1st trimester Flashcards
(109 cards)
1
Q
some causes of uncertain LMP? (5)
A
- poor menstrual history
- amernorrhea
- prolonged or short cycle- not every 28 days
- DUB (dysfunctional uterine bleeding)
- recent miscarriage
2
Q
Before the advent of pregnancy testing and sonography, what was the most identifiable reference point for the beginning of the pregnancy?
A
LMP
3
Q
How many days is pregnancy?
- calendar
- lunar months
A
280 days from the first day of the LMP
- 9 calendar
- 10 lunar months
4
Q
what is Nägele’s rule also known as?
A
- in clinical practice, the term gestational age is used interchangeably with menstrual age
5
Q
why is the knowledge of an accurate gestational age needed?
A
to manage the pregnancy optimally
6
Q
what are the two 1st trimester measurements? (4)
A
biometry:
- gestational sac (mean sac diameter)
- crown-rump length
additional measurements:
- yolk sac
- nuchal translucency
7
Q
what is a normal yolk sac measurement?
A
2-6mm
8
Q
what is the normal nuchal transluceny measurement?
A
<3.5mm between 11 and 14 weeks
9
Q
what is the 1st sonographic evidence pf an intrauterine pregnancy?
A
gestational sac
10
Q
gestational sac on u/s?
A
- anachoic fluid collection surrounded by an ecogenic ring in the fundal region of the endometrial cavity
11
Q
what is the echogenic ring in the gestational sac representitive of?
A
- chorion and decidua capsularis
12
Q
Absence of the echogenic ring should prompt what?
A
- suspicion of a pseudogestational sac associated with ectopic pregnancy
- this may warrant clinical correlation with beta-hCG levels
13
Q
how to measure the gestational sac?
A
- with 2 scan planes
- measurement made in each of the 3 dimensions, of the gestational sac can be used to calculate a mean sac diameter (MSD)
- should be made at the interface between the echogenic border and the fluid
14
Q
With high-frequency transvaginal technique, a pregnancy dating only 4 weeks and 1 or 2 days from the LMP may be visualized as what measurement?
A
- 2-3mm fluid collection within the uterus
15
Q
the MSD should correlate closely with what?
A
suspected gestational age
16
Q
Any significant variance or suspicion of pregnancy loss should be closely correlated with?
A
beta-hCG levels
17
Q
Normal first-trimester gestational sac growth rate should be approximately?
A
1mm per day
18
Q
what is Beta-hCG correlation?
A
- evidence of a developing intrauterine pregnancy should be seen transvaginally with serum beta-hCG greater that 1000-2000mIU/mL using the International Reference Preparation (IRP) standa
19
Q
Alpha fetoprotein-AFP?
- produced by
- found in
- normal value
A
- produced by fetus
- found in amniotic fluid and maternal serum
- normal values vary with gestational age
20
Q
causes of high AFP?
A
Underestimated gestational age Fetus older than expected Multiple gestations Open neural tube defect Abdominal wall defect Cystic hygroma Renal anomalies Fetal demise
21
Q
causes of low AFP values?
A
Overestimated gestational age Fetus younger than expected Chromosomal abnormalities Trophoblastic disease Long-standing fetal demise Chronic maternal hypertension Diabetes
22
Q
The sonographic presence of the yolk sac in an early gestational sac can be a predictor of?
A
a normally progressing pregnancy before visulization of the embryo
23
Q
With TVS: Gestational sac measuring ____ mm should demonstrate a yolk sac?
A
<8mm
24
Q
a <8mm yolk sac is consistent with what week gestation?
A
5- 5.5 week gestation
25
yolk sac on u/s?
- a round anechoic structure with an echogenic rim
26
what does a yolk sac supply?
- nutrition for developing embryo through the vitelline duct
27
what should the yolk sac and embryo be separated by?
- echogenic amnion but connected by the vitelline
28
size of yolk sac in 1st trimester?
2-6mm
29
an abnormally small or large measurement of a yolk sac may be indicative of?
- pending loss or fetal abnormality
30
how is the yolk sac diameter measured?
- with placement of capilers along the inner borders of the echogenic ring (AP)
31
the yolk sac is often used to assist in locating?
the developing embryo an dpossible cardiac activity
32
what characteristics of a yolk sac are associated with a poor prognosis? (3)
- anomalies of the size
- shape
- echogenicity
33
after the gestational sac has formed and the yolk sac has developed what is seen?
embryo
34
the embryonic period is considered to be week?
6-10 of the pregnancy
35
the embryo grows at a rate of?
1mm per day
36
initially, where is the embryo found and what does it appear as?
- found adjacent to the yolk sac
| - appears as a flat, disc-like structure
37
Faint flickering of this structure, which represents early cardiac activity, may be seen on real-time sonography at?
