Abnormal lie and malpresentations Flashcards
(83 cards)
1
Q
What is meant by the term ‘malpresentation’?
A
any non-vertex presentation - may be face, brow, breech, other part of body if lie is oblique or transverse
2
Q
What proportion of fetuses are in cephalic presentation at term?
A
over 95% of fetuses
3
Q
What are 3 examples of malpresentation?
A
- face
- brow
- breech
4
Q
How do cephalic malpresentations differ between one another?
A
presenting diameter is dependent on degree of flexion or extension of the fetal head
5
Q
What are 2 types of presentations which have a wide diameter to the pelvic inlet?
A
- Deflexed occipito-posterior
- Brow presentation
6
Q
What is the structure of the fetal skull at birth and how does this change in labour?
A
made up of individual bony plates (occipital, sphenoid, temporal and ethmoid bones), joined by cartilaginous sutures (frontal, sagittal, lambdoid and coronal sutures)
has potential to be moulded in labour, allowing head to fit birth canal more closely
7
Q
What must moulding of the skull in delivery be distinguished from and what is it?
A
Caput succedaneum - oedema of the presenting part of the scalp
8
Q
When do scalp moulding and caput succedaneum occur?
A
can occur in any cephalic presentation, but more likely to occur in malpresentation
9
Q
When should moulding and caput succedaneum be recorded and why?
A
presence or absence of both should be documented during each vaginal examination in labour; excessive moulding and caput are suggestive of an obstructed labour due to cephalopelvic disproportion (CPD)
10
Q
What is face presentation?
A
occurs when fetal head extends right back (hyperextended so that occiput touches the fetal back)
11
Q
What are 5 conditions that are associated with face presentation?
A
- Prematurity
- Tumours of fetal neck
- Loops of cord around the fetal neck
- Fetal macrosomia
- Anencephaly
12
Q
When is face presentation typically recognised?
A
usually only recognised after onset of labour
13
Q
What can face presentation be confused with?
A
if face swollen can be confused with breech presentation
14
Q
What are 2 ways that a face presentation may develop during labour?
A
- Head enters pelvic brim with chin in transverse position (mentotransverse)
- Most (90%) rotate to mentoanterior position so head is born with flexion and deliver without problems
- Those that rotate to mentoposterior will obstruct - extending head presents increasinly wider diameter to pelvis, leading to worsening relative CPD (cephalopelvic disproportion) and impacted obstruction
15
Q
What can develop as a result of face presentation?
A
oedema and bruising of face
16
Q
What management is required for a facial presentation which progresses in the mentoposterior position?
A
caesarean section usually required
17
Q
What is the presenting diameter in a brow presentation?
A
menovertical, measuring 14cm
18
Q
What will be palpable on vaginal examination in brow presentation?
A
supraorbital ridges and bridge of nose
19
Q
What are 3 ways that a brow presentation may develop during labour?
A
- Head may flex to vertex presentation
- May extend to face presentation
- Brow presentation may persist
20
Q
What management may be required for a brow presentation?
A
if it persists (doesn’t change to vertex or face), caesarean section will be required
21
Q
What proportion of fetal lie at term is 1. cephalic 2. breech 3. transverse or oblique?
A
- 95%
- 4%
- 1%
22
Q
What is the definition of breech?
A
fetus presenting bottom first
23
Q
What is the incidence of breech presentation at 1. 20 weeks, 2. 32 weeks 3. term?
A
- 40%
- 25%
- 3-4%
24
Q
What is the chance of a breech presentation turning spontaneously after 38 weeks?
A
<4%
25
What are 6 things that breech presentation is associated with?
1. Multiple pregnancy
2. Bicornuate uterus
3. Fibroids
4. Placenta praevia
5. Polyhyramnios
6. Oligohydramnios
7. Rarely - fetal anomaly, particularly NTDs, neuromuscular disorders and autosomal trisomies
26
What are 3 types of fetal anomalies that, rarely, breech presentation can be associated with?
