The Cervix In Pregnancy Flashcards
What are methods to assess the cervix? 3
- Trans abdominal sonographic approach
- Translabial sonographic approach
- Transvaginal sonographic approach
What is a limitation of trans abdominal ultrasounds?
Need a partially full bladder
What happens if we pass the limitation for the trans abdominal ultrasound?
If the bladder is too full the over distended bladder will result in a falsely elongated cervix
What does this image demonstrate?
A transabdominal cervix
What does this image demonstrate?
An over distended bladder when and the effect it has on the cervix for a trans abdominal exam
What does this image demonstrate?
A uterine contraction
How do we measure a uterine wall and contraction?
When do we utilize translabial ultrasound?
Utilized when ruptured membranes have occurred
Can translabial ultrasounds can be performed with placenta previa?
Yes
What are some benefits and disadvantage of doing a translabial ultrasound?
Benefit: Empty bladder
Disadvantage: Gas in the rectum
What does this image demonstrate?
Translabial ultrasounds
What is the most accurate method of measuring the cervix?
Transvaginal
How far do we insert the probe for a Transvaginal ultrasound?
3 to 4cm
What is the Transvaginal ultrasound contraindicated with?
Ruptured membranes
Transvaginal ultrasounds may cause what?
Bleeding or contractions
What does the cervix look like sonographically?
Echogenic canal: may appear hypoechoic on occasion
What does this image demonstrate?
Translabial ultrasound
What is the length of the normal cervix?
Lower limit of normal is 30mm or 3cm
any shorter than 3cm = shortening or effacement
What are the cervix ranges for effacement?
- 15mm corresponds with 50% effacement
- 10 mm corresponds with 75% effacement
What does this image demonstrate?
The cervical gland area in EV
What is happening in the below images? Label what is happening from left to right
- Cervix is not effaced
- Cervix is 50% effaced
- Cervix is fully effaced
What is funneling of the cervix?
Defined as herniation of the fetal membranes into the internal OS, but the external os remains closed
Funneling of the cervix is a early sign of what/
Incompetent cervix
Funneling of the cervix has a increased risk of what?
Preterm delivery
Is it possible to carry pregnancies to term with funneling of the cervix?
Some pregnancies will carry to term without intervention
When we do a Transvaginal what do we need to do?
Have the patient insert the probe live
What does this image demonstrate?
Funneling cervix
What does this image demonstrate?
Echogenic amniotic fluid sludge
What is abnormal for a AP diameter of a dilated cervical canal?
> 5mm before 30 weeks
Contractions in lower uterine segment can be confused with what?
Cervical incompetence
How often does cervical incompetence happen?
~1 in 100 pregnancies
What happens with cervical incompetence?
Cervix shorten, shortens or opens to early
What kind of process is cervical incompetence?
It is a dynamic process because the cervix changes spontaneously dramatically in a short period of time
Any one can develop cervical incompetence but there is higher risk if what? 6
- Irregular shaped cervix or uterus
- History of premature birth or miscarriage in the 2nd trimester
- Injury to cervix or uterus during a previous pregnancy
- History of surgery to cervix
- A genetic disorder like Ehlers- Danlos syndrome (which may cause cervical weakness)
- Expecting multiples
Cervical incompetence can happen when? (Weeks)
Any time but typically between 14-27 weeks
How does cervical incompetence present?
Presents as painless cervical dilation on US
What is cervical incompetence similar to?
Preterm labour
Cervical incompetence patients experience similar preterm labour symptoms such as what? 2
- Contractions strong enough to change the length of the cervix
- Cervix will shorten and dilate with these contractions
What does normal preterm labour contractions Present like? 2
- Contractions that are changing the length of the cervix
- Stronger than Braxton Hicks contractions but mom has difficulty differentiating between the two
What is cervical cerclage?
A purse string suture that is applied to the cervix
When is the cervical cerclage usually inserted?
Between 13 and 16 weeks in patients with known incompetent cervix
What does cervical cerclage result in?
Increased risk of amnionitis and rupture of membranes form the procedure
What does this image demonstrate?
Cerclage
When is cerclage placed?
After bulging membranes occurs
Even if we place the cerclage after bulging membranes, what happens?
Still carries a 30% pregnancy loss rate
What is important in terms of cerclage timing?
Early diagnosis
How does the cerclage appear on ultrasound?
Appears as hyperechoic linear structure usually with acoustic shadow seen in the anterior and posterior cervix
Ultrasound is used to assess _________ as well as _______ ______ and _____ the cerclage.
- Placement
- Funnelling
- Above
- Below
What is a preterm birth?
Labour and/ or delivery before 37 weeks
How often does preterm L and D happen?
5-10% of all pregnancies
Even with all the careful screening has the preterm birth rate changed in the last 30 years?
No
What are some clinical risks for preterm labour? 3 (what increases the risk)
- Twins, multiples
- Congenital malformation of the uterus
- Previous preterm labour
For those with risks for preterm labour, they require what?
EV assessments of the cervix at each fetal assessment visit until 32 weeks gestation
What is a low laying placenta and what does that mean for us?
- Placenta must be >2cm away from the internal OS and it is under 2cm from internal OS it will be dubbed Low lying
- We need to do a Cervical EV scan
What is marginal placenta previa?
Placenta just touching the internal OS but not covering it
When do we stop doing the EV scans of low laying placenta?
EV scanning is required at each fetal assessment visit until a minimum of 2cm is reached
What is one thing we must always examine within the uterus?
Always examine the area within the uterus just superior to the internal OS of the cervix wit Colour doppler on every EV performed
Wha is Vasa previa?
Vessels across the internal OS of the cervix
What is Vasa previa associated with?
A succentuiate placenta
What is a succenturiate placenta?
Placenta with an accessory lobe connected by vasa previa
What is the difference between preterm labour and incompetent cervix?
Incompetent cervix are painless and if they had previous second trimester losses