1) estrogen 2) prostaglandins - stimulate upregulation of myometrial receptors for oxytocin and prostaglandins - activate gap junctions b/w myometrial cells

First Stage of Labor Flashcards by Dorothy Cam

Define labor

regular, painful contractions that promote cervical change

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Phase 1

quiescence = prelude to parturition.

Contractile unresponsiveness; cervical softening

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What inhibits uterine contractions?

1) progesterone
2) prostacyclin
3) relaxin
4) nitric oxide
5) parathyroid hormone-related peptide
6) corticotropin-releasing placental lactogen

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Phase 2

activation = preparation for labor

uterine preparedness for labor; cervical ripening

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Define uterotropins

1) estrogen
2) prostaglandins

stimulate upregulation of myometrial receptors for oxytocin and prostaglandins
activate gap junctions b/w myometrial cells

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Phase 3

stimulation = processes of labor

uterine contraction; cervical dilation; fetal and placental expulsion

includes 3 stages of labor

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Define uterotonins

promote labor progression

1) prostaglandins
2) oxytocin

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Phase 4

involution = parturient recovery

uterine involution; cervical repair; breastfeeding

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What promotes involution?

1) oxytocin
2) thrombin
3) prostaglandin

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1st clinical stage of labor

begins w/ true labor contractions –> ends with full dilation; comprised of 2 phases

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What are the 2 phases of the first stage of clinical labor?

1) latent: contractions become more regular, painful, and frequent BUT little cervical dilation w/ little to no fetal descent
2) active: cervical dilation to completion

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Describe receptor changes that stimulate labor

progesterone binds more readily to PR-A (vs PR-B) –> quiescence ceases
estrogen stimulates expression of prostaglandin and oxytocin receptors
myometrial cells develop gap junctions that facilitate direct communication b/w muscle fibers

–> uterine contractions

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Goodell’s sign

cervical softening ~4wks after LMP

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Chadwick’s sign

increased cervical vascularity ~6wks after LMP (cervix and vaginal walls appear blue)

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cervical ripening

rearrangement of collagen prior to and during labor –> become less dense

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What are the 4 phases of cervical remodeling?

1) softening
2) ripening
3) dilation
4) postpartum repair

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effacement

lengthening of muscle fibers at internal os –> stretches endocervix upward into lower uterine segment

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dilation

widening of external os

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What promotes dilation?

1) force of contractions
2) hydrostatic action of amniotic fluid
3) pressure of presenting part if ROM

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What does passing of mucuos plug indicate?

likely labor w/in 48h

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Describe internal rotation

OT/LOA/ROA –> direct OA

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How long is the latent phase of the 1st clinical stage of labor?

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<20h

What is considered prolonged latent phase?

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nullips: >20h
multips: >14h

How dilated are people at the beginning of the active phase?

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nullip: ~4cm
multip: ~5cm

How long does the active phase last?

nullip: ~4.4-4.9h w/ 1.2cm dilation/h multip: ~2.2-2.4h w/ 1.5cm dilation/h

What are the 3 subphases of the active phase?

1) acceleration: little progress in dilation 2) maximum slope: 3.0cm/h (nullip); 5.7cm/h (multip) 3) deceleration: occurs b/w 8-10cm

How else may labor progression be identified beyond a cervical exam?

- fetal station and position - maternal behavior - contraction pattern - s/sx of transition into second stage of labor - change of location of back pain - change in location of maximum intensity of FHT - change in position of FHT

Define transition

change from first to second stage of labor; occurs typically b/w 8-10cm dilation

s/sx of transition

- lull in frequency/intensity of contractions - presenting part induces maternal urge to bear down - FHT progressively lower on maternal abdomen - rectal/perineal bulging - progressive visibility of fetal head at introitus - increase in bloody show

premature rupture of membranes (PROM)

occurs >1h before onset of labor

preterm premature rupture of membranes (PPROM)

PROM before 37wks GA

artificial rupture of membranes (AROM)

AKA amniotomy provider induced ROM

What is criteria for AROM?

1) cephalic presentation | 2) engagement in pelvis (0 or +1 station)

What are risks associated w/ AROM?

- cord compression --> FHT deceleration - cord prolapse - maternal discomfort - increased risk infection - rupture of fetal vessels (RARE)

What is ACOG criteria for labor dystocia?

1) active labor (>/= 6cm) 2) adequate contractions (>/=200 Montevideo units) 3) ROM for at least 4h

What is the effect of labor on gastric emptying time?

prolonged, especially after administration of analgesics

When is fasting recommended?

6-8h before elective C/S or puerperal tubal ligation

How is the risk of gastric content aspiration mitigated?

- clear fluids b/w normal pushing; no solids - antacids given routinely - prepped for intubation w/ cricoid pressure - employ regional anesthesia (vs general) when possible

When are antacids indicated during labor?

before general anesthesia (w/in 1h - give second dose if >1h and anesthesia not yet induced)

What is an example dose of antacids?

Bicitra (sodium citrate + citric acid) 30mL PO others: nonparticulate antacid; H2-receptor antagonist; metoclopramide

What are indications for IVs during labor?

- potential or actual risk factors - cannot tolerate PO fluids - administration of rx (eg abx prophylaxis, analgesics, oxytocin) prior to epidural

What is a recommended IV administration?

isotonic fluids 125-250mL/h

What are indications for measuring I/Os?

- IV fluid administration - pre-eclampsia/on magnesium = STRICT I/Os! - concern for pt hydration status (eg dehydration, hyperemesis) - post-C/S - during active labor

How often should pt empty bladder during active labor?

q2h

What effect does a distended bladder have on first stage of labor?

- blocks fetal head from descending | - increases lower abdominal pain

What effect does a distended bladder have on second stage of labor?

inhibits contractility of uterine contractions

What effect does a distended bladder have on postpartum state?

- can increase PPH d/t uterine atony | - bladder hypotonicity, stasis, infection risk

What is the effect of labor on WBC count?

peaks --> 20x10^3/mm^3

What is the effect of labor on BP?

increases during contractions; returns to baseline in b/w

What is the effect of labor on cardiac output?

- increases by 10-15% in first stage | - increases up to 50% during second stage d/t increased stroke volume

How often should vitals be checked during labor?

BP, HR, RR: q1h | T: q2-4h w/ membranes intact; q1-2h if abnormal T or ROM

hypotonic uterus

- slow/stalled labor progress d/t acute stress (eg fatigue, pain) - R/O malpresentation and CPD

hypertonic uterus

- series of contractions each lasting >2mins OR - contraction frequency of 5 or more in 10 mins

First Stage of Labor Flashcards

(53 cards)