1. Neural tube defects
2. Neuromuscular disorders
3. Autosomal trisomies
27
What are 3 types of breech presentation?
1. Frank breech (extended breech)
2. Flexed breech (knees flexed - complete)
3. Footling breech (foot down - incomplete)
28
At term, what proportion of breech babies are frank (extended)?
65%
29
What are the options for management of a breech baby?
1. External cephalic version
2. Caesarean section
3. Vaginal delivery
30
What are 6 risks of vaginal delivery of a breech baby?
1. Intracranial injury
2. Widespread bruising
3. Damage to internal organs
4. Spinal cord transection
5. Umbilical cord prolalse
6. Hypoxia following obstruction of the after-coming head
31
What are the risks of caesarean section for a breech baby?
largely maternal, related to surgical morbidity and mortality
32
How do the risks of planned caesarean section vs vaginal delivery of a breech baby compare?
* planned c-section associated with less perinatal mortality, less serious neonatal morbidity than planned vaginal birth at term
* risk of serious maternal complications similar because vaginal delivery often ens with intrapartum c-section - greater risks than planed elective section
33
Who should be offered external cephalic version?
all women with a breech presentation at term unless absolute contraindication
34
When should external cephalic version be offered in breech pregnancies?
from 36 weeks in nulliparous women, and from 37 weeks in multiparous women
35
What is the success rate of external cephalic version in breech pregnancies?
50%
36
What are 7 absolute contraindications to external cephalic version?
1. when caesarean delivery required regardles of presentation (e.g. presentation praevia)
2. Antepartum haemorrhage within the last 7 days
3. Abnormal cardiotocograph
4. Major uterine anomaly
5. Ruptured membranes
6. Multiple pregnancy (except delivery of second twin)
7. Absence of maternal consent
37
What are 7 relative contraindications to ECV where it might be more complicated?
1. Nuchal cord
2. Fetal growth restriction
3. Proteinuric pre-eclampsia
4. Oligohydramnios
5. Major fetal anomalies
6. Hyperextended fetal head
7. Morbid maternal obesity
38
What monitoring should be performed before, during and after external cephalic version has been performed for breech presentation?
* before: CTG and ultrasound scan
* during: check fetal heart throughout
* after: CTG, testing for fetomaternal haemorrhage if woman D-negative and anti-D should be offered
39
What preparation might be needed before external cephalic version is attempted for breech presentatios? 3 things
1. some obstetricians like patient to be fasted and prepared for theatre; not always done but good to have theatre close at hand
2. Use of tocolysis, such as betamimetic drug, to soften uterus - associated with increased success rate
3. Applying scanning gel to abdomen allows easier manipulation, permits scanning during procedure if required
40
In which women is external cephalic version most likely to work to correct a breech presentation?
parous women when presenting part is free, liquor volume normal, head easy to palpate, uterus feels soft
flexed breech more likely to turn than an extended (frank) breech
41
What type of breech presentation is most likely to be corrected by external cephalic version?
flexed (complete) breech
42
In what position should the most be to perform external cephalic version to correct breech?
lie flat with 30o lateral tilt
43
What are the steps used to perform external cephalic version?
* breech disengaged if necessary, with scan probe or hands
* attempts made to rotate in direction in which baby is facing (i.e. forward roll)
* if forward roll unsuccessful, backward somersault can be tried
* if procedure only partially successful (i.e. fetus converted to transverse lie), return to breech rather than leave it transverse
44
What are 3 longer-term risks of caesarean sections for breech presentation?
1. risks of opting for vaginal birth for subsequent pregnancies after caesarean section
2. increased risk of complications in future caesarean sections
3. risk of abnormally invasive placenta
45
What are 4 things that the individualised decision for mode of delivery for pre-term breech should be based on?
