Second stage of labour: Description,  Physiology & Management

Description of Second stage of labour

Second stage of labour starts from fully cervical dilatation to the delivery of the baby. It is also divided into two phases

  • First phase: latent phase of the second stage
  • Second phase: active phase of the second stage

Latent phase of the second stage

The cervix is fully dilated but the presenting part is still very high, it has not reach the pelvic outlet

Active phase of the second stage

The presenting part of the fetus reaches the pelvic outlet and with the presenting part on the perineum, this will stimulate the nerve at the perineum causing expulsive Uterine contraction or urge to bear down during contraction and is also known as Ferguson’s reflex.

Physiology of second stage of labour

Uterine Action

  • Contraction becomes stronger and longer
  • Becomes less frequent giving mothers and fetus more time for rest
  • Membranes often rupture at this period and fetal head directly applied to the vaginal tissue aid distention
  • Fetal axis pressure increases flexion of the head leading to presentation of smaller diameter
  • This aids rapid progress and less trauma to mother and baby
  • As the fetus decends further into the uterus contraction becomes more expulsive
  • At this stage, the pressure stimulate nerve receptors in the pelvic floor leading strong urge to push
  • This urge becomes involuntary as second stage progresses know as Ferguson’s reflex. The urge to bear down become overwhelming and the woman cannot resist the urge to bear down
  • The woman then employs secondary power

Soft Tissues Displacement

  • Descent of fetal head leads to soft tissues of the pelvis to be displaced
  • Bladder is pushed up into the abdomen to prevent it from injuries
  • The urethra stretches and thins out posteriorly, the rectum flattens into the sacral curve and pressure of the head residual feaces in
  • The levetor ani muscles thins out and moved laterally
  • The perineal body flattened, and thinned out
  • The head of the baby is visible at the vulva during contraction and recends after contraction. The second stage ends with birth of the baby.

Signs and symptoms of second stage

The following signs are indicative of second stage of labour. They are classified under presumptive and confirmatory evidence

PRESUMPTIVE SIGNS

The following signs

  • Expulsive Uterine contraction
  • Rupture of the forewaters
  • Dilatation and gaping of the anus
  • Appearance of anal cleff
  • Appearance of the rhomboid of Michaelis
  • Show
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CONFIRMATORY EVIDENCE

Vaginal examination must be taken in the presence of these signs to confirm full dilatation and ensure that the woman is not pushing too early. It also help to time second stage of labour

Management of second stage of labour

Assessment during second stage of labour

Assessment of the woman and the fetus is continuous during second stage of labour. There are four determinants of outcome of second stage and they must be carefully monitored. They are as follows:

  • Uterine contractions
  • Descent, rotation and flexion of the presenting part
  • Fetal condition
  • Maternal condition

UTERINE CONDITIONS

The midwife should observe the strength duration and frequency of uterine contractions during second stage. It is usually longer and stronger during the first stage of labour with longer resting phase. The position the mother adopt for delivery usually influences the contractions. The midwife observes contractions through maternal response and abdominal palpation.

DESCENT, ROTATION AND FLEXION

In primigravida, descent may be slow during latent phase of second stage and accelerates during the active phase. 

In multigravida,  the descent occurs more rapidly if descent is not progressive despite good uterine contractions and good maternal pushing on abdominal palpation, vaginal examination should be carried out to assess the station of the presenting part, whether or not internal rotation has taken place and rule out excessive caput succedaneum. 

The labour is likely to progress well if the occiput has rotated anteriorly ( well flexed head) and there is no excessive caput, the midwife should continue. 

Where there is no good rotation and flexion, poor contractions change position, give her nourishing fluid for hydration. Consult more experienced midwife. If fetal or maternal condition is compromised obstetrician should be involved in the management

FETAL CONDITION

Thick fresh meconium stained liquor when the membrane ruptures indicate fetal compromise (distress) and obstetrician should be called immediately.

Fetal heart rate is checked after every contraction in the second stage of labour using pinnard stethoscope or sonicaed. Fetal distress is suspected if the following are observed

  • Late deceleration (gradual decrease in heart rate) following Uterine contractions
  • Inability of the heart rate to return to normal
  • Rise in baseline
  • Diminishing beat- to beat variation. 

