Ob flash cards 20160824
(158 cards)
1
Q
What precursors does the placenta use to produce progesterone, and where do these come from?
What about for estrogen?
A
Progesterone precursor: Maternal cholesterol
Estrogen precursor: DHEA produced by fetal adrenal cortex (inner/fetal zone)
(So fetal development makes more estrogen precursors available)
(Fetus cannot convert progesterone to estrogen due to lack of 17alpha-hydroxylase)
2
Q
What maneuver can be used to prevent anal sphincter tears?
A
Modified Ritgen maneuver: finger in anus lifts up fetal chin
3
Q
What is commonly found on cardiac exam in pregnancy?
A
Systolic ejection murmur, S3 gallop, increased S2 splitting
4
Q
What category is recurrent late FHR decels associated with?
A
Category 2 unless accompanied by absent FHR variability, in which case is Category 3
5
Q
How is arrest in active phase of stage 1 defined?
A
StepUp: No cervical change for 2 hours
However, ACOG defines a longer threshold for indicating possible C-section:
No cervical change for 4 hours despite adequate contractions
OR
No cervical change for 6 hours with inadequate contractions managed with oxytocin
6
Q
How are Montevideo units calculated? What should the value be with optimal contractions?
A
Sum of contraction amplitudes of all contractions in 10 minutes (in mm Hg, from IUPC).
Should be >200 MVU
7
Q
What previous C-sections allow for TOLAC? CI TOLAC?
A
Allowed: One previous low transverce CSX
CI: Vertical or T-shaped incision, multiple CSX
8
Q
What is uterine massage used to treat?
A
Uterine atony in stage 3
9
Q
What are the implications of arrested or protracted 2nd stage of labor?
A
Does not require C-section unless fetal heart rhythm non-reasusring or cephalopelvic disproportion (CPD) has not been ruled out.
10
Q
How is Circulation managed during additional resuscitation in the immediate neonatal period?
A
If HR
11
Q
What category is variable FHR decelerations with shoulders associated with?
A
Category 2
12
Q
What is Chadwick’s sign?
A
Bluish discoloration of labia, vagina, and cervix.
From 8-10 weeks’ gestation
13
Q
How often should the FHR be evaluated in 1st and 2nd stages of labor, with and without risk factors?
A
1st stage: every 30 min w/o risk factors, every 15 min w/ risk factors
2nd stage: every 15 min w/o risk factors, every 5 min w/ risk factors
14
Q
How is a variable deceleration defined, in terms of:
1. Time to peak
2. Minimal amplitude
3. Duration
4. Association with contractions
A
- Time to peak within 30 s
- Amplitude: 15 bpm or more
- Duration: 15 s or more, 2 minutes or less.
(Sort of the opposite of an accel)
15
Q
What are the frequency and intensity of “optimal” contractions?
A
Frequency: 3-5/min
Intensity: 50-60 mm Hg by IUPC
(At least 200 MVU)
16
Q
When is fetal heart activity detected by electronic Doppler by?
A
12 weeks
17
Q
What triggers increased flexibility of the pubic symphosis during pregnancy?
A
Relaxin (produced by placenta0=)
18
Q
What nerve roots carry pain signals in 1st and 2nd stages of labor?
A
1st: T10-L1 visceral (contraction and dilation pain)
2nd stage: S2-S4 somatic (Pudendal n.)
19
Q
What are early signs of pregnancy on physical exam?
A
Cervix softens (Goodell’s sign) - 4 weeks’ gestation
Uterus sogtens and seems to be separate from cervix (Hegar’s sign) - 4-6 weeks’ gestation
Bluish discoloration of labia, vagina and cervix (Chadwick’s sign) - 8-10 weeks’ gestation
20
Q
What is normal pCO2 and bicarb on maternal ABG in late pregnancy?
A
pCO2: 25-33 (decreased)
Bicarb: 16-22 mEq/L (decreased)
21
Q
Where is corticotropin-releasing hormone (CRH) produced?
A
Placenta (as well as maternal hypothalamus)
22
Q
What is the path of blood from the umbilical vein to the IVC in the fetus?
A
50% goes via ductus venosus directly into IVC.
50% goes through portal veins, through liver, then hepatic veins, then to IVC.
23
Q
How long of a time period do you need to use to assess baseline FHR?