1. stage of labour
2. type of breech
3. fetal wellbeing
4. availability of skilled clinician in vaginal breech delivery
46
What should women with breech presentation be counselled on regarding vaginal delivery?
counselled about risks associated with vaginal breech birth
47
What are 4 circumstances in which a higher-risk planned vaginal breech birth is expected?
1. Hyperextended neck on ultrasound
2. high/low estimated fetal weight
3. footling presentation
4. evidence of fetal compromise
48
If a woman presents with an unplanned vaginal breech labour, what 2 things will the management plan depend on?
1. stage of labour
2. availability of clinical expertise
49
What is the recommendation for induction of labour and breech presentation?
induction of labour not usually recommended
50
What is currently thought about the role of epidural analgesia for the first stage of labour for a vaginal delivery of a breech baby?
use may facilitate manipulation of fetus, but presence may inhibit desire to push, which is particularly important in breech delivery
51
What is the recommendation about augmentation of slow progress of the first stage of labour in breech pregnancy?
augmentation shouhld only be considered in event of inadequate uterine activity in presence of an epidural
52
Can fetal 'scalp' electrodes be used in a breech vaginal delivery?
no contraindication, providing care is taken to avoid genital injury
53
What maternal position is recommended during a vaginal delivery of a breech baby?
semi-recumbent position on all fours has been recommended
54
At full dilatation what must the mother be encouraged to do?
encourage to push; temptation by healthcare professionals to pull must be resisted - 'hands off'
55
When can assisted delivery be used during vaginal delivery of a breech baby? 2 situations
1. if undue delay
2. if concerns about fetal well-being e.g. movements stopping, baby becoming floppy, no response to stimuli
56
When can breech extraction be considered during a vaginal delivery?
when delivering the second twin
57
What are 6 aspects to assisted breech vaginal delivery?
1. knees can be flexed to deliver the legs
2. once legs are delivered, important to wait for body to advance further, before holding bone pelvis firmly
3. rotation allow one arm to be freed, flexed and brought down
4. rotation other way allows other arm to be similarly delivered
5. after delivery of other arm, flexion of head encouraged by allowing breech to hand down
6. head is delivered as for the hands off vaginal breech delivery
58
What is one of the key risks of assisted breech vaginal delivery?
pulling may lead head to extend and therefore become stuck at the pelvic brim
59
Why is maternal effort so important for the delivery of a breech baby vaginally?
allows head to flex and minimised risk of head becoming stuck at pelvic brim
60
What is the management if the head of a pre-term breech baby becomes entrapped behind an incompletely dilated cervix?
* should first flex head as far as possible to narrow presenting diameter
* failing this, options are to incise cervix at 4 and 8 o'clock positions (risking massive haemorrhage) or push fetus back up and perform caesarean (difficult manoeuvre)
* as these are hazardous to mother, may be preferable to await spontaneous delivery
61
What 2 conditions should all babies presenting by the breech be examined for?
1. Developental dysplasia of the hip
2. Klumpke paralysis - birth injury to brachial plexus affecting movement of lower arm and hand
62
What are 8 things which abnormal lie may be associated with?
1. Multiparous women
2. Multiple pregnancies
3. Pre-term labour
4. Polyhydramnios
5. Placenta praevia
6. Congenital abnormalities of the uterus
7. Lower uterine fibroids
8. Other pelvic masses e.g. ovarian cyst
63
What are 4 things that should be excluded with a scan if transverse lie is identified antenatally?
1. Placenta praevia
2. Polyhydramnios
3. Lower uterine fibroids
4. Pathologically enlarged fetal head
64
What manouevre is usually possible to manage transverse lie and what follow up should be performed?
