Controlled cord traction for the third stage of labour
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
To evaluate the effectiveness of controlled cord traction during the third stage of labour, either with or without conventional active management.
Background
The third stage of labour refers to the period between birth of the baby and complete expulsion of the placenta. Some degree of blood loss occurs after the birth of the baby due to separation of the placenta. This is a risky period, because the uterus may not contract well after birth and heavy blood loss can endanger the life of the mother. Different approaches, such as active management and expectant management, are proposed for the management of the third stage of labour.
Postpartum haemorrhage (PPH) is a major cause of maternal mortality in both developed and developing countries. Globally it is estimated that PPH occurs in about 11% of women who give birth. The incidence is thought to be much higher in developing countries, where many women do not have access to a skilled attendant at birth and where active management of third stage of labour may not be routine (Mousa 2007).
Active management consists of a group of interventions including administration of a prophylactic uterotonic at or after delivery of the baby, early cord clamping and cutting, controlled cord traction to deliver the placenta, and uterine massage. Recently, due to emerging data on beneficial effects of delayed cord clamping on term (McDonald 2008 (Cochrane review)) and preterm (Rabe 2004 (Cochrane review)) newborn haematological indices, international recommendations on the timing of cord clamping have changed. It is recommended to delay cord clamping until the caregiver is ready to initiate controlled cord traction (thought to be around two to three minutes) (WHO 2007). Uterotonics used as part of the active management of third stage of labour include synthetic oxytocin, ergometrine, and various prostaglandins. Oxytocin has the advantage of minimal side effects when given intramuscularly or by slow intravenous infusion. The limitations are that it is not very heat stable, and requires parenteral administration. Uterine massage (trans‐abdominal rubbing of the uterus to stimulate contractions by release of endogenous prostaglandins) is usually recommended after delivery of the placenta.
On the other hand, expectant management means waiting for the signs of separation of the placenta and its spontaneous delivery, and late cord clamping, which is clamping the umbilical cord when cord pulsation has ceased (hands‐off approach) (Begley 2008).
There is good evidence that the package of active management of the third stage of labour (AMTSL) reduces the occurrence of severe postpartum haemorrhage by approximately 60% to 70% (Begley 2008). A survey of policies in 14 European countries (part of the EUPHRATES Study) found that policies of using uterotonics for the management of the third stage of labour are widespread, but policies about agents, timing, clamping, and cutting the umbilical cord and the use of controlled cord traction differ widely (Winter 2007). Differences in policies and quality of care (Bouvier‐Colle 2001) have been cited as being responsible for large differences (up to 10‐fold) in rates of PPH between countries in Europe (Zhang 2005).
Controlled cord traction is one of the components of AMTSL that requires training in manual skill for it to be performed appropriately. Cord traction was introduced into obstetric practice by Brandt in 1933 and Andrews in 1940 (Brandt 1933). The procedure, which became known as the Brandt‐Andrews manoeuvre, consists of elevating the uterus suprapubically while maintaining steady traction on the cord, once there is clinical evidence of placental separation and the uterus is contracted. In 1962 the term controlled cord traction was introduced by Spencer as a modification which aims to facilitate the separation of the placenta once the uterus contracts, and thus shorten the second stage of labour (Spencer 1962). This is achieved by applying traction on the cord, accompanied by counter‐traction to the body of the uterus towards the umbilicus (Stearn 1963). Current clinical recommendations and most recent studies describe this or a similar method (ICM 2003).
Controlled cord traction may result in complications such as uterine inversion, particularly if traction is applied before the uterus has contracted sufficiently, and without applying effective counter‐pressure to the uterine fundus. It is therefore a manual skill which requires considerable practical training in order to be applied safely. Its use is limited to settings with access to birth attendants with reasonably high levels of skill and training. If it is possible to omit controlled cord traction from the active management package without losing efficacy, this would have major implications for effective management of the third stage of labour in settings with limited human resources.
Expectant management of the third stage of labour is preferred by some women and practitioners. It is seen as a more physiological and less interventionist approach, avoids uncomfortable procedures shortly after birth when the mother wishes to concentrate on the baby, and reduces the risk of uterine inversion. Sometimes nipple stimulation is used to enhance uterine contractions by stimulating the release of endogenous oxytocin.
Cord traction may be used during caesarean section. This is covered in another Cochrane review (Anorlu 2008).
Description of the condition
Postpartum haemorrhage is defined as blood loss of 500 ml or more after birth; severe postpartum haemorrhage as 1000 ml or more.
Description of the intervention
Once the uterus is felt to contract, traction is applied to the umbilical cord with counter‐pressure suprapubically on the uterus, until the placenta delivers.
How the intervention might work
Cord traction may hasten the process of separation and delivery of the placenta, thus reducing blood loss and the incidence of retained placenta. It is thought that administration of a uterotonic drug may cause uterine contraction and retention of the placenta if not combined with controlled cord traction.
