Fetal abnormalities Flashcards
Breech presentation
When the fetus presents buttocks or feet first (rather than head first – a cephalic presentation).
Complete breech
Complete (flexed) breech – both legs are flexed at the hips and knees (fetus appears to be sitting ‘crossed-legged’).
Frank breech
Frank (extended) breech – both legs are flexed at the hip and extended at the knee. This is the most common type of breech presentation.
Footling breech
Footling breech – one or both legs extended at the hip, so that the foot is the presenting part.
Uterine risk factors for breech
Multiparity Uterine malformations (e.g. septate uterus)
Fibroids
Placenta praevia
fetal risk factors for breech
Prematurity
Macrosomia
Polyhydramnios (raised amniotic fluid index)
Twin pregnancy (or higher order)
Abnormality (e.g. anencephaly)
Management of breech before 32-35 weeks
Fetus likely to revert to a cephalic presentation before delivery
No management usually needed
Clinical features of breech
Round fetal head can be felt in upper part of uterus, irregular mass in the pelvis
Fetal heart auscultated higher on maternal abdomen
During labour: signs of fetal distress, meconium-stained liquor, sacrum or foot felt on vaginal examination
investigations for breech
USS
management of breech
External cephalic version
Caesarean section
Vaginal breech birth
External cephalic version
Offered from 37 weeks
Primip: 36 weeks
Complications of ECV
transient fetal heart abnormalities
persistent heart rate abnormalities
placental abruption
antepartum haemorrhage
vaginal breech birth contraindication
footling breech
vaginal breech birth
hand off the breech
flexing the fetal knees
Lovsett’s manoeuvre
Mauriceau-Smellie-Veit manouevre
Complications of breech birth
cord prolapse fetal head entrapment premature rupture of membranes birth asphyxia intracranial haemorrhage
risk factors for abnormal fetal lie, presentation and position
Prematurity Multiple pregnancy Uterine abnormalities (e.g fibroids, partial septate uterus) Fetal abnormalities Placenta praevia Primiparity
assessing fetal lie
Face the patient’s head
Place your hands on either side of the uterus and gently apply pressure; one side will feel fuller and firmer – this is the back, and fetal limbs may feel ‘knobbly’ on the opposite side
assessing fetal presentation
Face the patient’s head
Palpate the lower uterus (above the symphysis pubis) with the fingers of both hands; the head feels hard and round (cephalic) and the bottom feels soft and triangular (breech)
You may be able to gently push the fetal head from side to side
The fetal lie and presentation may not be possible to identify if the mother has a high BMI, if she has not emptied her bladder, if the fetus is small or if there is polyhydramnios.
assessing fetal position
During labour, vaginal examination is used to assess the position of the fetal head (in a cephalic vertex presentation).
The landmarks of the fetal head, including the anterior and posterior fontanelles, indicate the position.
investigation for fetal position
USS
management of abnormal fetal lie
ECV between 36-38 weeks gestation
management of fetal malpresentation
Breech – attempt ECV before labour, vaginal breech delivery or C-section
Brow – a C-section is necessary
Face
If the chin is anterior (mento-anterior) a normal labour is possible; however, it is likely to be prolonged and there is an increased risk of a C-section being required
If the chin is posterior (mento-posterior) then a C-section is necessary
Shoulder – a C-section is necessary
management of fetal malposition
90% of malpositions spontaneously rotate to occipito-anterior as labour progresses.
If the fetal head does not rotate, rotation and operative vaginal delivery can be attempted.
Alternatively a C-section can be performed.
causes of oligohydramnios
Preterm prelabour rupture of membranes
Placental insufficiency – resulting in the blood flow being redistributed to the fetal brain rather than the abdomen and kidneys. This causes poor urine output.
Renal agenesis (known as Potter’s syndrome)
Non-functioning fetal kidneys, e.g. bilateral multicystic dysplastic kidneys
Obstructive uropathy
Genetic/chromosomal anomalies
Viral infections (although may also cause polyhydramnios)
diagnosis of oligohydramnios
USS
amniotic fluid index
maximum pool depth
oligohydramnios history
Inquire about symptoms of leaking fluid and feeling damp all the time (often described as new urinary incontinence).
oligohydramnios examination
Measure the symphysis fundal height.
Perform a speculum examination (can a ‘pool’ of liquor be seen in the vagina?).
oligohydramnios USS
Assess for liquor volume, structural abnormalities, renal agenesis and obstructive uropathy.
Measure fetal size. Small babies can result from placental insufficiency, which also causes oligohydramnios.
There may also be a rise in pulsatility index of the umbilical artery Doppler in placental insufficiency.
investigations for oligohydramnios
USS
karyotyping
ruptured membranes: IGFBP-1
management of oligohydramnios: ruptured membranes
If oligohydramnios is due to ruptured membranes, labour is likely to commence within 24-48 hours in most pregnancies.
In cases of preterm rupture of membranes (i.e. before 37 weeks’ gestation), and where labour doesn’t start automatically, induction of labour should be considered around 34-36 weeks (in the absence of infection).
A course of steroids should be given to aid fetal lung development, and antibiotics to reduce the risk of ascending infection.
management of oligohydramnios: placental insufficiency
Timing of delivery depends on:
Rate of fetal growth
Umbilical artery and middle cerebral artery Doppler scans
Cardiotocography
prognosis of oligohydramnios
Oligohydramnios in the second trimester carries a poor prognosis. In the majority of these cases, there is premature rupture of membranes (which may or may not be associated with infection), with subsequent premature delivery and pulmonary hypoplasia – which can cause significant respiratory distress at birth
When oligohydramnios is associated with placental insufficiency, there is also a higher rate of preterm deliveries (usually through planned induction of labour). These cases will carry a poorer prognosis than that of a normally grown fetus.
Amniotic fluid also allows the fetus move its limbs in utero (exercise). Without this, the fetus can develop severe muscle contractures – which may lead to disability despite physiotherapy after birth.
causes of polyhydramnios
Any condition that prevents the fetus from swallowing – e.g. oesophageal atresia, CNS abnormalities, muscular dystrophies, congenital diaphragmatic hernia obstructing the oesophagus
Duodenal atresia – ‘double bubble’ sign on ultrasound scan
Anaemia – alloimmune disorders, viral infections
Fetal hydrops
Twin-to-twin transfusion syndrome
Increased lung secretions – cystic adenomatoid malformation of lung
Genetic or chromosomal abnormalities
Maternal diabetes – especially if poorly controlled
Maternal ingestion of lithium – leads to fetal diabetes insipidus
Macrosomia – larger babies produce more urine.
diagnosis of polyhydramnios
US examination
amniotic fluid index
maximum pool depth
investigations for polyhydramnios
Ultrasound scan
maternal glucose tolerance test
karyotyping
TORCH infections
management of polyhydramnios
aminoreduction if maternal symptoms are severe: associated with infection and placental abruption
indomethacin: cant use beyond 32 weeks as its associated with premature closure of ductus arteriosus
NG tube to ensure there is not a tracheooesophageal fistula or oesophageal fistula
prognosis of polyhydramnios
malpresentation more likely
postpartum haemorrhage
