A helpful mnemonic for remembering some causes and complications of oligohydramnios is:
R: renal abnormalities (decreased urine output)
P: premature rupture of membranes
C: chromosomal anomalies
Cebocephaly refers to a type of rare midline craniofacial anomaly where there is a single nostril (which usually ends blindly 6-7) with proboscis-like nose 8 and hypotelorism.
holoprosencephaly: particularly alobar holoprosencephaly
Cenani-Lenz syndactyly (CLS) is a very syndrome primarily characterised by:
syndactyly/oligodactly: syndactyly is often complete and gives a spoon hand type appearance
It carries an autosomal recessive inheritance.
It was first described...
The cephalic index (CI) is a value calculated using two fetal biometric parameters which are the occipitofrontal diameter (OFD) and the biparietal diameter (BPD).
It is calculated as:
cephalic index (CI) = biparietal diameter (BPD)/occipitofrontal diameter (OFD) x 100
The cephalic index gi...
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 sub-types. These may be a greater female predil...
Cephalohaematomas are traumatic subperiosteal haematomas of the skull that are usually caused by birth injury. They are bound by the periosteum and, therefore, cannot cross sutures. Being bound by a suture line distinguishes them from subgaleal haematoma, which can cross sutures.
Cephalopagus twins are a rare type of conjoined twins. They are fused from the vertex to the umbilicus. They share a common cranium with either one composite face or two faces on opposite sides of the conjoined head.
The thoraces are fused with fusion of liver, heart and the upper gastrointesti...
Cephalopelvic disproportion (CPD) occurs when there is a mismatch between the size of the fetal head and the maternal pelvis causing a difficulty in the safe passage of the fetus through the birth canal.
Cephalopelvic disproportion may be caused by the fetal head outgrowing the capac...
Cerebroplacental ratio (CPR) is an obstetric ultrasound tool used as a predictor of adverse pregnancy outcome in both small for gestational age (SGA) and appropriate for gestational age (AGA) fetuses. An abnormal CPR reflects redistribution of cardiac output to the cerebral circulation, and has ...
Staging of cervical cancer can either be based on the TNM or FIGO system.
Revised FIGO staging of cervical carcinoma 2009 8
stage 0: cervical intraepithelial neoplasia (HSIL or CIN III)
stage I: confined to cervix
stage Ia: invasive carcinoma only diagnosed by microscopy.
Ia1: stromal inva...
Cervical ectopic pregnancy is a rare subtype of ectopic pregnancy.
It accounts for ~0.15-1% of all ectopic pregnancies.
Implantation of the fertilized ovum occurs within the cervix rather than the uterine cavity. Unless the fetal heart rate can be identified, it is di...
Cervical incompetence refers to a painless spontaneous dilatation of the cervix, and is a common cause of 2nd trimester pregnancy failure.
The estimated incidence varies geographically and generally thought to be around 1-1.5% of all pregnancies 1,15.
Sequential morphological ultrasound changes of the endocervical canal with cervical incompetence can be remembered using the mnemonic:
Trust Your Vaginal Ultrasound
T-shaped (normal internal cervical os)
In obsteric and gynaecological imaging, the cervical length (CL) is defined as the length between the internal cervical os and the external cervical os.
the cervical length is most accurately assessed on a transvaginal scan with an empty bladder
in a normal...
The term cervical stenosis can refer to:
stenosis of the uterine cervix
bony cervical canal stenosis (cervical spinal stenosis)
The cervix or uterine cervix is the lower constricted segment of the uterus providing the passage between the uterus proper and the vagina.
The cervix is somewhat conical in shape, with its truncated apex directed posteriorly and inferiorly. The inferior aspect of the cervix pro...
Chiari III malformation is an extremely rare anomaly characterized by a low occipital and high cervical encephalocele with herniation of posterior fossa contents, that is, the cerebellum and/or the brainstem, occipital lobe, and fourth ventricle.
agenesis of the corpus...
Chiari II malformation, also known as Arnold-Chiari malformation, is a relatively common congenital malformation of the spine and posterior fossa characterised by myelomeningocoele (lumbosacral spina bifida aperta) and a small posterior fossa with a descent of the brainstem and cerebellar tonsil...
