Chapter 18 Ultrasound evaluation of the cervix HHHOLDORF Ultrasound of the Cervix Outline Patient History Cervical Anatomy and Histology Functionality Normal cervical Lengthmeasurements Normal cervical Position ID: 910457
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Slide1
SON 2122Obstetrical Sonography Part II
Chapter 18- Ultrasound evaluation of the cervix
HHHOLDORF
Slide2Ultrasound of the Cervix
Slide3Outline
Patient History
Cervical Anatomy and Histology
Functionality
Normal cervical Length/measurements
Normal cervical Position
The Lower Uterine Segment
Cervical Incompetence/insufficient cervix
Investigating the cervix
Insufficient Cervix (again)
Cervical funneling
The Hourglass sign
Cervical Cerclage
Pre—term labor
PROM
Placental Previa
Definitions
Slide4Prior to beginning the ultrasound examination, it is helpful for the sonographer to obtain a brief patient history. Information should include:
the first day of the last menstrual period (LNMP or LMP)
Results of any pregnancy tests
The presence of any clinical problems (pain, fever, bleeding, etc.)
Any pertinent medical history
the clinical estimation of the duration of the pregnancy
Slide5The cervix
(from Latin "neck") is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall. Approximately half its length is visible with appropriate medical equipment; the remainder lies above the vagina beyond view. It is occasionally called "cervix uteri", or "neck of the uterus".
The portion projecting into the vagina is referred to as the ectocervix. On average, the ectocervix is 3 cm long and 2.5 cm wide. It has a convex, elliptical surface and is divided into anterior and posterior lips.
Slide6Cervical diagram
Slide7External os
The ectocervix's opening is called the external os. The size and shape of the external os and the ectocervix varies widely with age, hormonal state, and whether the woman has had a vaginal birth. In women who have not had a vaginal birth the external os appears as a small, circular opening. In women who have had a vaginal birth, the ectocervix appears bulkier and the external os appears wider, more slit-like and gaping.
Slide8Endocervical canal
The passageway between the external os and the uterine cavity is referred to as the endocervical canal. It varies widely in length and width, along with the cervix overall. Flattened anterior to posterior, the endocervical canal measures 7 to 8 mm at its widest in reproductive-aged women.
Slide9Internal os
The endocervical canal terminates at the internal os which is the opening of the cervix inside the uterine cavity
Slide10The internal and external os
Slide11Histology
The epithelium of the cervix is varied. The ectocervix (more distal, by the vagina) is composed of stratified Squamous epithelium The endocervix (more proximal, within the uterus) is composed of simple columnar epithelium.
The area adjacent to the border of the endocervix and ectocervix is known as the 'transformation zone. The Transformation zone undergoes metaplasia numerous times during normal life. When the endocervix is exposed to the harsh acidic environment of the vagina it undergoes metaplasia to Squamous epithelium which is better suited to the vaginal environment. Similarly when the ectocervix enters the less harsh uterine area it undergoes metaplasia to become columnar epithelium.
Times in life when this metaplasia of the transformation zone occurs: - puberty; when the endocervix everts (moves out) of the uterus - with the changes of the cervix associated with the normal menstrual cycle - post-menopause; the uterus shrinks moving the transformation zone upwards
All these changes are normal and the occurrence is said to be physiological.
However all this metaplasia does increase the risk of cancer in this area - the transformation zone is the most common area for cervical cancer to occur.
At certain times of life, the columnar epithelium is replaced by metaplastic Squamous epithelium, and is then known as the transformation zone.
Nabothian cysts are often found in the cervix.
Slide12The Pap test (AKA
Pap smear
, cervical
smear
, or
smear test
) is a method of cervical screening used to detect potentially pre-cancerous and cancerous processes in the cervix.
A Pap smear is performed by opening the vaginal canal with a speculum, then collecting cells at the outer opening of the cervix at the transformation zone (where the outer squamous cervical cells meet the inner glandular endocervical cells).
The collected cells are examined under a microscope to look for abnormalities.
Slide13Cervical position
After menstruation and directly under the influence of estrogen, the cervix undergoes a series of changes in position and texture. During most of the menstrual cycle, the cervix remains firm, like the tip of the nose, and is positioned low and closed.