A
10 minutes
24
Q
What can meconium aspiration be an indicator of?
A
Fetal distress
25
What hormone induces maternal insulin resistance to make glucose available to the fetus?
Human Placental Lactogen (HPL)
26
What are the most common causes of overestimation of fetal descent?
Caput succedaneum (scalp edema) and molding of the skull
27
What stimulates increasing cortisol levels late in pregnancy? What opposes it?
Positive feedback loop:
Placental CRH stimulates fetal ACTH, which stimulates fetal cortisol production, which stimulates placental CRH production.
Progesterone suppresses placental CRH
28
What category tracing is absent baseline FHR variability associated with?
Category 3 is also have bradycardia or recurrent late or variable decels
Category 2 otherwise.
29
How is fetal station scored for the Bishop score?
0: -3 (-5 cm)
1: -2 or -1 (-4 to -1 cm)
2: 0
3: +1 or more (+1 cm or more)
30
How often should prenatal visits occur during uncomplicated pregnancies?
Every 4 weeks in first and second trimesters (until 28 weeks)
Then every 2-3 weeks until 36 weeks
Then every week until delivery
31
What category is recurrent FHR accels associated with?
May or may not be seen in category 1
32
What is the normal umbilical artery pH, PCO2, and bicarb?
pH 7.25-7.30
PCO2: 50 mm Hg
Bicarb: 25 mEq/L
33
How do Braxton-Hicks contractions and true labor contractions differ with respect to exercise?
Braxton-Hicks contractions: much less noticeable with exercise
True labor contractions: equally noticeable with exercise
34
What is a fetal biophysical profile (BPP) used for?
To guide whether or not to induce labor
35
When is the pregnant uterus usually palpable at the pubic symphosis?
12 weeks
36
What is the implication of a FHR acceleration?
Reassuring. FHR able to respond to stress of uterine contraction.
37
When is fetal biometry performed? What 4 things are measured?
18-20 week ultrasound in 2nd trimester.
Measure:
1. Biparietal diameter (BPD)
2. Head circumfrence (HC)
3. Abdominal circumference (AC)
4. Femur length (FL)
38
What medication is used to induce labor with a favorable Bishop score?
IV Pitocin
(Amniotomy may also be used)
39
What effects do estrogen and progesterone have on the breast?
Estrogen stimulates ductal growth
Progesterone stimulates alveolar hypertrophy
40
What medications are used to treat uterine atony (5)?
Uterotonics include:
1. Pitocin / oxytocin
2. Carboprost (hemabate): PF2alpha analog
3. Misoprostol (cytotec): PE1 analog
4. Methylergonovine (methergine)
5. Ergonovine
41
What neurologic complication can result from fetal ischemia around birth? How does it present?
Hypoxic-Ischemic Encephalopathy (HIE)
Presentation: difficulty breathing, depressed tone, abnormal level of conciousness, and/or seizures
42
How is a FHR acceleration defined, in terms of:
1. Time to peak
2. Minimal amplitude
3. Duration
1. Time to peak within 30 s
2. Amplitude: 15 bpm or more, OR if
43
How are maternal renin and angiotensin changed in pregnancy?
Greatly increased - renin by 10x, angiotensin by 5x
44
What is the maximum Bishop score?
13
45
Indications for first C-section (6)?
1. Placenta previa
2. Placental abruption
3. Umbilical cord prolapse
4. Labor arrest
5. Nonreassuring fetal status
6. Breech position
46
What fetal maneuvers can be used to dislodge fetal shoulder during fetal distocia? (3)
1. Rotating shoulder
2. Delivering posterior arm
3. Manually fracturing clavicle
47
What is commonly found on EKG in pregnancy?
Left axis deviation due to physiologic LV and LA hypertrophy
(May also lead to enlarged cardiac silhouette on CXR)
48
When does the neural tube close?
Closes by 6 weeks' gestation (from 24-26 days after conception)
49
What is the implication of face presentation?
Requires C-section unless in anterior mentum position (chin is towards abdomen)
50
When Is nuchal transclucency assessed?
First trimester ultrasound
51
How are the different levels of FHR variability defined?
Which is best? Worst?
