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Flashcards in Obstetrics 1st lecture Deck (89):
1

“The branch of medicine that concerns the management of pregnancy, childbirth and the puerperium.”

Obstetrics

2

“The study of… diseases & conditions that affect reproduction and the female reproductive system.”

Gynecology

3

Gravida

Pregnant

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Gravidity

# of pregnancies

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Primigravida

first pregnancy

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Nulligravida

never pregnant

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parous

bearing offspring of a specified number or reproducing in a specified manner.

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Parity

number of births a woman has had

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nulliparous ("nullip")

not given birth yet

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Primipara ("primip")

person who has had one birth. In OB is a woman, who is about to give birth a second time.

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Multipara ("multip")

given birth several times

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two main systems to indicate pregnancies & births

GPA
TPAL

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GPA

Gravidity, parity, abortions
G2 P1 A1

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TPAL

gravidity & 4 classifications of outcome
>Term deliveries
>Preterm deliveries
>Abortions
>Living children (live births)

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Term pregnancy (in weeks)

37-41 weeks

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Preterm (dates)

before 37 weeks

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Abortion

end of pregnancy before viability

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point of viability

22 weeks

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Perinatal death (mortality) rate

# of stillbirths and neonatal deaths per 1000 births

National goal < or equal to 10/1000

Neonatal death considered within 28 days after birth

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Maternal Mortality

Death of a pregnant woman during pregnancy or within 6 weeks of delivery or termination

21

Maternal Mortality rates

Expected rate: <20/100,000 births
11-12/100,000 in the USA
50 – 200/100,000 in developing nations

Historical rates: 1-3% (1,000 – 3,000/100,000)

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obstetrical dates

Weeks of pregnancy completed since the LMP (first day of the last menstrual period)

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Menstrual cycle variation

Mean = every 28-29 days
Normal range = 24 – 35 days

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Average length of human pregnancy

266 days after conception (fertilization)
40 weeks (280 days) after the LMP

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EDD

Estimated Date of Delivery (EDD)
90% of pregnancies end at EDD + 3 wks

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First Trimester

First: conception thru 13 weeks

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Second Trimester

Second: 14 – 27 weeks

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Third Trimester

Third: 28 – 40 weeks

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First Timester Highlights

Fetal stage of development begins at 10 weeks
Most pregnancy losses occur here

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Second Timester Highlights

Time of rapid and major physiological adjustments
Fetal viability begins at approximately 22 weeks

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Third Timester Highlights

Labor becomes increasingly likely
Fetal viability increases rapidly

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HCG

Human Chorionic Gonadotropin

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Uterine Growth Landmark

Non-Pregnant

Non-pregnant: “size of your fist”
Nulliparous: slightly smaller

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Uterine Growth Landmark

12 weeks

12 weeks: palpable just at or slightly above pubic symphysis

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Uterine Growth Landmark

20 weeks

20 weeks: palpable at the umbilicus

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Uterine Growth Landmark

36 weeks

36 weeks: palpable at the xiphoid

37

Ultrasound landmarks

Gestational sack at 5-5.5 weeks
2 mm embryo at 5.5-6 weeks
Cardiac activity at 5.5-6 weeks

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Ultrasound:

Diagnostic ultrasound is safe during pregnancy
Vaginal probe in the 1st trimester
Abdominal probe >12 weeks

39

X-rays

Fetal bones not visible until >14 weeks of gestation
X-rays hazardous to embryo & fetus

40

follow-up visits

second timester - 1 month
third trimester- 1 x month
36 weeks beyond - 1 x week
after 40 weeks - 2 x weeks

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fluid loss DDX

Amniotic fluid (“rupture of membranes”)

Urine

Blood

42

ROM

rupture of membranes

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too much amniotic fluid

polyhydramnios

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too little amniotic fluid

oligohydramnios

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Premature rupture of membranes (PROM)

Defined: rupture of membranes before labor
Preterm: before 37 weeks
Prolonged: >18 - 24 hours

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PROM

Common: 5 – 10 %
Cause: unknown
Risk factors: similar to preterm labor

47

Diagnosing PROM

Immunochemistry tests (dipstick format)

Sterile speculum examination

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Immunochemistry Tests

AmniSure
Placental alpha microglobulin-1


Actim Prom
Insulin-like Growth Factor binding protein-1

49


Determine ph of fluid

Nitrazine strip commonly used
Acidic (<7.0) = probably urine
Basic (>7.0) = probably amniotic fluid

50

Sterile Speculum Examination

Look for pooling of fluid on posterior blade of speculum
Determine ph of fluid
Nitrazine strip commonly used
Acidic (<7.0) = probably urine
Basic (>7.0) = probably amniotic fluid
Look for ferning on microscope slide
Culture fluid if labor not imminent or desirable

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Preterm Labor

labor between 22 -36 weeks

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THE single most important cause of:
Perinatal deaths
Neonatal morbidity

Preterm Labor
Incidence: 11 – 12 %

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Preterm Labor Risk Factors

Major Risks:
Prior preterm labor 6-8x
Multiple gestation 6-8x
African-Americans 3-4x
Low socioeconomic status 1.9-2.6x

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Minor risk factors for preterm labor

Poor weight gain
Physical work
Smoking
Anemia
Bacturia
Bacterial vaginosis
Systemic infections
Age < 17 or >40
Multiple abortions
DES exposure
Uterine abnormality
Short stature
Low pre-pregnancy weight

55

DES

DES = diethylstilbesterol
Synthetic estrogen (1930s)

