Module 4 Unit A: Labor Progress Flashcards
Understand the relationship between the framework used for care related to labor progress and cesarean birth rates.
Friedmans labor curve may have contributed to an increase in cesearean sections and contemporary research is re-evaluating what is normal and updating recommendations.
Define the stages and phases of labor as defined by Friedman. First stage:
Begins with the onset of regular contractions and ends with complete dilation. Includes: latent and active phases
Define the stages and phases of labor as defined by Friedman. Latent phase:
Beginning with maternal perception of regular contractions
Define the stages and phases of labor as defined by Friedman. Active phase:
The point at which the rate of change of cervical dilation significantly increases
Define the stages and phases of labor as defined by Friedman. Second stage:
Begins with complete dilation and ends with the birth of the baby
Controversy Note: There is now an argument that it should begin with the urge to push
Compare Friedman’s definition of the onset of the active phase vs. current research.
Friedman defined the onset of the active phase as the point at which the rate of dilation change rapidly increased; often, this was considered to be at 3cm despite Friedman stating this was not correct. Now active phase is considered 5-6 cm dilated.
Define prolonged latent phase according to Friedman
> 20 hours in a nulliparous woman, and > 14 hours in a multiparous woman
Note: Protracted=slower than normal, arrested=complete cessation of progress
Define protracted active phase according to Friedman
cervical dilation in the active phase of less than 1.2 cm/h in nullip and less than 1.5 cm/h in multip
Note: Protracted=slower than normal, arrested=complete cessation of progress
Define protracted descent according to Friedman
<1 cm/hr descent in nulliparous and <2 cm/hr descent in multip
Note: Protracted=slower than normal, arrested=complete cessation of progress
Define Secondary arrest of dilation (arrested active phase) according to Friedman
the absence of cervical change for 2+ hours
Note: Protracted=slower than normal, arrested=complete cessation of progress
Define Arrest of descent according to Friedman
no descent in 1 hour
Note: Protracted=slower than normal, arrested=complete cessation of progress
How did Friedman determine time limits for normal and prolonged labor?
Friedman calculate the upper and lower limits of normal with >95% and <5% being abnormal
Upper limit of normal for each stage and phase in total hours, then divided total hours by number of centimeters to calculate upper limit of normal in terms of hourly progress of dilation (first stage) and descent (second stage).
What did Friedman consider a normal length of time for the first stage, latent phase?
Nullparas < 20 hours
Multiparas < 14 hours
note that latent phase is calculated based on total duration, not rate of change per hour
What did Friedman consider a normal length of time for the first stage, active phase?
Nulliparas: At least 1.2 cm/hr dilation
Multiparas: At least 1.5 cm/hr dilation
What did Friedman consider a normal length of time for the second stage?
Nulliparas: 1 cm/hr descent
Multiparas: 2 cm/hr descent
How does contemporary research compare to what Freidman suggested?
Contemporary research shows patients dilate much slower than he suggested. Some show twice as long as he suggested. It is not uncommon for patients to take longer than two hours to make cervical change.
How does the CSL define the slowest cervical progress that is considered normal?
0.5-0.7 cm/hr nulliparas
0.5-1.3 cm/hr multiparas
(Rate increases as labor progresses)
What does Friedman say about the relationship between length of labor and perinatal complications?
Friedman said that protractions and arrest (excluding latent phase) were associated with a significant increase in fetal/neonatal morbidity and mortality
Much (though not all) of this increased morbidity and mortality associated with mid forceps births
In Friedman’s study, arrested labor associated with significant increase in perinatal mortality even with spontaneous birth.
What does contemporary research say about the relationship between length of labor and perinatal complications?
No increase in neurologic abnormalities with labor abnormalities
No difference in: PPH, Postpartum fever, Neonatal resuscitation, 5 minutes Apgar < 7
No difference in perinatal mortality, postpartum hemorrhage
More cesarean births (13.1% vs. 6.1%), chorioamnionitis (23.5% vs. 12.5%) admissions to NICU (9.8% vs. 4.7%) for unspecified reasons
No difference in 3rd/4th degree lacerations, pp endometritis, pp hemorrhage, Apgars, meconium aspiration, neonatal sepsis, shoulder dystocia, birth trauma
Authors conclude longer labor associated with more cesareans but no increase in adverse neonatal outcomes.