CHILD syndrome is an acronym for congenital hemidysplasia with ichthyosiform erythroderma and limb defects. It comprises of:
Ch: congenital hemidysplasia
I: ichthyosiform erythroderma
develops at or shortly after birth
unilateral erythema and scaling, with a distinct demarcation in the middl...
Chondrodysplasia punctata (CDP) is a collective name for a heterogenous group of skeletal dysplasias. Calcific stippling of cartilage and peri-articular soft tissues is often a common feature.
It can be broadly divided into rhizomelic and non-rhizomelic forms:
Chondroectodermal dysplasia, also known as the Ellis-van Creveld syndrome, is a rare type of skeletal dysplasia. It is classified as a type of mesomelic limb shortening 5.
Clinical features include:
narrowing of thorax with short ribs
small and flared ilia
Chorioamnionitis refers to infection of the chorion and amnion during pregnancy.
Chorioamnionitis affects an estimated 2-4% of term deliveries and 40-70% of preterm deliveries1.
Clinically, chorionamnionitis can present with the following maternal signs and...
Chorioamniotic separation (CAS) is an intra-uterine event which can occur in pregnancy and is characterised by separation of placental (chorion) and fetal (amnion) membranes.
The membranes are separated in early gestation, accounting for the appearance of the amniotic sac. Afte...
Choriocarcinoma is an aggressive, highly vascular tumour. When it is associated with gestation, it is often considered part of the spectrum of gestational trophoblastic disease; it is then termed gestational choriocarcinoma. When it occurs in the absence of preceding gestation, it is termed non-...
The staging system for choriocarcinoma (usually refers to uterine choriocarcinoma) is the FIGO staging system and is as follows 1:
stage I: disease limited to the uterus
stage II: disease out of the uterus but limited to the female genital tract
stage III: metastasis in the lung with or with...
The chorion is one of the embryonic membranous structures than encloses both the fetus as well as the amnion. The chorion begins to form chorionic villi towards its outer surface, which initially serves to provide nutrition to the developing embryo.
Part of the chorionic villi arborize more ex...
Chorionic bump is a finding that can be uncommonly seen in a first-trimester scan. It may represent a small haematoma bulging into the gestational sac or an anembryonic (failed) second pregnancy that is being resorbed. It is also seen in some patients undergoing infertility treatment.
The chorionic plate is a synonym for the fetal side of the placenta. The maternal side of the placenta is termed the basal plate.
Some pathologies and processes are localized to the chorionic plate, and evaluation of the chorionic plate is a part of placental grading.
Chorionic villus sampling (CVS) is an antenatal procedure for prenatal diagnosis of chromosomal or genetic disorders in the fetus. It entails getting a sample of the chorionic villus (placental tissue) and testing it.
A transabdominal or transcervical approach is selected depending on the posit...
Antenatal choroid plexus cysts are benign and are often transient typically resulting in utero from an infolding of the neuroepithelium.
They should not be confused with adult choroid plexus cysts (which are very commonly found at autopsy and likely degenerative), large intraventricular simpl...
There are large number of recognised chromosomal anomalies (many with eponymous names). When there is a change in the absolute number of chromosomes these are sub grouped as aneuploidic anomalies.
They can cause variable handicap - outcome ranging from some having no effect (in some balanced tr...
Circummarginate placenta is an uncommon variation in placental morphology.
The chorionic membranes insert inward from the margin of placental edge, similar to circumvallate placenta, but unlike circumvallate placenta, the placental edge is not thickened and rolled up, and there is no central d...
Circumvallate placenta refers to a variation in placental morphology in which, as a result of a small chorionic plate, the amnion and chorion fetal membranes ‘double back’ around the edge of the placenta.
The prevalance is estimated to be at around 1-7% 3.
There is inw...
Cleft lip +/- cleft palate is one of the commonest of neonatal facial anomalies. In ~80% of cases the two features tend to occur together 6.
It is estimated to occur with an incidence of ~1 in 700 to 1000 live births 1. This can increase to 4% for a sibling of a previously affecte...
Clinodactyly is a descriptive term that refers to a radial angulation at an interphalangeal joint in the radio-ulnar or palmar planes. It typically affects the 5th finger.
The estimated incidence is highly variable dependent on sampling and has been reported to range between 1-18...