Absent: None disernible
Minimal: 5 bpm or less
Moderate: 6-25 bpm
Marked: 25 bpm or more
Moderate is best, absent is worst, minimal is 2nd worst
52
What is the implication of a variabl FHR deceleration?
Non-reassuring: category 2 tracing, or category 3 if also absent FHR variability.
Suggests cord compression.
53
What are the Bishop score thresholds for a favorable and unfavorable cervix?
Favorable: 8 or more
Unfavorable: 6 or less (some used 4 or 5 or less)
54
What is the implication of a late FHR deceleration?
Non-reassuring: category 2 tracing, or category 3 if also absent FHR variability.
Suggests placental insufficiency (response to hypoxia after compression)
55
What is the implication of vertex presentation?
Ideal
56
What is the treatment for neonatal respiratory depression after maternal narcotics?
Naloxone
57
What category tracing is marked baseline FHR variability associated with?
Category 2
58
What are the genetic screens of pregnancy, and when are they performed?
First trimester screen: 10-13 weeks
beta-HCG and PAPP-A
Second trimester screen: 15-21 weeks
Triple screen (AFP, estriol, hCG) or quad screen (add inhibin)
59
What is the threshold for neonatal metabolic acidosis based on umbilical artery gas?
pH 16)
60
What is done to treat nonreassuring FHR pattern?
(5)
1. Mother in left lateral position
2. Administer maternal O2
3. Correct any maternal hypotension
4. Discontinue oxytocin
5. Treat uterine tachysystole (5 or more contractions in 10 minutes) with terbutaline (beta agonist)
(If does not resolve, expedite delivery)
61
How is arrest of fetal descent defined, for primi/multigravid and with and without epidural?
Premi w/ epi: > 3 hrs
Premi w/o epi: > 2 hrs
Multi w/ epi: >2 hrs
Multi w/o epi: >1 hr
(This is per First Aid - UpToDate times are 1 hour longer)
62
What are the 3 most common causes for primary C-section?
1. Labor arrest (34%)
2. Nonreassuring fetal tracing (23%)
3. Malpresentation (17%)
(Others include multiple gestation (7%), macrosomia (4%), and preeclampsia (3%))
63
What are the risks of amniotomy for augmenting protracted active phase? (2)
1. Cord compression or prolapse
2. Chorioamnionitis (if labor is prolonged)
64
What can be used to augment the active phase of stage 1?
Amniotomy (artificial ROM)
Oxytocin
65
What is tobacco use during pregnancy associated with?
IUGR, low birth weight, preterm labor, fetal loss
66
How is a nonstress test interpreted?
Reactive: 2 or more fetal HR accelerations within 20 minutes
Nonreactive: no reactive pattern in monitoring over 40-120 minutes
67
Where is progesterone produced during pregnancy?
Up to week 8: corpus luteum (maintained by HCG)
After: placenta
68
What is the definitive glucose challenge test?
When is it considered positive?
100 g glucose 3 hr test after fasting.
Positive if 2 or more of:
Fasting: >105
1 hr: >190
2 hr: >165
3 hr: >145
69
What antihypertensives are contraindicated in pregnancy?
ACE inhibitors
Thiazides
70
What is the implication of a sinusoidal FHR pattern?
Highly non-reassuring (Category 3 tracing).
Indicates fetal bleeding
71
What is the implication of an early FHR deceleration?
Reassuring. Fetal head has entered the pelvis, decel is a vagal response to head compression with contraction.
72
How is cervical consistency scored for the Bishop score?
0: Firm
1: Medium
2: Soft
(There is no 3)
73
What antibiotices are contraindicated in pregnancy?
Floraquinolones (cartilage damage)
Tetracycline (tooth discoloration)
74
How does heart rate change in pregnancy?
Increases by 10-18 beats/min above baseline (physiologic tachycardia)
75
What makes maternal calcium available for the fetus?
Increased maternal Parathyroid hormone production
(Leads to increased intestinal absorption, renal reabsorption, and bone resorption of calcium)
76
What are the implications of protracted latent phase?
Not a risk to mother or fetus and not predictive of future problems.
77
When is screening for gestational diabetes performed?
Late 2nd trimester (24-28 weeks)
78
How does maternal WBC count change in pregnancy?
Increases (9,000-15,000 is normal in pregnancy)
Even higher in labor (up to 30,000)
(Normal WBC in general is 4,500 to 11,000)
79
How is cervical position scored for the Bishop score?