However, as a woman approaches ovulation, the cervix becomes softer, and rises and opens in response to the high levels of estrogen present at ovulation. These changes, accompanied by the production of fertile types of cervical mucus, support the survival and movement of sperm.
Slide14Functionality
During menstruation the cervix stretches open slightly to allow the endometrium to be shed. This stretching is believed to be part of the cramping pain that many women experience. Evidence for this is given by the fact that some women's cramps subside or disappear after their first vaginal birth because the cervical opening has widened.
During childbirth, contractions of the uterus will dilate the cervix up to 10 cm in diameter to allow the fetus to pass through.
Slide15Normal cervical length (30mm or 3cm)
CL in the first trimester has no clinical value
CL normally decreases slightly between 20 and 32 weeks and more considerably after 32 weeks.
between 22 and 30 weeks, CL follows a normal bell-shaped curve:
5
th
percentile @ 20mm
10
th
percentile @ 25 mm
50
th
percentile @ 35 mm
90
th
percentile @ 45 mm
The median CL is 40 mm before 22 weeks, 35 mm at 22 to 32 weeks, and 30 mm after 32 weeks. CL is not affected much by maternal age, race, gravidity or parity.
Cervical shortening is indicated if CL is less than 25 mm (2.5 cm) between 22 and 30 weeks.
Slide16CL (cervical length)
is measured from internal to external os.
-Evaluated for shortening (effacement) and Funneling.
-Measurements of the cervix can be preformed after 15 weeks gestational age, when the cervix normally becomes distinct from the LUS.
Slide17Slide18Lower Uterine Segment
Lower uterine segment(LUS)
– does not have a definite sonographic identity prior to or during the different stages of labor and delivery. Can be considered the portion of the uterine body closet to the inner os of the cervix.
LUS and the internal os are evaluated with Color Doppler for the possibility of vasa previa (blood vessels in that region which could cause hemorrhaging with vaginal delivery).
Slide19Lower Uterine Segment
Slide20The LUS-lower uterine segment – does not have a definite sonographic identity prior to or during the different stages of labor and delivery. Can be considered the portion of the uterine body closet to the inner os of the cervix.
Techniques to evaluate the cervix include TAS, TPS, and EVS. (Trans-abdominal, Trans-Perineal- and Endo-vaginal sonography.
CL (cervical length) is measured from internal to external os.
Evaluated for shortening (effacement) and Funneling.
LUS and the internal os are evaluated with Color Doppler for the possibility of vasa previa (blood vessels in that region which could cause hemorrhaging with vaginal delivery.
Slide21Cervical Incompetence/Insufficiency
Cervical incompetence
is a condition in which a pregnant woman's cervix begins to dilate (widen) and efface (thin) before her pregnancy has reached term. Cervical incompetence is a cause of miscarriage and preterm birth in the second and third trimesters.
In a woman with cervical incompetence, dilation and effacement of the cervix occur without pain or uterine contractions. Instead of happening in response to uterine contractions, as in normal pregnancy, these events occur because of weakness of the cervix, which opens under the growing pressure of the uterus as pregnancy progresses. If the changes are not halted, rupture of the membranes and birth of a premature baby can result. It is thought to cause as many as 20—25% of miscarriages in the second trimester.
Risk Factors
Risk factors for premature birth or stillbirth due to cervical incompetence include:
diagnosis of cervical incompetence in a previous pregnancy,
previous preterm premature rupture of membranes,
history of cervical biopsy
*DES exposure, which can cause anatomical defects, and
uterine anomalies.
Treatment
Cervical incompetence is not generally treated except when it appears to threaten a pregnancy. Cervical incompetence can be treated using cervical Cerclage, a surgical technique that reinforces the cervical muscle by placing sutures above the opening of the cervix to narrow the cervical canal.
Slide22DES (Diethylstilbestrol) exposure
Diethylstilbestrol (DES) is a synthetic form of the female hormone estrogen. It was prescribed to pregnant women between 1940 and 1971 to prevent miscarriage, premature labor, and related complications of pregnancy. The use of DES declined after studies in the 1950s showed that it was not effective in preventing these problems.
