Normal Labor and Delivery

Question 1

Definition of normal labour

Answer 1

Labor is a physiologic process characterized by the onset of regular, painful uterine contractions resulting in progressive cervical effacement and dilatation after which the products of conception (ie, the fetus, membranes, umbilical cord, and placenta) are expelled outside of the uterus.

Question 2

Initial Assessment

Answer 2

The initial assessment of labor should include a review of the patient’s prenatal care, including confirmation of the estimated date of delivery.

Focused history taking should elicit the following information:

Time of onset of contractions and Frequency

Status of the amniotic membranes (whether spontaneous rupture of the membranes has occurred, and if so, whether the amniotic fluid is clear or meconium stained)

Fetal movements

Presence or absence of vaginal bleeding.

Question 3

Physical examination of a pregnant woman

Answer 3

The physical examination should include documentation of the following:

Maternal vital signs

Fetal presentation

Assessment of fetal well-being

Frequency, duration, and intensity of uterine contractions

Abdominal examination with Leopold maneuvers

Pelvic examination with sterile gloves

Question 4

Abdominal examination

Answer 4

Abdominal examination begins with the Leopold maneuvers described below [2] :

The initial maneuver involves the examiner placing both of his or her hands on each upper quadrant of the patient’s abdomen and gently palpating the fundus with the tips of the fingers to define which fetal pole is present in the fundus. If it is the fetus’ head, it should feel hard and round. In a breech presentation, a large, nodular body is felt.

The second maneuver involves palpation in the paraumbilical regions with both hands by applying gentle but deep pressure. The purpose is to differentiate the fetal spine (a hard, resistant structure) from its limbs (irregular, mobile small parts) to determinate the fetus’ position.

The third maneuver is suprapubic palpation by using the thumb and fingers of the dominant hand. As with the first maneuver, the examiner ascertains the fetus’ presentation and estimates its station. If the presenting part is not engaged, a movable body (usually the fetal occiput) can be felt. This maneuver also allows for an assessment of the fetal weight and of the volume of amniotic fluid.

The fourth maneuver involves palpation of bilateral lower quadrants with the aim of determining if the presenting part of the fetus is engaged in the mother’s pelvis. The examiner stands facing the mother’s feet. With the tips of the first 3 fingers of both hands, the examiner exerts deep pressure in the direction of the axis of the pelvic inlet. In a cephalic presentation, the fetus’ head is considered engaged if the examiner’s hands diverge as they trace the fetus’ head into the pelvis.

Question 5

Pelvic Examination

Answer 5

Digital examination allows the clinician to determine the following aspects of the cervix:

Degree of dilatation, which ranges from 0 cm (closed or fingertip) to 10 cm (complete or fully dilated)

Effacement (assessment of the cervical length, which can be reported as a percentage of the normal 3- to 4-cm–long cervix or described as the actual cervical length)

Position (ie, anterior or posterior)

Consistency (ie, soft or firm)

Palpation of the presenting part of the fetus allows the examiner to establish its station, by quantifying the distance of the body (-5 to +5 cm) that is presenting relative to the maternal ischial spines, where 0 station is in line with the plane of the maternal ischial spines.

Question 6

Assessment of the pelvis

Answer 6

The pelvis can also be assessed either by clinical examination (clinical pelvimetry) or radiographically (CT or MRI).

The pelvic planes include the following:

Pelvic inlet: The obstetrical conjugate is the distance between the sacral promontory and the inner pubic arch; it should measure 11.5 cm or more. The diagonal conjugate is the distance from the undersurface of the pubic arch to sacral promontory; it is 2 cm longer than the obstetrical conjugate. The transverse diameter of the pelvic inlet measures 13.5 cm.

Midpelvis: The midpelvis is the distance between the bony points of ischial spines, and it typically exceeds 12 cm.

Pelvic outlet: The pelvic outlet is the distance between the ischial tuberosities and the pubic arch. It usually exceeds 10 cm.

The shape of the mother’s pelvis can also be assessed and classified into 4 broad categories based on the descriptions of Caldwell and Moloy: gynecoid, anthropoid, android, and platypelloid.

Although the gynecoid and anthropoid pelvic shapes are thought to be most favorable for vaginal delivery, many women can be classified into 1 or more pelvic types, and such distinctions can be arbitrary.

Question 6

Workup

Answer 6

External tocometric monitoring for the onset and duration of uterine contractions

Use of a Doppler device to detect fetal heart tones and rate.