0: Posterior
1: Mid
2: Anterior
(There is no 3)
80
Where is prolactin produced?
What does it do?
Maternal anterior pituitary
Stimulates postpartum milk production
81
What pain control medication is preferred in pregnancy?
Acetaminophen is not teratogenic.
NSAIDs (ibuprofen, naproxen) are category D (known fetal risk) in the 3rd trimester
Aspirin is category D in all trimesters
82
What category tracing is FHR tachycardia associated with?
Category 2
83
What could disqualify a patient from TOLAC even if they have had only one previous low transverse C-section?
Uterine scarring or previous ruptures
(Also any other CI to vaginal delivery, like inadequate pelvis)
84
What is Goodell's sign?
Softening of the cervix.
Seen at 4 weeks' gestation
85
How are glucose, amino acids, and fatty acids handled at the placenta?
Glucose: crosses via facilitated diffusion, but 70% of transferred glucose sued by placenta itself
Amino acids: actively pumped into the fetus, fetal levels higher than maternal
FFA: limited transport, fetal levels lower than maternal
86
How is cephalopelvic disproportion (CPD) usually diagnosed?
Retrospectively after inadequate fetal descent.
(Clinical pelvimetry is poorly predictive unless there is "completely contracted" pelvis)
87
What changes in GI tract motility are seen in pregnancy? Why?
What can they lead to?
Progesterone leads to smooth muscle relaxation
Leads to GERD and constipation (along with mass effect of gestation)
88
What category is variable FHR decelerations with slow return to baseline associated with?
Category 2
89
What are risk factors for uterine atony? (3)
1. Prolonged labor
2. Overdistension of uterus
3. Magnesium sulfate
90
What two roles does oxytocin have, and what triggers them? Where is it produced and released from?
1. Stimulates uterine contraction in response to birth canal distension
2. Stimulates milk letdown in response to mammary stimulation
Produced in maternal hypothalamus, released from posterior pituitary.
91
How is Airway managed during additional resuscitation in the immediate neonatal period?
Open airway with head-tile ("sniffing position"), Bulb suction of nose and mouth
92
What acid-base changes occur in pregnancy?
Physiologic tachypnea leads to respiratory alkasosis, decreased CO2, bicarb.
93
What category is recurrent early FHR decels associated with?
May or may not be seen in category 1
94
What are the 5 components of the fetal biophysical profile (BPP)?
1. Nonstress test
2. Fetal HR
3. Fetal movement
4. Fetal tone
5. Amniotic fluid index
(Analogous to APGAR score except no 1 point intermediate. 2 points if good, 0 points if bad, so 0-10 scale).
95
What stimulates cervical ripening? Uterine contractions?
Cervical ripening: Prostoglandin PGE2
Contraction: PGF2alpha and oxytocin
96
What should be assessed for when membranes rupture?
1. Meconium staining
2. Cord prolapse (indication for csx)
97
What coagulation changes occur in pregnancy? After pregnancy?
Pregnancy is a hypercoagulable state, and this continues 6 weeks after delivery.
98
How does blood volume change in pregnancy?
Increases to 50% above baseline by 32 weeks
99
What category tracing is minimal baseline FHR variability associated with?
Category 2
100
What are the risks/benefits of high vs. low dose oxytocin for augmenting protracted active phase?
High dose: Better at decreasing labor time, chorioamnionitis risk, and C-section rate, but greater risk of uterine hyperstimulation.
Low dose: Lower risk of uterine hyperstimulation
101
Why is +1 glucose commonly seen on urine dipstick in pregnancy?
Increased GFR (by 50%) leads to faster flow and less time for glucose resorption
102
What is the screening glucose challenge test?
When is it considered positive?
50 g oral glucose load regardless of last meal.
Glucose measured 1 hour later.
Glucose >140 is positive (>130 according to some)
103
What category tracing is FHR bradycardia associated with?
Category 2, unless also absent variability, in which case is category 3
104
What defines a category III (3) tracing?
1. Absent FHR variabiality PLUS any of:
a. Bradycardia (
105
What vitamin is a teratogen?
Vitamin A
106
What is the whole signaling/production pathway for estrogen production (4 steps)?
