Fetal abnormalities Flashcards
What is breech presentation?
- A breech presentation is when the foetus presents buttocks or feet first (rather than head first - cephalic).
- Implications in terms of delivery - if it occurs at term (> 37 weeks).
- Higher perinatal mortality and morbidity - birth asphyxia/trauma, maturity and increased incidence of congenital malformations.
Types of breech position?
- Type depends on position of the legs.
1) Complete (flexed) breech - both legs are flexed at the hips and knees (foetus sitting cross legged)
2) Frank (extended) breech - both legs flexed at the hip and extended at the knee - MOST COMMON
3) Footling breech - one or both legs extended at the hip so that the foot is the presenting part.
20% of babies are breech at 28 weeks gestation, majority revert to cephalic presentation spontaneously and only 3% breech at term.
Aetiology and Risk factors of breech?
Uterine:
1) Multiparity
2) Uterine malformations
3) Fibroids
4) Placenta praevia
Foetal:
1) Prematurity
2) Macrosomia
3) Polyhydramnios
4) Twin pregnancy
5) Anencephaly
Clinical features of breech presentation?
- Of limited significance before 32-35 weeks as foetus likely to revert.
- Can be identified on clinical examination, head felt in upper part of uterus and irregular mass (buttocks/legs) in pelvis, foetal heart auscultated higher in maternal abdomen.
- Usually not diagnosed until labour - foetal distress signs such as meconium signed liquor. Sacrum or foot may be felt through the cervical opening.
Ddx: Oblique lie (diagonal with head or foot in one iliac fossa), transverse lie (positioned across uterus - shoulder usually presenting part).
Ultrasound scan - confirmation and identify type of breech, and reveal any foetal/uterine abnormalities that predispose to breech presentation.
Management of breech presentation?
3 options - external cephalic version, caesarian or vaginal breech birth.
1) External cephalic version - manipulation of foetus into cephalic presentation through the maternal abdomen, complications include transient foetal heart abnormalities and placental abruption. Contraindicated: recent antepartum haemorrhage, uterine abnormalities, ruptured membranes, previous caesarian.
2) If external cephalic version is contraindicated, declined or unsuccessful - executive C-section is recommended.
3) Vaginal breech birth - some women may chose this, and some may present with breech in advanced labour, contraindication is FOOTLING BREECH - head and shoulders could be trapped. “Hands off breech”. Occasionally baby does not deliver spontaneously - specific manoeuvres - flexing the foetal knees, Lovsett’s manoeuvre - rotates body and deliver shoulders, MSV manoeuvre to deliver head by flexion (forceps used if this fails).
Complications of breech birth?
1) Umbilical cord prolapse
2) Foetal head entrapment
3) Birth asphyxia
4) Intercranial haemorrhage
5) Premature rupture of the membranes
What is lie, presentation and position?
Lie - the relationship between the long axis of the foetus and the mother - longitudinal, transverse or oblique.
Presentation - the foetal part that enters the maternal pelvis first (cephalic vertex presentation is the most common and is considered the safest - others include, breech, shoulder, face, brow.
Position - Position of the foetal head as it exits the birth canal - usually in an occipto-anterior position. Can also be occipito-transverse, occipito-posterior.
Risk factors for abnormal foetal lie, malpresentation and malposition?
1) Prematurity
2) Multiple (twin triplet) pregnancy
3) Primiparity
4) Uterine abnormalities
5) Placenta praviae
6) Foetal abnormalities
Investigation of abnormal foetal lie, position and presentation?
Foetal lie and presentation can usually be identified via abdominal examination. The foetal position is ascertained by vaginal examination.
Any suspected abnormal foetal lie or malpresentation should be confirmed by an ultrasound scan - which would also show any foetal or uterine abnormalities.
Management of abnormal foetal lie, position and presentation?
- Abnormal foetal lie: ECV - complications including foetal distress, placental abruption, contraindicated in recent APH, ruptured membranes, uterine abnormalities or previous C-section.
- Malpresentation: breech - ECV attempted, C-section or vaginal breech delivery.
Brow - C-section necessary
Shoulder - C-section necessary
Face - if chin is anterior (mento-anterior) normal birth possible but prolonged with risk of C-section being required, if chin posterior (mento-posterior) C-section required. - Malposition - 90% of malpositions spontaneously rotate to occipital-anterior as labour progresses - if foetal head does not rotate - rotation and operative vaginal delivery can be attempted. Or C-section can be performed.
What is Oligohydramnios? PPx?
- Refers to a low level of amniotic fluid during pregnancy, defined by an amniotic fluid index that is below the 5th centile for gestational age.
- The volume of amniotic fluid increases steadily until 33 weeks gestation, and plates at 33-38 weeks and then declines.
- Predominantly comprised of foetal urine output - with small contributions from placenta and some foetal secretions.
- Foetus breathes and swallows the amniotic fluid - gets processed, fills the bladder and is voided and the cycle repeats - problems with any of the structures in this pathway can lead to too much or little amniotic fluid.
- Anything that reduces the production of urine, blocks output from the foetus or a rupture of the membranes (allowing amniotic fluid to leak) - polyhydramnios.
Aetiology of oligohydramnios?
1) Pre-term prelabour rupture of the membranes
2) Placental insufficiency - resulting in blood flow being redirected to the brain rather than abdomen and kidneys - reduced urine output.
3) Renal genesis/Potter syndrome
4) Bilateral multicystic dysplastic kidneys (non-functioning kidneys)
5) Obstructive uropathy
6) Genetic/chromosomal anomalies
7) Viral infections (may also cause polyhydramnios)
Diagnosis of oligohydramnios?
- Made via ultrasound - two ways of measuring amniotic fluid: Amniotic fluid index (AFI) or maximum pool depth (MPD). AFI more commonly used.
- Amniotic fluid index is calculated by measuring maximum cord-free vertical pocket of fluid in 4 quadrants of the uterus and adding them together.
Clinical assessment of oligogydramnios?
- History - inquire about symptoms of leaking fluid and feeling damp all the time (new urinary incontinence)
- Exam - Measure symphasis fundal height + speculum examination (pool of liquor seen in the vagina)
- Ultrasound - assess for liquor volume, structural abnormalities, renal agenesis, obstructive uropathy. Measure foetal size - small due to placental insufficiency/rise in pulsatility index in placental insufficiency?
- Karyotyping - if appropriate - in cases of early/unexplained oligohydramnios.
- CHECK FOR IGFBP-1 in vagina - found in amniotic fluid, if in vagina could be due to ruptured membrane.
Management of oligohydramnios?
DEPENDANT ON UNDERLYING CAUSE - two most common are placental insufficiency and ruptured membranes.
- Ruptured membrane: If oligohydramnios due to ruptured membranes - labour usually commences in 24-48hrs - in case of preterm rupture (<37wk) and where labour doesn’t start automatically - induce labour at 34-36 weeks (in absence of infection). Course of steroids to aid lung development and antibiotics to reduce risk of ascending infection.
- Placental insufficiency - Timing of delivery depends on number of factors: rate of foetal growth, umbelical artery and middle cerebral artery Doppler scans, CTG. These babies likely to be delivered before 36-37wk.
