Parturition Physiology and Mechanism: Phases of Parturition Flashcards
(98 cards)
0
Q
Activation makes up how much of parturition?
A
<5%
1
Q
Quiescence makes up how much of parturition?
A
95%
2
Q
Stimulation makes up how much of parturition?
A
.2%
3
Q
Which phase involves the “softening cervix”?
A
Quiescence
4
Q
Which phase involves the “ripening cervix”?
A
Activation
5
Q
Three stages of labor under Stimulation phase of parturition
A
uterine contraction, cervical dilation, fetal and placental expulsion
6
Q
Phase of parturition involving uterine involution, cervical repair, and breastfeeding
A
Involution
7
Q
What are synthesized during parturition?
A
Factors inducing parturition (self-explanatory)
8
Q
What happens to pregnancy maintaining factors during parturition?
A
They are lost
10
Q
True or False: During quiescence, cAMP levels are low.
A
False. Low cAMP levels induce labor contractions. High cAMP levels promote relaxation.
10
Q
The duration in which quiescence is maintained
A
Implantation until late in gestation
11
Q
Final product of quiescence (induces relaxation)
A
cGMP
13
Q
3 Functions of the cervix during pregnancy
A
- Maintenance of barrier function
- Maintenance of cervical competence
- Orchestrates extracellular matrix changes
14
Q
The barrier of the cervix from infection during pregnancy
A
Mucus Plug
14
Q
True or False: ECM structural changes are slow and progressive
A
True
15
Q
Changes in the cervix during pregnancy
A
- Increase in vascularity
- Stromal hypertrophy
- Glandular hypertrophy and hyperplasia
- ECM structural changes
These changes begin weeks or days before the onset of contractions
17
Q
In animal models, what are the changes in the cervix?
A
Collagen solubility, DECREASE in lysyl oxidase activity
17
Q
Why are there more instances of preterm labor in twins?
A
Due to uterine stretch limit. Once the uterus reaches its stretch limit, contractions begin.
18
Q
True or False: Non-classic progesterone withdrawal involves a decrease in progesterone secretion
A
False. It involves a decrease in progesterone EFFECTS, not necessarily the secreted amount.
19
Q
What about the nuclear progesterone receptor changes during Phase 2 of parturition?
A
Expression
20
Q
What happens to dermatan sulfate when cervical changes occur in ripening?
A
decrease, thus decreasing cross-linking of collagen fibers
22
Q
What happens to dermatan sulfate when cervical changes occur in ripening?
A
Decrease, thus decreasing cross-linking of collagen fibers
22
Q
Signs of uterine awakening or activation
A
Cervical ripening, increased frequency of Braxton-Hicks contractions, lower uterine segment development, myometrial irritability
23
Q
What happens to hyaluronic acid when cervical changes occur in ripening?
A
Promotes the increase of water retention
24
2 Changes of cervical ripening
1. Rearrangement of collagen fibers
| 2. Alterations in the relative amounts of the various GAGs
26
When does the uterine myometrial lining change to prepare for delivery?
Last 6-8 weeks of pregnancy, or 8th month of gestation
26
A gap junction protein that increases between myometrial cells when transitioning to contractile state
connexin 43
27
Contraction-associated proteins (CAPs) responsible for the shift from Braxton-Hicks (painless, irregular contractions) to more painful, frequent contractions.
Oxytocin receptor, prostaglandin F receptor, and connexin 43
29
What happens to uterine irritability and responsiveness to uterotonins during the transition to contractile state
Increases. Everything increases, actually- oxytocin receptors at the myometrium, connexin 43 between myometrial cells included.
30
What change in the uterus occurs to facilitate Lightening?
The development of the lower uterine segment.
31
When does the fundic height cease being a reliable measurement for AOG? This is due to what phenomenon?
32 weeks. Lightening
32
3 Stages of Labor (Phase 3)
1) Uterine Contractions and Cervical dilatation
2) Descent and Delivery of the Fetus
3) Placental delivery
33
2 Stages of contractions, cervical dilatations and effacement
Active and Latent
33
By how much should the cervix be dilated to be considered ready for delivery?
