Normal and abnormal labor

Doç. Dr. Oluş APİ

Labour (parturition)

• It is the process where by painful , regular uterine activity (contraction) with progressive cervical effacement and dilatation accompanied by decent of the presenting part leads to expelled of the fetus from the uterus at or beyond 24 (or 28) completed weeks of pregnancy.

1 LNMP 24 W 28 W 37 W 40W 42W

PTL

Term Labour

Labour can occur at:

prolonged

Normal labour:

• Spontaneous expulsion, through the natural passages (birth canal) of a single, mature (37-42 completed weeks of pregnancy)

• Alive fetus, presenting by vertex, within a reasonable time, without fetal or maternal complications.

Terms• Fetal lie the relationship of the long axis of the fetus to that of the

mother. If the two are parallel, then the fetus is said to be in a

longitudinal lie (present in over 99 percent of labors at term). If the two are at 90-degree angles to each other, the fetus is

said to be in a transverse lie. If the fetal and the maternal axes may cross at a 45-degree

angle, forming an oblique lie, which is unstable and always becomes longitudinal or transverse during the course of labor.

Fetal presentation

• The portion of the fetal body that is either foremost within the birth canal or in closest proximity to it

• In longitudinal lies, the presenting part is either cephalic or breech presentations, respectively.

• In transverse lie, the shoulder is the presenting part.

cephalic presentation breech presentation shoulder presentation

Types of Cephalic presentation

Vertex or occiput presentation

Sinciput presentation

brow presentation face presentation

Types of breech presentation

Frank type Complete type incomplete type or footling presentation

Fetal position

• Refers to the relationship of an arbitrarily chosen portion of the fetal presenting part to the right or left side of the maternal birth canal.

• The dertermining points in vertex, face, and breech presentations are fetal occiput, chin (mentum), and sacrum respectively.

• The presenting part in right or left positions may be directed anteriorly (A), transversely (T), or posteriory (P). There are six varieties of each of the three presentations.

Fetal positions of cephalic presentation

Fetal positions of breech presentation

Diagnosis of fetal presentation and position

• Abdominal palpation (Leopold maneuver)• Vaginal examination• Auscultation• imaging studies: ultrasonography, computed

tomography, or magnetic resonance imaging

Leopold maneuver

• Leopold maneuver is established by Leopold in1848• Preparations before examination• Instruct woman to empty her bladder first. • Place woman in dorsal recumbent position, supine with knees

flexed to relax abdominal muscles. Place a small pillow under the head for comfort.

• Drape properly to maintain privacy • Explain procedure to the patient. • Warms hands by rubbing together. (Cold hands can stimulate

uterine contractions). • Use the palm for palpation not the fingers

• First Maneuver: To determine fetal part lying in the fundus.

To determine presentation.

procedure: Using both hands, feel for the fetal part lying in the fundus.

• Head is more firm, hard and round, and is more mobile and ballottable.

• Breech feels as a large, nodular mass.

• Second Maneuver: • To identify location of fetal back.

To determine position.

Procedure: One hand is used to steady the uterus on one side of the abdomen while the other hand moves slightly on a circular motion from top to the lower segment of the uterus to feel for the fetal back and small fetal parts.Use gentle but deep pressure.

• Fetal back is smooth, hard, and resistant surfaceKnees and elbows of fetus feels with a number of small, irregular, mobile parts

• Third Maneuver: • To determine engagement of

presenting part.

procedure: Using thumb and finger, grasp the lower portion of the abdomen above symphisis pubis, press in slightly and make gentle movements from side to side.

• The presenting part is engaged if it is not movable.

• It is not yet engaged if it is still movable

• Fourth Maneuver: • To determine if the presentation has

descended into the pelvis• To determine the position of the fetal

presentation

procedure: Facing foot part of the woman, using the tips of the first three fingers, exerts deep pressure in the direction of the axis of the pelvic inlet

Use both hands.

Fundal Height

:Not definitely known – however there are several theories, but none of them is completely proven.

Mechanical theories: - uterine distension

Hormonal theories: 1. Maternal : o progesterone withdrawalo oxytocin stimulationo prostaglandinso serotonin2. fetal:o fetal cortisolo fetal membranes 3. Neuronal factors:o sympathetic- alpha receptor stimulation

Onset of labour

DiagnosisA. symptoms:1. True labour pains – colicky pain in the abdomen and back are

characterized by: False labour pain True labour pain character

Irregular regular contractions

Short duration, not progressive

Progressive (increase in frequency and

intensity)

Interval between contractions and

intensity

Not associated with effacement and

dilation of the cervix

Associated with effacement and

dilation of the cervix

Changes in the cervix

Not associated with bulging of

membranes

Associated with bulging of membranes

Membranes

Relieved by sedation Not relieved by sedation

Response to analgesia

Not followed by labour Followed by labour Labour

2. Show – blood stained mucous.3. SROM

B. Signs:o palpable or recorded uterine contractiono effacement and dilation of the cervixo formation of forewater

I-The First stage: stage of cervical effacement and dilatationDefinition: the first stage of labour refers to the period from the onset of true uterine contractions to the fully dilation of the cervix, when the diameter of the cervical os measures 10cm.