In the presence of labor progression, monitoring of uterine contractions by external tocodynamometry is often adequate.

If a laboring mother is confirmed to have rupture of the membranes and if the intensity/duration of the contractions cannot be adequately assessed, an intrauterine pressure catheter can be inserted into the uterine cavity past the fetus to determine the onset, duration, and intensity of the contractions.
While it is considered safe, placental abruption has been reported as a rare complication of an intrauterine pressure catheter placed extramembraneously.

Bedside ultrasonography may be used to assess the risk of gastric content aspiration in pregnant women during labor, by measuring the antral cross-sectional area (CSA), according to a study by Bataille et al.

Often, fetal monitoring is achieved using cardiotography, or electronic fetal monitoring.

If nonreassuring fetal heart rate tracings by cardiotography (eg, late decelerations) are noted, a fetal scalp electrode may be applied to generate sensitive readings of beat-to-beat variability. However, a fetal scalp electrode should be avoided if the mother has HIV, hepatitis B or hepatitis C infections, or if fetal thrombocytopenia is suspected.

Further evaluation of a fetus at risk for labor intolerance or distress can be accomplished with blood sampling from fetal scalp capillaries. This procedure allows for a direct assessment of fetal oxygenation and blood pH. A pH of < 7.20 warrants further investigation for the fetus’ well-being and for possible resuscitation or surgical intervention.

Routine laboratory studies of the parturient, such as complete blood cell (CBC) count, blood typing and screening, and urinalysis, are usually performed. Intravenous (IV) access is established.

Question 8

Pain Control

Answer 8

Laboring women often experience intense pain. Uterine contractions result in visceral pain, which is innervated by T10-L1. While in descent, the fetus’ head exerts pressure on the mother’s pelvic floor, vagina, and perineum, causing somatic pain transmitted by the pudendal nerve (innervated by S2-4). Therefore, optimal pain control during labor should relieve both sources of pain.

Agents given in intermittent doses for systemic pain control include the following:

Meperidine, 25-50 mg IV every 1-2 hours or 50-100 mg IM every 2-4 hours

Fentanyl, 50-100 mcg IV every hour

Nalbuphine, 10 mg IV or IM every 3 hours

Butorphanol, 1-2 mg IV or IM every 4 hours

Morphine, 2-5 mg IV or 10 mg IM every 4 hours

As an alternative, regional anesthesia may be given. Anesthesia options include the following:
Epidural
Spinal
Combined spinal-epidural

These provide partial to complete blockage of pain sensation below T8-10, with various degree of motor blockade. These blocks can be used duringlabor and for surgical deliveries.

Of note, use of nonsteroidal anti-inflammatory drugs (NSAIDs) are relatively contraindicated in the third trimester of pregnancy. The repeated use of NSAIDs has been associated with early closure of the fetal ductus arteriosus in utero and with decreasing fetal renal function leading to oligohydramnios.

Question 9

What is Lightening

Answer 9

Patients may also describe what has been called lightening, ie, physical changes felt because the fetus’ head is advancing into the pelvis. The mother may feel that her baby has become light.

As the presenting fetal part starts to drop, the shape of the mother’s abdomen may change to reflect descent of the fetus.

Her breathing may be relieved because tension on the diaphragm is reduced, whereas urination may become more frequent due to the added pressure on the urinary bladder.

Question 10

How many stages of Labor

Answer 10

3

Question 11

Stage 1 begins with and ends with

Answer 11

Begins with regular uterine contractions and ends with complete cervical dilatation at 10 cm

Question 12

Features of Braxton-Hicks contractions

Answer 12

Usually occur no more often than once or twice per hour, and often just a few times per day

Irregular and do not increase in frequency with increasing intensity

Resolve with ambulation or a change in activity

Question 13

Features of true labor contractions

Answer 13

May start as infrequently as every 10-15 minutes, but usually accelerate over time, increasing to contractions that occur every 2-3 minutes

Tend to last longer and are more intense than Braxton-Hicks contractions

Lead to cervical change

Question 14

Phases of stage 1

Answer 14

a latent phase and an active phase

Question 16

Latent phase

Answer 16

The latent phase begins with mild, irregular uterine contractions that soften and shorten the cervix

Question 17

Active phase

Answer 17

The active phase usually begins at about 3-4 cm of cervical dilation and is characterized by rapid cervical dilation and descent of the presenting fetal part

Question 18

2nd stage of labour begins and ends with

Answer 18

Begins with complete cervical dilatation and ends with the delivery of the fetus

Question 19

Management of first stage of labour

Answer 19

A woman having normal labor should be encouraged to assume the position that she finds most comfortable: Walking, Lying supine, Sitting or Resting in a left lateral decubitus position.