- 5.5 weeks or when the CRL measures 5mm
38
With transabdominal technique, the embryo should be visualized in a gestational sac that measures?
25mm
39
The normal embryonic heart rate range is?
120-180 bpm
40
If the embryonic heart rate is 100 beats per minute or less what steps should be taken?
- it should be compared with the maternal heart rate to ensure that maternal uterine vessels are not being sampled and inaccurately represented as embryonic cardiac activity
41
what does an embryo begin a C-shaped appearance?
8 weeks GA
42
where can the cystic rhombencephalon be seen?
in the posterior embryonic head
43
at 8 weeks what might be seen?
- cystic rhombencephalon
| - limb buds
44
If there is more than one first-trimester scan with a mean sac diameter or crown-rump length measurement, what should be used to determine the GA?
the earliest ultrasound with a crown rump length equivelent to at least 7 weeks (or 10mm)
45
the distinction between the head and torso of the fetus is more easily recognized at around what weeks?
11-12 weeks
46
An accurate CRL is obtained by placement of the calipers at?
the top of the fetal head (crown) to the bottom of the torso (rump)
47
care must be taken to not include what in a CRL measurement?
- yolk sac or fetal extremities
| - avoid CRL measurement on an embryo or fetus that is flexed
48
By 11 weeks, it is easier to distinguish the fetal head and torso; however, obtaining a CRL at this stage can be challenging because of?
fetal flexion
49
what is nuchal translucency measurement performed?
- during a sono exam at the 1st trimester as an early screening tool for possible fetal aneuploidy
50
The nuchal translucency (NT) refers to?
the normal subcutaneous translucent space along the back of the fetal neck
51
A thickened NT is associated with? (4)
- fetal aneuploidy- trisomy 21
- genetic syndromes
- structural anomalies
- adverse outcome
52
Before the NT measurement is used what must be assessed?
- GA must be assessed with the CRL
53
The NT may be evaluated with a CRL of no less than?
45mm and no more than 84mm
54
45mm and 84mm corresponds to what GA?
- 11+0 and 13+6 weeks
55
The NT is considered to be thickened if it measures?
3.5mm or more during time frame
56
The risk for adverse outcome increases as what increases?
NT
57
what plane is used for a NT measurement?
sagittal
58
What is the cystic space visualized developing within the embryonic head at approximately 8 weeks’ gestational age?
Rhombencephalon
59
Evidence of a developing intrauterine pregnancy should be recognized endovaginally at which of the following serum beta-hCG levels?
1000- 2000 mIU/mL
60
The absence of the thick echogenic rim surrounding the early gestational sac within the endometrial cavity is suspicious for which of the following conditions?
Pseudogestational sac of ectopic pregnancy
61
In the development of a normal intrauterine pregnancy, the yolk sac should be demonstrated transvaginally in a gestational sac with what minimum measurement?
8mm
62
A secondary yolk sac measuring greater than what measurement is considered to be abnormal and suspicious for abnormal pregnancy development?
6mm
63
A primary role of sonography in evaluating pregnancy in the first trimester is confirmation of? (4)
- If the crown-rump length measures 5 mm and cardiac activity is not seen, the diagnosis of embryonic death can be made with confidence
- Failure to meet other first-trimester sonographic milestones should be noted
- A subchorionic hemorrhage may also lead to pregnancy loss
- Ultrasound may be used to follow bleeding with pregnancy to monitor viability, to confirm fetal death, and to determine when dilatation and curettage (D&C) is necessary
64
if CRL measures ____mm and cardiac activity is not seen, the diagnosis of embryonic death can be made with confidence?
5mm
65
what might lead to pregnancy loss in the 1st trimester?
subchorionic hemorrhage
66
what is a subchorionic hemorrhage?
- low-pressure hemorrhages that occur most commonly in the 1st trimester of pregnancy
67
what do subchorionic hemorrhages often result from?
- implantation of the fertilized ovum into the uterus
68
where are subchorionic hemorrhages commonly seen?
- between the uterine wall and the membranes
| - are not associated with the placenta
69
s/s of subchorionic hemorrhage?
- spotting or bleeding with or without uterine contractions
70
outcome of a subchorionic hemorrhage?
- may spontaneously regress or may lead to spontaneous abortion (SAB)
71
A subchorionic hemorrhage prognosis is favorable when?
- fetal heartbeat is identified in the presence of a small hemorrhage
72
Hemorrhage in the lower uterine segment has a better prognosis than hemorrhage located at the uterine fundus T or F?
T
73
Subchorionic Hemorrhages in 13-week gestation is located?
adjacent to the GS and at the margin of the placenta
74
what can help differentiate hematoma from a neoplasm?
lack of vascularity identified with color doppler
75
what are the 3 classifications of a spontaneous abortion?