ECV
Mother should be reviewed a few days later to ensure the lie is still cephalic
65
What should you advise the mother of a fetus with transverse lie and why? 2 things
* come to hospital if any suspicion of **early labour,** as may still be possible to carry out ECV at that stage, providing membranes sitll intact
* go to hospital immediately if any suspicion of **membrane rupture**, as there's a risk of _cord prolapse_ or prolapse of a _limb_
66
What is the way that some women with transverse lie or unstable lie are managed and why?
some clinicians advise women are **admitted from 38 weeks** to await birth or until longitudinal lie maintained
67
What is the management of transverse lie in established labour, particularly after membrane rupture?
caesarean section usually required
will be a very technically difficult section; vertical uterine incision may be necessary to allow adequate access for delivery
68
What is the definition of an unstable lie?
one that varies from examination to examination
69
What are 3 options for the management of unstable lie?
1. conservative: repeated ECVs as required, and await spontaneous onset of labour. should membranes rupture with fetus in non-cephalic presentation, may be risk of cord prolapse - inpatient management considered appropriate by some
2. arrange to turn baby to cephalic presentation then induce labour - sometimes called 'stabilising induction'.
3. carry out C-section
70
What is the key risk of rupture of membranes with fetus in a non-cephalic presentation in unstable lie?
cord prolapse (inpatient management therefore considered appropriate by some)
71
What is umbilical cord prolapse?
umbilical cord slips down below presenting part of fetus after rupture of membranes; can then pass through open cervix
risk of death to baby is 10%
considered an emergency due to loss of oxygen to fetus
72
What is a disadvantage of turning baby to cephalic presentation and inducing labour in unstable lie?
induction itself is not without risks, and lie may become unstable again even after membranes have been ruptured
73
What is the normal position for the fetal head to engage in the pelvic brim?
occipitotransverse position, flexing head as it descends into the pelvic cavity and rotating to occipito-anterior at the level of the ischial spines
head then extends as it descents, distending vulva until it is delivered
74
In what proportion of pregnancies does the fetal head enter the pelvis in more of an occipito-posterior position than transverse or anterior?
in about 10% of pregnancies
75
What can cause the fetal head to enter the pelvis in a more OP position than transverse or anterior?
either by chance or in associated with unfavourably shaped pelvis - particularly long oval 'anthropoid' pelvis
76
If the fetal head enters the pelvis in a more OP position than traverse or anterior, what position will it subsequently be in?
direct occipitoposterior position or with occiput to right or left of midline - right or left occipitoposterior
77
What term is used if the fetal head engages at the pelvic brim an occipitoposterior position?
malposition
78
What are the 3 main possibilities once a baby has descended in a direct occipitoposterior position or with the occiput to the right of left of the midline?
1. occiput will rotate anteriorly (through approx 135 degrees) to OA, then deliver normally - 65%
2. will partially rotate to occipitotransverse and not deliver - 20%
3. will rotate more posteriorly to OP - 15%
79
What are 6 probles at delivery for fetuses whose heads remain in OP once descending in that position?
1. greater difficulty negotiating birth canal, less likely to deliver spotaneously
2. normal mechanism involves extension of head to OA but extension not possible in OP position and wider diameter is presenting to the outlet (occipitofrontal 11.5cm)
3. first and second stages of labour longer, due to greater relative CPD (cephalo-pelvic disproportion) and partly because head less well applied to cervix and therefore less able to cause dilatation
4. back pain more common, mother more likely to request epidural
5. secondary arrest more likely to occur due to relative CPD
6. more likely to require augmentation with Syntocinon
80
What is Syntocinon?
Oxytocin infusion IV
81
If cervix does not reach full dilatation after administration of syntocinon for OP baby, what is the next step of management?
caesarean section will be required
82
If syntocinon is adminstered for an OP baby during delivery and the cervix reaches full dilatation, what are the 2 possible next steps?
* possible for baby to deliver in **OP position** with head coming out face to pubis
* but often either **manual** rotation, rotational **ventouse** or **Kielland** rotational forceps delivery required
83
What is a possible complication when a baby delivers in an OP position?
third- and fourth-degree perineal tears