The frequency and strength of uterine contractions and changes in cervix and in the fetus’ station and position should be assessed periodically to evaluate the progression of labor.

Monitoring the fetal heart rate at least every 15 minutes, particularly during and immediately after uterine contractions; in most obstetric units, the fetal heart rate is assessed continuously

The patient and her family or support team should be consulted regarding the risks and benefits of various interventions, such as the augmentation of labor using oxytocin, artificial rupture of the membranes, methods and pharmacologic agents for pain control, and operative vaginal delivery (including forceps or vacuum-assisted vaginal deliveries) or cesarean delivery. They should be actively involved, and their preferences should be considered in the management decisions made during labor and delivery

Question 20

Risk factors for prolonged first stage of labour

Answer 20

premature rupture of the membranes (PROM)

nulliparity

induction of labor

increasing maternal age

and or other complications (eg, previous perinatal death, pregestational or gestational diabetes mellitus, hypertension, infertility treatment).

Question 21

Prolonged 2nd stage of labour in nulliparous women with and without regional Anaesthesia

Answer 21

In nulliparous women, the second stage should be considered prolonged if it exceeds 3 hours if regional anesthesia is administered or 2 hours in the absence of regional anesthesia GUI

Question 21

Augumentation of Labour

Answer 21

Two methods of augmenting labor have been established.

The traditional method involves the use of low doses of oxytocin with long intervals between dose increments. For example, low-dose infusion of oxytocin is started at 1 mili IU/min and increased by 1-2 mili IU/min every 20-30 minutes until adequate uterine contraction is obtained.

The second method, or active management of labor, involves a protocol of clinical management that aims to optimize uterine contractions and shorten labor.

This protocol includes strict criteria for admission to the labor and delivery unit, early amniotomy, hourly cervical examinations, early diagnosis of inefficient uterine activity (if the cervical dilation rate is < 1.0 cm/h), and high-dose oxytocin infusion if uterine activity is inefficient.

Oxytocin infusion starts at 4 mili IU/min (or even 6 mili IU/min) and increases by 4 mili IU/min (or 6 mili IU/min) every 15 minutes until a rate of 7 contractions per 15 minutes is achieved or until the maximum infusion rate of 36 mili IU/min is reached.

Question 22

Prolonged 2nd stage of labour in multiparous women with and without regional Anaesthesia

Answer 22

In multiparous women, the second stage should be considered prolonged if it exceeds 2 hours with regional anesthesia or 1 hour without it

Question 22

Maternal factors that lead to prolonged 2nd stage of labour

Answer 22

nulliparity

increasing maternal weight and/or weight gain

use of regional anesthesia

induction of labor

fetal occiput in a posterior or transverse position

increased birthweight.

Question 24

Management of 2nd stage of labour 1

Answer 24

With complete cervical dilatation, the fetal heart rate should be monitored or auscultated at least every 5 minutes and after each contraction.

Although the parturient may be encouraged to actively push in concordance with the contractions during the second stage, many women with epidural anesthesia who do not feel the urge to push may allow the fetus to descend passively, with a period of rest before active pushing begins.

Prolonged duration of the second stage alone does not mandate operative delivery if progress is being made, but management options for second-stage arrest include the following:

Continuing observation/expectant management

Operative vaginal delivery by forceps or vacuum-assisted vaginal delivery, or cesarean delivery.

Question 24

Management of 2nd stage of labour

Answer 24

Delivery of the fetus

Positioning of the mother for delivery can be any of the following: Supine with her knees bent (ie, dorsal lithotomy position; the usual choice), Lateral (Sims) position, Partial sitting or squatting position or On her hands and knees

Episiotomy used to be routinely performed at this time, but current recommendations restrict its use to maternal or fetal indications

Delivery maneuvers are as follows:

The head is held in mid position until it is delivered, followed by suctioning of the oropharynx and nares

Check the fetus’s neck for a wrapped umbilical cord, and promptly reduce it if possible

If the cord is wrapped too tightly to be removed, the cord can be double clamped and cut

The fetus’s anterior shoulder is delivered with gentle downward traction on its head and chin

Subsequent upward pressure in the opposite direction facilitates delivery of the posterior shoulder

The rest of the fetus should now be easily delivered with gentle traction away from the mother

If not done previously, the cord is clamped and cut

The baby is vigorously stimulated and dried and then transferred to the care of the waiting attendants or placed on the mother’s abdomen

Question 24

Consequences of prolonged 2nd stage

Answer 24

a prolonged second stage is not associated with adverse neonatal outcomes in nulliparas, possibly because of close fetal surveillance during labor, but it is associated with increased maternal morbidity, including:

higher likelihood of operative vaginal delivery and cesarean delivery,

postpartum hemorrhage,

third- or fourth-degree perineal lacerations, and

peripartum infection.

