Occipito-posterior position

Question 1

What is OP position?

Answer 1

• when the fetal occiput is malpositioned in the posterior of the pelvis

Question 2

What are the causes and pre-disposing factors?

Answer 2

• more common in primigravidae (stronger abdominal muscles)
• more common with anterior placenta (less room in uterus)
• android pelvis (fore pelvis is narrow so occiput occupies roomier hind pelvis)
• anthropoid pelvis (narrow transverse diameter favouring a direct OP position)

Question 3

What are some of the antenatal signs of OP position?

Answer 3

• backache
• fetal movements felt across both sides of the abdomen
• women may report feeling that the baby’s bottom is high up against her ribs
• saucer-shaped dip at umbilicus
• head often high and non-engaged (due to large presenting diameter)
• fetal head deflexed (occipito frontal diameter 11.5cm)
• back difficult to palpate
• limbs felt on both sides of the midline
• FH heard more easily at the flanks or midline

Question 4

What is the incidence of OP position?

Answer 4

• occurs in 15% of all labours, POP births account for around 5% of all births

Question 5

What are some of the intrapartum signs of OP?

Answer 5

• continuous back pain that worsens with contractions
• prolonged latent phase due to poorly fitting pp
• irregular contractions that tend to couple together
• early SROM (risk of cord prolapse due to ill-fitting pp)
• slow descent of fetal head
• early desire to push due to pressure of occiput onto rectum
• on VE —> anterior fontanelle felt anteriorly if deflexed
  —> posterior fontanelle felt posteriorly if flexed
  —> caput and moulding common

Question 6

What care should be provided in labour?

Answer 6

• one to one support in labour - will need continuous reassurance, explanation and support
• encourage mobility and upright positions, leaning forward
• all fours may help reduce back pain, exaggerated sims position also reduces back pain and aids rotation
• encourage nutrition and hydration to prevent dehydration and ketosis which will lessen slow progress
• keep bladder empty to aid discomfort and not delay progress
• lying on alternate sides (if LOP lie on left side, if ROP lie on right side) aids with rotation using gravity
• avoid ARM - encourages sudden descent precluding rotation
• back pain - massage, bath or birthing pool, heat pads, tens
• epidural analgesia may be useful but may prolong OP labour
• good quality midwifery care - use of partogram, any delay in labour and fetal or maternal distress are recognised and referred (NMC 2012)

Question 7

What is long rotation of the occiput?

Answer 7

• occipitofrontal diameter (11.5cm) lies in pelvic brim
• descent takes place with increasing flexion
• occiput reaches the pelvic floor first and rotates forwards 3/8th of a circle
• fetus is then born in OA position

Question 8

What is short rotation of the occiput (POP)?

Answer 8

• lack of flexion results in the sinciput reaching the pelvic floor first
• it then rotates forwards 1/8th circle
• occiput enters hollow of sacrum
• baby is born facing pubic bone

Question 9

What are some of the complications of OP position?

Answer 9

• deep transverse arrest —> head descends, some flexion occurs and some rotation but the OF diameter becomes arrested on the narrow bi-spinous diameter of the outlet
• conversion to face or brow presentation —> instead of flexion, extension occurs
• obstructed labour - increased instrumental/operative births
• perineal trauma (3rd or 4th degree)
• intracranial haemorrhage