56

The DES Story

Used 1947 – 1968 to treat or prevent:
Miscarriages, low birth weight, poor OB outcome
Shown by 1952 to not be helpful
Shown by 1968 to cause increased risk of:
Vaginal cancer
Miscarriages, ectopic pregnancy
Premature labor, infertility

57

Bacterial Vaginosis

Gardnerella vaginalis in vaginal flora
Common: 15 – 40%
Asymptomatic or may cause vaginitis
Treatment:
Metronidazole oral or vaginal gel
Clindamyicn vaginal cream

58

Early Detection of Preterm Labor

Risk scoring systems
Home contraction monitoring
Salivary estriol
Screening for bacterial vaginosis
Fetal fibronectin (in maternal serum)
Absence = low risk
Presence = increased risk

59

Cervical length by ultrasound

If cervix >25 mm, risk of preterm labor is very low

60

Fetal fibronectin

protein that's believed to help keep the amniotic sac "glued" to the lining of the uterus. ... If your health care provider is concerned about preterm labor, he or she might test a swab of secretions near your cervix for the presence of fetal fibronectin between week 22 and week 34 of pregnancy.

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Predicting Risk of Preterm Labor

Cervical length by ultrasound
If cervix >25 mm, risk of preterm labor is very low

Fetal fibronectin
If not found in cervical/vaginal secretions, risk of preterm labor is very low

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Prevention of Preterm Labor

Reduce risk factors when possible

Supplemental progesterone treatment
Vaginal progesterone
Injections of 17-OH progesterone

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Preterm Labor Treatment

Glucocorticoid therapy when <34 wks
Tocolysis to delay delivery 1-2 days

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Glucocorticoid therapy when <34 wks

Betamethasone 12 mg IM q24 h x 2 doses
Dexamethasone 6 mg IM q 6h x 4 doses

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Tocolysis to delay delivery 1-2 days

Allow transport to appropriate center
Allow time for glucocorticoid therapy

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Labor

Labor = regular contractions which cause changes in the cervix
Effacement (in percent)
Dilation (in cm)

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Tocolysis

Calcium channel blockers (like nifedipine)

Magnesium sulfate

Beta-2 sympathomimetics (“B-mimetics”)
Ritodrine, terbutaline

Others
Oxytocin analog (Antosiban)
Prostaglandin synthetase inhibitors
Ethanol

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Neonatal Survival Estimates

Gestational Age
< 22 weeks <1%
22 – 24 weeks 5-10%
26 – 28 weeks 50-90%
28 – 34 weeks 90-99%
>34 weeks 99%

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Morbidity with Prematurity

Respiratory

Respiratory:
RDS (respiratory distress syndrome)
Chronic lung disease

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Morbidity with Prematurity

GI

Necrotizing enterocolitis

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Morbidity with Prematurity

Neurologic

Cerebral palsy
Intraventricular hemorrhage

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Morbidity with Prematurity

visual

retinopathy

73

Apgar scores

color
pulse
reflex /irritability
muscle tone
breathing

74

Apgar scores (0 points)

color - blue all over
pulse - absent
reflex /irritability - no response
muscle tone - none
breathing - none

75

Apgar scores (1 ooint)

color - body pink/limbs blue
pulse - < 100 per min
reflex /irritability - grimace/feeble cray
muscle tone - some flexion
breathing - weak/irregular

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Apgar scores (2 points)

color - pink all over
pulse - > 100 per min
reflex /irritability - cough, pulls away
muscle tone - active movement
breathing - strong

77

Epidemiology of Diabetes

Affects 5-7% of the U.S. population

Corresponds to 15-20 million people
1-2 million have Type I diabetes
The rest have Type II

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Most Type II diabetics are

> age 25 at diagnosis

79

Most Type I diabetics are

< age 25 at diagnosis

80

Pathophysiology Type I

Abrupt (weeks, months) loss of pancreatic beta cells

81

Pathophysiology Type II

Insulin resistance
Gradual (years) loss of beta cells

82

Complications (diabetes)

Death from acute ketoacidosis

Increased risk of:
Cardiovascular disease
Renal disease (nephropathy)
Vision loss (retinopathy)
Nerve conduction disorders (neuropathy)

83

Diabetic Obstetrical Issues

Birth defects

Late pregnancy intrauterine fetal death (stillbirth)

Large fetal size (macrosomia)
> 10 lbs
Birth trauma risk (esp. shoulder dystocia)

84

Diabetes Treatment Strategy

Birth defects

Late pregnancy intrauterine fetal death (stillbirth)

Large fetal size (macrosomia)
> 10 lbs
Birth trauma risk (esp. shoulder dystocia)

Tight glucose control
Multi-dose insulin
Diet, exercise
Coordinated programs (“Sweet Success”)

Early delivery (37-39 weeks)

85

Insulin/Glucose Changes in Pregnancy

First Trimester

Insulin secretion and sensitivity rise
Fasting glucose fall (15 mg/dL)
Effect peaks at 12 weeks

86

Insulin/Glucose Changes in Pregnancy

Second Trimester

Insulin sensitivity falls 33 – 50%
Fasting & postprandial glucose levels rise
Due to Human Placental Lactogen (HPL)
Prolactin & cortisol may contribute

87

Insulin Requirements in Pregnancy

Stable or may drop in first trimester

Begins to rise in second trimester

Ultimately 2-3 times as much insulin may be needed in the 3rd trimester as was required before pregnancy

88

Gestational Diabetes

Glucose intolerance seen during pregnancy
No history of diabetes before pregnancy
Normal glucose tolerance after pregnancy

Best viewed as a variant of Type II diabetes

89

Gestational Diabetes Treatment

Diet

Add insulin if needed

Use insulin sensitizing drugs such as metformin