Therefore, it is crucial to weigh the risks of operative delivery against the potential benefits of continuing labor in hopes to achieve vaginal delivery. The question of when to intervene should involve a thorough evaluation of the ongoing risks of further expectant management versus the risks of intervention with vaginal or cesarean delivery, as well as the patients’ preferences.

Question 27

What is the mechanism of labour?

Answer 27

The mechanisms of labor, also known as the cardinal movements, involve changes in the position of the fetus’s head during its passage in labor.

These are described in relation to a vertex presentation.

Although labor and delivery occurs in a continuous fashion, the cardinal movements are described as 7 discrete sequences.

Question 28

Mechanisms of labour

Answer 28

Engagement 
Descent
Flexion
Internal Rotation
Extension
Restitution and External Rotation
Expulsion

Question 29

What is Engagement

Answer 29

The widest diameter of the presenting part (with a well-flexed head, where the largest transverse diameter of the fetal occiput is the biparietal diameter) enters the maternal pelvis to a level below the plane of the pelvic inlet.

On the pelvic examination, the presenting part is at 0 station, or at the level of the maternal ischial spines.

Question 30

What is Descent

Answer 30

The downward passage of the presenting part through the pelvis.

This occurs intermittently with contractions. The rate is greatest during the second stage of labor.

Question 31

What happens with flexion

Answer 31

As the fetal vertex descents, it encounters resistance from the bony pelvis or the soft tissues of the pelvic floor, resulting in passive flexion of the fetal occiput.

The chin is brought into contact with the fetal thorax, and the presenting diameter changes from occipitofrontal (11.0 cm) to suboccipitobregmatic (9.5 cm) for optimal passage through the pelvis.

Question 32

What is internal rotation

Answer 32

As the head descends, the presenting part, usually in the transverse position, is rotated about 45° to anteroposterior (AP) position under the symphysis. Internal rotation brings the AP diameter of the head in line with the AP diameter of the pelvic outlet.

Question 33

What happens in Extension

Answer 33

With further descent and full flexion of the head, the base of the occiput comes in contact with the inferior margin of the pubic symphysis.

Upward resistance from the pelvic floor and the downward forces from the uterine contractions cause the occiput to extend and rotate around the symphysis.

This is followed by the delivery of the fetus’ head.

Question 34

What happens in restitution and external rotation?

Answer 34

When the fetus’ head is free of resistance, it untwists about 45° left or right, returning to its original anatomic position in relation to the body.

Question 35

What happens in expulsion

Answer 35

After the fetus’ head is delivered, further descent brings the anterior shoulder to the level of the pubic symphysis.

The anterior shoulder is then rotated under the symphysis, followed by the posterior shoulder and the rest of the fetus.

Question 36

Definition of 3rd stage of labour

Answer 36

The period between the delivery of the fetus and the delivery of the placenta and fetal membranes

Question 36

Duration of 3rd stage of labour

Answer 36

Delivery of the placenta usually happens within 5-10 minutes after delivery of the fetus, but it is considered normal up to 30 minutes after delivery of the fetus.

Question 36

What is expectant management of 3rd stage of labour

Answer 36

Expectant management involves spontaneous delivery of the placenta

Question 37

Prolonged 3rd stage of labour

Answer 37

The third stage of labor is considered prolonged after 30 minutes, and active intervention is commonly considered

Question 39

Active management of 3rd stage of labour

Answer 39

Active management often involves:

Administration of uterotonic agent (usually oxytocin, an ergot alkaloid, or prostaglandins) before the placenta is delivered.

This is done with early clamping and cutting of the cord and with controlled traction on the cord while placental separation and delivery are awaited.

Question 41

Classic signs the placenta has seperated from the uterus

Answer 41

The uterus contracts and rises

The umbilical cord suddenly lengthens

A gush of blood occurs