1. threatened abortion
2. missed abortion
3. complete abortion
76
what is a threatened abortion?
- bleeding without cervical dialation
77
what is a missed abortion?
- embryonic death without expulsion of the products of conception
78
what is a complete abortion?
- when there is expulsion of the products of conception
79
what does risk of SAB decrease dramatically?
12 weeks
80
what can be used to confirm whether or not the sonographic milestones of a first-trimester pregnancy are met?
Correlation between the serum β human chorionic gonadotropin (β-hCG) and the findings in the uterus
81
en the gestational sac measures 25 mm (TAS) what should be identified?
embryo
82
Anembryonic pregnancy should be considered when?
an empty gestational sac is seen when the gestational sac measures 25mm (TAS)
83
when the embryo measures ____mm you should see cardiac motion
5mm
84
Embryonic bradycardia?
< 85 beats per minute in a gestation less than 7 weeks’ gestational age
<100 beats per minute from 7 weeks’ gestational age forward
85
TAS and TVS MSD should always see YS?
TAS: MSD 20 mm should always see YS
TVS: MSD 8mm should always see YS
86
TAS & TVS MSD you should see embryo?
TAS: MSD 25mm should see Embryo
TVS: MSD 16mm should see Embryo
87
what is a leading cause of maternal death in the 1st trimester?
ectopic pregnancy
88
risk factors of ectopic pregnancy?
- history of ectopic pregnancy
- PID
- tubal surgery
- maternal congenital anomalies
- later primiparity
- defective zygote
- fertility treatments
- intrauterine device (IUD) usage
89
Interstitial or cornual pregnancy occurs in what % of ectopic pregnancies?
2-5%
90
Ovarian pregnancies occur in what % of ectopic pregnancies?
- 2%
91
heterotopic pregnancy =
intrauterine pregnancy + ectopic pregnancy
92
S/S ectopic pregnancy (8)?
```
Intrauterine pseudosac or decidual reaction
Positive pregnancy test
Poor correlation with B-hCG
Bleeding and severe pain
Cul-de-sac fluid
Adnexal ring sign
Complex adnexal mass with or without live pregnancy
Significant amount of hemoperitoneum
```
93
what is Gestational Trophoblastic Disease?
- spectrum of diseases of the trophoblast that can be benign, malignant, or malignant/metastatic
94
Gestational Trophoblastic Disease includes? (5)
- Complete hydatidiform mole
- hydatidiform mole with coexistent fetus
- partial mole
- invasive mole
- choriocarcinoma
95
risk factors of gestational trophoblastic disease? (2)
- maternal age
| - previous history of a molar pregnancy
96
what is a sign of gestational trophoblastic disease?
hyperemesis
97
s/s of molar pregnancy?
- vaginal bleeding
- hyperemesis
- preeclampsia
- thyrotoxicosis
- respiratory distress
98
B-hCG in molar pregancy?
- elevated- >100 000 IU/mL
99
in what molar pregnancy are maternal serum AFP levels low?
complete hydatidiform mole
100
s/s molar pregnancy?
- uterus greater in size than expected GA
- bilateral ovarian enlargement
- theca-lutein cysts
101
what is a Complete hydatidiform mole?
Paternal origin and devoid of maternal chromosomes which results in a 46,XX karyotype without fetal development
102
what are partial moles?
- Triploidy with a 69,XXX or 69,XXY karyotype, of which 23 chromosomes are of the maternal contribution and 46 chromosomes are of the paternal contribution
- May be accompanied by a fetus or fetal tissue
103
rarely what kind of mole may also coexist with a normal fetus as the result of a twin gestation?
complete hydatidiform
104
Invasive Hydatidiform Mole?
when the hydropic villi of a partial or complete mole invade the uterine myometrium and sometimes uterine wall
105
Invasive Hydatidiform Mole may occur during?
during the development of a complete or partial mole (although rare with partial mole) or may develop after the evacuation of a mole
106
clinical symptoms of Invasive Hydatidiform Mole?
typically become apparent after the evacuation of a molar pregnancy, when the patient presents with heavy bleeding
107
what is Choriocarcinoma?
- A malignant tumor that arises from the trophoblastic epithelium
- Considered a malignant metastatic form of gestational trophoblastic disease
- May metastasize to the lung, skin, intestines, liver, spleen, heart, and brain
- Treatment is chemotherapy
108
Choriocarcinoma s/s?
Vaginal bleeding + enlarged uterus and ovaries + elevated β-hCG levels
109
Choriocarcinoma may develop when?
- after a molar pregnancy
| - can also occur after a normal pregnancy, SAB, or ectopic