Cloacal exstrophy (CE) is an extensive congenital abdominal wall defect which encompasses:
exstrophy of the bladder
lower abdominal wall defect
The estimated prevalence is at around 1 in 50,000 to 200,000 live births. There is a recognised male predilection with a ...
Cloverleaf skull, also known as kleeblattschädel, refers to a type of severe craniosynostosis which gives the skull a cloverleaf shape. It is very rare, with less than 130 case reports globally. It typically results from intrauterine premature closure of the sagittal, coronal and lambdoid suture...
Coexistent molar pregnancy refers to an extremely rare situation where there is a molar pregnancy occurring simultaneously with normal intra-uterine pregnancy.
The estimated incidence is at ~1:10,000-100,000 gestations (for a complete hydatidiform mole and a normal pregnancy) 2.
Coffin-Lowry syndrome (CLS) is a rare X-linked syndrome.
Tends to affect males much more due to its x linked inheritance. The estimated incidence is at around 1:40000-50000.
It is characterised by a number of clinical features which include:
central nervous sy...
Complete hydatidiform mole (CHM) is a type of molar pregnancy and falls at the benign end of the spectrum of gestational trophoblastic disease.
CHM is the commonest type of gestational trophoblastic disease.
Complete moles are characterised by the absence of a fetus o...
Complete hydatidiform mole with coexistent fetus (CHMCF) is an extremely rare entity where as the name suggests there is a twin pregnancy with a complete hydatidiform mole and a normal fetus.
It is seen extremely rarely, with an estimated incidence of one in 22,000–100,000 pregna...
A complete miscarriage is defined as a cessation of vaginal bleeding with no evidence of retained products of conception or a gestation sac in a woman who previously had an ultrasound confirmed intrauterine pregnancy.
Shows an empty uterus with no fetal compon...
A complete placenta praevia, also known as a type IV placenta praevia, is the most severe in terms of the placenta praevia spectrum. It is also the least likely to resolve with advancing gestation if detected in early pregnancy 1,3.
In this situation, the placenta entirely covers the...
Congenital cervical teratoma refers to a teratoma arising in the cervical region. They are thought to account for ~3% of teratomas in childhood/infancy 3.
The estimated occurrence in neonates is ~1:20,000-40,000 live births 8.
Most tumours are diagnosed at ...
Congenital cytomegalovirus infection results from intra-uterine fetal infection by cytomegalovirus (CMV).
CMV is the most common cause of intra-uterine infection and most common cause of congenital infective and brain damage, occurring in 0.2-2.4% of live births.
Antibodies to ...
A congenital granular cell myoblastoma (also known as congenital epulis) is a very rare benign tumour which classically presents in the fetal-neonatal population.
It occurs almost exclusively in females when it presents in the fetal-neonatal population although no such predilectio...
Congenital high airways obstruction syndrome (CHAOS) refers 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 oesophageal f...
Congenital hypothyroidism (CHT), previously known as cretinism, can be of thyroidal or central (hypothalamic/pituitary) origin and can have a widely diverse molecular aetiology.
Most children are asymptomatic at birth and are diagnosed after screening. In untreated CHT pa...
The group of the most common congenital infections are referred to by the mnemonic TORCH or STORCH. They usually cause mild maternal morbidity, but are related to serious fetal consequences 4.
O: other (e.g. syphilis, varicella-zoster, parvovirus B19)
Congenital limb amputations are a limb anomaly that usually occur due to disruption of vascular supply.
Congenital amputations occur in 0.5 (range 0.03-1) per 1000 live births 2.
Slightly more common in the upper limb (60%) than in the lower limb (40%) 2.
A congenital (primary) megaureter is a 'basket-term' to encompass 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 encompasses:
obstructed primary megaureter
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.
Until recently they were described as congenital cystic adeno...
Congenital renal anomalies comprise of vast spectrum of pathologies and include:
congenital renal hypoplasia
congenital cystic renal disease
infantile polycystic renal disease: autosomal recessive polycystic kidney disease (ARPKD):...
Congenital talipes equinovarus (CTEV) is considered the most common anomaly affecting the feet diagnosed on antenatal ultrasound.
While some use CTEV and club foot (CF) synonymously, in certain publications term clubfoot is considered a more general descriptive term that describes ...
