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Yr4: Obstetrics & Gynaecology > Obstetrics: Antenatal Care- Fetal Abnormalities > Flashcards

Obstetrics: Antenatal Care- Fetal Abnormalities Flashcards

1
Q

What do we mean by the following:

  • Lie
  • Presentation
  • Position
A
  • Lie: relationship between long axis of fetus and the mother. Can be longitudinal, transverse or oblique
  • Presentation: fetal part that first enters pelvis. Can be cephalic vertex (safest, most common), breech, shoulder, face
  • Position: position of fetal head as it exits birth canal. Can be occipito-anterior (most common), occipito-posterior, occipito-transverse
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2
Q

State some risk factors for abnormal lie

A
  • Multiple pregnancy
  • Uterine abnormalities e.g. fibroids
  • Placenta praevia
  • Primiparity
  • Prematurity (remember most breech resolve later in pregnancy)
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3
Q

What investigation should be done if you suspect abnormal lie?

A

Ultrasound scan

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4
Q

90% of malpositions spontaneously rotate to occipito-anterior as labour progresses; true or false?

A

True (if not, rotation & instrumental delivery can be done- or caesarean)

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5
Q

What do we mean by breech presentation?

How common is it?

A
  • Presenting part of fetus is the buttocks or feet (rather than head as in cephalic presentation)
  • ~20% breech at 28 weeks but then <5% by 37 weeks
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6
Q

Most breech presentations seem to be chance occurrences; true or false?

A

True

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7
Q

There are 4 types of breech presentation; define the following:

  • Complete breech
  • Incomplete breech
  • Extended breech
  • Footling breech
A
  • Complete breech: the legs are fully flexed at the hips and knees
  • Incomplete breech: one leg flexed at the hip and extended at the knee
  • Extended breech (frank breech): both legs flexed at the hip and extended at the knee
  • Footling breech: one or both legs extended at hit so that foot is the presenting part

Most sources say there are 3 main types: complete, extended/frank & footling

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8
Q

Babies that are breech before 36 weeks often turn spontaneously; true or false?

A

True

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9
Q

How is breech presentation usually diagnosed?

A

Clinical examination (round head can be felt in upper part of uterus and irregular mass of fetal buttock & legs in pelvis)

Fetal heart may be auscultated higher

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10
Q

Discuss the management of breech presentation

A

If not turned by 36 weeks, options include:

  • External cephalic version (ECV)
  • If ECV fails, two options:
    • Vaginal delivery with experienced midwifes with access to emergency theatres if required (~40% chance requiring caesarean)
    • Elective caesarean section
  • However, if first baby in a twin pregnancy is breech caesarean section IS required

RCOG say ‘Women should be informed that planned caesarean section carries a reduced perinatal mortality and early neonatal morbidity for babies with a breech presentation at term compared with planned vaginal birth’ hence caesarean section is recommended

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11
Q

For external cephalic version (ECV), discuss:

  • What it is
  • Who/when it can be used
  • Success rate
A
  • Technique used to attempt to turn fetus from breech position into cephalic position using pressure on abdomen
  • ECV can be used:
    • After 36 weeks for nulliparous women
    • After 37 weeks for women who have given birth previously
  • ~50%
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12
Q

What is required before ECV and why?

What is required within 72hrs of ECV?

A
  • Tocolysis with SC terbutaline to relax uterus before ECV making it easier to turn baby
  • Rhesus-D negative women require anti-D prophylaxis within 72hrs (including Kleihauer test to determine dose of anti-D required)
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13
Q

State some potential complications of ECV

A
  • Transient fetal heart abnormalities
  • Placental abruption
  • Failure
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14
Q

What is the major potential complication of a breech presentation?

A

Cord prolapse

Others include:

  • Fetal head entrapment
  • Premature rupture membranes
  • Birth asphyxia
  • Intracranial haemorrhage
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15
Q

Define stillbirth

A

Birth of a dead fetus after 24 weeks gestation as a result of intrauterine fetal death (IUFD)

Occurs in ~1 in 200 pregnancies

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16
Q

State some risk factors for stillbirth

A
  • Fetal growth restriction
  • Smoking
  • Alcohol
  • Increased maternal age
  • Maternal obesity
  • Twins
  • Sleeping on the back (as opposed to either side)
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17
Q

State some potential causes of stillbirth

A
  • Unexplained (around 50%)
  • Pre-eclampsia
  • Placental abruption
  • Vasa praevia
  • Cord prolapse or wrapped around the fetal neck
  • Obstetric cholestasis
  • Diabetes
  • Thyroid disease
  • Infections, such as rubella, parvovirus and listeria
  • Genetic abnormalities or congenital malformations

***HOWEVER, unexplained stillbirth is still common

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18
Q

What are 3 key symptoms to always check when taking history from pregnant woman?

