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Samantha A. Sommerness DNP, APRN, CNMClinical Assistant ProfessorUniversity of Minnesota School of Nursing

� Describe the overall physiology of a uterine

contraction and how the three p’s: the powers, the

passenger and the passage work together to achieve

complete dilation and expulsion.

� List two physiologic benefits of open glottis pushing

for both mom and baby.

� State two ways to improve second stage labor

support and initial steps to moving away from

directed pushing on your labor and delivery unit.

“I attribute my success to this: I

never gave or took any excuse”

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So Why Do I Care so

Much About the Second

Stage….

Two phases to the Second Stage

�Phase I: “the lull”

or Latent phase:

From complete

dilatation until the

urge to bear down

� Phase II: Active

phase or pushing

phase: From the

onset of active

pushing efforts to

crowning of the

presenting part

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Cardinal movements through the Curve of

Carus (we will focus steps 2-4):

1. Head floating, before engagement

2. Engagement, descent, flexion

3. Further descent, internal rotation

4. Complete rotation, beginning extension

5. Complete extension,

6. Restitution (external rotation)

7. Delivery of anterior shoulder

8. Delivery of posterior shoulder

Cardinal movements through the Curve of

Carus (we will focus steps 2-4):

Pushing too early without the urge to

push, not only leads to exhaustion,

but works against the natural curve of

the maternal spine2

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� Lack of standardization of management of the length of the

second stage of labor

� Inconsistent use of operative vaginal delivery bundle

� Fetal heart rate patterns are managed differently in the second

stage than in the first stage

� Inadequate fetal monitoring in second stage

� Failure to rescue in the second stage

� Lack of documentation in second stage

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Forces of the contractions� it is dependent on the intense and complex interactions

with the variables which make up the mechanical portion of

variables, which are known as the three P’s:

� the powers (contractions),

� the passenger and the passage. The powers and its

companion the contraction work together to achieve

complete dilation, but without the continuation the

rotation through the birth canal……

� the passenger (fetus) will not be able to navigate the

passage (birth canal).

� Fundus—rounded upper

part superior to the

entrances of the uterine

tubes

� Body (corpus) —upper two

thirds

� Isthmus—narrower area just

above the cervix

� Cervix (neck) —cylindrical

inferior part that projects

into the superior vagina

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Uterine anatomy is comprised of three tissue layers

� The inner layer, called the endometrium, is the most active

layer and responds to cyclic ovarian hormone changes; the

endometrium is highly specialized and is essential to menstrual and

reproductive function

� The middle layer, or myometrium, makes up most of the

uterine volume and is the muscular layer, composed primarily of

smooth muscle cells (focus on today)

� The outer layer of the uterus, the serosa or perimetrium, is a

thin layer of tissue made of epithelial cells that envelop the uterus

How do these tissue layers work

together to form a contraction?

� An outer layer which runs

longitudinally and continues through

the fallopian tubes and round

ligaments,

� A vascular layer which consists of

coiled smooth muscle and blood

vessels

� Inner layer which comprises mainly

smooth muscle fibers arranged both

longitudinally and obliquely

Muscle Fibers

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Tissue Layers

� The top 2/3rd of the uterus (the body) has muscle fibers going different directions. The uterus and heart are smooth muscle cells.

� They are arranged in bundles of 10-15 cells in a matrix of connective tissue.

� This matrix transmits the forces of the contractions, and represents the propulsion behind the ever powerful uterine contraction.

Supported by Ligaments

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During labor the uterus is divided into two functional

segments: the upper and the lower.

� The upper segment or body of the uterus, contracts

strongly and with each successive contraction the smooth

muscle fibers become shorter and thicker. This powerful

segment draws passive lower part of the uterus up over

itself and causes the cervix to dialate.

� The lower uterine segment consists of the lower body of

the uterus and the cervix and although it can contract it is

relatively passive compared to the powerful forces of the

upper uterine segment.

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The cervix itself is not conducting any

contractions; it is reacting to them,

allowing the forces to do their job to pull

the uterus up over itself, slowly dilating the

cervix

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� Currently AWHONN and ACNM encourages the use of

physiologic bearing down versus sustained breath holding

during expulsive efforts.

“Physiologic bearing down (several short pushes

without breath holding), while resulting in a

slightly longer second stage, may result in

improved maternal/fetal gas exchange and

maternal satisfaction with her birth experience”.

(Varney, 2004)

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� The phase of active pushing is usually accompanied by a decline in fetal pH. By allowing an early phase of rest and fetal descent and delaying pushing until the woman has an urge to push only when obstetric conditions are optimal, the decline in fetal pH will be decreased

(Roberts, 2003).

� Traditionally a woman is encouraged to take one or two cleansing breaths at the start of the contraction and while the contraction is building. Then she is to take a deep breath and hold while she pushes for as long as she can. Two or three good pushes are usual during a contraction

Current issues in our labor and delivery practice

� Sustained breath holding combined with prolonged

bearing down may produce fetal hypoxia and acidosis due

to mother’s closed glottis and increased thoracic pressure.

