Obstetrics Flashcards

1
Q

The only respiratory parameter that does not increase or decrease during pregnancy ?

A

Vial capacity

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2
Q

Thromboxane A2 levels in preeclampsia?

A

DUE TO DYSFUNCTIONAL ENDOTHELIAL CELLS:

Increased thromboxane A2
+
Decreased prostaglandin I2 (prostacyclin)
=
vasoconstricted state

(Often treated with aspirin bc as a cyclooxygenase inhibitor —> thromboxane production is decreased)

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3
Q

pathogenesis of late decelerations?

A

uteroplacental insufficiency –> decreased oxygen delivery to placenta and fetus –> activation of fetal chemoreceptors –> fetal VAGAL activity stimulated (parasympathetic nervous system)

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4
Q

Ritodrine and terbutaline mechanism of action

A

Tocolytics: beta-2 > beta-1 agonists —> ATP —> cAMP —> DECR calcium —> impaired contractility —> smooth muscle relaxation

Side effects: tachycardia (beta 1 stimulation), hypotension (blood v relaxation), hyperglycemia, hypOkalemia, PULMONARY EDEMA

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5
Q

Late decelerations signify?

A

Uteroplacental insufficiency: gradual decrease of fetal heart rate AFTER peak of uterine contraction

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6
Q

Variable decelerations signify?

A

Cord compression: ABRUPT decrease in fetal heart rate NOT associated with uterine contractions

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7
Q

Early decelerations signify?

A

Fetal head compression: GRADUAL decrease in fetal heart rate that correlates with peak of uterine contraction

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8
Q

What is fetal scalp pH < 7.20 suggests?

A

Fetal acidosis

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9
Q

A negative fetal fibronectin test suggests?

A

Risk of preterm labor < 1% for one week

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10
Q

Most common cause of early post-partum hemorrhage?

A

Uterine stony (BIG/SICK/TIRED uterus)

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11
Q

Normal umbilical artery blood gas?

A

7.25/50/20

20-30-40-50 (Ua O2 - Uv O2 - Uv CO2 - Ua CO2)

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12
Q

Normal umbilical vein blood gas?

A

7.35/40/30

20-30-40-50 (Ua O2 - Uv O2 - Uv CO2 - Ua CO2)

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13
Q

Coagulation factors that DECREASE during pregnancy?

A

Most INCREASE! Fibrinogen nearly doubles.
INCREASED resistance to activated Protein C
INCREASED RBC mass
INCREASED plasma volume

Factors that DECREASE: XI, XIII, ATIII, tPA, Protein S, and platelet count

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14
Q

“tHINGS” that don’t cross the placenta?

A

Heparin
Insulin
Non-depolarizers
Glycopyrrolate
Sux
Phenylephrine

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15
Q

First stage of labor mediated by which dermatomes?

A

T10-L1: paracervical and hypogastric plexus (visceral sensation from uterus and cervix)

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16
Q

Second stage of labor mediated by which dermatomes?

A

T12-L1 (hypogastric plexus) and S2-S4 (pudendal nerve): somatic sensation from perineum and vaginal stretch

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17
Q

Cervical dilation to 10 centimeters is which stage of labor?

A

First stage

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18
Q

10 centimeters to delivery of baby is what stage of labor?

A

Second

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19
Q

Neuroaxial adjunct with kappa opioid agonism and local anesthetic properties?

A

Meperidine: extends duration of analgesia and strengthens degree of sensory/motor blockade

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20
Q

Blood gas in non-pregnant person versus pregnancy?

A

Non-pregnant: 7.4/40/100/24

Pregnant: 7.44/30/107/21

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21
Q

Driver for increased minute ventilation in pregnancy?

A

Progesterone —> TV increased more than RR

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22
Q

closing capacity and FRC in pregnancy?

A

CC>FRC especially in supine position or under GA —> leads to increased atelectasis and decreased PaO2 in a setting of INCREASED O2 consumption —> rapid desaturations

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23
Q

Protective factors against PDPH?

A

Increased age (>60)
Obesity
Men
Saline LOR technique (versus air)

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24
Q

Dermatome coverage needed for cerclage placement?

A

Cervix: T8-S4
Vagina: T10-L1
Perineum: S2-S4

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25
Q

What type of anesthesia preferred if “bulging membranes” during labor?

A

General

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26
Q

Normal p50 for Hb?

A

27 mmHg

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27
Q

Maternal P50 for Hb?

A

30 mm Hg (right shift)

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28
Q

Fetal p50 for hemoglobin?

A

19-21 mmHg (left shift)

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29
Q

After how many weeks in pregnancy does risk of aspiration become significant?

A

18 weeks

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30
Q

Preferred mode of anesthesia for retained placenta?

A

none to minimal bleeding: IV/sublingual nitroglycerin -OR- regional with minimal sedation

hemorrhaging: general anesthesia

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31
Q

Mode of anesthesia when uterine inversion is needed?

