Topic 2 - First trimester dating and early pathology Flashcards
(199 cards)
1
Q
What is the purpose of first trimester ultrasound?
A
confirm viability
establish the number of viable fetuses
determine accurate gestational age
plus if requested, evaluate fetal gross anatomy and the risk of aneuploidy
2
Q
What patient history should be attained?
A
• Estimate gestation based on last menstrual period or time of conception.
• Document symptoms the result and date of any pregnancy test
• In women undergoing assisted reproduction
o date of oocyte retrieval
o age of the blastocyst
o fresh or frozen cycle
3
Q
When is the gestational sac visible?
A
4 weeks and 3 days using TVS
4
Q
What is important when imaging and early gestational sac?
A
• Make a clear distinction between a true gestational sac and intra-cavity fluid
5
Q
How would a true gestation sac appear?
A
o eccentrically placed within the endometrial cavity s
o surrounded by an ‘echogenic ring’
6
Q
How does intra cavity fluid appear?
A
o previously called a ‘pseudo-gestational sac’
o midline of the endometrial cavity
o displacing the anterior and posterior surfaces of the endometrial cavity
7
Q
What should you do if the gestational sac is not present with a positive pregnancy test?
A
o adnexal regions should be carefully examined
o look for evidence of an ectopic pregnancy.
o Most can be visualised with high-frequency TVS assuming the practitioner is experienced.
8
Q
When would you report a PUL (pregnancy of unknown origin)?
A
o there is a positive pregnant test
o no signs of intra- or extra-uterine pregnancy
o no obvious retained products of conception on TVS
o Under these circumstances, there are three possibilities:
1 intra-uterine pregnancy;
2 ectopic pregnancy or
3 failed PUL.
9
Q
What test is recommended in case of PUL?
A
hCG over time is of value so serial tests are recommended
10
Q
What should you do in the case of a gestational sac in an atypical location?
A
o should be noted and reported
o important for low positioned gestational sac, adjacent to or bulging into a Caesarean section scar.
11
Q
How is fetal number and type determined in the first trimester?
A
o The first trimester is the optimum time to determine chorionicity of the fetuses.
o The presence of separate sacs and the thickness of the intervening membrane and the shape of its junction with the placenta should be assessed.
o Early in the first trimester an intervening amnion may not be visible in monochorionic diamniotic twins
o A transvaginal ultrasound scan should be offered to help determine amnionicity when monoamnionicity is suspected on a trans-abdominal scan.
o Later, in the first trimester, the number of placentas can be evaluated.
12
Q
When are fetal heart movements visible?
A
With a high-resolution vaginal transducer, fetal heart movements are often visible from five to six (5– 6) weeks (i.e. crownrump length (CRL) = 2 mm), but may not be seen until CRL = 6–7 mm
13
Q
How is gestational age assessed?
A
• Most accurately assessed by measurement of the CRL in the first trimester
• Before an embryo is visible
o mean sac diameter (MSD) can support gestational age by last menstrual period (LMP)
o should not be used as the sole determinant of due date
• Once an embryo is visible
o the crown rump length (CRL) can be used to calculate the due date
o MSD should not be included in this calculation
• After eleven (11) weeks
o multiparametric assessment can be used
o biparietal diameter (BPD) is the most often used second measurement.
14
Q
The EDD by LMP (adjusted for cycle length) should be used unless:
A
- The LMP is unknown
- The GA by CRL is <10 weeks and differs from GA by LMP by more than five (5) days; or
- The GA by CRL (+/- BPD) is ten to fourteen (10-14) weeks and differs from GA by LMP by more than seven (7) days.
15
Q
How is the EDD determined for twins?
A
the CRL for the larger twin is used in assessing the EDC.
16
Q
When can pregnancy failure be diagnosed?
A
- When the MSD is ≥25 mm with no visible yolk sac or embryo; or
- When there is a visible embryo with CRL ≥7mm but no cardiac activity can be demonstrated.
17
Q
If no live embryo is demonstrated but the pregnancy failure criteria are not met, then the following criteria can be used
A
- if the initial scan showed a fetal pole < 7 mm with no cardiac activity beat and a repeat scan in seven (7) or more days also shows no cardiac activity;
- if the initial scan showed a MSD ≥12 mm with no embryo and a repeat scan in seven (7) or more days does not show interval development of a yolk sac or an embryo with cardiac activity;
- if the initial scan showed a MSD < 12 mm with no embryo and a repeat scan in fourteen (14) or more days shows no visible yolk sac or cardiac activity and the MSD has not doubled;
- if a yolk sac is visible on initial scan and there is no embryo with a heartbeat after 11 days;
- absence of cardiac activity, which was seen to be present on an earlier scan.
18
Q
What are the different fetal structures seen at different weeks?
A
- 9 weeks - Head, trunk and limbs
- 10 weeks - Some ossification of long bones, jaw and skull
- 11 weeks - Stomach, spine, ossified cranium, four chamber heart, hands and feet
- 12 weeks - Kidneys, bladder
- 13 weeks - Mid gut herniation resolution
19
Q
What is the purpose of a nuchal transluceny measurement?
A
- assess the risk of chromosomal abnormality, in particular of trisomy 21.
