Abnormal presentation/ lie Flashcards
What is abnormal lie?
Any non-cephalic presentation
Terms used to describe foetal positioning
Lie = relationship between the long axis of the foetus and the mother
Presentation = part of the foetus that first enters the maternal pelvis
Position = position of the foetal head as it exits the birth canal
Most common foetal presentation
Cephalic vertex
Most common position of foetal head as it exits birth canal
Occiput-anterior
The left occiput anterior (LOA) position is the most common in labor. In this position, the baby’s head is slightly off center in the pelvis with the back of the head toward the mother’s left thigh. The right occiput anterior (ROA) presentation is also common in labor
What is the most common malpresentation?
Breech
Affects 3-4% foetuses at term
Factors causing malpresentation
Maternal
- Pelvic tumours/ fibroids
- Congenital uterine anomalies
- Oligohydramnios
- Placenta praevia
Foetal
- Prematurity
- Anomalies e.g. hydrocephalus
- Multiple pregnancy
- Intrauterine death
Clinical features of malpresentation
Suspected clinically on abdo palpation and confirmed by USS
Discuss abnormal lie
Transverse and oblique lie occur in 1:300 pregnancies and resut in shoulder, limb and cord presentation
Vaginal delivery not possible unless abnormal lie corrected
Diagnosis of abnormal lie
Mothers abdomen may appear wide
Fundus lower than expected for dates
Neither foetal pole is palpable entering pelvis
Foetal head palpable on one side
Pelvis empty on vaginal exam
Limb/ cord may prolapse through cervix
Management of abnormal lie
External cephalic version @36-38 weeks depending on contraindications - if successful, exclude cord prolapse before allowing labour to progress
C-section is indicated in almost all cases
Contraindications to external cepahlic version
Antepartum haemorrhage within last 7 days
Ruptured membranes
Uterine anomalies
Previous c-section
Multiple pregnancy
Abnormal CTG
Outline abnormal presentations in labour
Any presentation other than vertex:
- Breech
- Brow
- Face
- Shoulder
- Arm
- Cord
Frequency of brow presentation
1/1000 - 1/3500 deliveries
Can revert to face or vertex but if it persists normal delivery is not possible
Management: watch and wait, may become face or vertex presentation, if persists c-section needed
How many births does face presentation occur in?
1:600 - 1:1500
Management: 90% are mentoanterior meaning the chin is anterior - normal labour can occur as head can flex
10% = mentoposterior and babies cannot be delivered in this presentation as would require hyperextension of the neck
Poor progress and failure to roate means c-section needed
In which presentation is ventous absolutely contraindicated?
Face presentation
Can lead to opthalmic haemorrhages
Discuss cord presentation
When one or more loops of the cord lie below the presenting part and membranes are still intact
Associated with malpresentation, abnormal lie and high head
Risk of cord prolapse when membranes rupture >> this is an obstetric emergency
Occult (incomplete) cord prolapse – the umbilical cord descends alongside the presenting part, but not beyond it.
Overt (complete) cord prolapse – the umbilical cord descends past the presenting part and is lower than the presenting part in the pelvis.
Cord presentation – the presence of the umbilical cord between the presenting part and the cervix. This can occur with or without intact membranes.
Management of cord presentation
Avoid handling the cord to reduce vasospasm
Manually elevate the presenting part by lifting the presenting part off the cord by vaginal digital examination
Encourage into left lateral position with head down and pillow placed under left hip OR knee-chest position. This will relieve pressure off the cord from the presenting part.
Consider tocolysis (e.g. terbutaline) – if delivery is not imminently available this will relax the uterus and stop contractions, relieving pressure off the cord
Delivery is usually via emergency Caesarean section
Discuss breech presentation
Buttocks/ feet first
Most common malposition is frank breech where baby’s hip joints are flexed and knees extended
Complete breech: baby’s knees and hips flexed
Footling breech: baby’s hip and knee joints extended and flexed respectively
Management of breech presentation
Babies <36 weeks may turn spontaneously so watch and wait
ECV if >36 weeks
Mother may have vaginal delivery but access for conversion to emergency c-section needed
Vaginal = safer for mother
C-section = safer for baby
What medication is used to promote efficacy of ECV?
Tocolysis: terbutaline
Given subcut, it is a b-agonist and works to relax the myometrim and promote ECV success
What is given to rhesus negative women before ECV is done?
Anti D because ECV is a sensitising event
How do we decide how much anti-D to give before a sensitising event?
Kleihauer test - measure foetal Hb levels in the mother