A
  • Fetal movements?
  • Abdominal pain?
  • Vaginal bleeding?
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19
Q

Prevention of stillbirth involves screening for and treating- where possible- any conditions that can cause stillbirth. All pregnant women have a risk assessment for having a baby that is small for gestational age (SGA) or with fetal growth restriction (FGR). What do those at risk have?

A
  • Serial growth scans
  • May need planned early delivery when growth is static or other concerns
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20
Q

What is the investigation of choice for diagnosing intrauterine fetal death (IUFD)?

A

Ultrasound to visualise fetal heartbeat

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21
Q

Passive fetal movements are possible after IUFD; true or false?

A

True (repeat scan can be offered to confirm situation)

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22
Q

Discuss the management of IUFD

A
  • First line= vaginal birth
    • Induction of labour
    • Or expectant management (if immediate delivery not required. Need close monitoring)
  • Anti-D prophylaxis in rhesus negative women & Kleihauer test to determine dose
  • Dopamine agonists (e.g. cabergoline) can be used to supress lactation after stillbirth
  • With parental consent testing is carried out to determine cause
  • Support following delivery:
    • Counselling
    • Support with wishes such as seeing baby, naming baby, photographs
    • Support with funeral arrangements
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23
Q

Following IUFD and stillbirth, testing is carried out- with parental consent- to try and determine underlying cause; what may be involved in such testing?

A
  • Genetic testing of the fetus and placenta
  • Postmortem examination of the fetus (including xrays)
  • Testing for maternal and fetal infection
  • Testing the mother for conditions associated with stillbirth, such as diabetes, thyroid disease and thrombophilia
24
Q

Define the following:

  • Low birth weight
  • Small for gestational age (SGA)
  • Severe SGA
  • Fetal SGA
  • Severe fetal SGA
A
  • Low birth weight= birth weight <2500g
  • SGA= infant with birth weight <10th centile for it’s gestational age
  • Severe SGA= infant with birth weight <3rd centile for it’s gestational age
  • Fetal SGA= fetus with estimated fetal weight (EFW) or abdominal circumference (AC) <10th centile for it’s gestational age
  • Severe fetal SGA= fetus with estimated fetal weight (EFW) or abdominal circumference (AC) <3rd centile for it’s gestational age
25
Q

SGA is assessed based on two ultrasound measurements; sates these

A

Measurements taken on ultrasound:

  • Estimated fetal weight (EFW)
  • Fetal abdominal circumference (AC)

Customised growth charts are used to assess the size of the fetus, based on the mother’s:

  • Ethnic group
  • Weight
  • Height
  • Parity
26
Q

Causes of SGA can be divided into two main categories; one of these categories can be further subdivided into two further categories. Outline the categorisation of SGA

A
  • Constitutionally small
  • Fetal growth restriction (GFR)/intrauterine growth restriction (IUGR)
    • Placenta mediated growth restriction
    • Non-placenta mediated growth restriction
27
Q

Define the following:

  • Constitutionally small
  • Fetal growth restriction (FGD)/intrauterine growth restriction (IUGR)
  • Placenta mediated growth restriction
  • Non-placenta mediated growth restriction
A
  • Constitutionally small: small size at all stages but following centiles; matching mother & others in family
  • Fetal growth restriction (FGD)/intrauterine growth restriction (IUGR): fetus is small or not growing as expected due to pathology
  • Placenta mediated growth restriction: fetus is small or not growing as expected due to pathology affecting the transfer of nutrients via the placenta. Growth often normal initially then slows.
  • Non-placenta mediated growth restriction: fetus is small or not growing as expected due to fetal pathology e.g. chromosomal abnormality, issues with metabolism, fetal infection
28
Q

Why may the ratio of head circumference to abdominal circumference be significant when assessing whether a fetus is small for gestational age?

A

The ratio of head circumference (HC) and AC may be significant; a symmetrically small fetus is more likely to be constitutionally small whilst an asymmetrically small fetus is more likely to be caused by placental insufficiency. The ‘brain-sparing’ effect can be identified by abnormal doppler studies.

