Malposition and Malpresentation

Question 1

3 factors that affect birth?

Answer 1

POWER
-maternal effort
-uterine contractions (strength, length, frequency, regularity)
PASSAGE
-bony pelvis and soft tissue
PASSENGER
-lie (how’s it lying in relation to uterus)
-presentation (which part is closest to exit)
-position (what is position of occiput)
-size
-attitude (how well flexed is it)

Question 2

What are some examples of types of lie?

Answer 2

LIE (how’s it lying in relation to uterus)

• Longitudonal (ideal)
• Transverse
• Oblique

Question 3

What is presentation and what are some examples?

Answer 3

PRESENTATION (which part is closest to exit)

• Cephalic
• Breech

Question 4

What is position and what are some examples?

What is its not ideal?

Answer 4

POSITION (what is position of occiput relative to the maternal pelvis)
IDEAL: Occipito-transverse at the pelvic brim rotating to occipitoanterior at the pelvic floor

*manual rotation with instruments can be tried, if not C/S

Question 5

How common is face presentation? What are its associations and complications?

Answer 5

1 in 500 births

• Associated with anencephaly (missing part of brain)
• Usually only recognised at the onset of labour
• Described with relation to chin ‘mento-‘
• Cesarean section usually required

This delivery is possible because the face is a similar diameter to the occiput but it is associated with more trauma (bruising and oedema)

Question 6

How common is brow presentation? How can you tell?How concerning is it? How is it managed?

Answer 6

BROW PRESENTATION

• 1 in 1000
• Can feel anterior fontanelle and some facial features
• It is the least favourite of the malpresentations (largest diameter-MENTAL-13.5cm)
• If it persists then a CS will be required

Question 7

How common is breech presentation at 20w, 32w and term?

What is breech presentation associated with (contributing factors)?

Answer 7

40% at 20w are breech, 25% at 32w and 3-4% at term
- Chance of turning spontaneously after 38w is 4%

Associated with multiple pregnancy, bicornuate uterus, fibroids, poly and oligo-hydramnios

Question 8

What is the name of the BEST presenting diameter and how wide is it?

Answer 8

Suboccipitobregmatic diameter = 9.5cm
Frontal-12cm
MENTAL-13.5cm (brow position)

Question 9

What are the management options for malposition?

Answer 9

BREECH can offer external cephalic version (ECV) - palpation of the abdomen to try and encourage the baby to turn

Question 10

When is ECV offered?

Answer 10

36w in nullips and 37w in multips

***GIVE ANTI D AFTER

Question 11

How likely is ECV to be successful?

Answer 11

30% success rate in nullips and 50% success in multips

Question 12

What makes the chances of ECV succeeding more likely?

Answer 12

If the baby’s head is flexed rather than extended (frank)

Question 13

What should you do if the turn is only partially successful on ECV?

Answer 13

If only partially successful (e.g. get baby into transverse lie) then you should put the baby back into breech position as this is safer than transverse

Question 14

Can you deliver breech babies vaginally?

How should it be managed?

Answer 14

YES but should only be attempted by an experienced obstetrician
You should try and discourage the mother from pushing
The greatest risks are of the baby’s head extending and getting caught on the pelvic brim OR the cervix constricting around the neck of the baby