- may also be abnormal in other fetal anomalies (for example, some congenital heart disease)
20
Q
When should an NT scan be performed?
A
• performed between the gestational ages of eleven (11) weeks and thirteen (13) weeks plus six (6) days (CRL 45-84 mm)
21
Q
What is an abnormal NT measurement?
A
• measurement of greater than 3-3.5 mm is usually considered to be abnormal but must be correlated with gestational age
22
Q
What is the sonographic appearance of the corpus luteum?
A
Sonographic appearances include a solid, rounded target like lesion
Or a predominately cystic structure.
Peripheral vascularity is usually detectable.
The size of a corpus luteum is also variable, commonly measuring up to three (3) cm.
23
Q
IN the first trimester the uterus should be examined…
A
o for evidence of a fibroids or uterine developmental defects
o uterine position should also be noted (anteverted, axial and retroverted)
o cervical length may be assessed in certain high-risk women
24
Q
Why should the adnexa examined in the first trimester?
A
• The adnexa should be examined for coexistent ectopic pregnancy and free fluid
25
What is the minimum a first trimester report should inclued?
1. The clinical gestational age based on LMP or IVF procedure.
2. Embryonic or fetal size and number with corresponding gestational age.
3. Presence of fetal heart motion.
4. In the presence of twins or higher order multiples, an assessment of chorionicity and amnionicity.
26
Define menstrual age
is measured from the first day of the menstrual period that preceded fertilisation.
27
Define gestational age
It is important to realise that clinicians use the term 'gestational age' referring to menstrual age
The true gestational age, based on the date of fertilisation, is two weeks less than the menstrual age because fertilisation occurs about two weeks after the first day of menstruation.
28
Define Due date, estimated day of delivery (EDD) and estimated day of confinement (EDC)
All refer to the same thing.
They can be calculated quickly with the 'seven and three' rule: add seven days to the first day of the last menstrual period and then subtract three months. Or, your ultrasound machine will calculate it for you.
29
Define PUL
The non-visualisation of a live intrauterine early embryonic pole will lead to a conclusion of "pregnancy of unknown location". This term embraces the possibility of very early pregnancy, miscarriage and ectopic pregnancy.
30
Define macrosomia
LGA aka >90th centile EFW
31
What is the first trimester
Extends through to week end 13
32
What is the second trimester
14th through to 26th weeks
33
What is the third trimester
the 27th week to term
34
Define preterm
A pregnancy is considered preterm before the 38th week.
35
Define term
A pregnancy is said to be 'at term' in the 38th through to the 41st week
36
Define post term
it is considered post-term thereafter. Generally, it is not desirable for a pregnancy to extend into the 42nd week, due to a substantial increase in delivery and postpartum complications
37
What is the standard of care for dating?
The crown-rump length between 8-14 weeks has become the standard of care
38
How is MSD measured?
• The average of the three orthogonal measurements of the fluid-filled space within the gestational sac
39
How is CRL measured?
* can be carried out transabdominally or transvaginally
* Orientate fetus horizontal across the screen
* Zoom so fetus fills the screen
* the measurement line between crown and rump is at about 90◦ to the ultrasound beam
* ensure that the fetus is not flexed, amniotic fluid should be visible between the fetal chin and chest
40
Why is accurate dating important?
provides valuable information for the optimal assessment of fetal growth later in pregnancy, appropriate obstetric care in general and management of preterm or post-term pregnancies in particular
41
Comment on the accuracy of menstrual age
Accuracy is inversely related to fetal age
technical error of measurement is relatively constant.
accuracy of gestational age estimates by ultrasound increases as more variables are measured
In late gestation, the accuracy of fetal age determination is enhanced by serial measurements.
42
Why is the menstrual age determination more accurate early in pregnancy?
There is very little biological size variability during this time. A certain measurement corresponds with a well-defined menstrual age. This is in contrast to the third trimester, in which individual genetic expression in fetal size can result in a very heterogeneous population. A certain measurement can then correspond with very different gestational ages.
43
Very often pregnant women will ask you during a third trimester scan: "Is the due date still the same as the one given during my earlier scan?" Write down your answer to that question.
Once the due date has been established on a reliable basis, it is never adjusted later in pregnancy. It always stays the same because the earlier menstrual age determination is always the more accurate one. The only thing we can tell you in the third trimester is whether the fetus grows adequately for the gestation based on your previously given due date.
44
What is gastrulation?
Formation trilaminar disk from the bilaminar disk with the three primary germ cell layers: ectoderm, mesoderm, and endoderm
the primitive streak and notochord form.
45
What is neurulation?
- The formation of the neural plate and its closure to form the neural tube
- process begins in the fifth week in the thoracic region and extends caudally and cranially, resulting in complete closure by the end of the sixth week (day 42).
- Failure of closure of the neural tube results in neural tube defects.
46
Briefly describe the formation of the primitive heart?
- two cardiac tubes develop from splanchnic mesodermal cells. By the end of the fifth week, these tubes begin to pump
47
What is the earliest sonographic sign of an IUP?
a focal echogenic zone of decidual thickening at the site of implantation at about 3½ to 4 weeks of gestational age. This sign is nonspecific and of limited diagnostic value.
