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OBGYN Sonography > First Trimester Sonography > Flashcards

First Trimester Sonography Flashcards

1
Q

What is the potential space between the uterus and rectum where free fluid naturally accumulates?

A

Posterior cul-de-sac

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2
Q

Where are the ovaries in relation to the uterus?

A

Lateral

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3
Q

What kind of organ are the ovaries?

A

Intraperitoneal

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4
Q

What are the normal measurements of the ovaries?

A 
Length = 5cm
Width = 3cm
Height = 2cm
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5
Q

What connects the ovaries to the uterus?

A

Ovarian ligaments

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6
Q

What ligament encases the ovarian ligaments and uterine vasculature and provides minimal support for the uterus?

A

Broad ligament

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7
Q

What do studies say about contraindications for ultrasound scanning?

A

Benefits outweigh the safety concerns

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8
Q

What is the mechanical index?

A

Output-display standard used to predict the likelihood of non-thermal ultrasound bioeffects

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9
Q

What are the eight components that the sonographer evaluates and identifies in early OB ultrasound?

A

Chorionic sac, yolk sac, fetal pole, amniotic sac, fetal heartbeats, gestational age, number of fetuses, and uterus/adnexa

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10
Q

Where does implantation occur in the endometrium?

A

It occurs on one side, not in the center of the endometrium

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11
Q

What is the first sonographic feature of early pregnancy?

A

The intradecidual sign surrounding the gestational sac

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12
Q

What characteristics indicate an anembryonic pregnancy?

A

MSD of 25.0 mm
No fetal pole
No yolk sac

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13
Q

What is the diamond ring sign?

A

When the fetal pole can be visualized on outside of yolk sac

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14
Q

When does the diamond ring sign appear?

A

Six weeks GA

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15
Q

How should the sonographer measure fetal heart rate?

A

Using M-mode

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16
Q

What is the double bleb sign?

A

Amniotic sac can be seen at the same time as the same time as the yolk sac
Amniotic sac and yolk sac with fetal pole between

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17
Q

What is a subchorionic hematoma?

A

A blood collection that occurs between chorion and decidua

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18
Q

When do the chorion and amnion fuse?

A

14 weeks GA

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19
Q

What is the chorionic bump?

A

An irregular bulge from the chorion decidual surface into gestational sac

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20
Q

How does a chorionic bump present?

A

A hematoma bulging into gestational sac

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21
Q

What is the level of hCG that you should visualize gestational sac?

A

1900 mIU/mL

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22
Q

When hCG is below 2000, positive pregnancy test but no gestational sac could mean?

A

Early intrauterine pregnancy, ectopic pregnancy, recent abortion, possible tumor

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23
Q

When hCG levels over 2000, non-visualization of gestational sac could mean?

A

Ectopic pregnancy, recent abortion, tumor, or false elevation of tests
Most likely ectopic pregnancy

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24
Q

On normal early pregnancy, at what rate does hCG double?

A

hCG doubles every 1.2-2.2 days for the first 4-6 weeks

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25
Q

How is hCG affected by embryonic death or abortion?

A

hCG decreases abruptly

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26
Q

How does ectopic pregnancy or retained POC affect hCG?

A

hCG levels decrease slowly

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27
Q

When is the gestational sac visualized sonographically?

A

4.5 weeks GA

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28
Q

What is the rate of growth of the gestational sac?

A

1.1 mm for the first 8 weeks

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29
Q

What is the normal size of the yolk sac?

A

<6 mm diameter

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30
Q

Where is the yolk sac located?

A

Outside the amnion

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31
Q

What is the GA at which the embryonic pole is visualized?

A

5th menstrual week

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32
Q

When should cardiac activity be seen on ultrasound?

A

6.3 weeks GA

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33
Q

What does CRL of 5mm with no cardiac activity indicate ?

A

No viable pregnancy

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34
Q

When are the limb buds seen?

A

8 weeks GA

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35
Q

When are the mandible/maxilla seen?

A

10 weeks GA

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36
Q

What is the rhombencephalon?