29
Q

State some causes of placenta mediated growth restriction

A
  • Idiopathic
  • Pre-eclampsia
  • Maternal smoking
  • Maternal alcohol
  • Anaemia
  • Malnutrition
  • Infection
  • Maternal health conditions
30
Q

State some causes of non-placenta mediated growth restriction

A
  • Genetic abnormalities
  • Structural abnormalities
  • Fetal infection
  • Errors of metabolism
31
Q

Other than being below 10th centile, there may be other signs of fetal growth restriction; state some of these

A
  • Reduced amniotic fluid volume (placental insufficiency can impair fetal kidney function)
  • Abnormal Doppler studies
  • Reduced fetal movements
  • Abnormal CTGs
32
Q

State some minor and major risk factors for SGA

A
33
Q

Discuss the monitoring required for SGA

A

Low risk women

  • Have symphysis fundal height (SFH) measured at every antenatal appointment from 24 weeks onwards to identify possible SGA
  • This is plotted on customised growth chart to assess appropriate size for individual woman
  • If SFH <10th centile → book for serial growth scans with umbilical artery doppler

Women with risk factors or issues measuring SFH

  • ≥ 3 minor risk factors:
    • Reassess at 20 weeks
    • If still ≥ 3, arrange uterine artery doppler
      • If normal, reassess in 3rd trimester
      • If abnormal, serial growth scans and umbilical artery doppler
  • ≥1 major risk factor:
    • Reassess at 20 weeks
    • If still ≥ 1, serial growth scans and umbilical artery doppler

Issues with monitoring SFH e.g. large fibroids,, BMI >35

  • Serial growth scans & umbilical artery doppler
  • ***NOTE:* The local guidelines for the initiation and frequency of ultrasound scans may vary. An example regime is a growth scan every four weeks from 28 weeks gestation. Ultrasound frequency is increased where there is reduced growth velocity or problems with umbilical flow.
34
Q

What do ultrasounds, monitoring for SGA, measure?

A
  • Estimated fetal weight (EFW) (determine the growth velocity)
  • Abdominal circumference (AC) (determine the growth velocity)
  • Umbilical arterial pulsatility index (UA-PI) (measure flow through the umbilical artery)
  • Amniotic fluid volume
35
Q

How do you measure symphysis fundal height?

What are

A

Measuring SFH

  • Ensure bladder empty
  • Ensure woman comfortable in semi-recumbent position
  • Measure from fundus to top of pubis symphysis

Expected measurements (see image)

36
Q

Discuss the management of SGA

A
  • Identifying those at risk of SGA and monitoring with UAD +/- serial growth scans
  • Treating modifiable risk factors e.g. stop smoking, weight loss
  • Aspirin given to those with SGA from 16 weeks onwards
  • Aspirin to those at risk of pre-eclampsia
  • If fetus identified as SGA, investigating to find underlying cause:
    • BP & urine dipstick: pre-eclampsia
    • Uterine artery doppler scanning
    • Detailed fetal anomaly scan by fetal medicine
    • Karyotyping for chromosomal abnormalities
    • Testing for infections (e.g. CMV, toxoplasmosis, syphilis)
  • Early delivery considered if growth static or other problems identified
    • *Remember, give corticosteroids if delivery between 24 - 35+6 planned
37
Q

State some potential short term complications of FGR/IUGR

A
  • Fetal death or stillbirth
  • Birth asphyxia
  • Neonatal hypothermia
  • Neonatal hypoglycaemia
  • Neonatal polycythaemia
  • Usual complications of being premature if premature delivery
38
Q

State some potential long term complications of FGR/IUGR

A
  • Cardiovascular disease, particularly hypertension
  • Type 2 diabetes
  • Obesity
  • Mood and behavioural problems
  • Malignancy (breast, ovarian, colon, lung, blood)
39
Q

Why may the ratio of head circumference to abdominal circumference be significant when assessing whether a fetus is small for gestational age?

A

The ratio of head circumference (HC) and AC may be significant; a symmetrically small fetus is more likely to be constitutionally small whilst an asymmetrically small fetus is more likely to be caused by placental insufficiency. The ‘brain-sparing’ effect can be identified by abnormal doppler studies.

40
Q

Define the following:

  • Large for gestational age
  • Fetal large for gestational age
A
  • Large for gestational age: birthweight >4500g
  • Fetal large for gestational age: estimated fetal weight >90th centile
41
Q

State some potential causes of macrosomia

A
  • Constitutional
  • Maternal diabetes
  • Previous macrosomia
  • Maternal obesity or rapid weight gain
  • Overdue
  • Male baby
42
Q

Most women with large for gestational age pregnancy will have a successful vaginal delivery; true or false?

A

True, NICE guidelines (2008) advise against induction of labour only on the grounds of macrosomia.

43
Q

What investigations are done when there is a large for gestational age fetus?