Understand evidence and expert opinion regarding when we should intervene in slow or non-progressive labor.
There is little evidence on which to base the decision about when to intervene.
Almost all the contemporary research concerns defining normal rates of progress (our first question), so we do not have strong recommendations regarding when intervention should begin. And there is a wide array of possible interventions. Obstetricians generally think amniotomy, oxytocin or cesarean birth when referring to timing of interventions. Midwives tend to consider a longer list including non-pharmacologic options.
What does the contemporary evidence show in regard to intervening in slow labor?
Faster intervention=faster delivery. Otherwise no significant differences. There is no optimal waiting times suggested.
Are there current recommendations on how to intervene in regard to slow labor?
No
Only one study: Oxytocin vs Water immersion=less epidurals and oxytocin in water group but no other differences in terms of outcomes.
What does ACOG say about when a c/s should be recommended for slow labor?
“Slow but progressive labor should not be an indication for cesarean section” and “Cesarean delivery for active phase arrest in the first stage of labor should be reserved for women at or beyond 6 cm with ruptured membranes who fail to progress despite 4 hours of adequate uterine activity or at least 6 hours of oxytocin with no cervical change.”
List some indications for induction of labor.
-Gestational hypertension
-Preeclampsia/eclampsia
-Fetal growth restriction
-Cholestasis of pregnancy
-Diabetes mellitus
-Fetal demise
-Intra-amniotic infection
-Oligohydramnios
-Nonreassuring fetal status
-Prelabor rupture of membranes
-Post-term pregnancy.
List some contraindications for induction of labor.
-OOH Birth (Inductions should occur in the hospital)
Contraindications=anything that would contraindicate a vaginal birth:
-Placenta previa
-Vasa previa
-Transverse lie
-Umbilical cord prolapse
-Myomectomy entering the endometrial cavity
-Previous classical uterine incision
-Active genital herpes infection
-Category III fetal heart rate (FHR) tracing
List possible complications associated with induction and augmentation of labor with oxytocin.
-**Risk for tachysystole
-Is an antidiuretic: use cautiously in those at risk of pulmonary edema
-Hypotension, tachycardia
-Transient myocardial ischemia if given as bolus
-PP Hemorrhage (with prolonged use or high doses)
-Uterine rupture
Understand the controversies and pertinent pharmacokinetics and pharmacodynamics regarding dosage regimens for oxytocin as used for induction and augmentation of labor.
The onset of action of synthetic oxytocin is 3 to 4 minutes, and the half-life is approximately 15 minutes. The uterine response reaches a steady state after 30 to 40 minutes.49 The individual response to a particular dose is both variable and dose dependent: As the infusion rate increases, the frequency and intensity of contractions follow.
“High dose” Pitocin increases the risk of tachysystole and other complications and is associated with shorter labor. Evidence of C/S risk is inconsistent. There is a trend towards low-dose Pitocin.
What is the physiologic function of prostaglandins and why can we use prostaglandins at any gestational age?
Physiologic function: the ability to cause contraction or relaxation of smooth muscle. Decreases collagen in the cervix. Prostaglandin receptors are always present in myometrial tissue.
What are the three prostaglandins discussed in this class? What are their uses?
Misoprostol (Cytotec®): synthetic PGE1 analog used for pre-induction cervical ripening, and first and second-trimester abortions.
Dinoprostone (Cervidil® or Prepidil®): PGE2 used for pre-induction cervical ripening and first or second-trimester abortion.
Carboprost (Hemabate®): PGF2 used for control of postpartum hemorrhage and first or second-trimester abortion.
Discuss the effectiveness and possible adverse effects of PGE2 (dinoprostone) and PGE1 (misoprostol) as used for cervical ripening.
Risk of tachysystole, both are effective cervical ripeners.
Analyze the controversy generated by Searle’s (the pharmaceutical company that manufactures Cytotec® [misoprostol]) warning against use of misoprostol in pregnant clients.
