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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
The average level of blood thinning, resulting from an individual weight determined dose of Clexane, when given to women after caesarian section to prevent blood clots.
Scientific title
The effect of a weight-based enoxaparin thromboprophylaxis on antiXa levels in women post caesarian section.
Secondary ID [1] 263032 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
thromboprophylaxis for caesarian section 270758 0
Condition category
Condition code
Blood 270938 270938 0 0
Clotting disorders
Reproductive Health and Childbirth 270939 270939 0 0
Childbirth and postnatal care

Study type
Description of intervention(s) / exposure
Enoxaparin dose is based upon patient weight at time of confinement booking (usually 6 - 12 weeks gestation)
Dosage schedule is:

Less than 40 kg 20 IU subcutaneous daily
> 40 to 90kg 40 IU subcutaneous daily
> 90 to 130 kg 60 IU subcutaneous daily
> 130 to 170 kg 80 IU subcutaneous daily
> 170 kg 0.5 IU/kg subcutaneous twice daily

Administered day 1,2 and 3 post partum
Intervention code [1] 269373 0
Treatment: Drugs
Intervention code [2] 269424 0
Comparator / control treatment
Control group

Primary outcome [1] 279607 0
plasma AntiXa levels
Timepoint [1] 279607 0
baseline, 4 hours post first & third doses
Secondary outcome [1] 294028 0
Timepoint [1] 294028 0

Key inclusion criteria
post caesarian section.
patient classified as high or intermediate risk of VTE based upon BCOG guidelines 2009
Minimum age
No limit
Maximum age
No limit
Can healthy volunteers participate?
Key exclusion criteria
refusal to enter trial
no booking maternal weight obtainable

Study design
Purpose of the study
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
convenience sampling to fill weight based strata
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Single group
Other design features
Phase 4
Type of endpoint(s)
Statistical methods / analysis

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 269832 0
Name [1] 269832 0
Mercy Hospital For Women
Address [1] 269832 0
163 Studley Road
Heidelberg Victoria 3084
Country [1] 269832 0
Primary sponsor type
Mercy Hospital For Women
163 Studley Road
Heidelberg Victoria 3084
Secondary sponsor category [1] 268864 0
Name [1] 268864 0
Address [1] 268864 0
Country [1] 268864 0

Ethics approval
Ethics application status
Ethics committee name [1] 271855 0
Ethics committee address [1] 271855 0
Ethics committee country [1] 271855 0
Date submitted for ethics approval [1] 271855 0
Approval date [1] 271855 0
Ethics approval number [1] 271855 0

Brief summary
Following major surgery patients are at increased risk of developing blood clots in the veins of the lower limb and in some patients these may dislodge, travel to the lung as pulmonary emboli, resulting in breathing difficulties and rarely death. The situation is no different after caesarian section, where patients are at increased risk of blood clots, however the risk is not the same for all but influenced by factors such as previous history of blood clots, the need for emergency surgery, age and body weight.
After your surgery we can minimize the risk of blood clots by mobilizing you as soon as possible, using below knee compression stockings, which prevent pooling of blood in calf veins and in certain patients by once daily injections under the skin of a blood thinning low molecular weight heparin drug (LMWH) called enoxaparin. For many years the dose of enoxaparin has been fixed and not adjusted for body weight, however there is evidence from studies in overweight non-pregnant patients that as body weight increases an increase in dose is required to maintain prevention. Pregnancy also alters the way these enoxaparin is handled by the body resulting in an increase in the dose required (at the end of pregnancy and immediately after delivery) to provide the same action as in the non-pregnant patient.
Recently, the Royal College of Obstetrician and Gynaecologists (RCOG) in the United Kingdom have updated their guidelines for prevention of thrombosis after caesarian section and recommend that patients classified as intermediate risk or greater should be given LMWH with the dose determined by their actual body weight at 8 -16 weeks of gestation (usually referred to as the booking weight).

We believe that you fall into the intermediate (or high) risk category and therefore would benefit from having LMWH preventative treatment. The dose given to you will be that recommended by the RCOG guideline and will be calculated based on your body weight at the time of registering for care at the Mercy Hospital for Women. For patients of less than 90 kg you will receive what for many years has been the standard dose of enoxaparin. For patients above 90 kg you will receive a dose greater than this fixed dose, which we believe is safe and is likely to result in better prevention of clots compared to the usual dose.
We are asking that you consent to having three samples of blood (10 mls each) taken and analyzed for LMWH blood thinning activity (antiXa levels). The first and second samples will be taken immediately prior to & then four hours after your first preventative injection some 4-12 hours after completion of your caesarian section. A third sample will be taken four hours after your third or fourth dose given on the day prior to your discharge from hospital. An additional small plastic cannula will be inserted into a arm vein at the time of your caesarian section and the first blood sample taken at that time. A second sample, hopefully via the cannula, will be taken 3 – 5 hours after the injection of Enoxaparin some 4-12 hours after your caesarian delivery. The third sample will require a separate blood test to be taken.
The study does not change the obstetric or anaesthetic management of your delivery. Breast feeding is considered safe whilst on enoxaparin.
All blood thinners lead to a slightly increased risk of wound and uterine bleeding. We don't believe that the risk of bleeding is increased over that seen in non pregnant patients given enoxaparin to prevent blood clots following surgery.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 33148 0
Address 33148 0
Country 33148 0
Phone 33148 0
Fax 33148 0
Email 33148 0
Contact person for public queries
Name 16395 0
Clin Assoc Prof Scott Simmons
Address 16395 0
Mercy Hospital for Women
163 Studley Road
Heidelberg Victoria 3084
Country 16395 0
Phone 16395 0
61 0384584113
Fax 16395 0
Email 16395 0
Contact person for scientific queries
Name 7323 0
Clin Assoc Prof Scott Simmons
Address 7323 0
Department of Anaesthesia
Mercy Hospital for Women
163 Studley Road
Heidelberg Victoria 3084
Country 7323 0
Phone 7323 0
61 03 84584113
Fax 7323 0
Email 7323 0

No information has been provided regarding IPD availability
Summary results
No Results