48
What is the first reliable grey scale sign of an IUP?
visualization of a small (1-2 mm fluid collection surrounded by an echogenic rim) gestational sac within the thickened decidua (referred to as the intradecidual sign, which is seen at about 4.5 weeks’ gestation)
49
Where should the intradecidual sac be located?
eccentrically located within the endometrium.
50
Why is it important to ensure the sac abuts the endometrial canal?
to distinguish an intrauterine gestational sac from a decidual cyst.
51
When present the intradecidual sign is useful for diagnosing an IUP. What abut when it is absent?
When absent, it does not reliably exclude an IUP.
52
Briefly outline the double decidual sign and its use.
(also called double decidual sac sign)
a method for distinguishing between an early IUP and an endometrial fluid collection of other origin, such as the pseudosac of an ectopic pregnancy
well-defined double-decidual sign is an accurate predictor of the presence of an IUP.
vague or absent double-decidual sign should be considered nondiagnostic because it does not reliably exclude an IUP.
53
What are the names of the layers of the endometrium in the pregnant state?
the decidua capsularis, decidua vera, and decidua basalis.
54
What forms the two echogenic rings of the double decidual sign?
decidua capsularis and chorion laeve eccentrically located within the decidua vera
55
The decidua basalis–chorion frondosum (future placenta) may also be visualized as
an area of eccentric echogenic thickening.
56
When can the double decidual sign be identified?
identified by about 5.5 to 6 weeks’ gestational age
57
When is the double decidual sign useful?
useful in establishing an intrauterine gestation prior to TAS ability to visualize the yolk sac.
58
When does the double decidual sign become less useful?
almost always resolvable by the time the gestational sac reaches 10 mm, at which point the yolk sac is typically visible by TVS, thus diminishing the usefulness of this finding.
59
When will BHCG results be positive?
There will be positive results at approximately 23 days of gestational age, before a normal intrauterine gestational sac may be imaged with TVS.
60
What does disproportionately lower than expected BHCG mean?
an indicator of a poor prognosis.
61
What is the most helpful way to use BHCG?
Serial β-hCG measurements are usually more helpful than a single measurement in identifying abnormal from normal pregnancy
62
What should be seen at HCG of 2000?
we should be seeing an intrauterine sac. If not, high index of suspicion for ectopic or miscarriage.
63
What is the first structure to be seen in the gestational sac and at what time?
At 4 weeks the primary yolk sac begins to regress and the secondary yolk sac develops.
The secondary yolk sac is the first structure to be seen normally within the gestational sac.
64
At what size MSD should the yolk sac be visualised?
* Using TAS, it is often seen when the MSD is 10 to 15 mm and should typically be visualized by an MSD of 20 mm
* Using TVS typically visualized by an MSD of 8 mm.
65
Why is visualising the yolk sac important in early pregnancy?
critical in differentiating an early intrauterine gestational sac from a pseudosac.
double-decidual sign is not 100% specific for presence of an IUP, the identification of a yolk sac within the early gestational sac is.
66
Why is the number of yolk sacs present helpful?
• number of yolk sacs present can be helpful in determining amnionicity of a multifetal pregnancy
67
What is the role of the yolk sac?
transfer nutrients to the developing embryo
68
What should the yolk sac measure?
Should be less than 5.6mm
69
What should happen to the yolk sac in the 6th week?
Incorporates into the embryo as the primitive gut in the 6th week
70
Visualization of the amnion in the absence of an embryo usually occurs...
in intrauterine embryonic death as a result of resorption of the embryo.
71
When does the amnion become visible?
when the embryo has a CRL of 2 mm at 6 weeks.
72
What is the shape of the amnion at 7 weeks?
spherical by about 7 weeks
73
When does the amniotic cavity expand to fill the chorionic cavity completely
by week 16
74
When is cardiac activity established?
cardiac activity adjacent to the yolk sac can be established before the embryo can be fully visualized at the end of the fifth week.
75
When can cardiac activity typically be seen?
Using TVS, cardiac activity is typically seen by the time an embryo is 2 mm in size, and is almost always seen by 5-mm CRL
76
What is the strict cut off for CRL for a non viable pregnancy (ie without cardiac activity)
for strict diagnosis of nonviable pregnancy the threshold is set at 7 mm CRL.
77
What is the normal BPM for an embryo?
Less than 6.3 week Normal is 100 beats per minute (bpm) or more
120 bpm at or beyond 6.3 weeks.
rate is less than 100 bpm, then follow-up should be obtained.
78
When is the umbilical cord formed?
at the end of the sixth week (CRL = 4.0 mm)
79
What does the umbilical cord contain?
two umbilical arteries, a single umbilical vein, the allantois, and yolk stalk (also called the omphalomesenteric duct or vitelline duct)
the amnion expands and envelops the connecting stalk, the yolk stalk and the allantois and all are embedded in whartons jelly
80
What is the purpose of the umbilical vein?
Umbilical vein carry oxygenated blood from the placenta to the foetus which is shunted through the DV into the IVC and heart.
81
What happens to the umbilical vein, DV and allantois after birth?
