Cervical Insufficiency
(Cervical Incompetence)
aka “too easy out”
Brian McCulloch MD
Maternal – Fetal Medicine
March 5, 2011
 FIRST
RECOGNIZED IN 1658 BY COLE
AND CULPEPPER
 THE MANAGEMENT HAS BEEN MORE SO
SURGICAL THAN MEDICAL
 ABRAHAM LASH AND HIS BROTHER
WORKING HERE IN CHICAGO
REMOVED A PIECE OF TISSUE FROM
THE Cx ISTHMUS AREA IN THE NON
PREGNANT STATE (THIS LEFT ~ 45 %
INFERTILITY )
 V.N.
SHIRODKAR FROM BOMBAY
INDIA IN 1955 ADVOCATED
ENCIRLING THE INCOMPETENT
CERVIX WITH FASCIA LATA. HE
PLACED THE SUTURE MEDIAL TO
THE BLOOD VESSELS
 IAN
MCDONALD FROM MELBOURNE
AUSTRLIA IN 1957 COMPILED 70
CASES
 MOSTLY BETWEEN 20 – 24 WEEKS
 NO SUCCESS LESS THAN 20 WEEKS
 NO TOCOLYSIS
 EVEN TRIED TO TIE AMNION
PERFORATIONS
 EMBRYLOGICALLY
IT IS DERIVED FROM
THE FUSION OF THE MULLERIAN
DUCTS AND SUBSEQUENT CENTRAL
ATROPHY
 THE CERVIX IS PRIMARILY FIBROUS
TISSUE WITH SOME MUSCLE
 THE PROXIMAL CERVIX MAY HAVE UP
TO 29 % MUSCLE AND THE DISTAL
PORTION LESS THAN 10 %
 DURING
PREGNANCY THE
MUSCULAR UTERINE ISTHMUS
DISTENDS AND ELONGATES
BETWEEN 12 TO 20 WEEKS
 BEFORE 15 WEEKS CERVICAL
MEASUREMENTS ARE DIFFICULT ON
ULTRASOUND AND NOT
RECOMMENDED
NON PREGNANT CERVICAL TEST
ARE INACCURATE OR UNPROVEN
AND NOT RECOMMENDED TO Dx
INSUFFICENCY
HEGAR DILATOR SIZE 8
TRACTION TEST USING AN
INFLATED FOLEY CATHETER
INTERNAL OS MEASUREMENT
>8mm ON HYSTEROSALPINGOGRAM
If a Non – Pregnant HSG or a
Sonohysterogram or a MRI does
diagnose a septum or anatomic
abnormality then it can help alert the
clinician to the possibility of a
cervical issue or a factor leading to
preterm delivery .
 ONE
PER 222 DELIVERIES TO ONE PER
182 DELIVERIES ACOG PRACTICE BULLETIN 2004
 OTHER AUTHORS HAVE A WIDER
RANGE OF 1 IN A THOUSAND TO 1 IN A
HUNDRED
 LUTHERAN GENERAL HOSPITAL
CERCLAGE STATISTICS

1989 78

1990 62

1991 48
 Gradual
painless dilatation and
effacement of the cervix with bulging
and later rupture of the membranes
 Typically short labor
 Progressively shorter labors with
subsequent deliveries
 Progressively earlier deliveries
 Vaginal
or lower abdominal pressure
 Frequent urination
 Increased vaginal discharge (watery)
 Bloody or mucus discharge
 Congenital
Mullerian anomalies with
the highest risk with bicornuate and
unicornuate utrei
 Abnormal uterine shape
 Also abnormal cervical muscular
content( Ehlers – Danlos syndrome )
Acquired incompetence
 Traumatic
cervical procedures (cone
bx)
 Cone bx’s with a height of > 2 cms is
a risk factor
 Obstetrical cervical lacerations
 Iatrogenic
 Embryological Drug induced (DES)
(about 25 % have structural defects)
 THE
INCIDENCE OF PRETERM BIRTH
IN THE USA HAS BEEN INCREASING
FROM 9.4 % IN 1981 TO 12.7 % in
2007 Martin Nat. Vital Stat. Rep 2009;57:1
- 102

RELIANCE ON RISK FACTORS ALONE
WILL FAIL TO IDENTIFY MORE THAN
50 % OF PREGNANCIES THAT
DELIVER< 37 WEEKS CREASY AJOG
1980 MERCER AJOG 1996
 DIGITAL
EXAMINATION
 SPECULUM EXAM
 TRANSABDOMINAL ULTRASOUND
 TRANSPERINEAL OR TRANSLABIAL
ULTRASOUND
 TRANSVAGINAL ULTRASOUND
Ultrasound assessment of the
cervix
Vincenzo Berghella MD 2003
 Trans
abdominal scanning needs a full
maternal bladder and can therefore
elongate the cx length
 can be very difficult to see the
external os
Transperineal cervical
measurements
 Gas
of the rectum will hamper
visualization of the cx especially the
external os
Transvaginal technique
 Enlarge
the image so that it occupies
about two thirds of the total image
 Obtain 3 images and record the
shortest.
 Transfundal pressure should be for
about 15 seconds
 Generally sonographers should be
supervised for about 50 procedures.

