First trimester Uterine Artery - PowerPoint Presentation

Slide1

First trimester Uterine Artery Cervival length

E.Keshavarz

MD

Mahdiye

Hospital

SBMU

Slide2

PreeclampsiaPreeclampsia, which affects about 2% of pregnancies, is a major cause of

perinatal

and maternal morbidity and mortality

The likelihood of developing preeclampsia is increased by a number of factors in the maternal history, including

Afro-Caribbean race,

nulliparity

, high body mass index and personal or family history of preeclampsia

. However, screening by maternal history may detect only about

30%

of those that will develop preeclampsia for a

false positive rate of 5%.

Slide3

measurement of the uterine artery

pulsatility

index (PI) at 11-13 weeks' gestation in combination with

maternal history

(inc)

mean arterial pressure

(inc)

serum PAPP-A

(

dec

…>inc)

placental growth factor (PLGF)

(

dec

…>inc)

The factors in the maternal history that appear to make a significant independent contribution to the preeclampsia risk assessment included

maternal BMI, age, ethnicity, smoking, and parity.

Slide4

Early rather than late preeclampsia is associated with an increased risk of perinatal mortality and morbidity and both short-term and long-term maternal complications.

Combination of the above mentioned risk factors was shown to predict

90%

of early preeclampsia,

35%

of late preeclampsia, and

20%

of gestational hypertension.

This compares favorably with screening based on maternal history alone where only

30%

of early and

20%

of late preeclampsia are predicted for a 5% false positive rate.

Slide5

Slide6

Sagittal

section of the uterus must be obtained and the cervical canal and internal cervical

os

identified. Subsequently, the transducer must be gently tilted from side to side and then

colour

flow mapping should be used to identify each uterine artery along the side of the cervix and uterus at the level of the internal

os

.

Pulsed wave Doppler should be used with the sampling gate set at

2 mm

to cover the whole vessel and ensuring that the angle of

insonation

is

less than 30º

. When

three similar

consecutive waveforms are obtained the PI must be measured and the mean PI of the left and right arteries be calculated

Slide7

confirm that the vessel being

1-the direction of the blood flow should be towards the transducer when the

transabdominal

approach is used. This assures that the cervical branches are not being

insonated

.

2-the peak velocity of the

insonated

vessel should be 60 cm/sec or greater. This assures that the main uterine artery is being

insonated

rather one of its branches.

Slide8

The presence of a normal uterine artery flow velocity waveform bears a

high negative predictive value

, with a likelihood ratio of 0.5 and 0.8 for the development of preeclampsia and IUGR respectively.

Slide9

Uterine artery

Non

preg

: Low peak sys-early

dia

notch

Before 18-22 w: High peak sys

Early

dia

notch

After that: High EDV

NO

dia

notch

Slide10

Cervical length

Transabdominal

sonography (TAS)

Transvaginal

sonography (TVS)

Transperineal

(

translabial

) sonography

Slide11

The

closed length of the cervix

is the

single most important parameter

to report, as it is most closely linked to the risk of PTB.

Slide12

TAS

Second-

and

third-trimester

 

The bladder

often needs

to be

adequately

filled

to obtain a good image, resulting in

elongation

of

the

cervix

and

masking

of

any

funneling

of

the 

internal

os

.

Fetal parts

can obscure the

cervix

, especially after

20

weeks.

- The

distance

from

the

probe

to

the

cervix

results in

degraded

image

quality.

Obesity

and

manual

pressure

interfere with

the

resulting

image.

Cervices

less than 2 cm in length

cannot be easily visualized against the vaginal and bladder tissue

.

Slide13

Research has demonstrated conflicting results

regarding the usefulness of TAS screens in that the cutoff in TAS to identify a cervix length of

25 mm

or less is

variable.

Slide14

  TAS  should  not  be  used

  for  assessment  of  the  cervix,  even  as  a  screening  test,  because  its  sensitivity  for  prediction  of  disease

and relatively

  poor  reliability  and  validity.

Slide15

TVSAll major guidelines and text books that have described

CL 

screening have clearly recommended TVS.

Slide16

Transperineal/Translabial

Approach

Cervix

cannot be adequately visualized by TAS, and in whom TVS is unacceptable for personal or discomfort-related concerns.