A

At every antenatal appointment after 24 weeks, will measure SFH; if this is greater than expected on ≥2 occasions or rapid growth on one occasion should be offered:

  • Ultrasound: estimate fetal weight and exclude polyhydramnios
  • May then do oral glucose tolerance test: test for gestational diabetes
44
Q

State some potential maternal complications associated with large for gestational age

A
  • Shoulder dystocia
  • Failure to progress
  • Perineal tears
  • Instrumental delivery or caesarean
  • Postpartum haemorrhage
  • Uterine rupture (rare)
45
Q

Main risk with large for gestational age fetus if shoulder dystocia. Discuss how risks at delivery can be reduced

A
  • Delivery on a consultant lead unit
  • Delivery by an experienced midwife or obstetrician
  • Access to an obstetrician and theatre if required
  • Active management of the third stage (delivery of the placenta)
  • Early decision for caesarean section if required
  • Paediatrician attending the birth

Then if shoulder dystocia does occur following management for that

46
Q

State some potential fetal complications associated with large for gestational age

A
  • Birth injury (Erbs palsy, clavicular fracture, fetal distress and hypoxia)
  • Neonatal hypoglycaemia
  • Obesity in childhood and later life
  • Type 2 diabetes in adulthood
47
Q

What do we mean by oligohydramnios?

A

Low level of amniotic fluid

Amniotic fluid index (AFI) <5th centile for gestational age

48
Q

Describe what happens to volume of amniotic fluid during pregnancy

A
  • Increases until 33 weeks
  • Plateaus 33-38 weeks
  • Then declines

Volume at term is ~500mL

49
Q

Remind yourself how amniotic fluid is created

A
  • Mostly made of fetal urine output with small contributions from placenta and some fetal secretions (e.g. respiratory)
  • Fetus breathes and swallows amniotic fluid
  • Processed by kidneys
  • Excreted as urine
  • Anything that reduces production of urine, blocks urine output or a rupture of membranes can lead to olighydramnios
50
Q

State some potential causes of olighydramnios

A
  • Placental insufficiency (results in blood flow being redistributed to fetal brain ratehr than abdomen & kidneys)
  • Renal agenesis (Potter’s syndrome)
  • Non-functioning kidneys e.g. bilateral multicystic dysplastic kidneys
  • Obstructive uropathy
  • Preterm prelabour rupture membranes
  • Genetic/chromosomal abnormalities
  • Viral infections (but may also cause polyhydramnios)
51
Q

Discuss the management of oligohydramnios

A

Depends on underlying cause; two most common are:

  • Ruptured membranes (see separate FCs)
  • Placental insufficiency (see separate FCs; involve serial growth scans, early planned delivery)
52
Q

State some potential complications of oligohydramnios

A
  • Premature delivery
  • Pulmonary hypoplasia
  • Muscle contractures (amniotic fluid allows fetus to move limbs in utero hence without it fetus can develop muscle contractures)
53
Q

What do we mean by polyhydramnios?

A

Polyhydramnios refers to an abnormally large level of amniotic fluid during pregnancy.

It is defined by an amniotic fluid index that is above the 95th centile for gestational age.

54
Q

State some potential causes of polyhydramnios

A
  • Idiopathic (50-60% cases)
  • Abnormal fetal swallowing (e.g. oesophageal atresia, CNS abnormalities, muscular dystrophies, congenital diaphragmatic hernia obstructing the oesophagus)
  • Duodenal atresia
  • Anaemia
  • Fetal hydrops
  • Twin-to-twin transfusion syndrome
  • Increased lung secretions
  • Genetic or chromosomal abnormalities
  • Maternal diabetes
  • Maternal ingestion of lithium (causes fetal diabetes insipidus)
  • Macrosomia – larger babies produce more urine.
55
Q

What investigations might you consider for polyhydramnios?

A
  • OGTT for maternal diabetes
  • TORCH test for infections (Toxoplasmosis, Other (Parvovirus), Rubella, Cytomegalovirus, Hepatitis)
  • Karyotyping
56
Q

Discuss the management of polyhydramnios

A
  • No medical intervention is required in the majority of women with polyhydramnios
  • If severe symptoms, amnioreduction can be considered (not routinely done)
  • Indomethacin can be used to enhance water retention & reduce fetal urine output (BUT it is associated with premature closure of ductus arteriosus so not used before 32 weeks)
  • In cases of idiopathic polyhydramnios, baby needs to be examined by paediatrician before first feed; NG tube is passed to check there is not an oesophageal atresia or tracheoesophageal fistula
57
Q

State some potential complications of polyhydramnios

A
  • Increased incidence preterm labour (over distension of uterus)
  • Increased risk of malpresentation (fetus has more room to move around)
  • Increased risk PPH (uterus has to contract further)

Yr4: Obstetrics & Gynaecology (24 decks)

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