Max Brinsmead MB BS PhDMay 2015

Classic Cervical Incompetence: Is present when painless mid-trimester loss of

apparently normal fetuses occurs recurrently AND The cervix accepts a 9 mm dilator without

resistance in the non-pregnant interval It can be successfully treated by prophylactic

cervical cerclage○ >95% term deliveries when patient acts as her own

control

But there is probably a continuum of disorder with...

○ Pre term delivery○ Findings of a short cervix

And that’s where it all gets confused

A little bit of history... 1955 Shirodkar – an operation for recurrent

miscarriage that restores the internal cervical sphincter

○ Performed at 14w○ Bladder dissection & Mersilene tape○ Removed at 37w

1957 McDonald – a purse-string suture with nylon or any similar monofilament suture

An epidemic of “stitches for pregnancy loss” began

○ Not less than 1:100 patients

1980 The era of Evidence-based medicine begins and questions were asked

More recent history...

Colposcopic evaluation of CIN and its limited treatment aims to avoid the risks of cervical incompetence associated with cone biopsy

Vaginal ultrasound and measures of cervical length

○ A relationship between short cervix and risk of pre term delivery emerges

○ Excellent visualisation of the internal os

Risks of cervical suture emerge○ Infection with fetal & maternal sequelae○ Cervical stenosis○ Further cervical injury

Questions How is cervical incompetence diagnosed? Does a cervical suture do more good than

harm? What is the best form of suture?

○ Shirodkar or McDonald○ Vaginal or abdominal

When should it be inserted? Is there a place for cervical cerclage with

advanced cervical dilatation? Or should it be used prophylactically in

high risk patients

But let ‘s digress & discuss aetiology... Congenital

Associated with uterine abnormalityExample bicornuate uterus

With connective tissue disorderExample Ehler’s Danlos

Idiopathic

AcquiredInappropriate cervical dilation

For primary dysmenorrhoeaFor termination of pregnancy

Cervical surgeryCone biopsyCervical amputation

Surgical treatment of CIN Limited treatments such as diathermy, Laser,

LETZ & cryotherapy were designed to leave the upper cervix intact

Increased risk of pre term delivery after these procedures ascribed to concomitant factors esp. smoking

Current data suggests that all treatments for CIN increase the risk of pre term delivery

But whether this is due to “Cx incompetence” is unknown

And it is one reason why protocols for the management of HPV/CIN have been revised

Cochrane reviews of cervical cerclage Meta analysis in 1989 by Grant of Cx

cerclage for liberal indications concluded that...They prevent ONE pre term delivery for every

20 inserted

The current review by Drakeley et al was posted in 2003 and updated 2010

○ Reviewed RCT’s of cerclage vs no treatment○ Compared methods of cerclage○ Evaluated prophylactic and emergency cerclage

Particularly with respect to the optimal management of a short cervix diagnosed by ultrasound

Outcomes included possible adverse effects

2010 Cochrane Review 6 trials, 2175 women No overall reduction in pregnancy loss or

pre term delivery rate Adverse effects include:

Mild pyrexia more commonMore tocolysis usedMore hospitalisationsSerious morbidity is uncommon

2 trials of prophylactic cerclage for ultrasound-diagnosed short cervixNo reduction in the rate of delivery before 28

and 34 weeks

MRC/RCOG study of 1993 Single largest trial, 1292 women Multicentre and international 80% were McDonald purse-string sutures 74% used Mersilene tape 13.8% of treated patients delivered before 32w 18.5% of untreated controls (RR 0.75, CI 0.58

- 0.98) But this means >80% patients did not deliver

pre term And one trial of strict bed rest had only 15% of

patients delivering <32w

The most recent study: Nicolaides et al 2001 Recruiting 5000 women with cervix <15 mm

diagnosed on ultrasound This study has been stopped Details awaited

Other data suggests that measures of Cx length are a normative continuum

And it is best used for its negative predictive value

○ Should be >18 mm before 18 weeks○ And >25 mm before 28 weeks

Cochrane conclusions: Cervical cerclage should NOT be

offered to women at low or medium risk of mid-trimester pregnancy loss regardless of the length of the cervix as determined by ultrasound

The management of patients with pregnant patients with a short cervix requires further study

My recommendations: Patients with a classic history of cervical

incompetence should have a prophylactic cerclage after first trimester screening for aneuploidy

A McDonalds purse-string suture with nylon for most

○ But a few will require an abdominal suture

Other patients who are on the continuum of disorders that begins with classic cervical incompetence require individualised management

Individualised management may include: Screening and treatment for bacterial

vaginosis Progesterone prophylaxis

Proven by RCT to reduce the risk of pre term delivery by 50%

Monitoring cervical length and dynamic evaluation of the internal cervical os

Emergency cervical cerclage before 24 weeks

Hospitalisation and bed rest after 26 weeks

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