A

1st line = low-dose IV/sublingual nitroglycerin

volatiles if 1st line fails

this is a surgical EMERGENCY - must be manually reversed before cervical ring closes upon uterine fundus

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32
Q

Mechanism of increased atrial natriuretic peptide in response to oxytocin?

A

oxytocin structurally similar to vasopressin –> at doses >5 units, urine output is decreased –> volume overload sensed by atria –> atrial natriuretic peptide released –> natriuresis –> hyponatremia

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33
Q

Magnesium competitively inhibits which pain receptor?

A

NMDA

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34
Q

treatment for magnesium toxicity?

A

calcium

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35
Q

APGAR score requiring immediate resuscitation?

A

0-3

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36
Q

APGAR score requiring close observation and more advanced care?

A

4-7

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37
Q

normal APGAR score?

A

8-10

38
Q

Effect of pregnancy on gastric emptying, peristalsis and intestinal transit?

A

Gastric emptying: NORMAL during pregnancy, DECR during LABOR ONLY

Peristalsis: decreased

intestinal transit: decreased

(due to increased progesterone and DECR motilin)

39
Q

Preferred first line treatment for acute management of tachyarrhythmias in pregnancy?

A

Adenosine if vagal maneuvers and carotid massage ineffective.

2nd line: digoxin, verapamil, and beta blockers

Very short half-life makes it unlikely to affect fetus

40
Q

Preferred mode of anesthesia for EXIT procedure?

A

3 options:
high dose volatiles (2-3 MAC)
lower dose volatiles with nitroglycerin
-OR-
CSE with nitroglycerin boluses and/or infusion

GA has added advantage of fetal anesthesia; but additional meds can be given IM to fetus after partial delivery including fentanyl and relaxants

41
Q

Most common side effects of EXIT procedures?

A

maternal hypotension and uterine atony

42
Q

Cardiac output changes in 1st, 2nd and 3rd trimester?

A

1st: HR increases
2nd/3rd: stroke volume increases

CO=HR x SV

43
Q

Cause for 150% increase in CO immediately after delivery of baby?

A

delivery removes vena caval compression by baby and uterine contraction causes autotransfusion of blood

44
Q

CO level at 48 hours postpartum compared to pre-pregnancy?

A

50% higher

45
Q

CO level at 2 weeks postpartum compared to pre-pregnancy?

A

10% higher

46
Q

When does CO return to pre-pregnancy levels?

A

24 weeks postpartum

47
Q

Concentration of volatiles required to decrease myometrial contractility by 50%?

A

Sevo/des: 0.8-1.7 MAC

isoflurane: 2.4 MAC

48
Q

Mainstay treatment of antiphospholipid syndrome?

A

anticoagulation with aspirin and heparin (or LMWH)

treatment should continue for 6 weeks postpartum

49
Q

Mechanism of antiphospholipid syndrome?

A

Autoantibody inhibits fibrinolytic system leading to complement mediated thrombosis

50
Q

Lab evidence of antiphospholipid syndrome?

A

elevated aPTT = This does not suggest a bleeding tendency bc NOT due to factor deficiency; This is due to phospholipid-related coagulation alterations.

Neuroaxial anesthesia can be done safely.

51
Q

Intrathecal dose of LA used for cerclage placement?

A

Approximately half the dose used for a cesarean

52
Q

Risk factors for neonatal transmission of genital herpes simplex virus 2?

A

primary infection

active disease at labor/vaginal delivery

invasive fetal monitoring

**neuroaxial anesthesia is not contraindicated with recurrent maternal HSV2

53
Q

Placental accreta from least to greatest risk?

A

accreta < increta < percreta

increta: invades myometrium
percreta: invades thru uterine serosa (past myometrium and potentially into other pelvic structures)

54
Q

abnormality in placental accreta?

A

placenta implants with an absent decidua resulting in abnormal detachment after birth -→ life treatening bleed

55
Q

marginal placenta previa vs. partial placenta previa

A

marginal: insertion of placenta close to os but does not cover os
partial: placenta covers partial but not all of cervical os

56
Q

How does placenta previa increase risk of hemorrhage?

A
  1. uterine incision may cut into anteriorly located placenta
  2. the lower uterine segment does not contract as well as normal fundal implantation
  3. presence of previa increases risk of accreta
57
Q

Most common cause of prolonged LATENT phase of labor? (>20 hours in nulliparous, >14 hours in multiparous)

A

unripe cervix or false labor

58
Q

2 types of delayed labor during the ACTIVE phase?

A
  1. primary dysfunctional labor: cervix does not dilate at appropriate rate of 1.2-1.5 centimeters per hour
  2. secondary arrest of dilation: no cervical dilation x 2 hours

**both due to cephalopelvic disproportion

59
Q

cause of dysfunctional labor during active phase?

A

cephalopelvic disproportion - clearly linked to increased cesarean rate

60
Q

risk factors for uterine rupture?

A

uterine scar, polyhydramnios, and advanced maternal age

61
Q

formula for uterine blood flow

A

UBF = systemic vascular resistance/uterine vascular R

62
Q

Why does central venous pressure not increase during pregnancy given the increased blood volume?