Check the Equipment
–
–
Appropriately cleaned w/ soap & water +
soaked
Use 5 to 7 MHz endovaginal probe

–
Make sure the image is set to “EV”


Don’t use 8 MHz – poor tissue penetration
(endovaginal )
Not Obstetrical or Abdominal
Empty Maternal Bladder
–
–
Void just before the exam
If bladder is seen to be large, stop exam & void
again
 CONSISTENTLY
UNDERESTIMATES
THE CERVICAL LENGTH COMPARED
TO VAGINAL PROBE ULTRASOUND
 HIGHLY SUBJECTIVE
 NON- STANDARDIZED
 SERIAL
DIGITAL EXAMS IN THE MID TO
LATE SECOND TRIMESTER IS USEFUL
IF THE EXAM REMAINS NORMAL
 UNFORTUNATELY ABNORMAL CERVICAL
FINDINGS ARE ASSOCIATED WITH
ONLY 12 - 20 % OF HIGH RISK
PRETERM DELIVERES AND EVEN LESS
IN THE LOW RISK PATIENTS ~ 4 %
 THERE
IS A STRONG REPRODUCIBLE
INVERSE CORRELATION BETWEEN
CX LENGTH AND PRETERM DELIVERY
 IF THE CX LENGTH IS LESS THAN
10 % (25 mm) THERE IS A 6 FOLD
INCREASED RISK OF DELIVERY
PRIOR TO 35 WEEKS
IAMS NEJM 1996;334:567-57
 PROGRESSIVE
CX SHORTENING TO
20 mm OR LESS
 FUNNEL LENGTH >16 mm OR
FUNNELING >40 %
 MEASUREMENTS MUST BE
OBTAINED TRANSVAGINALLY
 WHY
IS LENGTH RELATED TO
PRETERM DELIVERY ?
 OCCULT CONTRATIONS
 BIOLOGIC VARIATION
 LOWER TRACT INFECTION
 UPPER TRACT INFECTION
 CX
LENGTH OF LESS THAN 15 mm
AT 23 WEEKS OCCURS IN LESS
THAN 2 % OF LOW RISK WOMEN
 WHEN THIS DOES OCCUR IT IS
PREDICTIVE OF PTD
 < 28 WEEKS IN 60 % OF CASES
 < 32 WEEKS IN 90 % OF CASES
Where to Put the Calipers?
Where the
anterior and
posterior walls of
the canal touch
 Spend enough
time to see
whether a small
echolucent area is
stable or is going
to open up

