Labour

Stages of labour

First stage of labour is divided into 2 phases, latent and active.
Latent phase : onset of true labour pain -> cervical dilatation of 3cm and full effacement.


Cervical effacement is the shortening of cervical length during labour. It can occur weeks before the onset of labour, but will end by latent phase.

It's thought that both effacement and dilatation is a consecutive process in primigravidas, whilst it occurs simultaneously in multigravida.

For primigravidas -> latent phase : 6-8 hrs
For multigravidas -> latent phase : 4-6 hrs

The active phase : from 3cm cervical dilatation to 10cm cervical dilatation

For primis -> 4 hrs
For multis -> 2 hrs

2nd stage of labour is the duration from full 10cm dilatation to delivery of fetus/fetuses. It's divided into 2 phases as well, passive and active.

During passive phase, there's no maternal urge to push. Fetal presenting part is still high in pelvis, and descent is mainly brought by uterine forces.

During active phase, there's maternal urge to push by "bearing-down".
(Valsalva manouvre)

Duration : For primis -> 2 hrs, Multis -> 1hr

3rd stage of labour is the phase from delivery of fetus/fetuses to delivery of placenta. Usually takes around 10-15 minutes, and if duration >30 mins is considered abnormal.

Management of labour

1st, history of onset of true labour pain is obtained from mother :

Started from the back, radiating towards front of lower abdomen
Effective uterine contraction :


4-5 contractions in 10 min
Every contraction lasting >40-45 sec

Increasing in frequency and strength

Hardening of uterus
Bloody show (Cervical mucus + blood-stain)
Cervical dilatation and effacement (not from h/o)

Descend of presenting part

Progress is not interrupted by enema/sedatives

Then, general examination is done.
Blood is sent for :

FBC, BUSE, Blood grouping and CXM, Coagulation profile

Urine is sent for :

Urine FEME

Abdominal examination is done.
First, inspect whether there's any surgical scars.
Next, determine the fetal lie and presentation.
If it's cephalic presentation, try to find out the extent of engagement by the number of fifth's of fetal head palpable.
Then, palpate uterus directly to determine the frequency and duration of contraction (for at least 15 sec).

If presentation is in doubt, fetal presenting part is still high up unengaged, which can be due to deflexed head, OP position, uterine fibroids, placenta praevia, etc, USG is performed.

Proceed to vaginal examination.
After taking an informed consent, insert index and middle finger into the top of vagina and cervix. 3 important information is obtained :

Extent of Cervical dilatation
Extent of effacement
Station of presenting part

Cervical length by 36 week of gestation is around 3cm.
If cervix is 3cm dilated -> cervix is fully effaced.
If no cervix is palpable, full dilatation has taken place.

Fetal position can be determined by the position of the denominator.
In normal labour, fetal presenting part is the vertex, and denominator is occiput.
The occiput is actually the posterior fontanelle of fetal skull.
The usual positions are OA and OT.

If no occiput is palpable, it might be due to a deflexed head, where the occiput is located so posteriorly which renders it non-palpable.
This can be a sign of prolonged labour.

Then, the relation of lowest point of fetal head to the ischial spine is the station of presenting part.
Hence, OA with 0/+1 station -> high chances of succesful vaginal delivery.

If membranes are ruptured, the amount and colour of amniotic fluid is determined.
If the liqour is blood or meconium stained -> sign of fetal distress

Assessment of fetal well-being during labour

There are 4 methods :

1) Amount and colour of liqour
2) Intermittent auscultation of fetal heart
3) External fetal monitoring (EFM) : CTG and/or fetal scalp electrode
4) Fetal scalp blood sampling

Stain of meconium in liqour, which is usually thin, dark greenish/brown, indicates maturation of the GI physiology of fetus.
However, when it turns scanty, thick and brighter in colour -> fetal hypoxia/distress.

Intermittent auscultation of heart is performed every 15 min during and after a uterine contraction.

If on admission, h/o and examination is normal, with normal admission CTG, mother is classified as low risk.

If there's any pre-existing maternal risk factors, new onset risk factors (prolonged labour, meconium staning, etc), continuous EFM is required. (By continuous CTG and fetal scalp electrode)

To determine whether there's fetal hypoxia, fetal scalp blood sampling can be done, since CTG intepretation is difficult and high false positivity.
Fetal blood is subjected to ABG -> determine whether there's acidosis.

Partogram

Partogram is a graphical representation of the progress of labour.
It provides instant visual assessment of cervical dilatation as compared to the norm, and hence, if there's any slow progression, intervention can be sought earlier.