Why it is important to do this review
Controlled cord traction is one of the components of active management of the third stage of labour. This technique, however, requires training in manual skill for it to be performed appropriately. At community level, where there are limited trained personnel, controlled cord traction may be difficult and costly to implement. It is therefore, important to evaluate whether controlled traction is really necessary.
Objectives
To evaluate the effectiveness of controlled cord traction during the third stage of labour, either with or without conventional active management.
Methods
Criteria for considering studies for this review
Types of studies
We will consider randomised trials evaluating the effects of controlled cord traction. We will exclude quasi‐random allocation trials .
Types of participants
Women who have given birth vaginally at 24 weeks' gestation or more.
Types of interventions
Controlled cord traction versus no controlled traction (both with uterotonics).
Controlled cord traction versus no controlled traction (both with no uterotonics, with or without uterine massage as an additional intervention).
Types of outcome measures
We have chosen severe postpartum haemorrhage (blood loss 1000 ml or more) as the primary outcome, as blood loss between 500 ml and 1000 ml is not usually associated with serious clinical morbidity.
Primary outcomes
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Blood loss of 1000 ml or more after birth
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Manual removal of the placenta
Secondary outcomes
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Blood loss of 500 ml or more after birth
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Mean blood loss
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Mean duration of third stage of labour
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Retained placenta for more than 60 minutes or as defined by trial author
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Blood transfusion
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Maternal haemoglobin less than 9 g/dl at 24 to 48 hours post delivery or blood transfusion
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Use of additional uterotonics during or after the third stage of labour
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Maternal death or severe morbidity (e.g. operative procedures, organ failure, intensive care unit admission)
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Operative procedures (e.g. hysterectomy, uterine compression sutures)
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Organ failure
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Inensive care unit admission
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Maternal death
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Maternal satisfaction
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Caregiver satisfaction
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Measures of cost‐effectiveness as defined by trial authors
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Evacuation of retained products
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Infection
Search methods for identification of studies
Electronic searches
We will contact the Trials Search Co‐ordinator to search the Cochrane Pregnancy and Childbirth Group’s Trials Register.
The Cochrane Pregnancy and Childbirth Group’s Trials Register is maintained by the Trials Search Co‐ordinator and contains trials identified from:
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quarterly searches of the Cochrane Central Register of Controlled Trials (CENTRAL);
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weekly searches of MEDLINE;
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handsearches of 30 journals and the proceedings of major conferences;
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weekly current awareness alerts for a further 44 journals plus monthly BioMed Central email alerts.
Details of the search strategies for CENTRAL and MEDLINE, the list of handsearched journals and conference proceedings, and the list of journals reviewed via the current awareness service can be found in the ‘Specialized Register’ section within the editorial information about the Cochrane Pregnancy and Childbirth Group.
Trials identified through the searching activities described above are each assigned to a review topic (or topics). The Trials Search Co‐ordinator searches the register for each review using the topic list rather than keywords.
In addition we will search PubMed using the search strategy detailed in Appendix 1.
We will not apply any language restrictions.
Data collection and analysis
Selection of studies
Two of the authors will independently assess for inclusion all the potential studies we identify as a result of the search strategy. We will resolve any disagreement through discussion or, if required, we will consult the third author or, if necessary, the editor assigned to the review.
Data extraction and management
We will design a form to extract data. For eligible studies, two review authors will extract the data using the agreed form. We will resolve discrepancies through discussion. We will enter data into Review Manager software (RevMan 2008) and check them for accuracy.
When information regarding any of the above is unclear, we will attempt to contact authors of the original reports to provide further details.
Assessment of risk of bias in included studies
Two authors will independently assess risk of bias for each study using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2008). We will resolve any disagreement by discussion or, if need be, by involving another assessor.
Sequence generation (checking for possible selection bias)
We will describe for each included study the method used to generate the allocation sequence in sufficient detail to allow an assessment of whether it should produce comparable groups.
We will assess the method as:
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adequate (any truly random process, e.g. random number table; computer random number generator);
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inadequate (any non‐random process, e.g. odd or even date of birth; hospital or clinic record number); or
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unclear.
(2) Allocation concealment (checking for possible selection bias)
We will describe for each included study the method used to conceal the allocation sequence in sufficient detail to determine whether intervention allocation could have been foreseen in advance of, or during recruitment, or changed after assignment.
We will assess the methods as:
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adequate (e.g. telephone or central randomisation; consecutively numbered sealed opaque envelopes);
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inadequate (open random allocation; unsealed or non‐opaque envelopes, alternation; date of birth);
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unclear.
(3) Blinding (checking for possible performance bias)
We will describe for each included study the methods used, if any, to blind study participants and personnel from knowledge of which intervention a participant received. We will judge studies at low risk of bias if they were blinded, or if we judge that the lack of blinding could not have affected the results. We will assess blinding separately for different outcomes or classes of outcomes.