A

Hypoechoic structure in posterior fetal head

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37
Q

When does rhombencephalon appear?

A

8-10 weeks GA

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38
Q

What does rhombencephalon look like on ultrasound?

A

A cyst or defect within the fetal skull

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39
Q

What is midgut herniation?

A

Intestines elongate and move outside the gut, herniating into umbilical region

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40
Q

When is midgut germination visible?

A

9-11 weeks GA

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41
Q

Transabdominally, by what MSD should the yolk sac and fetal pole be visualized?

A

Yolk sac at MSD over 20 mm

Fetal pole at MSD over 25 mm

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42
Q

Transvaginally, by what MSD should the yolk sac and fetal pole be visible?

A

Yolk sac 8 mm MSD

Fetal pole 16 mm MSD

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43
Q

What heartbeat is suspicious for abnormality at 5-8 weeks GA?

A

<85 BPM

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44
Q

What location of the gestational sac is highly suspicious for impending abortion?

A

The cervix

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45
Q

What is another term for blighted ovum?

A

Anembryonic pregnancy

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46
Q

What is a blighted ovum?

A

When gestational development arrested before the embryo formed

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47
Q

What are differential diagnoses for blighted ovum?

A

Early IUP

Pseudogestational sac of ectopic

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48
Q

What is embryonic death?

A

Absence of cardiac activity when the embryonic pole can be seen on TAS or with CRL of 5 mm and no cardiac activity

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49
Q

When is follow up ultrasound indicated for embryonic death?

A

When an embryo with CRL less than 5 mm has no cardiac activity

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50
Q

What are sonographic indications of threatened/spontaneous/missed abortion?

A

Gestational sac extending into cervix
Deformed sac and embryo
Embryonic without cardiac activity

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51
Q

When subchorionic hemorrhage is present, where is it typically seen?

A

With the placental edge to one side

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52
Q

What is gestational trophoblastic disease?

A

When abnormal trophoblast cells grow in the uterus after conception

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53
Q

What is a hydatidiform mole?

A

When fetal tissue is absent, resulting in degenerating placenta
Cluster of fluid filled sacs in the uterus

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54
Q

How often are hydatidiform moles malignant?

A

15-25% of the time

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55
Q

What is the sonographic appearance of a hydatidiform mole in the first trimester?

A

Echogenic or hyperechoic

56
Q

What is the sonographic appearance of a hydatidiform mole in the second trimester?

A

Echogenic masses with cystic spaces

57
Q

What are theca lutein cysts?

A

Benign neoplasms

Abundance of cysts within the ovaries

58
Q

How do theca lutein cysts appear sonographically?

A

Large, multilocular, bilateral cysts

59
Q

What is an invasive mole?

A

When molar pregnancy has infiltrated the myometrium and remains within the uterus

60
Q

What is a mole referred to once it metastasizes?

A

Choriocarcinoma

61
Q

What is a partial or incomplete mole?

A

When a triploid karyotype and three sets of chromosomes are accounted for in the fetus

62
Q

What are the differential diagnoses considered when gestational trophoblastic disease is suspected?

A

Complete mole or partial mole
Hydropic regeneration of placenta
Retained POC
Degenerating leiomyoma

63
Q

What percentage of pregnancies are ectopic?

A

1.4%

64
Q

What percent of ectopic pregnancies cause maternal death?

A

25%

1/4

65
Q

What percent of ectopic pregnancies are tubal?

A

95%

66
Q

Where else can ectopic pregnancies be found?

A

Abdomen
Ovary
Cervix

67
Q

What are risk factors for ectopic pregnancies?

A

Infertility
PID (pelvic inflammatory disease)
Prior ectopic
H/O tubal surgery

68
Q

Who is more likely to have intrauterine and ectopic pregnancies?

A

Those undergoing IVF or ovarian ovulation induction treatment

69
Q

What are ultrasound findings associated with ectopic pregnancy?

A

Adnexal ring sign and a large amount of fluid accumulated in cul-de-sac

70
Q

Where else might blood/fluid be found in ectopic pregnancy?