There are many classification systems for congenital utero-vaginal anomalies. These include:
Buttram and Gibbons classification 2
American Fertility Society (AFS) classification
Modified Rock and Adam - AFS classification
Modified Rock and Adam - AFS classification
This classification divid...
Conjoined twin pregnancy are rare occurrence resulting from failure of a zygote to separate completely after 13 weeks. This results in the twins being physically joined.
The prevalence of conjoined twins ranges from 1:50,000 to 1:200,000. They are more common in parts of Southeast...
Conotruncal heart defects are a group of congenital cardiovascular anomalies. They are a leading cause symptomatic cyanotic cardiac disease diagnosed in utero.
They may account for up to a fifth of all congenital cardiac anomalies diagnosed prenatally 2.
Cordocentesis is a method of fetal blood sampling which is usually carried out under ultrasound guidance.
It may be performed for various reasons which include:
establish the degree of a fetal anaemia
further investigation of an underlying chromosomal anomaly
A cord presentation (also known as a funic presentation) is a variation in fetal presentation where the umbilical cord points towards the internal cervical os or lower uterine segment. It may be a transient phenomenon and usually considered insignificant until ~32 weeks. It is concerning if it ...
Cornelia de Lange syndrome (CdLS) is an extremely rare clinically heterogenous developmental disorder of unknown aetiology.
The estimated incidence is at ~1:10,000-160,000 births ref. There is no recognised racial or gender predilection 8.
The syndrome carries ...
Ruptured corpus luteal cysts are one of the commonest causes of spontaneous haemoperitoneum in a woman of reproductive age.
Presentation is variable, ranging from completely asymptomatic to severe abdominal pain due to peritoneal irritation.
The corpus luteum ...
The corpus luteum is a temporary endocrine structure involved in ovulation and early pregnancy.
During ovulation, the primary follicle forms the secondary follicle and subsequently the mature vesicular follicle.
At ovulation the follicle ruptures expelling the ovum into the fallopian tube. The...
Craniopagus twins are conjoined twins that are fused at any part of the skull, except the face, foramen magnum, skull base and the vertebral column.
The fused structures are most often the cranium, meninges, and dural venous sinuses. Brains tend to be separate; however may be connected by a bri...
Crouzon syndrome is rare disorder characterised by premature craniosynostoses.
abnormal calvarial shape: in severe case can give a "cloverleaf skull"
shallow orbits with exopthalmos
mid facial hypoplasia
It carries an autosomal dominant ...
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.
CRL is measured as the largest dimension ...
The Currarino (or ASP) triad is characterised by:
anorectal malformation or congenital anorectal stenosis
sacrococcygeal osseous defect
e.g anterior sacral meningocele
and/or tumours such as teratoma and hamartoma
An association with epidermoid cysts of the central nervous s...
Cyclopia refers to a rare fetal malformation characterised by a single palpebral fissure and a single midline orbit. This orbit may contain either a single globe or two separate globe.
The condition is thought to affect approximately 1 in 40,000 to 95,000 births (inclusive of stil...
Cystic hygroma, also known as cystic or nuchal lymphangioma, refers to the cystic variety of congenital lymphangioma which, most commonly, occur in the cervicofacial regions, particularly at the posterior cervical triangle.
They usually occur in the fetal/infantile and paediatri...
Cystic hygroma and occipital meningocele are both differential diagnosis for an antenatally detected cystic collection noted on the posterior aspect of the head and neck.
A simple differentiation can be made based on the contents and presence of septations:
cystic hygroma will present as a wel...
Cystic renal dysplasia refers to a group congenital renal anomalies characterised by the formation of cysts. Many of the congenital cystic renal diseases fall under this group.
Dandy-Walker variant (DWv) is a less severe posterior fossa anomaly than the classic Dandy-Walker malformation (DWM) and is considered being on the lesser end of the disease spectrum in the Dandy-Walker continuum.
This term was created to include those malformations that do not mee...
Decidual cast refers to the presence of an amount of relatively echogenic material in the uterine cavity in the context of an ectopic pregnancy.
A decidual reaction is feature seen in very early pregnancy where there is a thickening of the endometrium around the gestational sac. A thin decidual reaction of less than 2 mm is considered one of the features suggestive of an anembryonic pregnancy 2. A decidual reaction in some situations can...
