First Stage Labor

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By: Dr. Ayman Bukhari

House officer

Obstetrics & Gynaecology

Contents:

 Introduction

 Stages of labor

 Diagnosis

 Management on admission

 Active management of labor

 Monitoring

 Partogram

 Abnormalities

 Pain control

Introduction

 Labor : Uterine contractions resulting in progressive dilation and effacement of the cervix and accompanied by descent and expulsion of the fetus.

 Abnormal labor, dystocia, and failure to progress are terms used to describe a difficult labor pattern

 Approximately 20 % of labors involve dystocia

Stages of labor

NORMAL LABOR — divided into Four stages

 First stage : time from the onset of labor until complete cervical dilatation

 Second stage : time from complete cervical dilatation to expulsion of the fetus

 Third stage : time from expulsion of the fetus to expulsion of the placenta

 Fourth stage : the 1 st post partum hour..

Recommendations on definitions of the first stage of labor:

The first stage is further subdivided into the latent and

active phases.

1.

2.

3.

active phase subdivided into three additional phases: acceleration phase phase of maximum slope deceleration phase

Recommendations on definitions of the first stage of labor:

 Latent phase is typically characterized by mild, infrequent, irregular contractions with gradual change in cervical dilation (usually <1 cm / h) and effacement.

Latent phase

Abnormal

Nulliparous

6.4 h

20 h

Multiparous

4.8 h

14 h

• Not influenced by maternal age, birth weight, or obstetric abnormalities

Recommendations on definitions of the first stage of labor:

 Active phase — begins at 3 to 4 centimeters when cervical dilatation is plotted against time..

characterized by painful contractions of increasing frequency, intensity, and duration accompanied by more rapid (usually >1 cm /h) cervical change.

Recommendations on definitions of the first stage of labor:

Recommendations on definitions of the first stage of labor:

Diagnosis of labor

The determination of whether a woman is in labor is made within one hour of admission .

Diagnosis of labor is made only when painfull contractions are accompanied by any one of the following :

Bloody show

 Rupture of the membranes

Full cervical effacement .

Cervical dilatation is not part of the criteria

Meet the criteria

Didn’t meet the criteria

Antinatal ward

Rest & observation

Until next day

Diagnosis of labor

 The correct diagnosis of labor is considered to be the

single most important

determination in the management of labor because an incorrect diagnosis of active labor will lead to inappropriate interventions and an increased likelihood of cesarean delivery.

Management on admission

Patient preparation — There is no evidence that routine enemas or perineal shaving is beneficial .

A urinary catheter is not necessary unless the woman is unable to void, but she should be encouraged to empty her bladder regularly as a full bladder can impede fetal descent.

Fluids and oral intake — There is no consensus on acceptable maternal oral intake during uncomplicated labor

Management on admission

Placement of an intravenous line or a hep-lock at the time admission is recommended.

 Interestingly, one randomized trial found that women who received intravenous hydration at 250 mL/h had fewer labors persisting for over 12 hours and less need for oxytocin augmentation than those who received 125 mL/h

Management on admission

Antibiotic prophylaxis : (in some centers) to prevent early-onset neonatal infection in appropriate patients; the agent of choice is intravenous penicillin . A minimum of four hours of intrapartum therapy has been recommended prior to delivery

 Although normal labor and vaginal delivery is not an indication for prophylaxis against infective

endocarditis, some centers generally administer antibiotic prophylaxis during labor to pregnant women with underlying valvular heart disease.

Management on admission

Monitoring — All pregnant women require surveillance (eg, monitoring of vital signs and FHR) since 20 to 25 % of all perinatal morbidity and mortality occurs in pregnancies with no underlying risk factors for adverse outcome .

 Assessment of the quality of the uterine contractions and cervical examinations are repeated at appropriate intervals to follow the progress of labor.

Management on admission cervical examination should be kept to a minimum to avoid promoting intraamniotic infection.

In general, vaginal examinations are performed:

On admission

• At one to four hour intervals in the first stage and at one hour intervals in the second stage

• At rupture of membranes to evaluate for cord prolapse

• Prior to intrapartum administration of analgesia

• When the parturient feels the urge to push to determine whether the cervix is fully dilated

• If the FHR falls, to evaluate for conditions such as cord prolapse or uterine rupture.

The results can be noted on a partogram

Management on admission

Active management of labor

It refers to active control, rather than passive observation, over the course of labor by the obstetrical provider.

It includes three essential elements

I.

Careful diagnosis of labor by strict criteria

II.

III.

Constant monitoring of labor with specific standards for normal progression

Prompt intervention (eg, amniotomy , high dose oxytocin ) according to established guidelines if progress is unsatisfactory .

Active management of labor

The active management of labor is generally limited to women who meet the following criteria:

1)

2)

3)

4)

Nulliparous

Term pregnancy

Singleton infant in cephalic presentation

No pregnancy complications

5) Experiencing spontaneous onset of labor.