DES
is linked to a rare cancer called clear cell adenocarcinoma (CCA) in a very small number of daughters of women who used DES during pregnancy.
This cancer of the vagina and cervix usually occurs in DES-exposed daughters in their late teens or early 20s.
Slide23Techniques to evaluate
the cervix
include Trans abdominal Sonography, Trans Perineal Sonography and Endovaginal Sonography.
Focal uterine contractions, fibroids, and even Nabothian cysts can interfere with cervical interpretation.
Slide24TA evaluation-
Full bladder. Pitfalls: Overdistended bladder can elongate the cervix. Interference from the presenting fetal part can interfere with adequate cervical visualization.
Large maternal body habitus can result in inferior image quality.
Trans-perineal / Trans Labial evaluation:
TAS transducer is placed on the anterior perineum between the labia minora and the vagina. The transducer may be covered with a glove or plastic wrap.
Empty or near empty bladder
TPS may be especially valuable in patients with ruptured membranes when EVS is contraindicated.
Pitfalls include rectal air and packed fecal matter
Difficult to technically master
Slide25Slide26Transvaginal approach of investigating the cervix
Slide27Trans-perineal /Trans Labial evaluation:
TAS transducer is placed on the anterior perineum between the labia minora and the vagina. The transducer may be covered with a glove or plastic wrap.
Empty or near empty bladder
TPS may be especially valuable in patients with ruptured membranes when EVS is contraindicated.
Pitfalls include rectal air and packed fecal matter
Difficult to technically master
Slide28Transperineal/Translabial approach of evaluating the cervix
Slide29Measurements of the cervix can be preformed after 15 weeks gestational age, when the cervix normally becomes distinct from the LUS.
It should be noted that even with all three techniques of cervical evaluation (TAS, TPS, and EVS), focal uterine contractions, fibroids, and even Nabothian cysts can interfere with cervical interpretation.
TA evaluation-
Full bladder. Pitfalls: Overdistended bladder can elongate the cervix. Interference from the presenting fetal part can interfere with adequate cervical visualization.
Large maternal body habitus can result in inferior image quality
Slide30Endovaginal Evaluation
Preferred technique for evaluation of the cervix and measurement of cervical length.
Rectal contents do not interfere.
The cervix may be adequately evaluated in the third trimester in 99% of patients.
bladder empty
Excessive pressure can artificially increase the CL.
Sagittal long axis view of the cervix should be obtained from the internal os to the external os.
ROT: cervix should occupy one-half to two-thirds of the image display area.
Three measurements should be taken
Abdominal pressure applied t the uterine fundus can sometimes be helpful to show the internal os more clearly and can sometimes elicit a funnel (cervical stress test).
Slide31The LUS-lower uterine segment – does not have a definite sonographic identity prior to or during the different stages of labor and delivery. Can be considered the portion of the uterine body closet to the inner os of the cervix.
Techniques to evaluate the cervix include TAS, TPS, and EVS. (Trans-abdominal, Trans-Perineal- and Endo-vaginal sonography.
CL (cervical length) is measured from internal to external os.
Evaluated for shortening (effacement) and Funneling.
LUS and the internal os are evaluated with Color Doppler for the possibility of vasa previa (blood vessels in that region which could cause hemorrhaging with vaginal delivery.
Slide32Endovaginal Evaluation
Preferred technique for evaluation of the cervix and measurement of cervical length.
Rectal contents do not interfere.
The cervix may be adequately evaluated in the third trimester in 99% of patients.
bladder empty
Excessive pressure can artificially increase the CL.
Sagittal long axis view of the cervix should be obtained from the internal os to the external os.
ROT: cervix should occupy one-half to two-thirds of the image display area.
Three measurements should be taken
Slide33ENDO VAG SCANNING CONT…
Abdominal pressure applied to the uterine fundus can sometimes be helpful to show the internal os more clearly and can sometimes elicit a funnel (cervical stress test).
Pitfalls:
Operator and interpreter dependent.
bladder must be empty
excessive probe pressure can mask funneling artificially elongate the cervix (false negative result)
If there is evidence of LUS contraction, wait for it to subside.