The deepest (maximal) vertical pocket (DVP) depth is considered a reliable method for assessing amniotic fluid volume on ultrasound 1-2. It is performed by assessing a pocket of maximal depth of amniotic fluid which is free of umbilical cord and fetal parts.
The usually accepted values are:
Demise of a twin is a complication that can occur in a twin pregnancy (particularly monochorionic pregnancies) and may be due to a wide range of conditions. Once the twin dies, most of the dead twin tends to be absorbed leaving behind a small flattened remnant known as the fetus papyraceus.
Diabetic embryopathy refers to a spectrum of fetal anomalies that precipitate when the mother has background type I diabetes. The fetus may develop many of the fetal conditions associated with maternal diabetes although strictly speaking the the anomalies should only include those that start in ...
Diastrophic dysplasia (DTD) is a type of short limb skeletal dysplasia (micromelic dwarfism). Adult patients have a stature between 100 and 140 cm.
There may be a relatively increased prevalence in Finland ref.
Typically there is limb shortening, hitchhiker thu...
A dichorionic diamniotic (DCDA) twin pregnancy is a type of twin pregnancy where each twin has its own chorionic and amnionic sacs. This type occurs most commonly with dizygotic twins, but may also occur with monozygotic twin pregnancies. This type of pregnancy may have characteristic findings o...
A dichorionic twin pregnancy is type of twin pregnancy characterised by two chorions. The are always dichorionic-diamniotic but can be be either monozygotic (~ 11%) or dizygotic ( ~ 88%).
Uterine bleeding during pregnancy is a common clinical presentation that often necessitates obstetric ultrasound for the assessment of the haemorrhage, and of fetal well being.
The potential causes vary with the stage of gestation.
Bleeding in the first trimester
A dizygotic (DZ) twin pregnancy is a type of twin pregnancy where two seperate ova are independantly fertilised by two seperate sperm resulting the two seperate zygotes. These twins are known as fraternal twins. They may or may not be of the same gender.
Dizygotic twins are the m...
A dominant ovarian follicle refers to the follicle that enlarges to release an ovum during a menstural cycle. Usually approximately 10 Graafian follicles begin to mature where one becomes a dominant follicle and the rest become atretic ovarian follicles. After release of the ovum the remainder o...
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 double bleb sign is a sonographic feature where there is visualisation of a gestational sac containing a yolk sac and amniotic sac giving an appearence of two small bubbles 2. The embryonic disc is located between the two bubbles. It is an important feature of an intrauterine pregnancy and thu...
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 visualised. It consists of the decidua parietalis (lining the uterine cavity) and decidua capsularis (lining the gestati...
Duane radial ray syndrome (DRRS) (also known as the Okihiro syndrome) is a rare an autosomal dominant condition characterized by radial ray defects and a Duane anomaly (a form of strabismus with horizontal gaze palsy).
Dubowitz syndrome (DS) is a rare genetic disorder with a wide clinical spectrum which includes:
intrauterine growth restriction (IUGR)
postnatal growth retardation
moderate mental retardation
characteristic facial anomalies
The ductus arteriosum (or arteriosus) is the thick short conduit for blood to bypass the non-ventilated lungs in the fetus. It is located between and connects the proximal left pulmonary artery and the undersurface of the aortic arch distal to the origin of the last branch of the arch, at the ao...
The term dystocia in obstetrics means a "difficult birth"
There can be many types of dystocia which include
Shoulder dystocia (SD) refers to the failure of the shoulder to be delivered during childbirth and the need for extra-obstetric maneuvers to facilitate their passage after normal smooth gentle downward traction has failed. Dystocia literally means difficult labour.
The incidence o...
Early pregnancy roughly spans the first ten weeks of the first trimester.
0-4.3 weeks: no ultrasound findings
possible small gestational sac
possible double decidual sac sign (DDSS)
possible intradecidual sac sign (IDSS)
Echogenic amniotic fluid can potentially arise from a number of entities which include
vernix caseosa : commonest cause
haemorrhage into amniotic cavity
However according to some studies 2 pathological analysis of echogenic appearing fluid had reveal normal amniotic fl...
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...