Malposition and Presentation Flashcards
What are the 6 main types of presentation?
- Vertex
- Brow
- Face
- Breech
- Shoulder (dorsoanterior)
- Shoulder (dorsoposterior_
What is malposition?
Where the occiput is in one of the other posterior quadrant of the pelvis; the foetus adopts a deflexed attitude as in an OP position
What is malpresentation?
Any presentation other than vertex (foetus adopts an extended attitude)
How is the engagement of the PP different in primips and multips?
Primips = head usually engages at 32/40 but often comes back out for baby to move position Multips = head engages and rarely comes back out
What is lie?
The relationship of the long axis of the foetus to the long axis of the uterus
What are the 3 types of lie?
- Longitudinal
- Oblique
- Transverse
What is presentation?
The part of the foetus lying in the lower pole of the uterus
What is position?
The denominator and the position in relation to the woman’s pelvis
What are the 7 types of position?
- Direct OA
- ROA
- LOA
- Direct OP
- ROP
- LOP
- LOT/ROT
What are the 3 types of denominator?
- Occiput
- Sacrum
- Mentum
What is attitude?
The relationship of the foetal head and limbs to the body
What are the 3 types of attitude?
- Fully flexed (head forward)
- Poorly flexed (straight line)
- Extended (head back)
What are the 4 sutures on the foetal skull?
- Frontal
- Coronal
- Sagittal
- Lamboidal
What are the 4 bones of the foetal skull?
- Frontal
- Coronal
- Parietal
- Occipital
What are the 8 diameters of the foetal skull?
- Bi-parietal (9.5cm)
- Bi-temporal (8cm)
- Suboccipitobregmatic (9.5cm)
- Suboccipitofrontal (10cm)
- Occipitofrontal (11.5cm)
- Mento-vertical (13cm)
- Submentobregmatic (9.5cm)
- Submentovertical (11cm)
What diameters cause a vertex PP?
Suboccipitobregmatic (well flexed) and Suboccipitofrontal (poorly flexed/deflexed)
What diameter causes a brow PP?
Mentovertical
What diameters cause a face PP?
Submentobregmatic (fully extended) and Submentovertical (not fully extended)
What are the 3 diameters of the pelvic brim?
AP = 11cm Oblique = 12cm Transverse = 13cm
What are the 3 diameters of the pelvic cavity?
AP = 12cm Oblique = 12cm Transverse = 12cm
What are the 3 diameters of the pelvic outlet?
AP = 13cm Oblique = 12cm Transverse = 11cm
Give some of the causes of OP position
- Maternal position and lifestyle
- Android/anthropoid pelvis (Myles)
- Anterior placenta
- Epidural and synto
- Nulliparity
- Increased mat age/ gestation
How can OP position be diagnosed antenatally?
- Inspection of abdomen (dip near umbilicus)
- Palpation
- FH auscultation
What does the OP position increase the risk of?
IOL for postdates; don’t go into established labour as head cant descend
How can OP position be diagnosed in labour?
- Listen to the woman
- Inspection and palpation
- FHR round side/deep
- VE (feel ears, see which way they move)
- Progress of labour (e.g. early SROM, incoordinate contractions)
What might the woman say that suggests the baby is in an OP position?
- Reduced FM
- Severe back pain
- Urge to push in early labour
What are the first 5 steps of long rotation?
- Occipitofrontal diameter engages in R oblique diameter
- Increasing flexion and descent = sub-occipito bregmatic diameter in pelvic cavity
- Occiput meets resistance of pelvic floor and rotates forwards
- Head now in same position as occipitoanterior mechanism
- Shoulders follow head from left to right oblique
What are the last 5 steps of long rotation?
- Head is born by extension
- Restitution
- Internal rotation of shoulders
- External rotation of head to mother’s right
- Lateral flexion
What are the first 5 steps of short rotation?
- Occipitofrontal diameter engages in right oblique diameter
- Descent occurs with little/no flexion
- Sinciput meets the resistance of the pelvic floor and rotates forward
- Occiput passes into the hollow of the sacrum
- Shoulder enters the pelvis in left oblique
What are the last 5 steps of short rotation?
- The root of the nose pivots under the pubic arch
- Occiput sweeps the pelvic floor by flexion and face is born by extension
- Restitution
- External rotation of the head
- Lateral flexion
Describe the process of Deep Transverse Arrest
- Head descends with some flexion
- Head starts long rotation but flexion not maintained and head caught in bi-spinous diameter of the outlet in deflexed position
- Head cannot deliver
= Obstetric emergency
What are the usual outcomes of OP position?
- Deflexed head (long rotation to OA)
- Deflexed head (long rotation but deep transverse arrest)
- Deflexed head (short rotation to direct OP)
- High deflexed head - partial extension = brow
- Full extension = face
Why is maternal/perinatal morbidity increased in OP position?
- Obstructed labour
- Maternal exhaustion
- Epidural and instrumental
- Trauma
- Cord prolapse
- Moulding (prolonged labour)
- Hypoxia
- PPH
What are the causes of face presentation?
- Pelvis shape
- Grand multiparity
- Polyhydramnios
- Multiple coils of cord around neck
- Anencephalic foetus
- Prematurity
How can face presentation be diagnosed antenatally?
- Non-engaged head
- Deep groove between head and back palpable
- Difficult to identify
How can face presentation be diagnosed during labour?
- VE (eyes, nose, mouth)
- PP high, soft and irregular
Why are facial features harder to palpate as labour progresses?
Facial oedema
What is usually the presenting diameter in face presentation?
9.5cm
What are the first 5 steps of the mento-anterior mechanism?
- Descent with extension of the head
- Mentum = leading part
- Internal rotation of the head; chin reaches pelvic floor and rotates forward
- Chin escaped under symphysis pubis
- Flexion of head; sinciput, vertex and occiput sweep perineum
What are the last 4 steps of the mento-anterior mechanism?
- Restitution; mentum turns to original side of back
- Internal rotation of shoulders (anterior shoulder rotates)
- External rotation of head
- Lateral flexion
What are the complications associated with face presentation?
- Cord prolapse
- Obstructed labour
- Foetal distress
- Severe perineal trauma
- Facial oedema/ intracranial bleeding
What care should be given in labour with face presentation?
- Involve obstetric team
- Careful VE’s
- No FSE
- Adequate analgesia
- Episiotomy
- Prepare parents for baby’s appearance
What are the primary ways of diagnosing brow presentation?
- Large non-engaged head on palpation
- Not usually detected before onset of labour
What are the secondary ways of diagnosing brow presentation?
- PP high and difficult to reach
- VE; anterior fontanelle felt on 1 side of pelvis and orbital ridges/root of nose felt on other side
- No descent of PP
What are the 3 possible outcomes of brow presentation?
- Convert to vertex
- Convert to face
- Remain as brow
What are the complications associated with brow presentation?
- Cord prolapse
- Foetal distress
- Excessive moulding
- Obstructed labour
What is usually the cause of shoulder presentation?
Unstable lie (transverse/oblique)
What are the common causes of unstable lie?
- Laxity of uterine muscles
- Multiple pregnancy
- Polyhydramnios
- Placenta praevia
- Fibroid
How can unstable lie be correct?
External version to longitudinal lie
What is the outcome of shoulder presentation?
This is an obstetric emergency and the baby will be delivered by CS
How can mothers optimise foetal position?
Spend time on hands and knees/ upright rather than slouched/lying down
What is the heaviest part of a foetus?
Its back
