Malpresentation, cephalopelvic disproportion, uterine rupture Flashcards
What is a malpresentation?
Malpresentation is the situation where a foetus within the uterus is in any position that is not cephalic - i.e. head down.
Malposition is any cephalic position other than occiput anterior.
What is the most common malpresentation?
breech presentation, occuring in 3% of term births (the incidence is higher at earlier stages of gestation, however the tendency is to rotate to a cephalic presentation with time)
your baby’s bottom or feet are facing downwards - is breech
What are the maternal factors of malpresentation?
- pelvic inflammation
- pelvic tumour / fibroid
- arcuate or septate uterus
- oligohydramnios
- placenta praevia
What are some foetal factors of malpresentation?
- prematurity
- multiple pregnancy
- fetal malformation e.g. hydrocephalus
- intrauterine death
What are the various types of breech?
frank breech - hips flexed, legs extended at the knee (i.e. feet by ears) - 60-70%
flexed breech - also called complete - both legs flexed at hip and knee (i.e. legs crossed) - 30-40%
footling breech - at least one leg presents below the breech - < 1%; this type of breech presentation carries the greatest risk of cord prolapse
What is an unstable lie?
When the presentation of the foetus changes from day to day the lie is said to be unstable.
Why is unstable lie not a sinister sign?
the uterus is relatively flaccid and able to accommodate a lot of movement of the fetus.
What is an unstable lie caused by?
- placenta praevia
- polyhydramnios
- prematurity
- subseptate uterus
- pelvic tumours such as fibroids and ovarian cysts
What is a transverse lie?
not uncommon for the foetus to have a transverse lie until about the 32nd week of pregnancy. However if the foetus continues to adopt a transverse lie after this period then a possible cause should be determined
What can a transverse lie occur in association with?
- grand multiparity
- polyhydramnios
- prematurity
- subseptate uterus
- pelvic tumours such as fibroids, - ovarian cysts
- placenta praevia
- multiple pregnancy
- foetal abnormality
What are the main dangers of a transverse lie?
Pre-term ruptures of membranes
Cord porlapse
What is the incidence of a transverse lie?
1:320
What is the aetiology of transverse lie?
- prematurity
- contracted pelvis
- praevia
- polyhydramnios
- intrauterine fetal death
- twins - very rare for both twins to be transverse lie unless conjoined
foetal abnormality
What are the investigations for transverse lie?
- uterus broad and symmetrical
- no fetal pole in the pelvis
- vaginal examination - forewaters or limb felt
When should a woman with a diagnosis of transverse or oblique lie be admitted to a hospital and what should be excluded once in hopsital?
After 37 weeks
praevia
twins
foetal anomaly
pelvic tumour
polyhydramnios
What therapies and management is available for oblique and transverse lie?
- external version
- stabilising induction
- elective caesarian section
- There is a risk of cord presentation and prolapse. Under such circumstances an immediate caesarian section is essential.
What is the most common malposition?
Occipito posterior position
What happens in occipito posterior position?
The head is usually incompletely flexed and the occipitofrontal diameter presents - ie a larger diameter is involved.
How does the occipito posterior position occur?
Approximately 10% of labours begin this way, but many correct in labour. The shape of the pelvis, the strength of contractions and thus the presence of an epidural all influence this correction.
What do people of occipito posterior position rotate to?
From LOP 65% rotate to OA, 15% rotate to OP and are delivered as “face to pubes” - this is more difficult due to the increased diameter - and 20% rotate to OT, which is incompatible with normal delivery. In this last case the management depends on the stage of labour - 5cm dilation of the cervix indicates the need for a caesarian section, full dilation might be managed with forceps
What is the face presentation?
This is where the head is extended such that the face presents. The presenting diameter is submento-bregmatic, averaging 9.5 cm.
It occurs in 1 in 500 deliveries, and is less favourable than OP (occipitoposterior). Progress depends on the relative sizes of foetus and pelvis.
What is the most favourable position of face presentation?
Mento-anterior
delivery may convert to OA in much the same way as OP, this can be assisted by manually flexing the head. Turning the head to mento-anterior has advantages.
What is the incidence of face presentation?
Incidence: 1:500 deliveries
77% of face presentations are mento-anterior.
What is the aetiology of face presentation?
- prematurity
- anencephaly
- cord around neck
- neck tumours
- polyhydramnios
- pelvic tumour
- praevia
- uterine anomalies
What does the foetus often do in an extended position?
Often the foetus actively holds its head in an extended position; such an infant may voluntarily extend the neck after delivery.
What happens in cases of cephalopelvic disproportion?
- the occiput may become lodged on the pelvic brim, while the sinciput advances.
- This results in an arrested face presentation.
What are the investigations for the face position?
This is generally made on vaginal examination in advanced labour.
Other diagnostic clues include:
- S-shaped fetal spine
- ovoid shaped uterus without fullness in the flanks
- a deep groove is palpated between the back and occiput
What is the management for the face position?
exclude:
foetal anomaly
contracted pelvis
check foetal size
careful assessment, monitoring
episiotomy usually required if vaginal delivery
in a mentoanterior presentation normal vaginal delivery should be the ideal; in cases of delayed second stage, forceps should be used
persistent mentoposterior makes vaginal delivery almost impossible
