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Sonography of the Cervix“An Update”

• Sonographic Anatomy

• How to measure• Key questions

• Important US features

• Treatment

• Surveillance

Overview

VaginaOuter muscular layer (1/4)Inner layer – Collagen (3/4’s)

- Source strength / elasticityEctocervixEndocervix / Cervical mucous plug

Sonographic Anatomy

• Outer wall hypertrophies• Inner collagen wall

• Reabsorped / Replaced by fluid• Cervix softens

Anatomy

• Morbidity / Mortality• 7.5% of all pregnancies (O’Hara 2015)

• Monash Obstetrics M&M

• Poorly Understood

Cervix: Pre-term birth

https://www.sciencenews.org/article/mom-immune-system-microbiome-may-help-predict-premature-birth

• Cervical Insufficiency- (Structural failure)• Congenital

• Rare- Uterine Abnormalities

• Acquired • Prev Cx Intervention/ Obstetric trauma

• Recurs

• Preterm Ripening- (Cervical ‘softening’)• Infection, Recurrent haemmorhage

• Doesn’t recur

• Treatable Conditions

Cervix: Pre-term birth

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• Treatable: Cerclage ✓• Prophylactic- 2x mid losses

• Cervix < 1cm

• Importance U/S High Risk

• Cervical Pessary ~

• Bed Rest ~ Ｘ• Progesterone Ｘ

Preterm birth: Cervical Insufficiency (Single)

• Treatable: Vaginal Progesterone ✓ (Fernandez-Macias R 2019)

• Cervical Pessary ~• Bed Rest ~ Ｘ

• Cerclage Ｘ

Preterm birth: Preterm Ripening (Single)

• 3x risk perinatal mortality (Murray 2018)• Prematurity key contributor

• Treatable: Vaginal Progesterone ? (Norman 2016, )

• Cervical Pessary Ｘ (Conde-Agudelo A 2020)

• Bed Rest Ｘ

• Rescue Cerclage ? (Abbas 2018))

Preterm birth: Multiple Pregnancy

https://depositphotos.com/32062211/stock-video-medical-doctor-negative-shrug-and.html

• Very high risk: eg Multiple losses• Cerclage- Monitor with Ultrasound

• High Risk• Prev Cx Intervention, Prev. Preterm bith

• 16,18, 20, 22, 24 week scans

• Low Risk• 20 week Ultrasound

• No cervical assessment• After 28 weeks

Pre-term birth risk stratification

https://www.whattoexpect.com/second-trimester-of-pregnancy.aspx

• All about Cervical Length (Iams 1996)

• Closed length of cervix

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• Do not exert undue pressure.• Equal AP diam

• Magnify the image- 75% of the image

Measurement: Cervix

• Straight not Curved

Measurement: Cervix

Image from Pedretti

• Take 3 measurements/ min. 3 minutes (5 mins)

Measurement: Cervix

• Unhelpful

• n = 109

• 43 asymptomatic /66 symptomatic preterm labour• 10 min cervical US

• Fundal pressure- No benefit -shortest length

Fundal Pressure ?

US O&G 2004

• Not an independent risk factor• Not useful -Stratifying risk (Hughes 2016)• Emotive term

• Clinician vary: Need to know?

Funneling

• Increases preterm birth• Asymptomatic + Short cervix

• Marker for haemmorhage/ infection• Dilemma for clinicians

• No treatment

• Value? - Maybe amnio before rescue cerclage

Intra-amniotic debris

Ultrasound Obstet Gynecol. 2018

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Placental location / Vasa Previa

• 85% -PTB, No History (Parry et al)• Single measurement/ Surveillance?• Transabdominal/ Transvaginal?

• Resources, Time, Cost Interventionvs Yield/ benefit

The low risk woman ?

Universal Screening Ineffective (2018)

• Routine TV scanning (Hyett 2011)

• n= 380 cervix TA

• 17- short cervix

• 1 detected transabdominally

• Ultrasound missed 16/17

Low Risk- Second Trimester Screening

“ ALL Second Trimester morphology scans should

include a TV scan for the cervix”

• Other literature• TA- Ultrasound missed 62% short cx

• Some evidence Transabdominal – ‘Good’ test• Operator dependant

• Monash – Low risk women• Single transabdo meas.-20weeks

• Rules• Empty Bladder

• Int os/ Ext os clear• Image- Colour

• Straight

• If

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• Dr Peter Neil

• MH: Sonographers, Radiologists• Women’s Health Obstetricians

Acknowledgements