Slide34Pitfalls of Endovaginal Evaluation
Operator and interpreter dependent.
bladder must be empty
excessive probe pressure can mask funneling artificially elongate the cervix (false negative result)
If there is evidence of LUS contraction, wait for it to subside.
Slide35The median CL is 40 mm before 22 weeks, 35 mm at 22 to 32 weeks, and 30 mm after 32 weeks. CL is not affected much by maternal age, race, gravidity or parity.
Cervical shortening is indicated if CL is less than 25 mm between 22 and 30 weeks.
What all this means is that the magic number is 30 mm or 3 cm.
There are other cervical measurements from other studies, but forget them.
Slide36The Abnormal cervix
Slide37Incompetent cervixNext slide: Funneling of the cervix
Slide38Slide39Incompetent/Insufficient Cervix
AKA painless premature dilation of the cervix, it is the inability of the cervix to prevent the premature expulsion of the uterine contents. Incompetent cervix may be acquired or congenital, and is most frequently related to cervical trauma.
Surgical repair of cervical tears following previous vaginal deliveries may be one cause.
Habitual abortion in the 2
nd
trimester may be the only clinical feature.
Slide40An incompetent cervix is identified by the following sonographic criteria:
Cervical length
<
3 cm before 34 weeks
Cervical dilation > 2 cm in the 2
nd
trimester
bulging membranes (such as PROM)
Slide41Incompetent Cervix-Sonographic Findings:
Sonographic findings:
Cervical length <3cm before 34 weeks
Cervical dilation with a width >2 cm in 2
nd
trimester-MOST RELIABLE
Firm diagnosis cannot always be made using Sonography
Diagnosis based on history and clinical findings
Bulging membranes
Bladder distention may cause false negative diagnosis
Slide42Cervical insufficiency/incompetent cervix
DEF: structural weakness of cervical tissue that causes or contributes to the loss of an otherwise healthy pregnancy.
Slide43FUNNELING
DEF
: the sonographic observation of protrusion of the amniotic fluid and intact membranes into an open internal os.
Cervical effacement is shortening and
thinning
of the cervix; it is one of the first steps in the birthing process and precedes labor by four to eight weeks.
Three funneling shapes (Y, V, U) have been described based on the severity of funneling, however, the distinctions between the shapes are somewhat subjective.
In general, the risk of Preterm birth (PTB) increases with funnel shape (U-shaped funneling is more likely to be associated with PTB than V-shaped funneling.
Slide44Slide45“Hourglass Sign”
With dilation of the cervix, the amniotic-chorionic membrane herniates into the cervix and bulges. In the most severe cases, the membranes may bulge into the vagina with fetal parts or loops of umbilical cord, and delivery must take place.
The US appearance of bulging membranes in the cervix and vagina has been referred to as the HOURGLASS SIGN.
Slide46Slide47Slide48Bulging membranes
The cervix begins to thin out and widen without any contractions or labor.
The
membranes
surrounding the fetus
bulge
down into the opening of the cervix until they break, resulting in the loss of the baby or a very premature delivery.
The fetal membrane are membranes associated with the developing fetus. The two
chorioamniotic
membranes are the amnion and chorion, which make up the amniotic sac that surrounds and protects the fetus.
Slide49Cervical Cerclage
Refers to a variety of surgical procedures in which sutures, wires, or synthetic tape are used to reinforce the cervix.
Intended to mechanically increase the strength of the cervix to prevent the prolapsed of the fetal membranes into the vagina (bulging membranes), PTB, and fetal loss.
Note: It has been reported that a short cervix can be caused by factors other than structural weakness and can be treated successfully with medication.
Slide50A cervical Cerclage is a suture that can be placed in the cervix to prevent dilation and effacement in patients who have a history of incompetent cervix
Slide51Cervical insufficiency/incompetent cervix
DEF: structural weakness of cervical tissue that causes or contributes to the loss of an otherwise healthy pregnancy.
Cervical Cerclage
Refers to a variety of surgical procedures in which sutures, wires, or synthetic tape are used to reinforce the cervix.
Intended to mechanically increase the strength of the cervix to prevent the prolapsed of the fetal membranes into the vagina (bulging membranes), PTB, and fetal loss.
Note: It has been reported that a short cervix can be caused by factors other than structural weakness and can be treated successfully with medication.