STAGES OF LABOUR

Duration:o primigravida = 8-12 ho multigravida = 6-8 h

Phases of the first stage: Latent phase: started when the cervix dilatated

slowly and reached to about 3cm.A. in primigravida = 8hB. in multigravida = 4h - Active phase: rapid dilatation of the cervix to reach

10cm A. in primigravda = 4hB. in multigravida =2h

•

PARTOGRAM: FRIEDMAN’S CURVE

II-The Second stage of labour: stage of delivery of the fetus.

Definition: the second stage of labour refers to the period from complete cervical dilatation to the birth of the fetus.

Duration:A.in primigravida =1 hB.in multigravida = ½ h however the timing of the second stage is very different to determine and controversial and can be extended as much as there is progress in descent and no harm to the mother or fetus

The second stage of labour has two phases: 1. Passive phase – stage of descent of the

presenting part and dilatation of the vagina – due to contraction and retraction of the uterine muscle.

2. Expulsive phase – stage of bearing down – due to contraction and retraction of the uterine muscle and voluntary efforts by diaphragm and abdominal muscles.

CARDINAL MOVEMENTS OF FETAL HEAD

III-The Third stage of labour:

• The stage of expulsion of the placenta and membranes.

• Duration: up to 30 minutes, however the average length of the third stage of labour is 10 minutes.

Mechanism: the third stage is made of two phases:

1.The first phase: phase of placental separation occurs through the spongiosa layer of the decidua at the time of expulsion of the baby or very soon afterwards. The shearing force responsible for the separation is the contraction and retraction of the uterus, reducing the uterine volume and the area of the placental site, as the fetus is expelled.

2.The second phase: phase of placental expulsion – The separated placenta descends from the upper (active) segment into lower (passive) uterine segment, cervix, and vagina by two mechanisms:

A. -Schultze mechanism:(80%)The placenta delivered as an inverted

umbrella with it’s fetal surface presenting first followed by the membranes with retro-placental haematoma.

B. Mattews – Duncan mechanism: (20%)The placenta delivered side way and it presents

with it’s inferior surface first.

Placenta

• DEFINITION • Dystocia is defined as difficult labor or childbirth. • It may be associated with abnormalities

involving:• Abnormalities of the Passage • Abnormalities of the Passenger • Abnormalities of the Powers • or a combination of these factors

ABNORMAL LABOUR: DYSTOCIA

• INCIDENCE• Over the last quarter of a century, the cesarean

section rate in the United States has risen to approximately 25% of deliveries done each year. Dystocia is currently the most common indication for primary cesarean section, and is about three times more common than either non reassuring fetal status or malpresentation.

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Latent phase Active phase

2nd stage1st stage

max slope

acceleration

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Time (hours)

Cervical dilatation (cm)

Friedman labor curve in nulliparous

• ABNORMAL PATTERNS OF LABOR • The progress of labor is evaluated primarily

through estimates of cervical dilatation and descent of the fetal presenting part. Normal labor patterns in primigravidas and multiparas have been described in detail by Friedman and others.

• Friedman also described four abnormal patterns of labor: (1) prolonged latent phase, (2) protraction disorders (protracted active-phase dilatation and protracted descent), (3) arrest disorders (prolonged deceleration phase, secondary arrest of dilatation, arrest of descent, and failure of descent), and (4) precipitate labor disorders.

• 1. Prolonged Latent Phase• The latent phase of labor begins with the onset of regular

uterine contractions and extends to the beginning of the active phase of cervical dilatation. The duration of the latent phase averages 6.4 hours in nulliparas and 4.8 hours in multiparas.

• Causes of prolonged latent phase include:• excessive sedation or sedation given before the end of the

latent phase. • labor beginning with an unfavorable cervix.• uterine dysfunction characterized by weak, irregular,

uncoordinated, and ineffective uterine contractions. • fetopelvic disproportion.

• 2. Protraction Disorders• Protracted cervical dilatation in the active phase of labor • Protracted descent of the fetus constitute the protraction

disorders. • Protracted active-phase dilatation is characterized by an

abnormally slow rate of dilatation in the active phase, ie, less than 1.2 cm/h in nulliparas or less than 1.5 cm/h in multiparas.

• Protracted descent of the fetus is characterized by a rate of descent under 1 cm/h in nulliparas or under 2 cm/h in multiparas.

• The second stage of labor, which normally averages 20 minutes for parous women and 50 minutes in nulliparous women, is protracted when it exceeds 2 hours in nulliparas or 1 hour in multiparas, or 3 and 2 hours respectively in the presence of conduction anesthesia.

• The underlying pathogenesis of protracted labor is probably multifactorial.

• Fetopelvic disproportion. • minor malpositions such as occiput posterior.• improperly administered conduction

anesthesia. • excessive sedation. • pelvic tumors obstructing the birth canal.

• 3. Arrest Disorders• The four patterns of arrest in labor: • (1) prolonged deceleration, with deceleration phase

lasting more than 3 hours in nulliparas or more than 1 hour in multiparas.

• (2) secondary arrest of dilatation, with no progressive cervical dilatation in the active phase of labor for 2 hours or more.