The umbilical vein becomes the ligamentum teres
The ductus venosus becomes the ligamentum venosum
Allantois is associated with bladder development and becomes the urachus and median umbilical ligament
82
Describe an umbilical cord cyst
usually seen in the eighth week and usually resolve by the 12th week.
Usually singular, closer to the embryo/fetus than the placenta
mean size of 5.2 mm
Single cysts in the first trimester associated with a normal outcome
multiple or complex cysts associated with an increased risk of miscarriage or aneuploidy
83
Comment on the different between first, second and third trimester umbilical cord cysts
although umbilical cord cysts have been associated with chromosomal abnormalities if seen in the second and third trimesters, those seen in the first trimester typically resolve and are not associated with poor outcome.
84
Recite the ASUM criteria for diagnostic early pregnancy failure
When using a TV approach, embryonic demise can be established by the following criteria:
CRL of 7mm without a heartbeat after 30 seconds of observation
MSD of 25mm or greater without an embryonic pole
85
What are the ASUM guidelines for follow up of suspected early pregnancy failure?
If no live embryo is demonstrated, but the above criteria are not met, then the following criteria can be used to diagnose pregnancy failure by follow-up imaging:
1 - Initial scan showed foetal pole <7mm with no cardiac activity and a repeat scan in 7 or more days also shows no cardiac activity
2 - Initial scan showed an MSD >12mm with no embryo and a repeat scan in 7 or more days does not show interval development of a yolk sac or an embryo with cardiac activity
3 - Initial scan showed an MSD <12mm with no embryo and a repeat scan in 14 or more days shows no visible yolk sac or cardiac activity and the MSD has not doubled
4 - Yolk sac is visible on the initial scan and there is no embryo with a heart beat after 11 days
5 - Absence of cardiac activity which was present on an earlier scan.
Any doubt = further scanning
86
What are some sonographic predictors of embryonic demise?
Embryonic bradycardia
- Heart rate <80bpm in embryos with a CRL <5mm is universally associated with embryonic demise
Cases where the MSD is <5mm greater than the CRL
- prone to first trimester miscarriage despite a normal heart rate
- it may be an early indication for oligohydramnios
In patients of 8-12 weeks gestation, a yolk sac <2mm is associated with poor outcomes
Yolk sac >5.6mm in 5-10 week singleton pregnancies always has an abnormal outcome
Large yolk sacs may be associated with chromosomal abnormalities (trisomy 21, omphalocele)
RPOC:
Empty uterus
Large, echogenic mass of tissue filling the endometrial cavity
High-flow velocity vascularity in RPOC
87
What is miscarriage/spontaneous abortion?
the expulsion of the conceptus before viability
88
What is the most common time for miscarriage?
most common time for a miscarriage to occur is between eight and 13 weeks
89
What is the cause of miscarriage?
the cause of most spontaneous abortions is uncertain
90
What i the average pregnancy loss in the first trimester?
the pregnancy loss rate is approx 11.5% overall, from 5 weeks onward.
91
What is the chance of a successful outcome CRL>10mm?
Once the embryo reaches a CRL of 10 mm, there is about a 98% chance of a successful outcome.
92
What are some clinical signs of early pregnancy loss?
brownish spotting
| decrease in the symptoms of pregnancy (breast tenderness, nausea)
93
Comment on the presence of bleeding in early pregnancy?
Bleeding is common in early pregnancy (25%) however women with bleeding are at much higher risk of spontaneous abortion (50% chance of spontaneous abortion)
94
Briefly outline a threatened miscarriage
- bleeding in the choriodecidual space that is not sufficient enough to cause embryonic demise.
- unexpected and usually painless blood loss
- The cervix remains closed and the uterus is appropriately sized for gestation
- Abortion does not always follow.
- become inevitable when the cervix dilates.
- More than 95 percent of women with a viable pregnancy (cardiac activity visualised) will continue to term uneventfully.
- No treatment has been demonstrated to alter the prognosis in threatened miscarriage.
95
Briefly outline an inevitable miscarriage
- threatened miscarriage becomes inevitable when the cervix dilates.
- Bleeding usually increases
- strong contractions may follow.
- becomes complete if the entire contents of the uterus are extruded.
- If products are left behind, all the complications of an incomplete abortion may arise.
96
Briefly outline complete miscarriage
- all the products of conception have been expelled
- pain is absent
- bleeding is slight
- cervix has closed again.
97
Briefly outline incomplete miscarriage
there are RPOC
amount of bleeding varies but it can be up to severe
can be severe enough to cause hypovolemic shock.
Infection can occur
If there is still bleeding a week after a miscarriage that was thought to be complete, it is more likely that it is incomplete.
98
What is a septic miscarriage?
Infection can follow incomplete abortion and it is then referred to as septic miscarriage.
99
Briefly outline a missed abortion
- the embryo dies but the gestational sac is retained in the uterus for several weeks
- patient usually notices a little blood-stained discharge for a day or two between eight and 12 weeks
- may have no bleeding at all
- uterus is smaller than expected for the gestation
- formerly described as a blighted ovum
- eventually expelled spontaneously, but sometimes not for many weeks.
- A suction curettage is therefore often performed.
100
What is the leading cause of maternal death?