A

In the adnexa

71
Q

Does a normal ultrasound 100% rule out ectopic pregnancy?

A

No

72
Q

When is a followup ultrasound needed in regards to yolk sac size?

A

If the yolk sac is greater than 7 mm after 9 weeks

73
Q

When is the yolk sac no longer visible?

A

12 weeks

74
Q

At what rate does the embryo grow?

A

1 mm per day

75
Q

What kind of structure is the yolk sac?

A

Extraaminotic

76
Q

What is the most accurate biometric measurement in the first trimester?

A

Crown-rump length

77
Q

Sonographic detection of what is possible before the patient develops signs/symptoms?

A

Pregnancy failure

78
Q

What is a leading cause of pregnancy-related deaths in the first trimester?

A

Ectopic pregnancy

79
Q

What percent of pregnancies are ectopic?

A

1%

80
Q

When is cornual ectopic present?

A

Advanced gestation stage

81
Q

What are indications of cornual ectopic pregnancy?

A

Severe hemorrhage and maternal shock

82
Q

When are heterotopic pregnancies more common?

A

Pregnancies of assisted reproduction

83
Q

What are the steps for checking for IUP?

A
  1. Assess endometrial cavity for a gestational sac
  2. Use TV to assess anterior and posterior cul-de-sacs for free fluid and abd bleeding
  3. Assess adnexal regions in trans and sag (ovaries, ectopic GS)
84
Q

What can happen when the gestational sac embeds within the myometrium and cesarean scar implantation?

A

Uterine rupture

85
Q

What is a normal volume for fluid in the posterior cul-de-sac?

A

5-21 mL volume

86
Q

What happens in a subchorionic hemorrhage?

A

The placenta separates from the underlying uterine wall, leaving blood between the amniotic sac and uterine wall

87
Q

What is true of subchorionic hemorrhage?

A

They can be seen on ultrasound but are not always associated with poor fetal outcomes

88
Q

What is a hemorrhagic cyst?

A

Bleeding inside an ovarian cyst

Looks like marble in appearance on serial US exam

89
Q

Which type of twin pregnancy can be considered high risk?

A

Monochorionic because they share vasculature

90
Q

What is an endometrioma?

A

Found in the ovary

Causes minimal changes on ultrasound, and has homogenous and ground glass appearance

91
Q

What should be the clinical application of the first trimester?

A

Confirming IUP and documenting fetal cardiac activity

92
Q

What is a pregnancy of uncertain viability?

A

An intrauterine gestational sac with no embryonic heartbeat and no definitive signs of pregnancy failure

93
Q

Where are the majority of ectopic pregnancies located?

A

Ampulla and isthmus of fallopian tube

94
Q

What pregnancies are associated with the lambda sign?

A

Dichorionic

95
Q

What should not be used as part of an early pregnancy ultrasound scan?

A

Pulsed wave doppler

96
Q

What are definitive signs of failed pregnancy?

A

A CRL > or = 7 mm w no cardiac activity

A MSD > or = 25 mm w no embryo

97
Q

Where is the uterus in relation to the bladder?

A

Posterior

98
Q

What kind of structure is the bladder?

A

Extraperitoneal

99
Q

An ovarian mass seen in transverse can be a what?

A

Dermoid cyst

100
Q

Where can free fluid be found?

A

Anterior and posterior cul-de-sacs

101
Q

How should the bladder be filled for TV and TA ultrasound?

A

Empty for TV

Full for TA

102
Q

What is synonymous with gestational age?

A

Menstrual age

103
Q

What age differs from menstrual age?

A

Conceptional age

104
Q

What can occur in a suspected ectopic pregnancy?

A

Pseudosac can be misidentified as gestational sacs

105
Q

What does a hemorrhagic cyst show on color doppler?

A

No blood flow

106
Q

What does a simple ovarian cyst appear like on ultrasound?

A

Has thin, well-rounded wall with excellent sound transmission and no internal irregularities

107
Q

How does a malignant adnexal mass appear on ultrasound?