Slide52Pre-Term Labor
Defined as the onset of labor before 37 weeks.
Etiologies include:
Previous uterine surgery
Uterine anomalies
Maternal stress
Heavy cigarette smoking
Multiple gestations
Polyhydramnios
Ante partum bleeding, from previa, abruption
Slide53Preterm labor (PTL)
Defined as regular uterine contractions that cause progressive dilation of the cervix prior to a GA of 37 completed weeks. It is the second most common cause of Perinatal mortality next to congenital anomalies.
Slide54Spontaneous Preterm Birth (PTB)
before 37 weeks (AKA prematurity)
After 20 weeks gestational age, the CL shortens in prep for term labor.
A CL less than 25 mm at 24 weeks is the best of all the predictors of PTB evaluated in twins.
Most of the data collected and the questions on the boards will deal with Singletons and CL. Twins…not so much. Triplets… not so much. The data is not good enough to draw solid conclusions from.
Slide55Premature Rupture of Membranes
PROM
Premature rupture of membranes is defined as the spontaneous rupture of the membranes prior to the onset of labor.
Clinical signs are the passage of a large amount of watery fluid from the vagina
Sonographic findings are Oligohydramnios with a normal fetal bladder
Slide56Homework
Show several different images of PROMs
Slide57Placenta previa
Placental Previa is an obstetric complication in which the placenta has attached to the uterine wall close to or covering the cervix . It can some times occur in the latter part of the first trimester, but usually during the second or third. It is a leading cause of antepartum hemorrhage (vaginal bleeding). It affects approximately 0.5% of all labors.
Slide58Pathophysiology
No specific cause of placenta previa has yet been found but it is hypothesized to be related to abnormal vascularization of the endometrium caused by scarring or atrophy from previous trauma, surgery, or infection.
In the last trimester of pregnancy the isthmus of the uterus unfolds and forms the lower segment. In a normal pregnancy the placenta does not overlie it, so there is no bleeding. If the placenta does overlie the lower segment, it may shear off and a small section may bleed.
Women with placenta previa often present with painless, bright red vaginal bleeding. This bleeding often starts mildly and may increase as the area of placental separation increases. Previa should be suspected if there is bleeding after 24 weeks of gestation. Abdominal examination usually finds the uterus non-tender and relaxed.
The proper timing of an examination in theatre is important. If the woman is not bleeding severely she can be managed non-operatively until the 36th week. By this time the baby's chance of survival is as good as at full term.
Slide59Placenta previa is classified according to the placement of the placenta:
Type I
or low lying: The placenta encroaches the lower segment of the uterus but does not infringe on the cervical os.
Type II
or marginal: The placenta touches, but does not cover, the top of the cervix.
Type III
or partial: The placenta partially covers the top of the cervix.
Type IV
or complete: The placenta completely covers the top of the cervix. This type of previa often will not bleed until labour starts.
Placenta previa is itself a risk factor of placenta Accreta.
Slide60Placenta Previa
Slide61Know the following definitions:
Hydrocolopos: is literally “water in the vagina.” It is often used as a generic term for the collection of fluid in the vagina or uterine cavity.
Hematometra is literally “Blood in the uterus.”
Hydrometrocolopos is literally “Water in the uterus and vagina.”
Pyometrocolopos is literally “pus in the uterus and vagina.
Slide62The most common cause of Hydrocolopos in the pediatric patient is an imperforate hymen.
Slide63The sonographic findings of Hydrocolopos include:
a hypoechoic distention of the endometrial cavity and or vagina
posterior acoustic enhancement
internal echoes may be present, representing debris or clot
Hydronephrosis may be present in cases of severe obstruction
Slide64Spontaneous Preterm Birth (PTB)
before 37 weeks (AKA prematurity)
After 20 weeks gestational age, the CL shortens in prep for term labor.
A CL less than 25 mm at 24 weeks is the best of all the predictors of Preterm Birth evaluated in twins.
Most of the data collected and the questions on the boards will deal with Singletons and Cervical Length. Twins…not so much. Triplets… not so much. The data is not good enough to draw solid conclusions from.