Ectopic pregnancy
101
What are some factors that increase the risk of ectopic?
tubal abnormality preventing passage of the zygote or resulting in delayed transit
previous ectopic pregnancy
cesarean section
tubal reconstructive surgery
pelvic inflammatory disease
chlamydial salpingitis
intrauterine contraceptive devices
increased age
Increased parity.
increased incidence of multiple pregnancies with ovulation induction and IVF further increases the risk for both ectopic and heterotopic (coexistent intrauterine and ectopic) gestation.
There is an association between infertility and ectopic pregnancy, likely because of the shared tubal abnormalities in both conditions
102
What is the clinical presentation for ectopic
classic clinical triad of pain, abnormal vaginal bleeding, and a palpable adnexal mass is present in approximately 45% of patients
Other presenting signs and symptoms include any combination of the classic triad, as well as;
Amenorrhea
adnexal tenderness
cervical motion tenderness.
103
What are the differentials of the clinical findings of ectopic pregnancy
```
The clinical presentation is nonspecific and may also indicate;
symptomatic ovarian cysts
pelvic inflammatory disease
dysfunctional uterine bleeding
spontaneous abortion
```
104
Would you use TAs or TVS to look for an ectopic?
TAS is recommended in all cases of suspected ectopic pregnancy in which the TVS does not provide a clear diagnosis, looking for findings that may be outside the range of the transvaginal probe.
105
What is the most common location for an ectopic?
Between the ovaries and uterus is the most common location of an ectopic adnexal mass. Most commonly in the fallopian tube
106
How can you differentiate between and adnexal mass and an ovarian mass?
Using manual TA pressure if a mass moves separately from the ovary, it is more likely to be an ectopic mass rather than an ovarian mass/corpus luteal cyst
apply light pressure with the probe and it almost always elicits pain similar to the sensation that brought the patient to hospital initially
107
Why should the adnexa still be scanned even if IUP is confirmed?
Even in the presence of an IUP, evaluation of the adnexa should be performed to screen for a possible coexistent ectopic pregnancy
108
What is the most specific finding for an ectopic pregnancy?
The most specific sonographic sign of ectopic pregnancy is documentation of a live embryo in an extrauterine location. This finding is 100% specific but a has a low sensitivity of 15% to 20%
109
List the non specific findings for an ectopic
adnexal mass
tubal ring
free fluid
some endometrial findings
110
What are the rates of incidence for implantation in different areas of the fallopian tube?
75% to 80% in the ampullary portion, 10% in the infundibular, 5% in the fimbria, and 2% to 4% in the interstitial segment.
111
What is the most common sonographic finding of an ectopic?
Ectopic pregnancies in a tubal location often produce a mass in the adnexa, which is the most common ultrasonographic finding and may be
solid
heterogeneous
comprised mostly of blood products from bleeding into the wall and lumen of the fallopian tube
112
What increases the specificity of an adnexal mass being an ectopic?
Adnexal masses containing a tubal ring with or without central identifying features such as yolk sac or embryo increases the specificity of the finding.
113
How do you differentiate a tubal ring from a corpus luteum cyst?
because the cyst is eccentrically located with a rim of ovarian tissue.
often within a hematoma that may be confined to the fallopian tube or that may extend outside it
typically more echogenic than ovarian tissue (corpus luteum less echogenic)
114
Why may tubal ring mass be overlooked?
easily overlooked or mistaken for fat or bowel
115
Why is hyperaemia not a specific finding in a tubal ring?
May be hyperaemic but corpus luteum may also be hyperaemic
116
Why is tubal ring not diagnostic on its own?
other entities can cause an adnexal mass such as hemorrhagic corpus luteum cyst, endometriosis, and abscess
117
Why is free fluid not diagnostic of an ectopic?
may be present in both ectopic and IUP
118
What free fluid appearance is high risk for an ectopic
Presence of echogenic free fluid or blood clots with the absence of IUP especially in high quantities combined or in the presence of an adnexal mass is high risk for ectopic
Can also be seen in ruptured corpus luteum cyst
119
What is most important when a large amount of blood is identified in the pelvis?
If there is a large amount of blood in the pelvis and an ectopic pregnancy is not visualized, ruptured ectopic or ruptured ovarian cyst diagnosis is not as important as the hemodynamic stability of the patient. Unstable patients are treated surgically with either diagnosis
120
Where else should you look once free fluid is identified in the pelvis?
Always look for free fluid in the hepatorenal and splenorenal space as this would provide a sense of the blood loss
121
How may the endometrium appear during an ectopic?
no specific endometrial appearance or thickness to indicate an ectopic
Most common appearance during ectopic is normal or increased echogenicity
Pseudogestational sacs are endometrial fluid collections surrounded by echogenic endometrium from a prominent decidual reaction
present in 5% to 10% of ectopic pregnancies
can be smooth and rounded with debris that could be mistaken for products of conception
122
What signs are important in differentiating a pseudo sac from a gestational sac?
Intradecidual and double-decidual sign can be used to identify an intrauterine pregnancy before the yolk sac or embryo
Pseudosac is an intrauterine fluid collection surrounded by a single decidual layer as opposed to two concentric rings
123
What are the possible implantation sites for ectopics?