Active management of labor

 Nulliparous labor tends to be more subject to failure to progress .

 administration of oxytocin , sometimes at high dosages, is one of the interventions involved in active management. This is safer in nulligravid women since the nulligravid uterus is virtually immune to rupture

(except as a result of manipulation or previous surgery)

Active management of labor

Recommendation on routine amniotomy

Limited evidence showed no substantial benefit for early amniotomy and routine use of oxytocin compared with conservative management of labor.

In normally progressing labor, amniotomy should not be performed routinely.

 Combined early amniotomy with use of oxytocin should not be used routinely.

Active management of labor

Interventions with amniotomy and/or high dose oxytocin are initiated if progress does not proceed according to the defined standards.

 Rutpure of the fetal membranes provides information about fetal status, but does not appear to significantly accelerate labor . In the Dublin protocol, rupture must be performed before treatment with oxytocin , which is administered only in the presence of clear amniotic fluid .

Active management of labor

 If membranes are ruptured when there is polyhydramnios or an unengaged fetal presenting part, it is prudent to use a small gauge needle , rather than a hook, to puncture the fetal membranes in one or more places, and to perform the procedure in the

operating room. This " controlled amniotomy “ permits emergency cesarean delivery in the event of an umbilical cord prolapse .

 Routine amniotomy should not be performed in women with active hepatitis B & C or HIV in order to minimize exposure of the fetus to ascending infection.

Active management of labor

 So usually, Amniotomy is indicated to further evaluate fetal status (eg, placement of a fetal scalp electrode) or uterine contractions (eg, placement of an intrauterine pressure catheter).

Active management of labor

 Slower progress in the nulliparous patient is most often the result of inefficient uterine action .

 In the absence of medical contraindications, labor that fails to progress is treated with oxytocin

Monitoring

 It is desirable that all examinations be performed by a single individual to minimize interobserver variations

 A vaginal examination during labor often raises anxiety and interrupts the woman’s focus & if there is

(PRoM), increasing numbers of VEs have been found to be associated with neonatal sepsis ….

Monitoring:

Recommendations on monitoring during the established first stage of labor

 A pictorial record of labor (partogram) should be used once labor is established.

 4 hourly temperature and blood pressure

 hourly pulse

 half-hourly documentation of frequency of contractions

 frequency of emptying the bladder

vaginal examination offered 4 hourly, or when there is concern about progress

 Intermittent auscultation of the fetal heart after a contraction should occur for at least

1 minute, at least every 15 minutes, and the rate should be recorded as an average.

Monitoring:

Recommendations on initial monitoring:

1) Psychological & Emotional

2)

3)

Vitals & Urinalysis

Uterine contractions

4)

5)

6)

7)

8)

Abdominal examination_Leopold manouvers

Vaginal loss – show, liquor, blood

Vaginal examination....when necessary

Pain control

FHR

Monitoring:

Explain

Monitoring:

Fetal heart rate — fetal heart rate assessment has become a standard of care for all women in the United States because patients and clinicians are reassured by normal results and believe there is some value in detecting abnormal patterns.

Monitoring:

 The American College of Obstetricians and

Gynecologists suggests that electronic fetal monitoring tracings to be reviewed :

Low risky

High risky

First stage

30 min

15 min

Second stage

15 min

5 min

 In general, continuous intrapartum FHR monitoring is suggested for high-risk patients and when FHR below 110 or over 160 BPM

Monitoring:

 Intermittent auscultation of the F.H is recommended

 Once a woman is in established active labor, intermittent auscultation of the fetal heart after a contraction should be continued

 Intermittent auscultation can be undertaken by either

Doppler ultrasound or Pinard stethoscope.

Monitoring:

 Uterine contractions i.

ii.

iii.

iv.

simple observation of the mother palpation of the fundus

CTG direct measurement of intrauterine pressure via internal manometry or pressure transducers

 95% of women in active labor will have

3-5 contractions per 10 minutes.

Partogram:

 Maternal status

 Fetal heart rate

 Dilatation & descent

 Uterine contractions

Partogram:

 a graphical representation that clearly shows the patient's labor compared to the expected lower limit of "normal progress

 Some clinicians employ a partogram with alert and action lines. The alert line represents the rate of dilatation of the slowest 10 % of labors in primigravidae. Crossing the alert line suggests that the patient should be transferred to a hospital if she is laboring in a rural setting. The action line is parallel and four hours to the right of the alert line; crossing the action line suggests the need for intervention

(eg, artificial rupture of the membranes, administration of oxytocics).

Abnormalities

Cervix

Uterus

M aternal pelvis

Fetus i.e ( power, passenger, or pelvis).

 Hypocontractile uterine activity — is the most common cause of protraction or arrest disorders in the first stage

of labor. This entity refers to uterine activity that is either not sufficiently strong or not appropriately coordinated to dilate the cervix and expel the fetus. It occurs in 3-8 % of parturients and can be quantified as uterine contraction pressures less than 200 Montevideo units.

Abnormalities

Hypocontractile uterine activity is treated with oxytocin in the United States. Oxytocin is the only medication approved by the US Food and Drug Administration (FDA) for labor stimulation in the active phase

Abnormalities

Active phase arrest is diagnosed when a protraction disorder persists despite oxytocin therapy to achieve ≥ 200

Montevideo units for greater than two hours; cesarean delivery is typically performed at this point

 The National Institute for Health and Clinical Excellence

(NICE) also recommended starting oxytocin and monitoring the progress of labor over the next four hours.