1. Placenta produces CRH
2. CRH stimulates fetal AP to release ACTH
3. ACTH stimulates fetal adrenal cortex (inner/fetal zone) to produce DHEA
4. Placenta converts DHEA to estrogen (especially E3)
107
What nerve block can be used during delivery?
Pudendal block (S2-S4 somatics)
(Note: will not block contraction/dilation pain)
(Paracervical block no longer routinely used due to fetal bradycardia and epidural working better)
108
When do HCG levels reach their peak?
8-11 weeks (level off at lower level at 15 week')
109
What risk factors warrant more frequent evaluation of fetal wellbeing? (6)
1. Vaginal bleeding
2. Acute abdominal pain
3. Fever > 100.4 F / 38 C
4. Preterm labor
5. Hypertension
6. Nonreassuring fetal pattern
110
How are the three stages of labor defined?
Stage 1 Latent: Cervical effacement and dilation to 4 cm*
Stage 1 Active: Rapid dilation from 4* to 10 cm
Stage 2: Delivery of baby
Stage 3: Delivery of placenta
* Some have replaced 4 cm with 6 cm as threshold for active phase
111
How is Breathing managed during additional resuscitation in the immediate neonatal period?
Positive pressure ventilation. Endotracheal intubation if PPV does not lead to expansion.
112
What anticoagulation medications are preferred in pregnancy?
Heparin and LMWH (do not cross placenta)
Warfarin is a teratogen
113
What are the two genetic diagnostic sampling methods, and when can they be performed?
Chorionic villus sampling: 10-13 weeks
Amniocentesis: 15 weeks
114
How is an early deceleration defined, in terms of:
1. Time to peak
2. Minimal amplitude
3. Duration
4. Association with contractions
1. Time to peak is gradual (30 s or more)
2. Amplitude: no definite criteria
3. Duration: no definite criteria. Tends to mirror contraction
4. Nadir simulatenous with peak of contraction
115
What is the implication of brow presentation?
Usually converts to vertex or face. If not, can lead to labor dystocia.
116
What can lead to white vaginal discharge in pregnancy?
Physiologic discharge (leukorrhea) due to increased blood flow
117
What are three tests for assessing fetal lung maturity?
What is the threshold for maturity for each?
Lecithin-sphingomyelin ratio: >=2
Phosphatidylglycerol: >=0.3
Lamellar body count: (>=20,000/uL (lamellar bodies contain surfactant)
118
How does maternal hemoglobin concentration change in pregnancy?
Decreased by about 1.5 g/dL (average is 12.5 g/dL, compared to 14 g/dL before pregnancy)
Total RBC mass increases but not as much as blood volume, so concentration decreases.
119
How is cervical effacement scored for the Bishop score?
0: 30% or less
1: 40-50%
2: 60-70%
3: 80% or more
120
When is GBS screening performed?
35-37 weeks
121
What is the first-line treatment for morning sickness?
Pyrodoxine (B6) and doxylamine (H1 blocker) together
(In general antihistamines are used)
122
What category is variable FHR decelerations with overshoots associated with?
Category 2
123
What is done to treat meconium-stained amniotic fluid?
Upper airway suction after delivery
124
How does maternal blood pressure change in pregnancy?
Normal in 1st 7 weeks.
Decreases over 2nd trimester to become 10 mm Hg below baseline.
Returns to baseline by end.
125
How is a late deceleration defined, in terms of:
1. Time to peak
2. Minimal amplitude
3. Duration
4. Association with contractions
1. Time to peak is gradual (30 s or more)
2. Amplitude: no definite criteria
3. Duration: no definite criteria.
4. Nadir delayed compared to peak of contraction
126
Why is paracervical block no longer used?
Concern for post-fetal bradycardia (and epidurals work better)
127
How is prolonged active phase defined based on Friedman data?
Cervical dilation rates below:
1.2 cm/hr in nulliparous
1.5 cm/hr in multiparous
(However, this is controversial as a result of newer data showing slower dilation ACOG says rates are slower, and that active phase begins at 6 cm, not 4 cm)
128
What is the implication of the head appearing then retraction during vaginal delivery?
Turtle sign suggestive of shoulder dystocia
129
What signaling events does estrogen drive to initiate labor?
Increased levels of oxytocin receptors, prostoglandin receptors, and COX-2
130
What defines a category I FHR tracing?
