Ultrasound Flashcards
What are the 5 ultrasound features that can help calculate the RMI score?
- Mutilocular cyst
- Presence of solid areas
- Bilaterality of lesions
- Presence of ascites
- Presence of intra-abdominal metastases
SOGC 230
In the first trimester, if the EDC from the LMP and the ultrasound calculated CRL is different by more than how many days should the EDC be changed?
Before 9 weeks, if there is a discrepancy of more than 5 days between the GA of the LMP and the CRL, then we should use the EDC of the CRL from the ultrasound.
Between 9 and 13+6 weeks, the discrepancy should be more than 7 days.
Berghella Obs Chapter 4
At how many weeks of gestation should the nuchal translucency be performed?
Between 10+6 and 13+6 weeks.
Or CRL of 45-84mm
Berghella Obs Chapter 4
Name the 3 diagnostic criteria for embryonic or anembryonic demise in the first trimester.
1) Mean gestational sac diameter >=25mm without embryo
2) CRL>= 7 mm with no visible cardiac activity
3) No embryo with cardiac activity if:
>= 14 days after gestational sac without yolk sac
OR >=11 days after gestational sac with yolk sac
Berghella Obs Chapter 4
What is the best non-invasive screening test for fetal anemia?
Fetal middle cerebral artery (MCA) peak systolic velocity (PSV)
Berghella Obs Chapter 4
Name indications to send pregnant women for fetal echocardiography. (13)
Maternal indications:
1) Autoimmune antibodies (anti-Ro/anti-La)
2) Familial inherited disorders (22q11.2 deletion syndrome)
3) IVF
4) Metabolic disease (pregestational diabetes, phenylketonuria)
5) Teratogen exposure (e.g. retinoids, lithium)
Fetal indications:
6) Abnormal cardiac screening exam
7) First degree relative of fetus with CHD
8) Abnormal heart rate or rhythm
9) Fetal chromosome anomaly
10) Extracardiac anomaly
11) Fetal hydrops
12) Increased nuchal translucency
13) Monochorionic twins
Berghella Obs Chapter 4, p.55
What is the rate of PTB in Canada?
8%
SOGC 375
What is the incidence of short cervix defined as <25mm at 24wk in Canada?
3%
based on one study only
limited data in the Canadian population
SOGC 375
Screening for short cervix with TVUS has a good:
?sensitivity, specificity, NNV, PPV
specificity
NPV
In the Canadian study, Sens 13%, Spec 97%, PPV 19%, NPV 95%.
SOGC 375
In a low-risk nulliparous population, CL <25mm at 16-22wk identified % PTB?
8%
SOGC 375
If changing the focus from general population CL screening to patients with RF for PTB (LEEP, previous PTB, uterine anomaly), which statistical parameters will increase
PPV
Sensitivity and specificity are not influenced by the incidence in the population
NNT will likely decrease
SOGC 375
What techniques can prevent PTB in patients with short CL by US at 24wk?
vaginal progesterone
cerclage if prior PTB
cerclage= weak evidence, not approved by Health Canada for this reason
SOGC 375
Comment on use of CL as a screening tool.
Use the elements of a screening test
- easy to do: yes, acceptable to patients and safe
- accessible: no, only large and medium centres can offer
- condition prevalent in the population: no, unclear –incidence in the Canadian population, only one study showed 3% CL <25mm 16-22wk
- actual detection of PTB: no, only detect 8% of PTB
- presence of a treatment: yes, PV progesterone
- cost effective: unknown; 4 studies looked at this and said yes, however based on a prevalence that is higher than actually described in the literature.
SOGC 375
SOGC T1 US refers to US up to how many weeks
14 wk GA
SOGC 374
Why do HEG patients need T1 US
rule out:
- SAB
- ectopic
- molar
- twins
assess:
- dating
- early anatomy
SOGC 374
Why do T1 TAB needs US
- confirm IUP
- confirm dating (eg. mifemyso only at certain GA)
SOGC 374
List reasons for T1 US
dating rule out twins: if so, access chorionicity, amnionicity rule out molar SAB/TAB assessments IUP- rule out ectopic, C-scar accreta assessment early anatomy, NT screen prior to procedure: cerclage, CVS, reduction NOT for diagnosis of pregnancy pelvic mass assessment PET screening
SOGC 374
What are the components of T1 PET risk assessment algorithm?
Centres that have expertise and resources should do it. Includes: -bilat UA dopplers (PI) -maternal MAP -maternal PAPP-a -PGF 11-14 wk -maternal history
this algorithm detects 77% early onset PET, 43% term PET, FP rate of 10%.
SOGC 374
What is the risk reduction in PTB when vaginal progesterone is prescribed for CL <25mm at <24wk?
decreases risk by 38% to deliver by 33wk
SOGC 375
A 35yo G2P1 at 19+3 with previous PTB at 27 weeks is found to have CL 22mm at 19week anatomy US. What is the indicated treatment?
cerglage
OR
vaginal progesterone
SOGC 373
What are indications and contraindications for emergency cerclage?
cervix >1cm open
up to 4+ cm. before 24 weeks
no contractions
no chorio
normal anatomy, N serum/NT screen
SOGC 373
What are the indications for cerclage removal?
routine 36-38wk
PTL not responding to tocolysis
strong suspicion of sepsis
PPROM within 48h (allows for beta; cannot wait if elevated CRP)
SOGC 373
What are maternal risk factors for cervical insufficiency?
previous T2 loss/ PTB hx of LEEP hx of TAB hx of cervical manipulation CS for FTD cervical tear/laceration DES exposure PPROM<32weeks congenital uterine anomaly connective tissue disorder
index pregnancy RF for PTB: funnel, short cervix
SOGC 373
What are the steps to do prior to vaginal cerclage?
verify: N anatomy, viable
low risk trisomy (NT, serum screen)
UA, UCx
vaginal culture for BV
SOGC 373
What infection should you screen for in a patient with PTB?
BV
(in addition to routine UCx, GC)
SOGC 373
What are the indications for an abdominal cerclage?
previous trachelectomy
3+ mid-trimester losses or early PTB only if: previous vaginal cerclage unsuccessful
SOGC 373
What is the effect of having a cerclage on FFN?
discuss PPV and NPV effects
worse PPV
NPV not affected
SOGC 373
When should the 1st T2 US be scheduled in a patient with a previous 23 wk loss?
16 weeks or 2 weeks prior to T2 loss, whichever is earlier. Then Q7-14 days.
SOGC 373
What kind of frequency and energy are the sound waves for US?
high-frequency, low energy
SOGC 304
Should you do US for determining gender?
Not for this sole reason
not for fun
US use only for diagnostic/screening- kept to minimum
only theoretical risk
SOGC 304
