Fetal abnormalities

Question 1

Breech presentation

Answer 1

When the fetus presents buttocks or feet first (rather than head first – a cephalic presentation).

Question 2

Complete breech

Answer 2

Complete (flexed) breech – both legs are flexed at the hips and knees (fetus appears to be sitting ‘crossed-legged’).

Question 3

Frank breech

Answer 3

Frank (extended) breech – both legs are flexed at the hip and extended at the knee. This is the most common type of breech presentation.

Question 4

Footling breech

Answer 4

Footling breech – one or both legs extended at the hip, so that the foot is the presenting part.

Question 5

Uterine risk factors for breech

Answer 5

Multiparity
Uterine malformations (e.g. septate uterus)

Fibroids

Placenta praevia

Question 6

fetal risk factors for breech

Answer 6

Prematurity
Macrosomia

Polyhydramnios (raised amniotic fluid index)

Twin pregnancy (or higher order)

Abnormality (e.g. anencephaly)

Question 7

Management of breech before 32-35 weeks

Answer 7

Fetus likely to revert to a cephalic presentation before delivery
No management usually needed

Question 8

Clinical features of breech

Answer 8

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

Question 9

investigations for breech

Answer 9

USS

Question 10

management of breech

Answer 10

External cephalic version
Caesarean section
Vaginal breech birth

Question 11

External cephalic version

Answer 11

Offered from 37 weeks

Primip: 36 weeks

Question 12

Complications of ECV

Answer 12

transient fetal heart abnormalities
persistent heart rate abnormalities
placental abruption
antepartum haemorrhage

Question 13

vaginal breech birth contraindication

Answer 13

footling breech

Question 14

vaginal breech birth

Answer 14

hand off the breech
flexing the fetal knees
Lovsett’s manoeuvre
Mauriceau-Smellie-Veit manouevre

Question 15

Complications of breech birth

Answer 15

cord prolapse
fetal head entrapment
premature rupture of membranes
birth asphyxia
intracranial haemorrhage

Question 16

risk factors for abnormal fetal lie, presentation and position

Answer 16

Prematurity
Multiple pregnancy
Uterine abnormalities (e.g fibroids, partial septate uterus)
Fetal abnormalities
Placenta praevia
Primiparity

Question 17

assessing fetal lie

Answer 17

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

Question 18

assessing fetal presentation

Answer 18

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.

Question 19

assessing fetal position

Answer 19

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.

Question 20

investigation for fetal position

Answer 20

USS

Question 21

management of abnormal fetal lie

Answer 21

ECV between 36-38 weeks gestation

Question 22

management of fetal malpresentation

Answer 22

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

Question 23

management of fetal malposition

Answer 23

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.

Question 24

causes of oligohydramnios

Answer 24

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)

Question 25

diagnosis of oligohydramnios

Answer 25

USS
amniotic fluid index
maximum pool depth

Question 26

oligohydramnios history

Answer 26

Inquire about symptoms of leaking fluid and feeling damp all the time (often described as new urinary incontinence).

Question 27

oligohydramnios examination

Answer 27

Measure the symphysis fundal height.

Perform a speculum examination (can a ‘pool’ of liquor be seen in the vagina?).

Question 28

oligohydramnios USS

Answer 28

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.

Question 29

investigations for oligohydramnios

Answer 29

USS
karyotyping
ruptured membranes: IGFBP-1

Question 30

management of oligohydramnios: ruptured membranes

Answer 30

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.

Question 31

management of oligohydramnios: placental insufficiency

Answer 31

Timing of delivery depends on:
Rate of fetal growth
Umbilical artery and middle cerebral artery Doppler scans
Cardiotocography

Question 32

prognosis of oligohydramnios

Answer 32

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.

Question 33

causes of polyhydramnios

Answer 33

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.

Question 34

diagnosis of polyhydramnios

Answer 34

US examination
amniotic fluid index
maximum pool depth

Question 35

investigations for polyhydramnios

Answer 35

Ultrasound scan
maternal glucose tolerance test
karyotyping
TORCH infections

Question 36

management of polyhydramnios

Answer 36

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

Question 37

prognosis of polyhydramnios

Answer 37

malpresentation more likely

postpartum haemorrhage