Malposition and malpresentation Flashcards
What is malposition?
Where the occiput is in one or other posterior quadrant of the pelvis’ The fetus adopts a deflexed attitude as in an OP position
What is malpresentation?
any presentation other than vertex The fetus adopts an extended attitude as in face or brow, or presents as breech or shoulder
What is the lie?
the relationship of the long axis of the fetus to the long axis of the uterus
What is the presentation?
the part of the fetus lying in the lower pole of the uterus
What is the position?
-The denominator is the part of the presentation used to determine the position
Occiput, sacrum, mentum (chin)
-The position is the relationship of the denominator to six areas of the woman’s pelvis
Left and right of all three
Plus whether it is an anterior or posterior position
What is the attitude?
The relationship of the fetal head and limbs to its body. May be flexed, deflexed or partially extended
State diameters of fetal skull and presenting part
- Suboccipitobregmatic 9.5cm, normal, well flexed
- Suboccipitofrontal 10cm, not quite flexed
- Occipitofrontal 11.5cm, deflexed, military, OP
- Mentovertical 13.5cmm, brow
- Submentobregmatic 9.5cm, face
- Submentovertical 11.5cm, face not fully extended
(Biparietal 9.5cm- widest transverse diameter and bitemporal 8cm)
State diameters of maternal pelvis
What is the normal mechanism of labour?
Descent/engagement
Flexion
Internal Rotation (of head-to suit change in diameter of maternal pelvis- becomes dead on AP, coz was preiously Loa or Roa)
Crowning of the Head/Extension
Restitution (head realigns with shoulders- they’re diagonal not completely vertical to pelvis)
External Rotation of the Shoulders (shoulders become dead on AP and are visible)
Lateral Flexion (posterior then anterior shoulder and trunk delievered)
Expulsion
Do Frogs In Canada Ride Epic Limos Everyday?
Why is knowing the position and presentation important?
Impacts greatly on care plan- is vaginal birth possible, c-section necessary, ECV?
Why does OP occur?
Passengers
Powers
Passage
Maternal posture and lifestyle
Android/anthropoid pelvis
Anterior placenta
Epidural analgesia plus oxytocin augmentation
Nulliparity
Increased maternal age
Increased gestation
Evidence on optimal fetal positioning
Research Evidence
Inconclusive
Further research recommended
May help as a comfort measure in labour
What clinical assessment is undertaken for the diagnosis of OP position?
Antenatal assessment
- Inspection of abdomen
- Palpation
- FH auscultation
In labour
- Listen to the woman (FM and pain)
- Inspection and palpation
- FH auscultation
- Vaginal examination
- Progress of labour (e.g. early SROM, in-coordinate contractions
What is the mechanism of occipito position – long rotation
Long internal rotation (commonest mechanism) ie LO
Long internal rotation (commonest mechanism) ie LOP
Occipito frontal diameter engages (11cms) in R oblique diameter
(12cms)
Increasing flexion and descent- Sub-occipito bregmatic diameter (9.5cms) in the pelvic cavity
Occiput meets the resistance of the pelvic floor and rotates 3/8th circle forwards
Head now in same position as occipitor anterior mechanism
The shoulders follow the head turning 2/8th
from left to right oblique
Head is born by extension
Restitution
Internal rotation of shoulders
External rotation of head to mothers right
Lateral flexion
Short internal rotation (Persistent OP)
Occipito frontal diameter (11cms) engages in right oblique diameter (12cms)
Descent occurs with little or no flexion
Sinciput meets the resistance of the pelvic floor and rotates forwards 1/8th of a circle (now direct OP)
Occiput passes into the hollow of the sacrum
Shoulder enters pelvis in left oblique
The root of the nose (glabella) pivots under the pubic arch
Occiput sweeps the pelvic floor by flexion and face is born by extension (‘face-to-pubes’)
Restitution
External rotation of head
Lateral flexion
What is the mechanism of OP – Deep transverse arrest?
Head descends with some flexion
Head starts long rotation but flexion not maintained and head caught in bi-spinous diameter (11cms) of the outlet in deflexed position
Head cannot advance and an instrumental or operative delivery will be necessary
What is the midwifery management and care during labour?
Check notes and history, Identify early, women with OP position, Abdominal palpation – accurate diagnosis
Full and clear explanation to woman re labour, length, options, discomfort, provide full support
Discuss optimal fetal positioning and alternative birth positions
Monitor maternal and fetal wellbeing – strength and length of contractions and descent of head abdominally. FH.
Check bladder
VE – findings – essential to confirm. PROGRESS? Large caput?
Observe for early ROMs, - risk of cord prolapse
Monitor for in-coordinated uterine action, and cervical dilatation and provide active management of labour for positive outcome – get head flexed!