1. HR 110-160
2. Moderate baseline FHR variability
3. No late or variable decelerations
(Accelerations and early decelerations may or may not be present)
131
What is the normal fetal heart rate?
110-160 bpm
132
When is the earliest that a nonstress test can be performed?
28 weeks (only if indicated for increased risk of fetal demise)
133
What can lead to orthostatic hypotension in pregnant women?
IVC syndrome: compression of IVC by gestation leads to decreased venous return
134
What is the implication of shoulder presentation?
Usually requires C-section
135
What are indications for umbilical cord gases? (6)
1. Prematurity
2. Multiple gestation
3. IUGR
4. Intrapartum fever of intra-amniotic infection
5. C-section resulting from non-reassuring fetal heart rhythm
6. Low 5 minute APGAR score
136
What category tracing is moderate baseline FHR variability associated with?
Category 1 if also have FHR 110-160 and no recurrent late or variable decels.
Otherwise, or if other problems, category 2
137
What defines abnormal uterine contractile activity?
(3)
1. Peristently 5 or more contractions in 10 min (
138
Where does the 17alpha-hydroxylase step in placental estrogen production take place?
Fetal adrenal cortex, inner/fetal zone
(Placenta lacks 17alpha-hydroxylase)
139
What important effect does a late increase in cortisol have on fetal development?
Differentiation into type II alveolar cells, which produce surfactant
140
At what beta-HCG threshold should the gestational sac be seen on Transvaginal ultrasound? Abdominal ultrasound?
Transvaginal: beta-HCG of 1,500-2,000
Abdominal: beta-HCG of 5,000-6,000 (5-6 weeks)
141
At what station has the fetal head engaged? What is the clinical significance?
Station 0 (crown at ischial spines)
Means the greatest head diameter (BPD) has passed through the pelvic inlet
142
What maternal maneuvers can be used to dislodge fetal shoulder during fetal dystocia? (2)
What is contraindicated in this situation?
1. McRoberts Maneuver: Hyperflex maternal hip (tight to abdomen) to increase AP diameter
2. Suprapubic pressure while tugging on the delivered head.
CI: Fundal pressure is contraindicated (worsens dystocia)
143
What is a sign of shoulder dystochia?
Turtle sign: head appears and then retracts. Face will be flushed and edematous
144
What category is absence of induced accelerations after fetal scalp stimulation associated with?
Category 2
145
What category is recurrent variable FHR decels associated with?
Category 2 unless accompanied by absent FHR variability, in which case is Category 3
146
What is the implication of compound presentation?
Usually retracts spontaneously or with manual assistance. If not, requires C-section
147
How is cervical dilation scored for the Bishop score?
0: no dilation
1: 1-2 cm
2: 3-4 cm
3: 5 cm or more
148
What endocrine pathway stimulates increased blood volume?
Estrogen and progesterone stimulate increased maternal renin production
149
When is ultrasound most predictive of gestational age?
First trimester
150
How is protracted latent phase defined?
Nulliparous: >20 hours
Multiparous: >14 hours
151
What medication is used to induce labor with an unfavorable Bishop score?
Dinoprostone (PGE2) gel (Prepedil) or inserts (Cervidil)
(Mechanical dilators of Foley bulb may also be used)
152
What defines a FHR deceleration as recurrent?
Occurs with at least 50% of contractions in a 10 minute period
153
What category is prolonged variable FHR decels associated with?
Category 2
154
What are the categories for the Bishop score?
Consitency (0-2 pts)
Position (0-2 pts)
Effacement (0-3 pts)
Dilation (0-3 pts)
Station (0-3 pts)
(Call PEDS mnemonic)
155
What fetal position is most favorable?
Occipital anterior (in vertex)
156
How does fetal blood from the IVC and SVC proceed in the heart?
IVC blood (high O2) mostly goes through foramen ovale into the LA.
SVC blood (low O2) mostly goes through RA/RV/PA, but most of this passes via ductus arteriosus into the descending aorta.
157
What is Hegar's sign?
Softening of uterus and seeming separation of uterus and cervix on exam
Present from 4-6 weeks until 12th week.
158
What last-resort maneuver can be used if shoulder dystocia cannot be resolved otherwise?
Zavanelli maneuver: push fetus back in for C-section delivery.