A

Has solid papillary projections and presence of vascular flow on color and pulsed wave doppler

108
Q

When is US evaluation of fetal cardiac activity typically seen?

A

When the embryo is 7 mm in length

109
Q

What does a pseudo sac share sonographic characteristics with?

A

Gestational sac

110
Q

How do corpus luteum cyst and ectopic pregnancy differ?

A

Corpus moves with the ovary and is surrounded by regular tissue
Ectopic moves separately and has echogenic ring

111
Q

What are normal hCG levels at 3 weeks GA?

A

5-50 mIU/mL

112
Q

What are normal hCG levels at 4 weeks GA?

A

5-426 mIU/mL

113
Q

What are normal hCG levels at 5 weeks GA?

A

18-7340 mIU/mL

114
Q

What are normal hCG leves at 6 weeks GA?

A

1080-56500 mIU/mL

115
Q

What are normal hCG levels at 7-8 weeks GA?

A

7650-229,000 mIU/mL

116
Q

What are normal hCG levels at 9-12 weeks GA?

A

25,700-288,000 mIU/mL

117
Q

What is the hCG level considered the threshold for a negative pregnancy test?

A

Less than 5 mIU/mL

118
Q

What is the hCG level considered the threshold for a positive pregnancy test?

A

Above 25 mIU/mL

119
Q

Why should hCG levels not be used to date a pregnancy?

A

The numbers vary so widely

120
Q

What is a qualitative hCG test?

A

Determines if there is hCG in the blood

121
Q

What is a quantitative hCG test?

A

Determines how much hCG is in the blood

122
Q

What is indicated when hCG levels are lower than expected?

A

Pregnancy dating miscalculation
Miscarriage
Blighted ovum
Ectopic pregnancy

123
Q

What is indicated when hCG levels are higher than expected?

A

Pregnancy dating miscalculation
Molar pregnancy
Multiple pregnancies

124
Q

When do hCG levels return to normal after pregnancy loss?

A

After 4-6 weeks

125
Q

What are indications for a first trimester OB ultrasound?

A 
Vaginal bleeding
Abdominal pain
Positive pregnancy test
Hypotension
Hyperemesis gravidum (vomiting)
126
Q

What are contraindications for first trimester OB ultrasound?

A

None for TA
TV contraindication for hypotenstion
Avoid color and spectral doppler imaging

127
Q

What do you ask a patient who comes in with abd pain and a positive pregnancy test?

A 
LMP
Vaginal bleeding
Pregnancy history
Ectopic risk factors - previous EP, PID, pelvic surgery, IUD, ovulation induction
Describe/ point to pain
128
Q

What would you do before giving the patient a TV ultrasound?

A

Document statement
Get abdominal imaging to rule out cysts or abd bleeding
Proceed w TV

129
Q

What are differential diagnoses for bleeding patient?

A

Very early IUP w/ corpus luteum cyst
Ectopic pregnancy but early - order hCG
White blood cell count to rule out appendicitis
Molar pregnancy, miscarriage, blighted ovum

130
Q

How does the sonographer determine chorionicity and amniocity before 10 weeks?

A

Identify number of GS, number of amniotic sacs, , number of yolk sacs

131
Q

How does the sonographer determine chorionicity and amnionicity after 10 weeks?

A

Identify sex discordance, number of distinct placentas, characteristics of intertwin membrane, and lambda sign

132
Q

How do we know we are looking at monozygotic pregnancy?

A

Fetuses are the same sex and share placental site

No membrane between cord insertion sites

133
Q

How do we know we are looking at dizygotic pregnancy?

A

One fetus is male and the other is female

Separate amniotic sac and placental site with thick membrane between

134
Q

When are we unsure whether the pregnancy is mono or dizygotic?

A

If the only information we have is that they are the same gender

135
Q

What is the frequency of US exams for dichorionic pregnancies?

A

3-4 weeks

136
Q

What is the frequency of US exams for monochorionic pregnancies?

A

2-3 weeks

OBGYN Sonography (2 decks)

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