Foetal abnormalities Flashcards
(30 cards)
What is a breech position? What are the 3 different types?
When the baby comes out buttocks or feet first rather than head first.
Complete: both legs flexed at hips and knee (cross legged), bum first
Frank (extended) breech: both legs flexed at hip but extended at knee (commonest)
Footling: one or both legs extended at hip so foot is presenting part
How common is breech presentation?
20% of babies are breech at 28 weeks gestation. most revert to a cephalic presentation (head down) spontaneously and only 3% are breech at term
What may cause breech presentation?
usually due to chance but 15% have RF:
- multiparity
- uterine malformation
- fibroids
- placenta praevia
- prematurity
- macrosomia
- polyhydramnios
What are the clinical features of a breech presentation?
- usually identified on clinical exam- round fetal head can be felt in upper uterus and irregular mass in the pelvis, the fetal heartbeat can be auscultated higher on maternal abdomen
- however this isnt usually important until 32-35 weeks
- 20% of breech presenation is not diagnosed until labour, this can present with fetal distress- eg meconium stained liquor, on vaginal examination the sacrum or foot may be felt though the cervical opening
how should a suspected breech presentation be investigated?
- confirm with uss, also tells you the type of breech and predisposing fetal abnormalities
What are the 3 management options for breech presentation?
- external cephalic version
- c section
- vaginal breech birth
What is external cephalic version and when is it used?
- manipulation of fetus to cephalic presentation through the abdomen
- if successful (40%) means they can have vaginal delivery
- attempted in all unless recent antepartum haemorrhage, ruptured membranes, uterine abnormalities or previous c section
- may get transient fetal heart abnormalities but these revert to normal
- rarer complications inc placental abruption and more persistent heart rate abnormalities
When is c section used for breech births?
- if external cephalic version is unsuccessful, contraindicated or declined, guidelines are they get a c section
- perinatal morbidity and mortality is higher in planned breech vaginal births compared w/ c section
When may a vaginal breech delivery be used and not used?
- cannot be used if footling breech as feet can slip through non- fully dilated cervix and shoulders/ head can be trapped
- pt may choose a vaginal breech or it may be the only option if they present in advanced labour
How should breech deliveries by conducted?
- ‘hands off breech’- putting traction on baby during delivery can cause fetal head to extend, getting it trapped during delivery
- support the fetuses pelvis anteriorly
- specific manoeuvres may be required: flexing fetal knees, lovsetts manoeuvre, MSV manoeuvre
List 3 complications of a breech presentation
- cord prolapse (cord drops down below the presenting part of the baby and becomes compressed)
- fetal head entrapment
- premature rupture of membranes
- birth asphyxia- usually secondary to delay in delivery
- intracranial haemorrhage- due to rapid compression of head during delivery
What is the definition of lie, presentation and position?
Lie: relationship between long axis of fetus and mother- londitudinal, transverse or oblique
Presentation: the fetal part which enters the maternal pelvis- cephalic, breech, shoulder, face or brow
Position: the position of the fetal head as it exists the birth canal- usually occipito- anterior, may be occipito- posterior or transverse
how are fetal lie and fetal position determined?
fetal lie and presentation by abdo exam
fetal position by vaginal examination during labour
- any suspicion of abnormality should get confirmed by USS
How is a brow and shoulder presentation managed?
- c section necessary
How is a face presentation managed?
- if chin is anterior (mento- anterior) a normal labour is possible however likely to be prolonged and increased risk of c section being required
- if chin is posterior then a c section is necessary
how are malpositions managed?
90% spontaneously rotate to occipito- anterior as labour progresses. If the fetal head does not rotate, rotation and operative vaginal delivery or c section can be performed
What is oligohydramnios
?
- low level of amniotic fluid
- below the 5th centile for gestational age
How and when does amniotic fluid get produced and absorbed?
- volume increases until 33 weeks and then plateaus at around 500ml
- produced by fetal urine output w/ small amount from placenta
- fetus breathes and swallows it, it gets processed and then voided out again
- any thing that disrupts production of urine, output of urine or rupture of membranes can reduce amniotic fluid
What may cause oligohydramnios?
- preterm prelabour rupture of membranes
- placental insufficiency (blood prioritised to brain rather than abdomen and kidney= low urine output)
- renal agenesis
- non functioning kidneys
- obstructive uropathy
- genetic/ chromosomal abnormalities
- viral infections
How is oligohydramnios diagnosed?
- USS
- amniotic fluid index or maximum pool depth, both have similar diagnostic accuracy but AFI more commonly used
How can ruptured membranes be tested for?
- actim prom- bedside test to detect IGFBP-1 in vagina
- this protein is found in amniotic fluid and if detected is strongly suggestive or membrane rupture
- particularly useful if diagnosis unclear
How should oligohydramnios be investigated?
- IGFBP-1 if suspect membrane rupture
- USS for structural abnormalities, renal agenesis and obstructive uropathy
- USS for fetal size- if small do umbilical artery doppler for placental insufficiency
- karyotyping if early unexplained oligohydramnios
how should ruptured membranes be managed?
- labour is likely to commence in 24- 48hrs
- if preterm, and labour doesnt automatically start then induction should be considered around 34-36 weeks if no infection
- course of steroids should be given to aid lung development and abx to reduce risk of ascending infection
What is the prognosis like for oligohydramnios?
- poor prognosis if in 2nd trimester as usually due to rupture of membranes (may be associated with infection) and so they get born very prem
- if due to placental insufficiency then also higher rate of prem
- fetus may develop severe muscle contractures despite physio after birth as low amniotic fluid reduces ability to move in utero