Fallopian tube, interstitial, cervix, caesarean scan, abdominal.
124
Why do interstitial ectopics have double the mortality rate?
because of later presentation (late first trimester or early second trimester)
125
Why do interstitial ectopic have a later presentation?
myometrium surrounds a portion of the gestational sac, allowing it to enlarge painlessly for a longer period of time
126
How does an interstitial ectopic appear sonographically?
sac visualized high in the fundus in an eccentric location
should be suspected if the sac is not surrounded in all planes by at least 5 mm of myometrium.
“The interstitial line sign” is more accurate at predicting. Seen in 90% of cases.
represents the interstitial portion of the tube or endometrial canal that extends from the cornu to the middle of the interstitial mass and is considered the diagnostic landmark of interstitial pregnancy.
surrounded by trophoblast but should not have a double-decidual sign
127
What are some differentials for interstitial ectopic?
septate or bicornuate uterus
fibroids
myometrial contraction
128
What is the treatment for interstitial pregnancies?
historically surgical with cornual resection, now local injection of potassium chloride or with local or intramuscular injection of methotrexate is performed to avoid uterine surgery.
129
How may a c scar ectopic present?
may present with painless vaginal bleeding and a history of one or more cesarean sections
130
How does a c scar ectopic appear sonographically?
sac implanted in the lower uterine segment
| local thinning of the myometrium
131
Why is treatment of c scar ectopics difficult?
May result in catastrophic haemorrhage and the need for a complete hysterectomy
Treatment is protracted
dilation and curettage procedure often not advised due to the thin scar area
Medical therapy is more common, with methotrexate taken systemically and often injected locally as well.
Presence of a live embryo may require careful injection of potassium chloride into the embryo to stop cardiac activity
132
What is the sonographic appearance of a cervical ectopic?
```
intracervical location of the sac
empty fundus
closed os
Trophoblastic flow can be identified within the cervix at the site of trophoblastic invasion
hourglass appearance of the sac
```
133
What is the differential for a cervical ectopic?
impending or incomplete abortion
134
How can you differentiate between a cervical ectopic and an impending abortion?
in an aborting gestation, the sac will be oblong, the embryo (if present) will not have a heartbeat, and there will be no trophoblastic vascularity because it has detached from the uterine wall
135
What is the treatment for a cervical ectopic?
methotrexate given either systemically or locally, as opposed to hysterectomies in the past. Alternatively, potassium chloride can also be injected locally.
136
What is the main reason for abdominal ectopic?
Ruptured interstitial pregnancy
137
Where will you find an abdominal ectopic?
usually attach to the surface of the uterus, broad ligaments, or ovaries, but may also attach to the liver, spleen, or intestines
138
What may an ovarian ectopic mimic?
May mimic corpus luteum
139
How can you differentiate between a tubal/adnexal and ovarian ectopic?
moves with the ovary when examined under real time, unlike a tubal or adnexal ectopic pregnancy
140
What are the differentials for an ovarian ectopic?
ovarian tumour, chocolate cyst
141
How is a pregnancy of unknown location diagnosed?
women with a positive pregnancy test who have no evidence of either an IUP or ectopic pregnancy on TVS
142
What are the differentials for PUL?
very early IUP, an abnormal IUP, spontaneous miscarriage, and ectopic pregnancy
143
Why are PUL closely followed up?
high incidence of ectopic pregnancy
144
Briefly outline ectopic treatment
conventionally surgical
resection of the diseased tube.
Improved diagnostic capabilities allow for earlier diagnosis and the a more conservative approach
For example medical management using methotraxate
145
When is medical management most successful?
most successful in tubal pregnancies (vs. interstitial ectopic pregnancy or cervical ectopic pregnancy), those cases with smaller ectopic masses, less free fluid, and those without embryonic cardiac activity.
146
What is a common complication of medical management of an ectopic pregnancy?
A common complication is a rupture of the ectopic pregnancy, with increased pelvic pain and tenderness and the appearance of a hemorrhagic mass.
Usually these will resolve with conservative management but occasionally will require surgical intervention.
147
What is the double time of β-hCG level in a normal pregnancy
2 days
148
What happens to bhcg in patients with a failed or failing gestation
it falls
149
How is bhcg affected by ectopic implantation?
Patients with ectopic pregnancy usually have a slower increase in β-hCG
150
In what way is bhcg superior to ultrasound?
negative β-hCG level excludes the possibility of live pregnancy in a woman presenting with pain whereas a negative ultrasound does not.
151
You are a sonographer in an infertility unit. Once they are pregnant, all IVF patients are referred for a 6-week ultrasound. You see a 38 yo woman, pregnant after her 3rd cycle of IVF. She is of course very happy. She has no pain or bleeding and feels very well. On ultrasound you find an empty uterus
No gestational sac can be visualized on this ultrasound image of the uterus. In a spontaneous pregnancy this can mean 3 things:
1. The pregnancy is only 4 weeks and the patient’s dates are wrong.
2. There is a failed intrauterine pregnancy
3. There is an ectopic pregnancy.
In IVF patients
no such thing as ‘wrong dates’
not normal to have an empty uterus at 6 weeks, where you expect to see a sac, a yolk sac, an embryo and fetal heart activity.
check the adnexal region very carefully for an ectopic pregnancy (95% is in the tube but remember, an ectopic can be abdominal, ovarian, cervical or cornual as well).
