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EndoRepro 2 Exam 1 > Clin: Dysfunctional Labor, Uterine Contractility and Dystocia - Moulton > Flashcards

Clin: Dysfunctional Labor, Uterine Contractility and Dystocia - Moulton Flashcards

1
Q

what triggers an enzymatic process that results in the formation of the actin-myosin element in the uterus?

A

billions of smooth muscle cells form contractile units

- when intracellular ionic calcium concentration increases it triggers the formation of actin-myosin elements

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2
Q

stimulation of oxytocin receptors on the plasma membrane does what?

A

further activates the actin-myosin element

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3
Q

where do contractions occur?

A

in localized areas during gestation, but during labor the entire uterus contracts in an organized fashion

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4
Q

coordinated smooth muscle cell contractions are secondary to what?

A

gap junctions that activate the movement of action potentials throughout the myometrium

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5
Q

what maintains relaxation?

A

factors that increase cAMP

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6
Q

what causes contraction?

A

increase of intracellular calcium stores

- promote interaction of actin and myosin causing uterine contractions

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7
Q

what are the two distinct segments of the uterus that are formed during labor?

A
  1. the upper segment: actively contracts and retracts to expel the fetus
  2. the lower segment along with the cervix: becomes thinner and passive
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8
Q

what physiologic changes are seen in the cervix during labor?

A

it changes from a firm, in-tact sphincter to soft, pliable, dilatable structure
- these changes are the result of collagenolysis, increase in hyaluronic acid, decrease in dermatan sulfate, which favors water content

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9
Q

the presence of regular uterine contractions of sufficient intensity, frequency and duration to bring about demonstrable effacement and dilation of the cervix

A

labor

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10
Q

onset of contractions to full dilation

A

first stage

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11
Q

full dilation of cervix to delivery of the infant

A

second stage

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12
Q

delivery of infant to delivery or placenta

A

third stage

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13
Q

cervical softening effacement occurs with minimal dilation (<6cm)

A

latent phase

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14
Q

this phase starts when cervix is dilated to 6cm

  • includes both cervical dilation and ultimately, descent of the presenting fetal part
  • acceleration phase, also deceleration phase
A

active phase

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15
Q

protraction

A

when contraction is slower than normal rate

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16
Q

arrest

A

complete cessation of progress (no further dilation or decent)

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17
Q

what does an arrested latent phase imply?

A

labor has not begun

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18
Q

what are the normal limits of the latent phase?

A

nuliparous: up to 20hs

mulitparous up to 14 hrs

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19
Q

what is the tx of the latent phase?

A
  • terapeutic rest
  • can give pt relief air between true and false labor
  • morhphine -> 62-85% of pts will progress to active phase
  • 10-29% will stop having contractions and diagnosis of false labor can be made
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20
Q

what are the normal limits of cervical dilation in the active phase?

A

nulliparous: cervical dilation 1.2cm/hr
multiparous: cervical dilation of 1.5cm/hr

NOTE: cervical dilation LESS than normal = protraction disorder of dilation of active
- if 2+ hours elapse with NO cervical dilation = arrest of dilation

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21
Q

what are the normal limits of fetal descent?

A

nulliparous: 1cm/hr
multiparous: 2cm/hr

NOTE: fetal descent LESS than normal = protraction of descent of active phase
- if no change in descent/station has occurred within 1hr, arrest of descent has occurred

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22
Q

“difficult labor”, results from abnormalities of the 3 P’s:

A
  1. power (uterine contractions or maternal expulsive0
  2. passenger (position, size, or presentation of fetus)
  3. passage (maternal pelvic bone contractures)
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23
Q

the dx of dystocia should NOT be made before what?

A

adequate trial of labor has been tried

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24
Q

stimulation of uterine contraction when spontaneous contractions have failure to result in progressive cervical dilation or descent of the fetus

A

augmentation

- **consider augmenting if contractions are less than 3/1 minutes

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25
Q

ACOOG recommends oxytocin in protraction and arrest disorders after assessing what?

A
  • maternal pelvis
  • fetal position
  • station
  • maternal and fetal status
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26
Q

what are the benefits of AROM?

A

augment labor, allows assessment of meconium status

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27
Q

what are the risks of AROM?

A

cord prolapse, prolonged rupture associated with chorioanmionitis

28
Q

3 contractions in a 10 minute period averaging 25mmHg above baseline

A

minimal effective uterine activity

29
Q

calculated by measuring the peaks of contractions in mmHg in a 10 min period

A 
montevideo units (MVU)
>200MVU for at least 2 hours
- before proceeding to cesarean section, should document adequate contractions at least 4 hours
30
Q

what is the only FDA approved medicine for labor augmentation

A

pitocin

- 80% of pts with documented disorder of labor will respond to oxytocin with progression of labor and vaginal delivery

31
Q

what is the MOA of pitocin?

A

stimulates uterine contractions

  • increases intracellular calcium -> results in increase in actin and myosin activity
  • sensitivity of the uterus to oxytocin increases between 20-40 gestational weeks
32
Q

labor induction?!

A

MISOPROSTOL

33
Q

labor augmentation?!

A

PITOCIN

34
Q

how much time is needed for full effect of pitocin to be evident in a contraction pattern?

A

20-30 mins

35
Q

refers to a disparity between the size of maternal pelvis and the fetal head that precludes vaginal delivery

  • causes a failure of descent and sometimes engagement of the head
  • nulliparous women who present in labor with an unengaged head indicates an increased likelihood of this
A

cephalopelvic disproportion (CPD)

36
Q

which pelvic shapes have a good prognosis for delivery?

