Chapter 4 (Obstetrics): Normal labor and delivery

Question 1

What should you do when a patient first present to the labor floor?

Answer 1

• Take history (Present pregnancy, obstetric history and full medical history)
• Ask specific questions (Contractions, vaginal bleeding, fluid leakage and fetal movement)
• Normal physical examination +
  Obstetric examination–> The obstetric examination includes maternal abdominal examination for contractions and the fetal lie, presentation, and size (Leopold maneuvers), cervical examination, fetal heart tones, and a sterile speculum examination if rupture of membranes is suspected. Obstetric ultrasound evaluation of the cervical length and fetal presentation can also be done to augment the obstetric examination.

Question 2

What is Leopold maneuvers?

Answer 2

The maneuvers involve palpating first at the fundus of the uterus in the maternal upper abdominal quadrants, then on either side of the uterus (maternal left and right), and, finally, palpation of the presenting part just above the pubic symphysis. Determination of fetal presentation, either breech or vertex (cephalic), can be more difficult, and even the most experienced examiner may require ultrasound to confirm presentation, particularly in the obese patient.

Question 3

What is PROM and what is PPROM? What is the main symptom? How do we diagnose PROM? What can cause false positive test and what can we do if we doubt the diagnosis?

Answer 3

1. Premature rupture of membranes (PROM) is when the membranes surrounding the fetus rupture prior to the onset of labor. When PROM occurs more than 18 hours before labor we call it prolonged PROM (PPROM).
2. Leakage of fluid from vagina
3. Diagnosis can be done by the pool, nitrazine, and fern tests. Using a sterile speculum to examine the vaginal vault, the pool test is positive if there is a collection of fluid in the vagina. This can be augmented by asking the patient to cough or bear down, potentially allowing one to observe fluid escaping from the cervix. Vaginal secretions are normally acidic, whereas amniotic fluid is alkaline. Thus, when amniotic fluid is placed on nitrazine paper, the paper should immediately turn blue. The estrogens in the amniotic fluid cause crystallization of the salts in the amniotic fluid when it dries. Under low microscopic power, the crystals resemble the blades of a fern, giving the test its name.
4. Caution should be exercised to sample fluid that is not directly from the cervix because cervical mucus also ferns and may result in a false-positive reading. If these tests are equivocal, an ultrasound examination can determine the quantity of fluid around the fetus. If the fluid volume was previously normal and there is no other reason to suspect low fluid, oligohydramnios is indicative of ROM.

Question 4

1. What does cervical examination allow obstetrician determine?
2. What are the 5 components of cervical examination and what do they make up?
3. Describe the 5 components?

Answer 4

1. The cervical examination allows the obstetrician to determine whether a patient is in labor, the phase of labor, and how labor is progressing.
2. The five components of the cervical examination are dilation, effacement, fetal station, cervical position, and consistency of the cervix. These five aspects of the examination make up the Bishop score. A Bishop score greater than 8 is consistent with a cervix favorable for both spontaneous labor and, as it is more commonly used, induced labor.
3. Describe:
   Dilation–> Dilation is assessed by using either one or two fingers of the examining hand to determine how open the cervix is at the level of the internal os. The measurements are in centimeters and range from closed, or 0 cm, to fully dilated, or 10 cm. On average, a 10-cm dilation is necessary to accommodate the term infant’s biparietal diameter.

Effacement–> Effacement determines how much length is left of the cervix and how effaced (i.e., thinned out) it is. Effacement can commonly be reported by percent or by cervical length. The typical cervix is 3 to 5 cm in length; thus, if the cervix feels like it is about 2 cm from external to internal os, it is 50% effaced. Complete or 100% effacement occurs when the cervix is as thin as the adjoining lower uterine segment.

Fetal station–> The relation of the fetal head to the ischial spines of the female pelvis is known as station. When the most descended aspect of the presenting part is at the level of the ischial spines, it is designated 0 station. Station is negative when the presenting part is above the ischial spines and positive when it is below.

Cervical consistency and cervical position–> Cervical consistency is self-explanatory. Whether the cervix feels firm, soft, or somewhere in between should be noted. Cervical position ranges from posterior to mid to anterior. During early labor, the cervix often changes its consistency to soft and advances its position from posterior to mid to anterior.

Question 5

What are the main fetal presentations and how can we determine the presentation?

Answer 5

The fetal presentation can be vertex/cephalic (head down), breech (buttocks down), or transverse (neither down). Although presentation may already be known from the Leopold maneuvers, it can be confirmed by examination of the presenting part during cervical examination. Assuming that the cervix is somewhat dilated, the fetal presenting part may be palpated as well during this examination. Position is determined by palpation of the sutures and fontanelles. If fetal presentation cannot be determined by physical examination, ultrasound can confirm presentation.

Question 6

What is the definition of labor?

Answer 6

The diagnosis of labor strictly defined is regular uterine contractions that cause cervical change. However, clinicians use many other signs of labor, including patient discomfort, bloody show, nausea and vomiting, and palpability of contractions.

Question 7

1. What is induction and augmentation of labor and how do we induce and augment labor?
2. What are the indications for induction of labor?
3. What are the indications for augmentation of labor?
4. How can we assess adequacy of contractions and what is the baseline intrauterine pressure vs pressure under contraction?