If this is observed for the first time, change the mothers position because this may be as a result of head compressing the cord. 

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However if it persists, give episiotomy if delivery is imminent to expedite delivery. Seek an experienced midwife to expediate delivery with use of vacuum extractor

MATERNAL CONDITION

The midwife observes both psychological and physiologic parameters of the woman during second stage of labour. The woman’s ability to cope emotionally is assessed. 

During the second stage there is increased apprehension or irritability. Some women may cry or make a lot of expression. These helps the midwife assesses woman’s coping ability. Also assess physical well being by checking maternal pulse rate ½ hourly and blood pressure.

Conduct of normal labour

Principles of Delivery

These includes

  • Observation of progress of labour
  • Emotional or physical comfort of the mother
  • Anticipation and support of normal progress of labour
  • Recognition of abnormal development and appropriate response to them

Preparation for the birth

Before delivery of the baby the midwife should prepare for the birth

  • The room should be warm; this is achieved by closing the windows, putting off fans and air conditioner and putting on the light
  • Clean the area where the baby will be received
  • Cover the delivery bed with mackintosh
  • Set up delivery trolley containing tray with two receivers, delivery pack, injection, lignocaine without adrenaline, 10cc syringe, cord scissors, episiotomy scissors, sterile gloves, elbow length gloves
  • Protective wears, plastic apron, Google, mask, boot to prevent splash on the attendant
  • Prepare a place for resuscitation of the baby in case the baby is asphyxiated. Equipment for resuscitation must be thoroughly checked before delivery

Promoting maternal comfort in second stage of labour

Most mothers feel very hot and exerted during the second stage, they sweat profusely due to pushing, a cool towel should be applied to the face, neck and body and these provide soothing. 

The lips and tongue are dried and cracked and saliva sticky. Sips of water or other fluids will be very smoothing. 

Ensure that the bladder is empty to avoid trauma to the bladder (pressure of the presenting part on the full bladder)

Delivery of the baby

The midwife should help position the woman (adopt the position she chooses)

  • The bed is screened to maintain privacy except the woman has private delivery room
  • Take equipment near the woman
  • Encourage her to empty her bladder
  • She should wash hands thoroughly and put on personal protective wears
  • Place sterile towel under the woman or delivery mat
  • Place the second one on the woman’s abdomen or near the woman depending on the position she adopts for receiving the baby
  • Cleaning the perineum with antiseptic solution eg Hibitane 1:80 or savlon 1:40
  • Encourage the woman to bear down with every contraction
  • As the head descends with each contraction superficial pelvic muscles stretches
  • The midwife places pad over the perineum but should not cover the fourchette
  • The midwife should demonstrate her skill by ensuring that the active phase is not hurried to avoid trauma
  • She should support the fetal head lightly with her fingers
  • Once crowning has occurred the woman is encouraged to blow gently in order to prevent pushing. This is to enable the head to be born gently without forcefully popping out. This prevents perineal trauma
  • The head is then born by extension as the face, the chin sweeps the perineum
  • The midwife quickly checked for cord around the neck. If there is  cord round the neck, it is slipped off if loose but if tight, place 2 artery forceps apart approximately 3 cm and cut the cord in between the 2 clamps covering the scissors to avoid splashes
  • If cord is cut the baby must be born soon because oxygen supply has been cut off
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Birth of the shoulder

  • Restitution and external rotation of the head is allowed so that internal rotation of the shoulder occur. The shoulder then lies in anterior posterior position, this minimizes risk of maternal trauma and shoulder dystocia. Though small babies and multiparous women may deliver with shoulders in transverse position
  • The midwife places her hands on both sides of the head, supporting the head and neck
  • Gently pull down the head to deliver the anterior shoulder. Once the axillary crease is seen, the head is pulled up with the little finger protecting the fourchette to deliver the posterior shoulder
  • The midwife then support the trunk and the chest to deliver the body in a lateral flexion towards the mothers abdomen
  • If the woman is in an upright position the birth occurs unguarded with aid of gravity. The midwife help to receive the baby
  • With the birth of the baby, palpate to check for another baby incase of an unidentified twin.
  • Give injection oxytocin for active management of the third stage of labour. 

Final notes on second stage of labour