It provides information of:

Extent of cervical dilatation against time in hours
Maternal vital signs
Number of fifths of fetal head palpable
Amount and colour of amniotic fluid
Frequency and duration of contraction

The "alert line", indicates the most ideal progress of labour, starting from the end of latent phase, with 1cm/hr progression of dilatation, extending from 3cm to 10cm.

The "action line", indicates any progression of labour beyond this for 2-4 hours, a cause of the slow progression must be determined.
Labour at this stage should be augmented with pitocin/syntocinon.
If labour is still not progressing satisfactorily, KIV LSCS.

1st stage of labour

Mother is encouraged to mobilise.
Management should be done away from labour suite.
Simple analgesics preferred over epidural or other stronger analgesics.
4 hourly vaginal examination is done, to determine whether patient is in active phase.
Note the progress of fetal descent as well.
Maternal vital signs are monitored regularly.
If labour is progressing well, no need to perform ARM if membrane is intact.

2nd stage of labour

First sign of second stage : presence of maternal urge to push.
By vaginal examination, full cervical dilatation is noted, if head is not visible.
With each contraction, mother will be experiencing an expulsive bearing down reflex, where she's be told to take a deep breath, hold it and strain to aid in delivery to fetus.
Mother should be propped up, with her hand placed below her thigh, supporting it.

Descend of the presenting part is monitored.
First, there'll be a slight buldging of the perineum.
As the perineum is stretched, anus is opened.
With each subsequent contraction, fetal head alternatively buldging out, and receeds back into pelvic cavity due to elastic tone of perineal muscles.
A stage is reached where the head doesn't receed back into the pelvic cavity.
This is known as crowning of fetal head.

Mother is advised not to bear down by taking rapid, shallow breaths.
One index finger and thumb is placed over each side of anus.
One hand is used to control fetal head extension, another is used to pull the fetal head forward before it extends.

However, if extension has already take place before biparietal diameter crosses the vulval outlet, a mediolateral episiotomy must be done to prevent perineal injury.

Once the fetal head is delivered, inspect, whether the cord wounds tightly around the baby's neck, which will later, causing delivery of the rest of body, difficult.
If it occurs, clamp and divide the cord immediately.
If the liqour is meconium stained, immediate nasopharyngeal suction is done to prevent MAS.

The baby's head is push downwards and forwards gently, so that the anterior shoulder hitches against PS. Then, head is lifted up to deliver the posterior shoulder, followed by the rest of the body.

It'll take few seconds before the baby takes his/her first breath.
Do not clamp the cord immediately! Wait until the cord pulsation ceases, then clamp and divide it. (80mL of blood can be transfused from placenta, to reduce/prevent neonatal anemia)

Baby's head is placed in prone position, for NS suction.

Baby is then placed over the mother's abdomen, for bonding, suckling and cuddling, which increases maternal oxytocin release.

First dose of Vitamin K is given and identification tag is placed before taking him/her to the neonatal unit.

3rd stage of labour

3rd stage of labour involves placental delivery. Placenta is separated from the uterus after delivery of fetus due to onset of uterine contraction and retraction, which reduces uterine cavity size, hence it no longer can accomodate the placenta.

Signs of placental separation :

Extravulval lengthening of cord
Gush of blood from placental bed
Uterine fundus elevated above umbilicus
Uterine fundus is now hard and globular in shape

Although natural placental separation does take place after 20 mins, but risk of PPH is about 5%.

Hence, in modern obstetrics, 3rd stage is managed actively.

After delivery of anterior shoulder, 10 IU of syntocinon or Synthometrine (5mg of oxytocin and 0.5 mg of ergometrine) is given to aid uterine contraction.

Left hand is placed over abdomen to palpate uterus and to feel for any contraction. At the same time, vulva is inspected for any haemorrahges.

Cord is double clamped, close to the vulva so that extravulval lengthening of cord can be appreciated better.

If uterine contraction is felt, perform controlled cord traction.
Left hand moves suprapubically, with palm facing the face of the mother, pushing the fundus above the umbilicus.
At the same time, apply gentle traction on right hand to separate the placenta, then with twisting motion, the membranes.

There's 2% chances of this method may fail. If there's no significant bleeding, controlled cord traction should be repeated after 10 min.
If still fails -> manual removal of placenta under GA or RA.

DO NOT PERFORM THIS MANOUVRE IF UTERINE CONTRACTION HAS YET TO BE FELT!
If not, uterine inversion takes place -> vasovagal inhibition

After delivery of placenta, inspect for any missing cotyledons, or subcentriuate lobes. If there is :

It's known as retained placental segment, to be removed under USG guidance, and risk of PPH is high.

Category: Obstetrics Notes