Even if you can’t see an ectopic include it in your differential diagnosis
certainly if the initial hCG is above 1500 or 2000 IU/L (you should have seen an intrauterine sac if there was one).
The clinician can then recheck the hCG. If the hCG decreases, it is a failed pregnancy (this can still be ectopic but doesn’t pose a threat to the patient).
If the hCG increases further, it is certainly an ectopic pregnancy.
152
What is gestational trophoblastic disease?
represents a spectrum of diseases which arise from abnormal trophoblastic tissue
is the name given to a group of tumors that form during abnormal pregnancies.
some GTD tumors are malignant (cancerous) or have the potential to turn cancerous
the majority are benign (noncancerous)
Includes
classic hydatidiform moles (CHM)
partial hydatidiform moles (PHM)
invasive hydatidiform moles (IHM)
Choriocarcinoma
placental site trophoblastic tumors (PSTT).
Thought to originate from the fertilisation of the ovum from one or more spermatozoa in a normal or abnormal matter
153
What is the most common and benign form of gestational trophoblastic disease
Hydatidiform molar pregnancy
154
What are the two types of Hydatidiform molar pregnancy?
Complete or partial
155
What are the risk factors for Hydatidiform molar pregnancy?
teenagers and women older than 35 years of age
women with a previous molar pregnancy
risk also increases with the number of previous spontaneous abortions.
156
What is the histologic characterisation of Hydatidiform molar pregnancy?
cystic (hydatidiform) degeneration of chorionic villi
absent or inadequate vascularization
abnormal trophoblastic proliferation
Embryos or fetuses are either absent or abnormal
157
What is the clinical presentation for Hydatidiform molar pregnancy?
Vaginal bleeding (90%)
uterus may be enlarged for dates
may also be rapid uterine enlargement
pregnancy-induced hypertension
hyperemesis gravidarum
preeclampsia
hyperthyroidism
Serum β-hCG levels in molar pregnancy are abnormally elevated, usually greater than 100,000 mIU/mL
ovaries may be greatly enlarged in complete molar pregnancy by multiple, bilateral theca lutein cysts
large, usually multilocular, and may undergo hemorrhage or torsion and can be a source of pelvic pain
158
What is the treatment for hydatidiform molar pregnancy?
Uterine evacuation
accurate diagnosis and classification of molar pregnancy are important because of the risk of persistent trophoblastic neoplasia (PTN)
159
When does a complete molar pregnancy occur?
occurs when an ovum with absent or inactive maternal chromosomes is fertilized by a normal haploid sperm (occasionally by two sperm)
160
Are there fetal parts seen in a complete molar pregnancy?
embryo dies at an early age so no fetal parts are seen
161
What happens to the placenta during a complete molar pregnancy?
placenta is entirely replaced by abnormal, hydropic chorionic villi with excessive trophoblastic proliferation
162
What is the sonographic appearance of a CHM?
enlarged uterus with a central heterogeneous echogenic mass that expands the endometrial canal
mass contains multiple cystic spaces of varying size, representing the hydropic villi
cystic spaces may vary in size from a few millimeters to 2 to 3 cm
second trimester appearance typically presents as an echogenic mass containing multiple tiny cysts
used to be termed a “snowstorm” pattern
has become a “bunch of grapes.”
first trimester - variable appearance on ultrasound and difficult to diagnose
sometimes appearing as a predominantly solid, echogenic mass
sometimes as an intrauterine fluid collection
In these cases, a molar pregnancy may not be able to be differentiated from a miscarriage.
<50% are diagnosed in the first trimester
bilateral theca lutein cysts may also be seen on ultrasound
colour Doppler interrogation may show high velocity with a low impedance flow
163
What is another name for a partial molar pregnancy?
Triploidy
164
When does a partial molar pregnancy occur? PHM
fertilization of a normal ovum by two haploid sperm
165
Are there fetal parts seen in a PHM?
presence of a well-formed but growth-retarded fetus, either dead or alive with hydropic degeneration of fetal parts being frequently present
166
Why can it be difficult to differentiate between a PHM and an abortion?
Hydropic degeneration of placental villi is focal, interspersed with normal placental villi
Hydropic degeneration occurs frequently in first-trimester abortion of any cause
Abortion associated cystic spaces may be difficult or impossible to differentiate from an early mole
167
What does a placenta look like in PHM?
greatly enlarged placenta relative to the size of the uterine cavity
168
What will Doppler interrogation show?
colour Doppler interrogation may show high velocity and low impedance flow
169
How is a Coexistent Hydatidiform Mole and Normal Fetus differentiated from a PHM?
differentiated from a partial molar pregnancy by identifying a normal-appearing fetus with a corresponding normal placenta adjacent to a mass of placental tissue that demonstrates molar changes
170
What is persistent trophoblastic neoplasia?
A life-threatening complication of pregnancy that includes invasive mole, choriocarcinoma, and the extremely rare placental-site trophoblastic tumor.
171
What is the most common cause of PTN?