A

gynecoid and anthropoid

  • pubic arch >90
  • ischial tuberosity >8.5cm
  • diagonal conjugate >11.5cm
  • prominence of ischial spines
37
Q

what position does the fetal head usually enter and engage the maternal pelvis?

A

occipitotransverse (OT) position

- then rotates to OA or OP

38
Q

what can cause shoulder dystocia?

A

abnormalities of the fetal structure

  • macrosomia
  • fetal anomalies
39
Q

this occurs when the head fails to rotate and flex into the OA position
- may be caused by CPD, altered pelvic architecture (android or platypelloid pelvis), or relaxed pelvic floor (epidural)

A

persistent occipitotransverse (OT) position

40
Q

OT with arrest of descent for 1 hr or more is know as what?

A

transverse arrest of descent
- arrest occurs because of the deflexion that occurs with persistent OT position the occipital diameter (11cm) becomes the presenting diameter (seen commonly at +1 - +2 stations

41
Q

what is the management of persistent OT if:

  • pelvis is adequate
  • infant is not macrosomic
  • contractions are inadequate
A
  • start pitocin

- rotate: manually or with forceps

42
Q

how do you manage an OT position if pelvis is inadequate or infant is deemed macrosomic?

A

cesarean is indicated

43
Q

even if the head rotates to OP initially, the majority will eventually rotate to what position?

A

OA spontaneously

  • only 5-15% will stay OP
  • course of labor in OP is usually normal (second stage may be prolonged, associated with more back pain for mom)
44
Q

fetus weighing > 4500g

A

macrosomia

45
Q

birth weight equal to or greater than 90% for a given gestational age

A

large for gestational age (LGA)

  • 37 wks: 90% = 3,755g
  • 40 wks: 90% = 4,060g
  • 42 wks: 90% = 4,098g
46
Q

is diagnosis of fetal macrosmia with ultrasound precise?

A

NO!

47
Q

what can be seen by ultrasound, and makes vaginal delivery impossible?

A

hydrocephalus

48
Q

what can result in dystocia secondary to enlarged fetal abdomen?

A

fetal ascites or enlargement of fetal organs (liver)

  • immune hydrops (Rh isoimmunization) most common
  • nonimmune hydrops caused by congenital infections, chromosomal abnormalities or fetal arrhythmias
49
Q

what are locked twins?

A

baby A breech, baby B vertex

50
Q

what are the 3 P’s??

A
  • power
  • passage
  • passenger
51
Q

what are the risk factors for macrosomia?

A
  • maternal diabetes
  • previous history of macrosomia
  • maternal pre-pregnancy obesity
  • weight gain during pregnancy
  • multiparity
  • gestational age >40
  • maternal birth weight
  • maternal age <17 years old
  • +50g glucose screen with a negative result on 3hr
52
Q

what are risk factors for fetal morbidity/mortality associated with macrosomia?

A
  • shoulder dystocia
  • fracture of clavicle
  • damage to brachial plexus

NOTE: risk of brachial plexus injuries among vaginal deliveries increase 21x when birth weight > 4500g

53
Q

upper arm palsy

  • most common brachial plexus injury
  • caused by injury to C5-6
A

Erb-Duschenne palsy

54
Q

lower arm palsy

- caused by damage to C8 and T1

A

Klumpke palsy

55
Q

what will damage to all 4 nerve roots cause?

A

paralysis of entire arm

56
Q

ACOG recommends prophylactic cesarean for estimated fetal weight of what?

A

> 5000g in non diabetic pt

>4500g in diabetic pt

57
Q

retraction of delivered fetal head against the maternal perineum

A

turtle sign

58
Q

what are the antepartum risk factors for shoulder dystocia?

A
  • fetal macrosomia
  • maternad diabetes
  • obesity
  • post term gestation
  • short stature
  • previous hx of macrosomic birth
  • previous hx of shoulder dystocia
59
Q

what are the risk factors for should dystocia during labor?

A
  • labor induction
  • epidural analgesia
  • prolonged labor
  • operative vaginal deliveries
60
Q

what are the neonatal risks associated with shoulder dystocia?

A
  • brachial plexus injuries (less than 10% result in permanent disability)
  • fractured clavicle or humerus
  • hypoxic-ischemic encephalopathy
  • death
61
Q

hyperflexion and abduction of the maternal hips

A

McRobert’s maneuver

62
Q

putting pressure where, may dislodge the impacted anterior should?

A

suprapubic pressure

- do NOT apply fundal pressure

63
Q

cephalic replacement

  • last resort
  • poor prognosis, significant risk of fetal morbidity/mortality
A

Zavanelli maneuver

  • fetal head is manually returned to it’s prerestitution position
  • slowly replaced in the vagina by steady upward pressure
  • delivery is by emergent c-section
64
Q

place pressure on an accessible shoulder to push it toward the anterior chest wall of the fetus to decrease the bisacrominal diameter and free the impacted shoulder

A

Rubin maneuver

65
Q

apply pressure behind the posterior (free) shoulder to rotate the infant and dislodge the anterior shoulder

A

Wood’s corkscrew maneuver

66
Q

obstetric emergency

  • call for help! (anesthesia, NICU)
  • can not be predicted or prevented and most occur in the absence of macrosomia
A

shoulder dystocia

67
Q

what are the initial maneuvers for shoulder dystocia?

A

McRobert’s and suprapubic pressure

EndoRepro 2 Exam 1 (25 decks)

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