First Stage of Labour

First Stage of Labour

                                                            

The first stage of labour is a stage of dilatation of the cervical os. It begins with the onset of true labour contractions to full dilatation of the cervix. Duration of first stage is an average of 13 hours for nullipara and 7.5 hours for multipara. The first stage is clinically manifested by progressive uterine contraction, progressive taking up of the cervix and ultimate rupture of membranes.

Phases of First stage of Labour

Latent Phase

• The latent or preparatory phase begins at the onset of regularly perceived uterine contractions and ends when rapid cervical dilatation begins.
• Contractions during this phase are mild and short, lasting 20 to 40 seconds.
• Cervical effacement occurs, and the cervix dilatates from 0 to 3 cm.
• The phase lasts approximately 6 hours in a nullipara and 4.5 hours in a multipara.

Active Phase

• During the active phase of labor, cervical dilatation occurs more rapidly, increasing from 4 to 7 cm.
• Contractions grow stronger, lasting 40 to 60 seconds, and occur approximately every 3 to 5 minutes.
• This phase lasts approximately 3 hours in a nullipara and 2 hours in a multipara.
• Show (increased vaginal secretions) and perhaps spontaneous rupture of the membranes may occur during this time. This phase can be a difficult time for a woman because contractions grow so strong, last longer, and begin to cause true discomfort.
• It can be a frightening time as she realizes labor is truly progressing and her life is about to change forever.

Transition Phase

• During the transition phase, contractions reach their peak of intensity, occurring every 2 to 3 minutes with a duration of 60 to 90 seconds and causing maximum dilatation of 8 to 10 cm.
• If the membranes have not previously ruptured or been ruptured by amniotomy, they will rupture as a rule at full dilatation (10 cm).
• If it has not previously occurred, show occurs as the last of the mucus plug from the cervix is released.
• By the end of this phase, both full dilatation (10 cm) and complete cervical effacement have occurred.

Factors affecting First Stage of Labour

1.      Uterine factors

• Fundal dominance: Uterine contraction strart from the fundus of the uterus and moves downward. Contractions of the fundus are strong and intense and last for a longer time in the fundus.
• Pollarity: It is used to describe the neuromuscular harmony between upper uterine segment and the lower uterine segment. Contractions of the uterus takes place at the upper pole and there is slight contractions and dilatation of the cervix taking place at the lower pole.
• Contraction and retraction: As the contractions begin it will not relax completely which is called as retraction. This retraction will favour in further contractions and expulsion of the fetus.
• Formation of upper and lower uterine segment: The uterus forms a thick upper layer and thin lower muscular layer. The upper longitudinal muscles pull on the lower circular muscles situated in the lower uterine segment which will aid in the descent of the presenting part.
• Retraction ring: This is a ridge formed between the upper and the lower uterine segment. Its also called as Bandl’s Ring.
• Cervical effacement: It is the thinning out of the cervix which is accomplished in the first stage of labour. It is expressed in terms of percentage. 100% effaced means that the cervix is fully effaced. In primi effacement preceeds the dilatation of the cervix. In multigravidae, both occur simultaneously.
• Cervical dilatation: It is a process of enlargement of the external os which is a tightly closed operture to an opening large enough to permit the passage of the fetal head. This is expressed in centimeters and ranges from 0-10cm.
• Presence of show: As the cervix dilates, operculum is discharged out with light blood stains called as ‘Show’. This is due to the ruptured capillaries of the deciduas, where the chorion detaches due to dilatation of the cervix.

2.      Mechanical factors

• Formation of forewaters: As the chorion detaches, a loosened sac of amniotic fluid bulges downwards into dilating internal os. In case of complete flexion where the presenting part gets completely fixed, fluid cuts into two compartments. One compartment with fetus and some fluid called ‘hind waters’ and another compartment with fluid in front of the presenting part called ‘forewaters’. Forewaters when ruptured releases prostaglandins causing uterine contractions.
• Rupture of membranes: It occurs at the end of the first stage of labour. It can sometimes rupture before the dilation of the cervix.
• General fluid pressure: When the bag of membranes is not ruptured, the pressure of uterine contraction is on the fluid also and is equalized over the uterus and fetal body parts.
• Fetal axis pressure: At each uterine contraction, the uterus rears forwards and the force of fundal contraction is transmitted to the upper pole of the fetus, down the long axis of the fetus and is applied by the presenting part of the cervix and is called fetal axis pressure.