Occurs most often after a molar pregnancy
| Up to 20% of complete moles develop persistent disease requiring additional therapy
172
What are the risk factors for PTN?
Complete moles with severe degrees of trophoblastic proliferation are at the highest risk
patients older than 40 years of age
women who have had multiple molar pregnancies
risk of persistent disease after partial molar pregnancy is much lower
173
What are the rarer risk factors for PTN?
Less often, PTN develops after a normal term delivery, spontaneous abortion, or, in rare cases, an ectopic pregnancy
174
What is the most common form of PTN?
Invasive mole (80% to 95% of cases)
175
What is the normal presentation of invasive mole?
vaginal bleeding
| persistent elevation of serum hCG within 1 to 3 months after molar evacuation
176
Is an invasive mole benign or malignant?
biologically benign
177
Where can you find invasive molar tissue?
usually confined to the uterus
rare cases, molar tissue can lead to uterine perforation
can invade beyond the uterus to parametrial tissues, adjacent organs, and blood vessels.
Rarely, invasive molar villi may embolize to distant sites, including the lungs and brain.
178
What is the most important risk factor for choriocarcinoma?
molar pregnancy
179
What is the incidence of choriocarcinoma?
extremely rare malignancy
1 in 30,000 pregnancies.
1 in 40 molar pregnancies
180
Where may you find choriocarcinoma?
Early vascular invasion is common, resulting in distant metastases
most frequently affecting the lungs, followed by the liver, brain, gastrointestinal tract, and kidney.
Venous invasion and retrograde metastases to the vagina and pelvic structures are also common.
181
What may be the initial presentation due to early vascular invasion?
Respiratory compromise may be the initial presentation
182
What is the rarest form of PTN?
Placental-Site Trophoblastic Tumor (PSTT)
183
What type of gestation may PSTT follow?
Any type of gestation as with invasive mole and choriocarcinoma
184
When may PSTT occur?
may occur from as early as 1 week to many years after pregnancy.
185
What is the most common presentation of PSTT?
Vaginal bleeding is the most common symptom
| may present with amenorrhea.
186
Where might you find PSTT?
may be confined to the uterus
may be locally invasive in the pelvis
may metastasize to the lungs, lymph nodes, peritoneum, liver, pancreas, or brain.
187
What is not a reliable marker for PSTT?
Serum hCG is not a reliable marker for PSTT
usually negative or only mildly elevated
staining for human placental lactogen is strongly positive.
188
What is the recommended treatment for PSTT?
Surgical therapy is recommended because these lesions tend to resist chemotherapy and have a high risk of metastasis.
189
Describe the initial appearance of the PTN sprectrum?
small, myometrial lesions typical of this condition may not be apparent on TAS.
Invasive mole, choriocarcinoma, and PSTT may appear similar sonographically
focal, echogenic myometrial nodule
usually lies close to the endometrial cavity
may be found deep in the myometrium
may appear solid and uniformly echogenic, hypoechoic, or complex and multicystic, similar to molar tissue.
Thick-walled, irregular anechoic areas may be seen, resulting from tissue necrosis and hemorrhage
Some cases, anechoic areas within lesions represent vascular spaces.
190
What happens when the tumour replaces the entire myometrium?
uterus is enlarged
| myometrium appears heterogeneous and lobulated.
191
How does PTN appear in extreme cases?
PTN appears as a large, undifferentiated pelvic mass.
192
In what setting can sonography be diagnostic of PTN?
Sonography can be diagnostic in the correct setting (e.g., recent molar pregnancy, rising serum hCG, previously documented normal sonogram).
193
How do PTN lesions appear after therapy?
lesions become progressively more hypoechoic and smaller in size
Eventually, no residual abnormality is apparent in many cases
up to 50% of patients will have persistent abnormalities after therapy
may be difficult to distinguish from active lesions sonographically.
194
How does PTN appear on colour Doppler?
marked hypervascularity of invasive trophoblast
Uterine spiral arteries feed directly into prominent vascular spaces, which then communicate with draining veins
functional arteriovenous shunts produce abnormal uterine hypervascularity and high-velocity, low-impedance blood flow on duplex interrogation (high PSV and low RI)
195
What are the PSV and RI thresholds for PTN?
PSV usually > 50 cm/sec, often > 100 cm/sec. RI < 0.5, often < 0.4
normal myometrial blood PSV < 50 cm/sec and an RI approx. 0.7.
196
Comment on spectral Doppler PTN
```
not unique to PTN
seen in all conditions with functioning trophoblast including;
failed pregnancy
retained products of conception
ectopic pregnancy.
```
197
When is colour and spectral Doppler useful in assessing PTN?
when PTN is not suspected clinically, duplex and color Doppler sonography may provide the first indication of trophoblastic disease by showing marked hypervascularity and typical trophoblastic blood flow within lesions.
Doppler ultrasound also improves diagnostic specificity by showing normal uterine waveforms when PTN is absent and sonography is abnormal
198
How is PTN usually diagnosed?
diagnosis is usually based on abnormal regression of hCG after uterine evacuation
199
What is the exception to the usually diagnosis of PTN?
With the exception of PSTT, hCG level is a sensitive and specific marker for detecting and monitoring PTN