Augment labour if appropriate
Avoid epidural if possible – mobile mix
RECORDS of progress and subsequent care
Inform woman of progress being made and possible outcomes
What are the 5 possible outcomes of an OP position?
Depends on the degree of flexion
90% will descend and rotate OL-OA and deliver
- deflexed head – long rotation to OA
- deflexed head – long rotation but DTA – assisted delivery
- deflexed head – short rotation to DOP
- High deflexed head – partial extension – brow
- Full extension - face
What is the management of a face to pubes delivery?
Allow the sinciput to escape as far as the glabella (smooth part of the forehead above and between the eyebrow)
The occiput sweeps the perinuem, the sinciput is held back to maintain flexion
Grasping the head to bring the face down from under the symphysis pubis
Extension of head
Who can perform a manual rotation of OP position?
A skilled practitioner
What ar the possible complications of OP position?
Increased maternal and perinatal morbidity and mortality due to…
- Obstructed labour if DTA or Brow
- Maternal exhaustion and ketosis
- Higher incidence of epidural and instrumental delivery or C/S
- Maternal trauma –probable need for episiotomy third /fourth degree Urinary retention – epidural, pressure, prolonged labour
- Cord prolapse with early ROMs
- Excessive moulding with long labour
- Intracranial haemorrhage with upward moulding of fetal skull
- Fetal hypoxia with prolonged labour
- PPH with prolonged labour
- Maternal/fetal infection due to intervention in a prolonged labour
- Postnatal depression or PTSD due to above (Lewis 2010)
What are the causes of a face presentation?
Face occurs when the presenting part and head is hyper-extended
Incidence 0.2%
Causes:
Pelvis shape
Grand multiparity (pendulous abdomen)
Polyhydramnios
Enlargement of fetal neck (tumour of the neck)
Multiple coils of cord around the neck
Anecephalic fetus
Multiple pregnancy
Prematurity
(Lewis 2010, )
How is a face presentation diagnosed?
Primary (Before Labour)
Not easily identified before labour
Non-engaged head
Deep groove between head & back palpable
Secondary (During Labour)
Most commonly detected on VE
Presenting part high, soft and irregular
Eyes, nose & mouth may be felt
Need to differentiate from breech
Facial features more difficult to palpate as labour progresses due to facial oedema
What is the mechanism of labour for a face presentation?
6 possible positions for face presentation
Mentum (chin) is the denominator
Presenting diameter is 9.5cm
Needs to rotate to a mento-anterior position to facilitate a vaginal delivery
There are no delivery mechanisms for persistent mento-posterior positions therefore a vaginal delivery is very unlikely
What is the mechanism of mento-anterior position?
Descent with extension of the head
Mentum- leading part
Internal rotation of the head- chin reaches pelvic floor & rotates 1/8th circle forward
Chin escapes under symphysis pubis
Flexion of head- sinciput, vertex & occiput sweep perineum
Restitution- mentum turns 1/8th circle to original side of back
Internal rotation of shoulders (anterior shoulder rotates 1/8th of a circle)
External rotation of head simultaneous with shoulders
Lateral flexion
What are the complications with face presentation?
Cord prolapse
Obstructed labour
Fetal distress
Operative delivery
Severe perineal trauma
Facial bruising & oedema in baby
Intracranial bleed in baby
What is a brow presentation?
Brow presentation involves partial extension of fetal head with the frontal bone as the presenting part
Least common of all presentations
Incidence 1:500 – 1:1400
Causes similar to face presentation
What is the mechanism of labour in a brow presentation?
Presenting diameter (mentovertical) 13.5cm
Vaginal delivery extremely rare
Obstructed labour normally results
Delivery usually by LSCS unless baby very small
Three possible outcomes
Brow may:
- Convert to vertex
- Convert to face
- Remain as a persistent brow
What is the management of care with a brow presentation?
Immediately inform Obstetrician
High risk care
If diagnosed early in labour & no fetal distress, obstetrician may wait to see if conversion to vertex or face takes place or LSCS
What are the complications with a brow presentation?
Cord prolapse
Fetal distress
Excessive moulding
Obstructed labour (very likely)
What causes an unstable lie, how is it diagnosed, when can you continue as normal and when does it become an obstetric emergency?
An unstable lie (transverse or oblique) can lead to a shoulder presentation
- Causes: laxity of uterine muscles, multiple pregnancy, polyhydramnios, placenta praevia, fibroid
- Diagnosed by abdominal palpation
- Can be corrected by external version to a longitudinal lie
- If fetal head enters the pelvis labour can continue as normal.
- If shoulder enters the pelvis once labour has started then this is an obstetric emergency and need delivery by LSCS