� This combination results in a drop in arterial pressure

caused by decreased cardiac output due to diminished

fetal return to the heart.

� Decreased arterial pressure has 2 effects:

� 1. decreases blood flow to the placenta

� 2. decreases oxygen content in the blood which circulates

to the placenta

� Fetal hypoxia may be prevented if the woman is given different

pushing and breathing instructions. (Varney, 2004)

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ACNM and AWHONN: Open-glottis pushing-� The woman should be told to push simultaneously with a

forced exhalation for short periods of time, usually over 5-6 seconds

� Often accompanied by a grunt….remember the definition of GRIT, the verb or action….☺

� The glottis is at least partially opened, abdominal muscles are shortened and contracted against the uterus and

*Intrathoracic pressure does not increase to interfere with venous return*

� WHERE do labor units go from here? 1. The elephant in the room….

2. Continuation of doing something that all know is not beneficial, but remains habit

� WAYS to improve labor support and initial steps to moving away from directed pushing on your labor and delivery unit

1. Establish a provider and nurse champion on your unit

2. Educate by both information (physiology) and leadership

3. Be the example in the room, regardless of how uncomfortable….

� Cheng, Y.W., Shaffer, B.L., Nicholas, J.M., & Caughey, A.B. (2014). Second Stage of Labor and Epidural Use: A larger effect than previously suggested. American College ofObstetricians and Gynecologists,0, 1-9.

� Garfield, R., Maner, W. (2007). Physiology and electrical activity of uterine contractions. Seminars in Cell and Developmental Biology, 18(3), 289-295.

� Institute for Healthcare Improvement (IHI). (2010). IHI perinatal collaborative and the impact on patient safety. Powerpoint presentation retrieved on July 27, 2011 from: http://www.ihi.org/offerings/membershipsnetworks/collaboratives/perinatalimprovementcommunity/Pages/default.aspx

� Mayberry, L.J., Gennaro, S., Strange, L., Williams, M., De, A. Maternal fatigue: Implications of second stage of labor nursing care. JOGNN.1999; 28, 175-181

� Mayberry, L.j., Wood, S.H., Strange, L.B., Lee, L., Haisler, D., Neilsen-Smith, K. Managing second stage labor: Exploring the variables during the second stage. Lifelines AWHONN. 2000; 3(6), 28-34.

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� Maul, H.,Maner, W., Saade, G., Garfield, R.(2003). Physiology of uterine contractions. Clinics in Perinatology. 30(4):665-76

� Medscape. Uterine Anatomy. http://emedicine.medscape.com/article/1949215-overviewSaccessed September 26, 2015.

� Netter Anatomy. Pelvis and Perineum: Uterus, Vagina & Supporting

Structure. http://netteranatomy.com/anatomylab/subregions.cfm?subregionID=R55 accessed September 26, 2015.

� Oxorn, H., & Foote, W. R. (1986). Oxorn-Foote Human labor & birth. 5th ed. Norwalk, Conn: Appleton-Century-Crofts

� Posner, G., Dy, J, Black, A., Jones, G. (2013). Oxorn-Foote Human

labor & birth. 6th ed. McGraw Hill Companies.

� Piquard, R., Schaefer, A., Hsiung, R., Dellenbach, P., & Haberey, P. (1989). Are there two biological parts in the second stage of labor? Acta Obstetricia et Gynecologica Scandinavica, 68(8), 713-718

� Rouse, D.W., Weiner, S.J., Bloom, S.L, Varner, M.W., Spong, C.Y., Ramin, S.,et al (2009). Second-stage labor duration in nulliparous women: Relationship to maternal and perinatal outcomes. American Journal of Obstetrics & Gynecology, 357, e1-e7.

� Roberts, J.E., & Hanson, L. (2007). Best practices in second stage labor care: Maternal bearing down and positioning. Journal of Nurse Midwifery and Women’s Health, 52 (3), 238-245.

� Spong, C.Y., Berghella, V., Wenstrom, K.D., Mercer, B.M, & Saade, G.R. (2012). Preventing the first cesarean delivery: Summary of a Joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, and American College of Obstetricians and Gynecologists Workshop. American College of Obstetrician and Gynecologists, 120 (5), 1181-1193.

� Zhang J, Landy HJ, Branch DW, Burkman R, Haberman S, Gregory KD, Hatjis CG, Ramirez MM, Bailit JL, Gonzalez-Quintero VH, Hibbard JU, Hoffman MK, Kominiarek M, Learman LA, Van Veldhuisen P, Troendle J, Reddy UM; Contemporary patterns of spontaneous labor with normal neonatal outcomes Consortium on Safe Labor. Obstet Gynecol. 2010 Dec;116 (6):1281-7. doi: 10.1097/AOG.0b013e3181fdef6e.

� Wood, Carl. (1964). Physiology of uterine contractions. BJOG. 71(3).360-373