10 cm
34
The "active stage" of contractions, dilatations, and effacement consists of what substages?
Acceleration, Point of Maximum Slope, Deceleration
36
Fresh blood expelled from the vagina during labor contractions may be indicative of what condition?
Placenta Previa
37
The water component that is expelled during labor contractions may consist of all or any of the ff
Leukorrhea, Urine, Amniotic Fluid
38
Unremitting contractions compromising uteroplacental blood flow may cause what condition to the fetus?
Fetal Hypoxemia. Periodic contractions are needed not just to help mother bear the pain, but also for the fetus to breathe properly throughout the duration of labor.
39
The mechanical stretching of the cervix enhancing uterine activity
Ferguson's Reflex
39
True or false: the lower uterine segment is the active part of the uterus during labor and works to push the fetus out
False. The upper uterine segment is the active one. The lower uterine segment is passive and allows for accommodation of the baby's head
41
True or False: The lower uterine segment is the active part of the uterus during labor and works to push the fetus out
False. The upper uterine segment is the active one. It contracts and retracts to expel fetus. The lower uterine segment is passive and allows for accommodation of the baby's head.
42
Does the myometrium of the upper uterine segment relax between contractions?
No. It only becomes shorter and thicker, and is relatively fixed that way.
43
True or False: The upper segment retracts only to the extent that the lower segment distends and the cervix dilates.
True
43
What ring is seen in the extremely thinned out lower uterine segment?
Ring of Bandl
44
What happens to the lower uterine fibers as the labor progresses?
Lengthens and thins
45
Why does the uterus shorten and thicken (retract in general)?
Why the hell would it go back to pregnant state when it doesn't have a baby anymore? It HAS to!
47
Where is uterine retraction dependent on?
The DECREASE in VOLUME of the uterus.
48
What happens to the muscle tone of upper uterine segment contraction during labor?
Unchanged
49
What happens to fetal axis pressure during labor uterine contractions?
It increases
50
What happens to the fetal vertebral column as the uterus undergoes changes during labor contractions?
It straightens
50
For how long should pushing be done?
10 counts
51
Which pole of the fetal vertebral column is pressed agains the fundus?
Upper Pole
53
What happens to the birth canal during cervical effacement?
Shorten from 2 cm to a ring-like orifice with paper-thin edges
54
What characterizes cervical effacement?
Obliteration or "taking up" of the cervix, expulsion of mucus plug
54
When does cervical effacement occur in nulligravids?
Before dilatation
55
True or False: The muscular fibers at about the level of the external cervical os are
pulled upward, or “taken up” into the lower uterine segment during cervical effacement
False. This occurs at the level of the internal os.
56
When does cervical effacement occur in multigravids?
May be in full dilatation but effacement only takes up about 50%
58
Before labor, dilatation of both ext and int os prior to effacement occurs in which?
a. Primigravid
b. Multipara
b. Multipara
59
Complete effacement: Dilatation is minimal
a. Primigravid
b. Multipara
a. Primigravid
60
During effacement: dilatation and funneling of internal os
a. Primigravid
b. Multipara
b. Multipara
61
When does the first stage of Phase 3 end?
When cervical dilatation is complete (bec. the 1st Stage of Phase 3 of Labor only consists of Cervical Dilatation)
62
When does the Second stage of Phase 3 end?
Vaginal expulsion of the fetus
63
What kind of curve is formed when the station of the fetal
| head is plotted as a function of labor duration?
Hyperbolic Curve
64
In nulliparas, when are increased rates of descent (during 2nd Stage of Phase 3) observed?
During cervical dilatation phase of maximal slope. This is maintained until the presenting part reaches the perineal floor
65
The three functional divisions of the labor curve and the fetal descent curve
1) Preparatory
2) Dilatational
3) Pelvic
66
The functional division including the Latent and Acceleration phases
Preparatory
67
The functional division encompassing the Deceleration and the Phase of Maximum Slope of fetal descent
Pelvic
67
Phases of placental expulsion
1. Decrease in uterine size
2. Decrease in area of placental implantation
3. Hematoma formation
4. Cleavage of decidua spongiosa
68
What happens during the third stage of labor?