Answer 7

1. Induction of labor is the attempt to begin labor in a nonlaboring patient, whereas augmentation of labor is intervening to increase the already present contractions.
   Labor is induced with prostaglandins, oxytocic agents, mechanical dilation of the cervix, and/or artificial ROM (Amniotomy). Oxytocin and amniotomy are also used to augment labor.
2. Common indications for induction of labor include postterm pregnancy, preeclampsia, diabetes mellitus, nonreassuring fetal testing, and intrauterine growth restriction.
3. The indications for augmentation of labor include those for induction in addition to inadequate contractions or a prolonged phase of labor.
4. The adequacy of contractions is indirectly assessed by the progress of cervical change. It may also be measured directly using an intrauterine pressure catheter (IUPC) that determines the absolute change in pressure during a contraction and thus estimates the strength of contractions. The baseline intrauterine pressure is usually between 10 and 15 mm Hg. Contractions during labor will increase by 20 to 30 mm Hg in early labor and by 40 to 60 mm Hg as labor progresses.

Question 8

1. How do we monitor mother during labor?
2. How do we monitor fetus during labor and what do we use?
3. When should we suspect that something is wrong with the fetus?
4. What are the three types of fetal heart rate decelarations?
5. What is fetal scalp pH and when should we take it?

Answer 8

1. By assessing vital signs and laboratory studies.
2. By determining the baseline rate and assessment of fetal heart rate variations. We can auscultate, or use external electronic monitors (more commonly used than auscultation now a days), or use fetal scalp electrode (In the case of repetitive decelerations or in fetuses who are difficult to trace externally with Doppler).
3. The normal range for the fetal heart rate is between 110 and 160 beats per minute. With baselines above 160, fetal distress secondary to infection, hypoxia, or anemia is of concern. Any prolonged fetal heart rate deceleration of greater than 2 minutes’ duration with a heart rate less than 90 beats per minute is of concern and requires immediate action.
4. Types of fetal HR decelerations:
   Early decelerations–> They begin and end approximately at the same time as contractions. They are a result of increased vagal tone secondary to head compression during a contraction.

Variable decelerations–> They can occur at any time and tend to drop more precipitously than either early or late decelerations. They are a result of umbilical cord compression. Repetitive variables with contractions can be seen when the cord is entrapped either under a fetal shoulder or around the neck and is compressed with each contraction.

Late decelerations–> They begin at the peak of a contraction and slowly return to baseline after the contraction has finished. These decelerations are a result of uteroplacental insufficiency and are the most worrisome type. They may degrade into bradycardias as labor progresses, particularly with stronger contractions.

5. If a fetal heart rate tracing is nonreassuring, the fetal scalp pH may be obtained to directly assess fetal hypoxia and acidemia. Fetal blood is obtained by making a small nick in the fetal scalp and drawing up a small amount of fetal blood into capillary tubes. The results are reassuring when the scalp pH is greater than 7.25, indeterminant when it is between 7.20 and 7.25, and nonreassuring when it is less than 7.20. Care must be taken to avoid contamination of the blood sample with amniotic fluid, which is basic and will elevate the results falsely.

Question 9

1. What are the cardinal movements of labor?
2. What are the stages of labor?
3. What is the normal/abnormal at different stages of labor?

Answer 9

1. The cardinal movements are engagement, descent, flexion, internal rotation, extension, and external rotation (also called restitution or resolution).
2. Labor and delivery are divided into three stages and each stage involves different concerns and considerations.
   Stage 1 begins with the onset of labor and lasts until dilation and effacement of the cervix are completed. Stage 2 is from the time of full dilation until delivery of the infant.
   Stage 3 begins after delivery of the infant and ends with delivery of the placenta.
3. Normal/abnormal:
   Stage 1–> An average first stage of labor lasts approximately 10 to 12 hours in a nulliparous patient and 6 to 8 hours in a multiparous patient. The range of what is considered within normal limits is quite wide, from 6 hours up to 20 hours in a nulliparous patient and from 2 to 12 hours in a multiparous patient.

Stage 2–> This stage is considered prolonged if its duration is longer than 3 hours in a nulliparous patient, although at least an extra hour is allowed in patients who have epidurals. In multiparous women, stage 2 is prolonged if its duration is longer than 2 hours without an epidural and at least 3 hours with an epidural.

Stage 3–> Placental separation usually occurs within 5 to 10 minutes of delivery of the infant; however, up to 30 minutes is usually considered within normal limits. The diagnosis of retained placenta is made when the placenta does not deliver within 30 minutes after the infant.

Question 10

What are the indications for Cesarean section?

Answer 10

1. Maternal/fetal-> Cephalopelvic disproportion and failed induction of labor
2. Maternal–>
   - Maternal diseases (Active genital herpes, untreated HIV or cervical cancer)
   - Prior uterine surgery (Classical cesarean section)
   - Prior uterine rupture
   - Obstruction to the birth canal (Fibroids or ovarian tumors)
3. Fetal–>
   - Nonreassuring fetal testing (Bradycardia, absence of FHR variability and Scalp pH <7.20)
   - Cord prolapse
   - Fetal malpresentation (Breech, transverse lie or brow)
   - Multiple gestations (Nonvertex first twin or high-order multiples)
   - Fetal anomalies (Hydrocephalus or osteogenesis imperfecta)
4. Placental–> Placenta previa, vasa previa or abruptio placentae