A

The increased blood volume is matched by an increase in venous capacitance.

63
Q

Do anticholinesterase drugs like neostigmine cross the placenta?

A

Only small amounts cross because quaternary in structure, hydrophilic and ionized

Enough to cause fetal bradycardia therefore use neostigmine and atropine for reversal instead of neostigmine and glycopyrrolate

64
Q

umbilical artery blood gas parameters necessary for cerebral palsy

A

pH<7

base deficit > or = 12

65
Q

why is nitrous avoided in pregnancy?

A

inhibition of methionine synthetase involved in folate metabolism and DNA synthesis

66
Q

Chronic benzodiazapine use in pregnancy associated with?

A

cleft lip

67
Q

Cocaine use in pregnancy associated with?

A

growth retardation

68
Q

Tetracycline use in pregnancy associated with?

A

fetal skeletal malformation and tooth enamel hypoplasia

69
Q

ACE-I use in pregnancy associated with?

A

fetolethality

70
Q

Warfarin use in pregnancy associated with?

A

MR and skeletal malformations

71
Q

How do beta-agonist tocolytics cause hypoglycemia in neonates?

A

raised maternal blood sugar -→ maternal glucose (but not maternal insulin) crosses placenta to fetus -→ fetal pancreas produces insulin -→ after delivery and clamping of umbilical cord, fetal insulin causes hypoglycemia due to sudden absence of maternal glucose transfer

72
Q

intrathecal administration of 2-chlorprocaine not recommended why?

A

case reports of adhesive arachnoiditis - severe form of inflammation that results in adhesion of nerve roots to one another -→ chronic pain and neuro deficits

73
Q

neuroaxial dermatome coverage needed in cesarean?

A

T4-S4

74
Q

What does a sinusoidal fetal heart rate pattern indicate?

A

smooth wave like pattern indicates fetal anemia (or occasionally maternal IV opioids)

75
Q

What does a saltatory fetal heart rate pattern indicate?

A

excessive alterations in variability indicates acute fetal hypoxia

76
Q

When is fetal heart rate monitoring feasible? When does it become particularly useful?

A

feasible at 18-20 weeks

particularly useful after 25 weeks since fetal heart rate variability is present

Normal FHR: 120-160 bpm

normal variability: 5-25 bpm

77
Q

Mechanism of bradycardia induced by fetal hypoxemia

A

Activation of fetal chemoreceptors -→ vagus nerve

Direct myocardial depression

78
Q

Autonomic nervous system responsible for fetal heart rate variability?

A

parasympathetics: matures later in gestation

early gestation mediated by sympathetics

79
Q

Effect of epinephrine on epidural lidocaine versus bupivicaine?

A

epinephrine prolongs DOA of epidural lidocaine

little to no effect on DOA of epidural bupivicaine

80
Q

How does serum albumin change in pregnancy?

A

Decreases due to plasma volume expansion.

Most other serum constituents (like transferrin, globulins) increase likely due to hormonal changes during pregnancy.

81
Q

fetal scalp pH suggestive of fetal acidosis and distress?

A

<7.2

82
Q

amniotic fluid embolism is akin to _____?

A

severe systemic inflammatory response with (1) severe pulmonary hypertension with RV failure that progresses to (2) LV failure and pulmonary edema

treat is supportive with intubation, vasopressors, fluids, and blood products

83
Q

A combination of which type of tocolytic in the setting of magnesium sulfate is MOST likely to result in respiratory insufficiency due to muscle weakness?

A

Calcium channel blockers

84
Q

Diagnostic test of choice for retained epidural catheter?

A

CT scan

MRI with poorer localization secondary to magnetic interference from the catheter tip and possible tissue damage due to heating of wires

Fluoroscopy has less resolution

85
Q

Relative contraindication for a labor CSE?

A

Anticipated difficult airway or non-reassuring fetus because a presence of an UNTESTED catheter which may become critical.

Alternative technique: dural puncture epidural, i.e. “dry CSE”

86
Q

VEAL CHOP

A

variable decels - cord compression

early decels - head compression

accelerations - OK

late decels - placental insufficiency

87
Q

Most common complication with epidural placement in early stage ! of labor?

A

maternal fever - mechanism unclear but this is not a reason to not place an epidural at this stage

88
Q

Mechanism for increased risk of cholesterol gallstones and cholecystitis during pregnancy?

A

Progeserone inhibits cholecystokinin release leading to reduced gallbladder emptying

89
Q

How does alkaline phosphatase change in pregnancy?

A

Isecreted by the placenta and leads to a 2- to 4-fold INCREASE

90
Q

Differences between accreta, increta, and percreta?

A

accreta: placenta adheres directly to surface of myometrium

INcreta: placenta invades INto myometrium

Percreta: placenta invades THRU myometrium into serosa

91
Q

When are pregnant multiple sclerosis patients at highest risk of relapse?

A

up to 3 months post partum

relapse rate decreased with each trimester due to increased immunity as normal physiology of pregnancy