• (3) arrest of descent, with descent failing to progress for 1 hour or more.

• (4) failure of descent, with descent failing to occur during the deceleration phase of dilatation and during the second stage.

• Causes:• About 50% of patients with arrest disorders

demonstrate fetopelvic disproportion. • various fetal malpositions (eg, occiput posterior,

occiput transverse, face, or brow).• inappropriately administered anesthesia, or

excessive sedation.• If fetopelvic disproportion is established, cesarean

section is done. • If fetopelvic disproportion is not present and

uterine activity is less than optimal, oxytocin stimulation is generally effective in producing further progress.

• 4. Precipitate Labor Disorders• Precipitate dilatation occurs if cervical dilation

occurs at a rate of 5 or more centimeters per hour in a primipara or at 10 cm or more per hour in a multipara. Precipitate descent occurs with descent of the fetal presenting part of 5 cm or more per hour in primparas and 10 cm or more per hour in multiparas.

• Causes:• 1-extremely strong uterine contractions • 2-low birth canal resistance. • abnormal contractions may be associated with administration

of oxytocin and abruptio placentae. • If oxytocin administration is the cause of abnormal

contractions, it may simply be stopped. The problem typically resolves in less than 5 minutes.

• If excessive uterine activity is associated with fetal heart rate abnormalities, and this pattern persists despite discontinuation of oxytocin, a b-mimetic such as terbutaline or ritodrine can be given and magnesium sulfate also

• Lacerations of the birth canal are common. • maternal amniotic fluid embolism. • predisposing to postpartum hemorrhage.• Perinatal mortality is increased secondary to hypoxia, possible

intracranial hemorrhage, and risks associated with unattended delivery.

• Uterine rupture may occur in prolonged labor complicated by midpelvic outlet obstruction, and vesicovaginal or rectovaginal fistula formation may result with pressure necrosis of the surrounding tissues of the birth canal by the fetal head.

• Cesarean section is therefore the delivery method of choice in this complication.

• Other anatomic abnormalities of the reproductive tract may cause dystocia is soft tissue dystocia may be caused by uterine or vaginal congenital anomalies, scarring of the birth canal, pelvic masses, or low implantation of the placenta.

• --Abnormalites of the Passenger • **A. malposition and malpresentation:• Fetal malpresentations are abnormalities of fetal

position, presentation, attitude, or lie. They collectively constitute the most common cause of fetal dystocia, occurring in approximately 5% of all labors.

• 1. Vertex malpositions—• a. Occiput posterior— • b. Occiput transverse—• 2. Brow presentation—Brow presentations usually are

transient fetal presentations with deflexion of the fetal head.

• 3. Face presentation—In face presentation, the fetal head is fully deflexed from the longitudinal axis.

• 4. Abnormal fetal lie—In transverse or oblique lie, the long axis of the fetus is perpendicular to or at an angle to the maternal longitudinal axis.

• 5. Breech presentation

• **B. fetal macrosomia• **C. fetal malformation• The most common malformation is

hydrocephalus, enlargement of the fetal abdomen caused by distended bladder, ascites, or abdominal neoplasms; or other fetal masses, including meningomyelocele or cystosarcoma.

• Abnormalities of the Powers• Normal uterine activity during labor: • (1) the relative intensity of contractions is greater in the

fundus than in the midportion or lower uterine segment (this is termed fundal dominance); (2) the average value of the intensity of contractions is more than 24 mm Hg. (3) contractions are well synchronized in different parts of the uterus; (4) the basal resting pressure of the uterus is between 12 and 15 mm Hg; (5) the frequency of contractions progresses from one every 3–5 minutes to one every 2–3 minutes during the active phase; (6) the duration of effective contraction in active labor approaches 60 seconds; and (7) the rhythm and force of contractions are regular.

• Quantification of uterine activity during labor by:

• -external tocodynamometry • -intrauterine pressure catheter measurement. • Uterine dysfunction generally comprises 3

categories: • hypotonic dysfunction, • hypertonic dysfunction, • uncoordinated dysfunction.

• Hypotonic dysfunction is uterine activity characterized by contraction of the uterus with insufficient force (> 24 mm Hg), irregular or infrequent rhythm, or both. Seen most often in primigravidas in the active phase of labor, it may be caused by excessive sedation, early administration of conduction anesthesia, twins, polyhydramnios, or overdistention of the uterus.

• Hypotonic dysfunction responds well to oxytocin; however, care must be taken to first rule out cephalopelvic disproportion and malpresentation. Active management of labor has been shown to decrease perinatal morbidity and cesarean section rates.

• hypertonic uterine contractions and uncoordinated contraction often occur together and are characterized by elevated resting tone of the uterus, dyssynchronous contractions with elevated tone in the lower uterine segment, and frequent intense uterine contractions. It is generally associated with abruptio placentae, overuse of oxytocin, cephalopelvic disproportion, fetal malpresentation, and the latent phase of labor.

• Treatment: • tocolysis, decrease in oxytocin infusion • cesarean section as indicated for concomitant

malpresentation, cephalopelvic disproportion, or fetal distress.