Empty

urinary

bladder.

abdominal

transducer

with a frequency of 3 MHz or higher

Full

length of the cervical canal can be visualized in 86% to 96

%

Reproducibility

of the

measurements(intra /inter observer variability) is poor.

Slide17

TVS

Reference-standard technique

Empty

urinary

bladder

Insert

transvaginal

probe to view the cervix, withdraw probe until the image blurs to reduce compression from the transducer, then reapply just enough pressure to create best

image

Visualize

the cervix for

3-5 minutes

and watch for shortening or

funneling

Slide18

Technique

The cervix occupies approximately 75% of the image.

The bladder area is visible

The echogenicity is similar for both anterior and posterior portion

Calipers

are placed where the anterior and posterior walls of the cervix touch at the internal

os

and external

os

.

Slide19

Slide20

Safe and acceptableThere

was

no

increased

risk

of

infection

for

mother

 

or fetus

with TVS of the cervix compared with no TVS of

the

cervix.

TVS has also been deemed safe to use in patients with placenta

previa

with no increased risk for

bleeding

; however, caution is advised to ensure that the probe is always carefully inserted under real-time

visualization.

Slide21

Reliable/reproducible

The

interobserver

and

intraobserver

vari

­ ability 

scores of

TVS

are both less than

10

%.

Slide22

Pitfalls

lower uterine segment contraction, immediately superior to the cervix, may result in a

pseudoelongation

of the cervix

length

of the cervix

>

5

cm

Thicker

diameter of the “cervix” at the proximal

extent

.(The

thickness of the internal and external cervical

os

should be

similar).

Lower

uterine segment contractions are transient and rarely persist beyond

15

minute

.

Slide23

Pitfalls

lower uterine segment contraction has been termed “

pseudodilation

” of the cervix, false appearance of a “funnel” above the closed cervix.

length

of the cervix

>

5

cm

transient

nature of this appearance

Slide24

Cervical Funneling

Dilation

of the internal

os

and the herniation of the fetal membranes into the cervical

canal by

more than 5mm.

 

percentage of funneling

 

:

funnel

L

/total

 

CL

(funnel L + functional L(closed CL))

Slide25

Cervical Funneling

Minimal funneling

(<25%/

common

finding)

noted between

 

14 and 22 weeks was not associated with

a 

significant increase in PTB

Moderate funneling

(25-­50

%) and

severe 

funneling

(>50

%) were associated with a 50% or

 

more probability of PTB.As an isolated finding compared with cervical length, the residual closed length measurements have a better predictive value than funneling.

Slide26

Shape of funneling ?

T

represents a closed normal cervix.

Y

represents a small funnel, which if

less than 25%,

with residual cervical length of 25 mm or greater, may not be clinically significant.

V

represents a more significant funnel, extending closer to the external

os

.

U

represents the funnel of most

concern.

Slide27

It appears that

U­shaped

funneling is more likely to be associated with PTB compared with a

V­shaped

funnel.

The

shape or size of the funnel

was not correlated

to SPTB. As such, funneling is best reported as a categorical variable (present or absent)

.(

Rumack

)

Slide28

If funneling is present, the CL is almost always short  (<25 mm) .

On the contrary, the presence of funneling in a woman with a normal (=25 mm) CL does not seem to increase her risk of PTB.

In the presence of a short CL, the presence of funneling may or may not add to the prediction of PTB or adverse

perinatal

outcome.

Compared with a CL less than 25 mm alone,  adding funneling can increase the sensitivity  for  PTB  (from 61-­74%)

Slide29

Report the functional length.

If it is lower than 25 mm then report the funneling if it is more than 25% and U shape.

Slide30

Progressive

shortening

of the cervix may be more important than a single abnormal cervical length

measurement.

“

Short

and shortening

” cervical length may be a more effective tool for SPTB prediction than a “

short but stable

” cervical length.

The

odds ratio for SPTB increased 6.8-fold per unit of change (one unit =

decline of 10 mm per

month

)

Slide31

Dynamic cervix:

In  less  than  5%  of 

transvaginal

  sonographic  examinations,  CL  may  change  dynamically  during  the  course  of 

a 3 to 5 ­minute

 

examina

tion

.