Part of the controversy stems from our inability to answer the question of whether misoprostol used in low doses to induce labor in clients without prior cesareans, is any less safe than other agents used for the same purpose.
In September 2000, mifepristone was approved by the FDA to be used in conjunction with misoprostol for early pregnancy termination, yet misoprostol was not approved for the same purpose. In fact, product labeling formerly included a warning that misoprostol is contraindicated in pregnancy because of its abortifacient properties. That warning was changed in May of 2002 to state that misoprostol is contraindicated for use as an antiulcer drug in pregnant people. However, misoprostol is still not FDA approved for any obstetric or gynecologic indication, and warnings about risks associated with its use for induction of labor remain on the label.
Discuss the mechanism of action, safety and effectiveness of cervical balloons as used for cervical ripening.
Mechanical methods of IOL work by softening
and stretching the cervix, exposing endometrial decidual
cells and stimulating the release of endogenous prostaglandins
PGE2 and PGF2alpha locally and systemically
Know the components and significance of the Bishop Score, and what Bishop score indicates a need for cervical ripening for nulliparas and multiparas. (You do not need to memorize the entire Bishop Score.)
The Bishop’s score is a numeric assessment of four different characteristics of the cervix and fetal station; it is used to predict the success of induction. Score includes: cerical position, consistency, length, dilation and fetal station.
The degree of ripening can be quantified using the modified Bishop’s score, which takes into consideration all of the factors associated with cervical remodeling (Table 29-5). This scoring system indicates whether the woman’s cervix is “favorable” or “unfavorable” with regard to predicting the success of labor induction and is the best predictor of induction success known to date.
A modified Bishops score of >8 is considered favorable and has a high probability of vaginal delivery. A score of **6 or less is considered unfavorable, and ripening may improve induction success. (Varney)
Bishop of 6+ for multip or 8+ for primip (Review of E-B Methods…)
List some other methods of induction aside from oxytocin, arom, ripening and balloons.
-Nipple stimulation
-Herbs: castor oil, evening primrose oil, rasberry lead, blue/black cohosh. These methods are safe and inexpensive. They can be use OOH
Analyze the impact of elective induction on rates of induction and the risk of cesarean birth.
The rate of labor induction has increased greatly in recent decades. Exact figures are difficult to determine, but we can accurately state that the rate has gone from about 9 % in 1990 to more than 20% currently. Though the protocol was intended to shorten labor, an unanticipated finding was a decrease in the cesarean birth rate from about 10% to about 5%. (note: the epidural rate was 5%)
**The take-home point is research is mixed on the effect of active management of labor (AMOL) on cesarean birth rates in the United States.
Define active management of labor.
Active management of labor (AMOL) is a package of care that originated in Dublin Ireland in the 1970s. It was developed by several Irish obstetricians to guarantee birth within 12 hours of admission to the hospital. The package included: no admission until active labor, continuous labor support by a midwife, strict protocols for labor progress and interventions in the absence of “adequate” progress. This was done as follows: If progress was less than one centimeter per hour, amniotomy was performed and an aggressive Pitocin augmentation begun with dosage increased every 15 minutes.
Discuss the evidence of PO misoprostol vs. vaginal dinoprostone.
A Cochrane Review on misoprostol for labor induction found that use of oral misoprostol resulted in fewer cesarean births than vaginal dinoprostone, with no differences in negative outcomes for client or baby
Discuss the evidence of PO misoprostol vs. vaginal dinoprostone.
A Cochrane Review on misoprostol for labor induction found that use of oral misoprostol resulted in fewer cesarean births than vaginal dinoprostone, with no differences in negative outcomes for client or baby
What differences were found with AMOL in the US?
The epidural rate was higher, and continuous labor support by a midwife was not included in the package of care.
What did the original AMOL package include?
No admission until active labor, continuous labor support by a midwife, strict protocols for labor progress and interventions in the absence of “adequate” progress. This was done as follows: If progress was less than one centimeter per hour, amniotomy was performed and an aggressive Pitocin augmentation begun with dosage increased every 15 minutes. (As a side note, the concept of high-dose Pitocin protocols-discussed elsewhere in this unit comes from AMOL.)