Expulsion of fetus, placenta, and fetal contents; aka Stage of placental separation and expulsion
70
True or false: The hematoma that forms during placental expulsion is the cause of the separation of the placenta and the decidua spongiosa
False. Hematoma is usually the RESULT, rather than the cause of separation. In some cases, the hematoma is negligible. However, the hematoma may accelerate cleavage
70
During the amnio-chorion separation, what undergoes contraction, which undergoes traction?
myometrium : contraction :: separated placenta: traction
71
2 actions that permit the separation of the amnio-chorion part
Contraction and Traction
72
True or false: The regulation of the phases of parturition is multifactorial
True
73
The amnion-chorion separation is due to what?
Due to a decrease in the surface area of the uterine cavity causing the fetal membranes – the AMNIOCHORION and DECIDUAS PARIETALIS – to be thrown into several folds
74
What can be done to an incompetent cervix to prevent spontaneous abortion?
It may be tied up
75
During quiescence, as the uterus expands, what happens to the cervix?
It contracts or stays firm
76
During Braxton-Hicks contractions, where is the discomfort localized?
Lower abdomen and groin
77
The maintenance of cervical competence can be likened to what?
An expanding balloon (uterus) and its blow hole (cervix). The more it expands, the easier it is to expel air (the baby/fetus) but the cervix will keep it closed
78
What happens during the "orchestration of ECM changes" during cervical softening?
Progressive increases in tissue compliance
79
True or False: Modifications of Progestin Receptors in Phase 2: Preparation for Labor are posttranscriptional
False. The changes are POST-TRANSLATIONAL
80
How is progesterone inactivated during Phase 2: Preparation for Labor?
Locally, by steroid-metabolizing enzymes, or via synthesis of natural antagonists
81
What do you ask the patient regarding contractions to determine whether these are False or True?
Interval, duration, intensity, frequency, localization
82
Increased activation of G-protein-coupled receptors cause ________
Inhibition of cAMP formation
83
When does the inhibition of cAMP formation occur among the phases of parturition?
3rd Stage: Labor
84
What happens to Phase 1 and Phase 2 according to the Uterotonin Theory of Labor Initiation?
Phase 1 is suspended and Phase 2 is implemented
85
Hormone suspected to cause Ferguson's Reflex
oxytocin
86
Uterine area with the greatest contraction during labor
Fundus
87
True or False: The Ring of Bandl is a physiological retraction ring.
False. It is a PATHOLOGICAL retraction ring, found commonly in cases of obstructed labor
88
True or False: The horizontal diameter is increased during uterine contractions
False. Fetal axis pressure is increased during uterine contractions and for this to happen, the horizontal diameter must be decreased.
89
Medical term for "pushing"/ "pag-irê" during labor
Ancillary Forces
90
When should you ask the patient to push during labor?
Only when contractions are present. Otherwise, the patient will get tired easily.
91
True or False: Pushing is more effective if the mouth is kept closed.
True
92
True or False: A centrifugal pull exerted on the cervix allows it to distend/dilate
True. This is due to the LOW resistance of lower uterine segment and the cervix
93
True or False: In nulliparas, engagement of the fetal head is accomplished during labor
False. Engagement of the fetal head occurs BEFORE labor, causing it to descend further late in labor already.
94
Repair processes of placental expulsion serves what purposes?
Resolve inflammatory responses and remove GAGs, proteoglycans, and structurally-compromised collagen
95
What are synthesized in the dense connective tissue to restore the structural integrity of the cervix?
Matrix and collagen
96
Involution of the uterus and cervical repair at Puerperium occurs at?
4-6 weeks
97
"Doc, liliit pa ba tiyan ko?" - Patient
Yes, within 4-6 weeks, ESPECIALLY if you're breastfeeding. :)
