Ultrasound diagnosis of miscarriage should only be considered when either a mean gestation sac d...
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...
Hydatidiform moles are one of the most common but benign forms of gestational trophoblastic disease.
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...
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.
Hemimegalencephaly is a cryptogen...
Gestational choriocarcinoma (GC) is a type of choriocarcinoma that follows a gestational event. Similar to choriocarcinomas in general, it lies at the malignant end of the spectrum of gestational trophoblastic disease.
Approximately 50% of gestational choriocarcinomas arise from a pr...
Gastroschisis refers to extra-abdominal herniation (evisceration) of fetal or neonatal bowel loops (and occasionally portions or the stomach and or liver) into the amniotic cavity through a para-umbilical abdominal wall defect.
The estimated incidence is at around 1-6 per 10,000...
Gartner duct cysts develop from embryologic remnants of the Wolffian (mesonephric) duct. They are often noticed incidentally on ultrasound or MRI.
They may cause mass effect on adjacent structures.
Gartner duct cysts are located in the anterolateral ...
Endometrial thickness is a commonly measured parameter on routine gynaecological ultrasound and MRI. The appearance, as well as the thickness of the endometrium, will depend on whether the patient is of reproductive age or postmenopausal and, if of reproductive age, at what point in the menstrua...
Twin growth discordance is a term used in obstetric imaging to describe a significant size or weight difference between the two fetuses of a twin pregnancy. To be classified as a growth discordance, some consider that the estimated fetal weight (EFW) of the smaller twin should fall under the 10t...