Items tagged “obstetric”
27 results found
Article
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...
Article
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...
Article
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) villous lesions
mol...
Article
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...
Article
Strawberry skull
Strawberry skull refers to the shape of the head on an antenatal ultrasound.
Epidemiology
Associations
In general, strawberry skull is considered one of the non-specific 'soft markers' for abnormal fetal development. It is considered more closely associated with trisomy 18 (Edward syndrome).
...
Article
Uteroplacental blood flow assessment
Uteroplacental blood flow assessment is an important part of fetal well-being assessment and evaluates Doppler flow in the uterine arteries and rarely the ovarian arteries.
Pathology
In a non-gravid state and at the very start of pregnancy the flow in the uterine artery is of high pulsatility ...
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) >8 cm 6
some centers, particularly in Australia, New Zealand, an...
Article
Oligohydramnios
Oligohydramnios refers to a situation where the amniotic fluid volume is less than expected for gestational age. Often these fetuses have <500 mL of amniotic fluid. When there is almost no amniotic fluid present, this is termed anhydramnios.
Epidemiology
The estimated prevalence can be up to ~...
Article
Intradecidual sac sign
Intradecidual sac sign (IDSS) is a useful feature in identifying an early intrauterine pregnancy (IUP) as early as 25 days of gestation1. The threshold level (earliest one can see the sign) is 24 days of gestation and the discriminatory level (one should always see the sac) is 47 days. As per th...
Article
First trimester
The first trimester is defined as the first 13 weeks of pregnancy following the last normal menstrual period (some authors refer to early pregnancy as 0-10 weeks). It can be divided into a number of phases, each of which has typical clinical issues. These phases are:
conceptus phase: 3-5 weeks
...
Article
Double bleb sign
A double bleb sign is a sonographic feature where there is visualization of a gestational sac containing a yolk sac and amniotic sac giving an appearance 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...
Article
Anencephaly
Anencephaly is the most severe form of cranial neural tube defect and is characterized by an absence of cortical tissue (although the brainstem and cerebellum may be variably present) as well as an absence of the cranial vault. The morphological spectrum within anencephaly ranges from holocrania...
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
Circumvallate placenta
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.
Epidemiology
The prevalence is estimated to be around 1-7% 3.
Pathology
There is an inw...
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
Vasa previa
Vasa previa refers to a situation where there are aberrant fetal vessels crossing over or in close proximity to the internal cervical os, ahead of the fetal presenting part. These vessels are within the amniotic membranes, without the support of the placenta. Vasa previa is a rare but potentiall...
Article
Succenturiate lobe
A succenturiate lobe is a variation in placental morphology and refers to a smaller accessory placental lobe that is separate to the main disc of the placenta. There can be more than one succenturiate lobe.
Epidemiology
The estimated incidence is ~2 per 1000 pregnancies.
Risk factors
Some au...
Article
Placenta accreta
Placenta accreta 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 (placenta accreta spectrum disorders). This article focuses on the second, more specific definition.
In a placenta accr...
Article
Velamentous cord insertion
Velamentous cord insertion is a type of abnormal umbilical cord insertion into the placenta.
Epidemiology
The estimated incidence is ~1% in singleton and 9-15% in twin pregnancies, respectively 11. It is also more common in placenta previa than in normally located placentas. The prevalence may...
Article
Marginal cord insertion
Marginal cord insertion, also known as a 'battledore insertion', is a type of abnormal cord insertion.
Terminology
Insertion of the umbilical cord within <2 cm from the placental margin is described as marginal cord insertion (usually defined as <2 cm 5, although some references define it as <...