Slide65Preterm labor (PTL)
Defined as regular uterine contractions that cause progressive dilation of the cervix prior to a GA of 37 completed weeks. It is the second most common cause of Perinatal mortality next to congenital anomalies.
Slide66Benign Cervical/Gynecological conditions
warts
fibroids
nabothian cysts
Gartner duct cysts
leiomyosarcomas
adenomyosis
endometrial polyps
endometrial hyperplasia
ovarian cysts
epithelial tumors
germ cell tumors
endometriosis.
Slide67Malignant cervical/Gynecological conditions
Endometrial carcinoma
Cervical Cancer
Slide68Cervical cancer
The cervix may be affected by cervical cancer, a particular form of cancer which is detectable by cytological study of epithelial cells removed from the cervix in a process known as the pap smear. Evidence now shows that those with exposure to HPV (human papilloma virus) are at increased risk for cervical cancer. These viruses are related to the viruses that causes warts. The incidence of new cases of cervical cancer in the United States was observed to be 7 per 100,000 women in 2004.
Slide69Cervical Cancer
Slide70Think Tank The Cervix
Slide71Question one
The portion of the cervix that projects into the vagina is referred to as the what?
Slide72Question two
The ectocervix's opening is called the what?
Slide73Question three
The passageway between the external os and the uterine cavity is referred to as the what?
Slide74Question four
Number three terminates at the
_________
which is the opening of the cervix inside the uterine cavity
Slide75Question five
_____________ cysts are often found in the cervix.
Slide76Question six
Some women's cramps subside or disappear after their first vaginal birth because the cervical opening has widened.
True or False
Slide77Question seven
During childbirth, contractions of the uterus will dilate the cervix up to ____cm in diameter to allow the fetus to pass through.
Slide78Question eight
CL in the first trimester has a significant clinical value
True or false
Slide79Question Nine
CL normally decreases slightly between 20 and 32 weeks and more considerably after 32 weeks.
True for false
Slide80Question 10
The median CL is 40 mm before 22 weeks, 35 mm at 22 to 32 weeks, and 30 mm after 32 weeks. CL is not affected much by maternal age, race, gravidity or parity.
___________mm
___________mm
___________mm
Slide81Question 11
CL is affected by which of the following:
A. maternal age
B. Race
C. Gravidity
D. Parity
E. None of the above
Slide82Question 12
Cervical shortening is indicated if CL is less than ______ between 22 and 30 weeks.
Slide83Question 13
CL (cervical length)
is measured from where to where?
Slide84Question 14
This area does not have a definite sonographic identity prior to or during the different stages of labor and delivery. Can be considered the portion of the uterine body closet to the inner os of the cervix.
Slide85Question 15
List the three Techniques used to evaluate the cervix
Slide86Question 16
A condition in which a pregnant woman's cervix begins to dilate (widen) and efface (thin) before her pregnancy has reached term.
Slide87Question 17
List at least two Risk Factors of number 16
Slide88Question 18
Measurements of the cervix can be preformed after ___ weeks gestational age.
Slide89Question 19
Habitual abortion in the 2
nd
trimester may be the only clinical feature of this.
Slide90Question 20
What is being identified by the following sonographic criteria?
length
<
3 cm before 34 weeks
dilation > 2 cm in the 2
nd
trimester
bulging membranes (such as PROM)
Slide91Question 21
The sonographic observation of protrusion of the amniotic fluid and intact membranes into an open internal os.
Cervical effacement is shortening and
thinning
of the cervix; it is one of the first steps in the birthing process and precedes labor by four to eight weeks.
The above is describing what cervical condition?
Slide92Question 22
Three shapes (Y, V, U) have been described based on the severity of What?
Slide93Question 23
The US appearance of bulging membranes in the cervix and vagina has been referred to as the _________SIGN.
Slide94Question 24
Refers to a variety of surgical procedures in which sutures, wires, or synthetic tape are used to reinforce the cervix.
Slide95Question 25
Pre-Term labor is defined as the onset of labor before
25 weeks
30 weeks
35 weeks
37 weeks
Slide96Question 26Define:
Hydrocolopos:
Slide97Question 27Define:
Hematometra
Slide98Question 28Define:
Hydrometrocolopos