Management of First Stage of Labour

The objective is to have a watchful expectancy and to monitor the progress of labour and to prevent complications.

Initial assessment

• Onset of contraction

• Frequency

• Duration

• Membrane

• Liquor

• Present and previous obstetric history

• Drug history

Clinical examination

• Pallor

• Jaundice

• Hydration

• Pulse/ BP/ temperature/ respiratory rate

• Chest/ CVS

• Oedema

Per abdomen examination

• Uterine contraction

• Frequency and duration in 10 mi

• Fundal height

• Lie/ presentation

• FHS/ minute to be noted every 15 minutes in the first stage

Per vagina examination

• Discharge show

• Presence or absence of membrane

• Station of head

• Effacement

• Dilatation

• Any bony part

• Caput/ moulding

Investigations

• Haemoglobin count

• ABO, RH typing

• Routine Urine

Management

1.      Take a brief history and assessment

2.      Encourage the woman to have a warm bath or vulval toileting.

3.      Give a soap and water enema.

4.      When membranes are intact, allow the woman to walk, sit or lie down in lateral position according to her convenience. If membranes are ruptured bed rest must be advised. Analgesics may be given as per doctor’ s prescription

5.      Encourage the woman to take fluid diet soup, fruit juice, salt lemon juice or plain water. Food and oral fluids to be withheld, when the woman is in active labour.

6.      Encourage the woman to empty her bladder herself frequently.

7.      Monitor the progress of the labour by recording a partograph.

8.      The following are recorded in partograph.

• Maternal vital signs
• Cervical dilation
• Station of fetal head
• Cervical effacement
• Presence or absence of membranes
• Fetal heart rate, (Normal FHR is 110 – 150 per minute).
• Drugs given

9.      Watch for maternal and fetal well-being

• Monitor pulse, blood pressure and temperature every second hourly and FHR every hour
• Monitor urine output
• Observe the tongue to assess the hydration status.

10.  Psychological preparation of the mother and her family is equally important as her ambitions play a great role in managing labour pain and discomfort.

11.  P/ V examination to be done four times:

1. At the onset of labour

2. For progress of labour-dilatation of cervix

3. Descent of head following rupture of membrane in early labour to exclude cord prolapse

4. Diagnosis of second stage-full dilatation of cervix

Diagnosis of poor progress of labour

• Prolonged bradycardia and meconium stained liquor
• Possibility of foetal distress
• Prolonged latent phase when more than eight hours in primigrvida and more than six hours in multigravida
• Prolonged latent phase may be due to fault in power, passage or passenger
• Passage is small due to contracted pelvis
• Passenger, hydrocephalous, brow [occiput not felt]
• Large baby, shoulder presentation

Role of nurse in caring of the woman in the first stage of labour:

• Admitting client to birthing area after determining that client is in labor
• Determining if client's membranes have ruptured
• Encouraging family participation as appropriate with the labor process
• Performing Leopold maneuver and vaginal exams as appropriate
• Monitoring maternal vital signs and fetal heart rate and patterns, reporting any deviations or abnormalities
• Applying electronic fetal monitor as appropriate
• Assessing pain level, instituting positioning, breathing, relaxation, and other methods for pain control; administering analgesics as ordered
• Providing ice chips, wet washcloth, or hard candy
• Encouraging voiding at least every 2 hours
• Assisting with anesthetic administration
• Assisting with amniotomy with assessment of fetal heart rate, fetal positioning, and fetal cord after amniotomy
• Cleansing perineum and assisting with pad changes regularly
• Monitoring progress including vaginal discharge, cervical dilation and effacement, position, and fetal descent
• Performing vaginal examinations as necessary
• Assisting coach and supporting client and partner
• Preparing supplies and equipment for delivery
• Notifying primary health care provider at appropriate time to scrub for attending delivery
• Verifying maternal and fetal heart rate response to uterine contractions during intrapartal care
• Instructing client and partner about reasons for electronic monitoring
• Applying tocotransducer snugly after determining fetal position via Leopold maneuver
• Palpating to determine contraction intensity
• Reassuring client about normal fetal heart rates
• Adjusting monitor to achieve and maintain clear tracing
• Interpreting rhythm strips when at least a 10-minute tracing has been obtained