Contents
Introduction
Dystocia means difficulty during labour – and typically results from abnormal fetal size or position. It occurs in about 1% of deliveries. The most common type of dystocia is shoulder dystocia where, after passage of the head the child’s anterior shoulder becomes stuck against the pubis.
- Breech presentation can cause dystocia.
Aetiology
- Diabetes mellitus
- Fetal macrosomia – – often caused by maternal diabetes
- Maternal obesity
- Induction of labour
- Prolonged labour
- Too much oxytocin
Anatomical causes of dystocia
There are three types of anatomical problems that can lead to dystocia:
- Uterine problems – normal contractions start at the fundus, and move down towards the vagina, in a co-ordinated manner, at regular intervals. Primigravida women are particularly susceptible to problems with contraction.
- Oxytocin – can be useful for increasing the regularity, co-ordination and strength of contractions
- Fetal lie – an abnormal lie increases the risk of dystocia.
- Pelvic problems – the shape of the pelvis can be an important factor. Women with a smooth, round pelvic brim fair best, whilst a small and/or oval shaped brim predisposes to dystocia.
- Small pelvis should be suspected if the head has not engaged by 37 weeks.
Examples of dystocia
Shoulder dystocia
A very common dystocia. This is where the shoulder cannot be delivered after the head has been delivered. Usually, the anterior shoulder is stuck behind the symphasis pubis.
Incidence – approx 0.6% of deliveries
Has a high rate of mortality and morbidity
- Death of the fetus can result from severe acidosis (due to CO2 retention) and anaphylaxis
- PPH occurs in 11% of cases
- 3.8% will get 4th degree tears – with or without additional manoeuvres
- Brachial plexus injury – in 5-15%
- 10% of these cases have permanent injury
- Important note for litigation
- Note which shoulder causes the problem (anterior / posterior), as posterior shoulder injuries are not considered for compensation, as the propulsive forces from the mother usually cause the damage.
Aetiology
- Big baby (about ½ of cases involve babies >4800g)
- Maternal BMI >30Kg
- Induced labour
- Oxytocin Augemented labour
- Prolonged first or second stages of delivery
- Assisted vaginal delivery (forceps, ventouse)
- Previous big baby
- Most cases occur in women with no risk factors
- Indications for C-section
- Previous shoulder dystocia (discuss with mother)
- Diabetic mother with macrosmia (discuss with mother)
Identification
- The head has delivered, but the shoulders will not
- The head is pulled back tightly against the vulva – turtle sign
- The mothers pelvis constricts the baby’s chest, and there is also often cord compression, thus asphyxiation is the main risk.
- Usually acidosis and asphyxiation will set in after about 4-5 minutes in the shoulder dystocia position.
Treatment
Will successfully deliver the baby in 90% of cases
Get the mother into the McRobert’s Position
- This will straighten up the sacrum relative to the lumbar spine, and will alter the rotation of the pubic symphasis, hopefully allowing the shoulder to enter the pelvis. In many cases, this will release the shoulder, without the need for manipulation of the fetus. Try gentle but firm pressure on the baby’s head to push it back towards the mother (don’t push too hard). At the same time, press on the suprapubic region of the mother (HARD!). This aims to displace the fetal shoulder. This is known as the McRobert’s manoeuvre.
- http://www.youtube.com/watch?v=eq9n1WJPhF4&feature=related
- Do not press on the fundus – this can cause excessive uterine contraction and rupture.
- If this doesn’t work, try the following (its not pretty!):
- Rubin manoeuvre – press on the posterior fetal shoulder to allow the anterior shoulder a bit more room to move
- Woodscrew manoeuvre – by insertion of a hand into the posterior vagina, the doctor attempts to rotate the fetus 180’, so that the posterior and anterior shoulder swap position. This can be aided with episiotomy is necessary During this period, it may be possible to manually deliver the posterior arm, by pulling
- Mother on all fours
- Could again try the Woodscrew
- Maternal Symphisiotomy
- As bad as it sounds
- A bit of local / epidural, then scalpel through the the symphasis pubis, and gently apply pressure to the sides of the pelvis to increase the size of the pelvic outlet.
- Usually heals reasonably well, but may provide walking apin / difficulties for the mother in future
- Push the head back in, and go for emergency caesarean
- Yes really! Really firm pressure to try to push the head back in.
- Last choice
- By this stage, the child is probably heavily acidotic, if not dead
- Break the clavicles
- If the child is already dead, then breaking the clavicles (cleidotomy) can help delivery
After successful delivery
Document very carefully in the notes, including the shoulder involved, the procedures attempted (what and at what time), who is present
Check for Erb’s palsy
- Paralysis of the arm, due to compression of nerve roots C5-7.
- Classically there is inward rotation of the shoulder, supination of the forarm, and loss of ability o flex the elbow
- Some cases recover without intervention
- Physio can help with muscle function
- Surgery may be required to repair any associated bone damage, to relieve pressure on the nerves (10-20% of cases)
- Many cases will recover, but some will be left with permanent damage
- If function is not regained by the end of the first year, further improvement is unlikely
- The nerves of such a young child are particularly good at healing!
Check umbilical cord blood for acid-base balance – and record in the notes
Cervical Dystocia is another form of dystocia. It occurs when the cervix fails to dilate during the first stage of labour
- Aetiology – previous cone biopsy, cervical dysplasia
In some cases, it is due to unco-ordinated uterine contraction, which will usually be resolved with administration of oxytocin.
If this does not resolve the situation, then emergency C-section will need to be performed