If less than 2 cm of cervical dilatation occurred, they recommended consideration of cesarean delivery

Abnormalities

 Cephalopelvic disproportion — A disproportion between the size of the fetus relative to the mother can lead to a diagnosis of dystocia . This diagnosis is based upon observation of slow or arrested labor during the active phase. However, it is usually duo to fetal malposition (eg, extended or asynclitic fetal head) or malpresentation

(mento- posterior, brow), rather than a true disparity between fetal and maternal pelvic dimensions

Abnormalities

Diagnosis of POSITION can generally be made by

digital examination, but if there is uncertainty,

ultrasound examination is useful and accurate

 (OA) (left 2/3)

 (Transverse positions are unstable) …

 (OP) …mostly spontaneously rotate to (OA) during the course of labor.

However, approximately 5 % experience malposition with persistent OP position or transverse arrest.

Pain C ontrol:

 The pain of childbirth is likely to be the most severe pain that a woman experiences during her lifetime.

Pain C ontrol:

 women should be involved in the decision of pain relief, to increase maternal satisfaction.

 This can be accomplished by educating women about pain relief techniques during pregnancy, prior to the onset of labor, as rational decision-making is difficult during times of emotional & physical stress .

 Furthermore, using patient-controlled epidural analgesia (PCEA) empowers the parturient by giving her direct control of her pain relief, and this may increase maternal satisfaction .

Pain C ontrol:

First stage of labor

Visceral or cramp-like source : uterus and cervix , produced by distention of uterine and cervical mechanoreceptors and by ischemia of uterine and cervical tissues///. The pain signal enters the spinal cord after traversing the T10, T11, T12, and L1 .

abdominal wall, lumbosacral region, iliac crests, gluteal areas, and thighs .///

 Transition refers to the shift from the late first stage (7 to 10 cm cervical dilation) to the second stage of labor.

Transition is associated with greater nociceptive input as the parturient begins to experience somatic pain from vaginal distention.

Pain C ontrol:

Hyperventilation — consistently accompanies labor pain. Arterial CO2 partial pressures less than 20 mmHg are not uncommon, and profound hypocarbia may inhibit ventilatory drive between contractions and result in maternal hypoxemia, lightheadedness, and loss of consciousness . respiratory alkalosis, which

impairs oxygen transfer from the maternal to fetal circulation, may occur.

Pain C ontrol:

 Psychological effects — unrelieved pain may also be a factor that contributes to the development of postpartum psychological trauma. This may negatively influence the mother's postpartum adjustment, and in its most severe form, result in post-traumatic stress disorder (PTSD) which shouldn’t be underestemated.

ANALGESIA FOR THE FIRST STAGE

OF LABOR : classified as either

 systemic

 locoregional

Systemic:

 Intravenous

 Intramuscular

 inhalation routes

 most popular agents are opioids (eg, morphine , fentanyl , meperidine )

Systemic:

Newer opioid analgesics — Fentanyl , a synthetic opioid, and its congeners (eg, sufentanil , alfentanil , and remifentanil ) have also been used to provide labor pain relief. These drugs have a short duration of action, so they are best administered using the intravenous, rather than the intramuscular route.

Systemic

 Inhalation agents — Nitrous oxide . The parturient self-administers the anesthetic gas using a hand-held face mask. The safety of this technique is that the parturient will be unable to hold the mask if she

becomes too drowsy. A systematic review on nitric oxide for relief of labor pain concluded it was inexpensive, easy to administer, and safe for both mother and fetus. The analgesic effect was better than that produced by opioids, but less than with epidural analgesia

Regional techniques:

Epidurals and Spinals are the most popular modalities

 Regional techniques are widely acknowledged to be the only consistently effective means of relieving the pain of labor and delivery. Local injection may also be administered to achieve paracervical or pudendal nerve block.

Pain control:

 Epidural analgesia provided better pain relief

than parenteral opioids. However, opioids were

associated with a shorter duration of labor, less oxytocin augmentation, and fewer instrumental deliveries compared to epidural analgesia.

Side effects- epidural: Nausea, vomiting, and sedation & Respiratory depression which was the major neonatal concern

References:

Up-to-Date

Clinical Guideline, September 2007,Funded to produce guidelines for the NHS by NICE

Royal College of Obstetricians and Gynaecologists: Clinical

Effectiveness Support Unit. The Care of Women Requesting Induced

Abortion. Evidence-based guideline No. 7. London: RCOG

Government Statistical Service and Department of Health. NHS

Maternity Statistics, England: 2002–03. Statistical Bulletin 2004/10.

London: Department of Health; 2004.

National Assembly for Wales. Maternity Statistics, Wales: Methods of

Delivery, No. SDR 40/2004. Cardiff: National

Assembly for Wales

National Collaborating Centre for Women’s and Children’s Health,

Intrapartum care of healthy women and their babies dur ing childbirth

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