YES
NO
 BERGHELLA’S
STUDY IN JAMA IN
2001 SHOWED A SENSITIVITY OF
69%
 BUT IF ONLY THE INITIAL
MEASUREMENT WAS USED (16-18
wks) THEN THE SENSITIVITY WENT
DOWN TO 19%
 VIABLE
DELIVERY RATE OF 70 – 90
%
 A LOWER RATE OF DELIVEY PRIOR
TO 33 WEEKS (13 % COMPARED TO
CONTROL OF 17 %)
 General a higher rate of tocolysis
usage 34% vs 27 %
 Higher puerperal infections 6% vs 3
%
 CERLAGE
GROUP HAD LESS
DELIVERIES BEFORE 37 WEEKS BUT
NO DIFFERENCE LESS THAN 35
WEEKS
 CERCLAGE HELPED IF CX LENGTH WAS
<25mm’s BUT IT DID NOT CHANGE
THE OUTCOME IF VERY SHORT CX
<15mm’s
 TWINS HAD A INCREASED DELIVERY
LESS THAN 35 WEEKS AND A HIGHER
PERINATAL MORTALITY
 NUMEROUS
STUDIES HAVE
CONFIRMED THE ASSOCIATION OF
CERVICAL SHORTENING AND PTB
 REVIEW OF 35 STUDIES HAD
SHOWN SENSITIVITY FROM
68
– 100 %
SPECIFICITIES FROM
44 – 79 %
 PROSPECTIVE
STUDY OF 2900 WOMEN
AT 24 AND AGAIN 28 WEEKS (LEVEL II-B
STUDY )
 40mm
 35mm
 30mm
 26mm
 22mm
 13mm
RR=2.8 PTD
RR =3.52
RR =5.39
RR= 9.57
RR=13.88
RR=24.94
 VAGINAL
PROBE MEASUREMENTS
CAN SUPPORT A DIAGNOSIS OF
CERVICAL INCOMPETENCE BUT
SHOULD NOT BE THE SOLE
CRITERIA
 RESIDUAL CERVICAL LENGTH IS
MORE IMPORTANT THAN THE OTHER
MEASUREMENTS
RR OF PTD AS CX LENGTH
SHORTENED
25
20
15
RR
10
5
0
40
35
30
26
22
13
 ROUTINE
USE OF CX LENGTH IS NOT
RECOMMENDED BECAUSE IT LACKS
ENOUGH DISCRIMINATORY POWER
 INTRINSIC
WEAK CERVICOISTHMIC
JUNCTION
 SOME STUDIES HAVE FOUND THIS
TO BE AN INDEPENDENT RISK
FACTOR FOR PTB ( INDEPENDENT OF
CX LENGTH )
 CERVICAL STRESS TEST
Transvaginal Cervical Sonography
Illustration by James Cooper MD
Found in Callen, 4th edition
 20
years ago Zilianti described the
continuum from a “T “ to a “ Y” to a
“V “ and finally to a “U” shaped lower
segment.
 Moderate funneling defined as
25- 50% cervical shortening had a
increased preterm birth of 50 %
Cervical Effacement = T Y V U
T
Y
V
U
Zilanti M, et al: JUM 1995
 If
the cervical length is deviated
(defined as greater than 5mm from
straight) then 2 straight lines should
be used.
 Usually a short Cx not deviated
 If the cx canal is closed then the only
measurement that is necessary is
the cervical length .
Don’t Trace to Measure the Cervical Length
If the 
is > 3 mm,
use two
measures
 SHOULD
BE REPORTED TO THE
PATIENT
 REPEAT IN 1 – 2 WEEKS
 OPTION OF CERCLAGE
 BED REST / RESTRICTED ACTIVITY
DISCUSSED
 DIFFERENT FOR MULTIPLE
GESTATION ?
 PTD
IN CURRENT PREGNANCY
 HISTORY OF PTD
 INDEPENDENT OF OTHER RISK
FACTORS: RACE , Ffn , BLEEDING ,
BACTERIAL VAGINOSIS ,BMI
,CONTRACTIONS
 RANDOMIZED
61 SINGLETON
 FUNNEL 1.5 cms WIDE 1.8 cms DEEP
 McDONALD vs OBSERVATION
 NO DIFFERENCE IN OUTCOME
 MORE PTD LESS THAN 34 WEEKS ,
LESS DELIVERIES BEFORE 28
WEEKS IF CERCLAGE
 Randomized
study of prophylactic
cerclage in twins showed no benefit
GOI 1982 13:55
 Cerclage in multiples with shortened
cervix also showed no benefit ajog
2002 186 634
 CX
LENGTH IS NORMALLY
DISTRIBUTED
 LENGTH INVESELY RELATED TO PTD
RISK
 T –Y –V –U AT ALL GESTATIONAL
AGES
 LENGTH MORE IMPORTANT THAN
FUNNEL
 CX SONOGRAPHY NOT EQUAL TO PTD
PREVENTION
Between 22 and 30 weeks of gestation, the length of the
cervix is
described by a normal bell-shaped curve
5th percentile at 20 mm
10th percentile at 25 mm
50th percentile at 35 mm
90th percentile at 45 mm
Cervical Effacement = T Y V U
T
Y
V
U
Zilanti M, et al: JUM 1995
 PRACTICE
MAKES PERFECT
 PELIC EXAM INITIALLY
 COAT THE EXTERNAL OS WITH GEL
 MATERNAL BLADDER EMPTY
 ANTERIOR FORNIX THEN
 INTERNAL OS
 EXTERNAL OS NEXT
 FUNDAL PRESSURE 10 – 15 SEC
 MOST
AUTHORS FEEL THEY ARE
ADDITIVE IN HELPING PREDICT
PRETERM BIRTH
 HIGH RISK WOMEN WITH A CX
LENGTH OF < 25mm AND A
POSITIVE fFN HAVE A 65 % CHANCE
OF DELIVERY AT < 35 WEEKS IAMS
AJOG 1998;178:1035-1040
 ULTRASOUND
AND fFN TESTING MAY
BE HELPFUL IN DETERMINING
WOMEN AT HIGH RISK FOR PTD
 HOWEVER THEIR CLINICAL
USEFULNESS MAY REST WITH THEIR
NEGATIVE PREDICTIVE VALUE
Debris:
Mobile
Variable
Echogenic
Material
Near the
Cervix
Intramniotic debris ( Sludge )
 Sonographic
finding of hyperechoic
matter floating in the amniotic fluid
 Possible cellular material related to
infection or inflammation
 A high correlation with poorer
prognosis
A
Cx length <25 mm between 16
and 24 weeks has been shown to be
the most reliable threshold for a
increased risk of preterm delivery.
Two Randomized trials
(cerclage for short cervix)

Rust study:(2001) 113
women all with either Cx
length 2.5 or funneling
25%
47% had preterm birth
and 20% had a prior 2nd
trimester loss and there
were 8 rescue cerclages,
and 16 % had twins
Used indocin for all patients

Cerclage in this group did
not change the preterm
delivery rate





Althuisius’ study: (2001)
was smaller 35 women
with a good history for
Cx insufficiency
Short Cx only were
excluded
74 % had a prior
preterm birth and 46 %
had a 2nd trimester loss
and only 2 rescue
cerclages
Indocin used in cerclage
arm only
Cerclage did show a
decreased preterm
delivery rate
Cerclage for prior preterm delivery
in women with a short cervix Owens
 1014
2009
screened
 302 randomized
 Decreased the previable rate <24
weeks
 Birth rate less than 35 weeks was
unchanged unless the cervix was
especially short <15 mm