The

 shortest CL should be recorded

The

value of a dynamic cervix for the prediction of SPTB is less clearly defined than that of a short

cervix.

Slide32

Noninvasive stress techniques :

Transfundal

pressure(most effective) (pressure applied at the

fundus

for 15 seconds that elicits >5 mm in cervical length shortening)

Standing

Coughing

Most cases in which the cervix shortens spontaneously or in response to TFP, it is already abnormal at baseline.

Slide33

Normal versus abnormal CL

A normal CL measures

25 to 50 mm

at 14 to

30

weeks of gestational age.

(

25

mm is approximately the 10% percentile for

low­risk

(i.e., without a prior spontaneous PTB)

singletons)

)

A

short CL

is

less than 25 mm

obtained at 16 to 24w A CL greater than 50 mm can be normal but warrants scrutiny, for it may reflect a measurement that includes the lower uterine segment, as often happens before 16

weeks.

Slide34

Each feature is associated with an increased risk of PTB

independent

of cervical length.

Canal dilation

:

2 to 4 mm

was associated with a 5.5-fold increased risk of SPTB

.

Absence

of the glandular area along the length of the

canal

:

hypoechoic

zone that runs along the length of the cervical

canal

Amniotic

fluid debris

: “Sludge” or debris can be observed at ultrasound examination as free-floating echogenic material in close proximity to the

cervix(

sludge

is an independent risk factor for SPTB

,

PPROM, increased concentration of microbes within the amniotic fluid, and histologic

chorioamnionitis

in asymptomatic

patient

)

Slide35

BEST GESTATIONAL AGE AND FREQUENCY OF EXAMINATIONS

Very

early screening

(

<14w

)

is that the lower uterine segment is difficult to distinguish from the true cervix in the late first and early second

trimesters.

CL 15 to 24 mm

, after

30

weeks can be physiologic and not associated with an increased risk of PTB in asymptomatic women.

Slide36

General Obstetric Population Screening

ONLY

10

%

of spontaneous early PTBs occur in women with a prior history

.

low risk : Screening 18-22w(TAS versus

TVS

)

During

TAS

for low risk in 18-22 w:

C

losed

cervical length is

less than 25 mm

any time before 28 weeks of

gestation

Suspicion of findings such as a dilated cervical canal Ballooned fluid-filled lower segment with no visible cervixC

ord

or fetal part in the canal

F

urther

evaluation of the cervix by

TVS is indicated.

Slide37

Very high ­risk women(prior second trimester loss or history of a large or repeated cervical cone biopsy

):

Before 14 weeks(12-

14

w) f/u q 2w

until

24

w

Slide38

Women with cerclage

T

ransvaginal

cerclage

is placed in the middle portion of the cervix in the vast majority of

case

Transabdominal

cerclage

is instead placed at the level of the internal

os

Slide39

Slide40

The higher (closer to the internal

os

) the

cerclage

suture is placed, the more effective the prevention of PTB.

CL measurement usually increases after

cerclage

.

CL less than 25 mm and

upper cervix

(the closed portion located above the level of the

cerclage

)

less than 10 mm are probably the two best predictive parameters.

Slide41

Twins:

Compared

with singleton

:similar TVS ­CL

at 14 to 19 weeks but a progressively shorter cervix after 20 weeks’ gestation

.

TVS

of the cervix

before

20 to 24

weeks

may lead to better prediction of PTB

.

Before 14 weeks(12-14w) f/u q 2w until 24w

A

CL

of 25mm or less at 24 weeks’

gestation has

 

been found to be the

best predictor

of PTB in twins.

Slide42

Slide43

Slide44

CCI=51%

Despite CL of 39mm and NO risk of PTB the patient had PPROM and pregnancy terminated in 35 weeks .

Slide45

CCI=54%

GA at birth=36w

Slide46

The cervix can loose up to 40% of its consistency with no evidence of changes in its length.

CCI

assessment during second trimester performs significantly better prediction of PTB<37 and <34 weeks than CL measurement with higher sensitivity(60%) comparing with CL(31.8%)

Slide47

Slide48

Thanks