We will assess the methods as:
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adequate, inadequate or unclear for participants;
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adequate, inadequate or unclear for personnel;
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adequate, inadequate or unclear for outcome assessors.
(4) Incomplete outcome data (checking for possible attrition bias through withdrawals, dropouts, protocol deviations)
We will describe for each included study, and for each outcome or class of outcomes, the completeness of data including attrition and exclusions from the analysis. We will state whether attrition and exclusions were reported; the numbers included in the analysis at each stage (compared with the total randomised participants); reasons for attrition or exclusion where reported; and whether missing data were balanced across groups or were related to outcomes. Where sufficient information is reported, or can be supplied by the trial authors, we will re‐include missing data in the analyses which we undertake. We will assess methods as:
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adequate;
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inadequate:
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unclear.
(5) Selective reporting bias
We will describe for each included study how we investigated the possibility of selective outcome reporting bias and what we found.
We will assess the methods as:
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adequate (where it is clear that all of the study’s prespecified outcomes and all expected outcomes of interest to the review have been reported);
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inadequate (where not all the study’s prespecified outcomes have been reported; one or more reported primary outcomes were not prespecified; outcomes of interest are reported incompletely and so cannot be used; study fails to include results of a key outcome that would have been expected to have been reported);
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unclear.
(6) Other sources of bias
We will describe for each included study any important concerns we have about other possible sources of bias.
We will assess whether each study was free of other problems that could put it at risk of bias:
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yes;
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no;
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unclear.
(7) Overall risk of bias
We will make explicit judgements about whether studies are at high risk of bias, according to the criteria given in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2008). With reference to (1) to (6) above, we will assess the likely magnitude and direction of the bias and whether we consider it is likely to impact on the findings. We will explore the impact of the level of bias through undertaking sensitivity analyses ‐ seeSensitivity analysis.
Measures of treatment effect
Dichotomous data
For dichotomous data, we will present results as summary risk ratio with 95% confidence intervals.
Continuous data
For continuous data, we will use the mean difference if outcomes are measured in the same way between trials. We will use the standardised mean difference to combine trials that measure the same outcome, but use different methods.
Unit of analysis issues
Cluster‐randomised trials
We will include cluster‐randomised trials in the analyses along with individually randomised trials. Their sample sizes will be adjusted using the methods described in the Handbook using an estimate of the intracluster correlation co‐efficient (ICC) derived from the trial (if possible), or from another source. If ICCs from other sources are used, we will report this and conduct sensitivity analyses to investigate the effect of variation in the ICC. If we identify both cluster‐randomised trials and individually‐randomised trials, we plan to synthesise the relevant information. We will consider it reasonable to combine the results from both if there is little heterogeneity between the study designs and the interaction between the effect of intervention and the choice of randomisation unit is considered to be unlikely.
We will also acknowledge heterogeneity in the randomisation unit and perform a separate meta‐analysis.
Crossover trials
Crossover trials would not be appropriate for this intervention.
Dealing with missing data
For included studies, we will note levels of attrition. We will explore the impact of including studies with high levels of missing data in the overall assessment of treatment effect by using sensitivity analysis.
For all outcomes we will carry out analyses, as far as possible, on an intention‐to‐treat basis, i.e. we will attempt to include all participants randomised to each group in the analyses. The denominator for each outcome in each trial will be the number randomised minus any participants whose outcomes are known to be missing.
Assessment of heterogeneity
We will use the I² statistic to measure heterogeneity among the trials in each analysis. If we identify substantial heterogeneity (> 50%), we will explore it by prespecified subgroup analysis.
Assessment of reporting biases
Where we suspect reporting bias (see 'Assessment of reporting biases' above), we will attempt to contact study authors asking them to provide missing outcome data. Where this is not possible, and the missing data are thought to introduce serious bias, we will explore the impact of including such studies in the overall assessment of results by a sensitivity analysis.
Data synthesis
We will carry out statistical analysis using the Review Manager software (RevMan 2008). We will use fixed‐effect inverse variance meta‐analysis for combining data where trials are examining the same intervention, and the trials’ populations and methods are judged sufficiently similar. Where we suspect clinical or methodological heterogeneity between studies sufficient to suggest that treatment effects may differ between trials, we will inspect the forest plot visually and consider the use of random‐effects meta‐analysis or not producing a summary estimate.
Subgroup analysis and investigation of heterogeneity
We plan to carry out the following subgroup analyses.
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Women with routine use of uterotonics, no routine use, or mixed/uncertain use.
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Women with routine use of uterine massage before or after placental delivery, no routine use, or mixed/unclear use.
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Women with and without placental drainage, or mixed or unclear use of placental drainage.
We will use all outcomes in the subgroup analysis.
For fixed‐effect meta‐analyses, we will conduct planned subgroup analyses classifying whole trials by interaction tests as described by Deeks 2001. For random‐effects meta‐analyses, we will assess differences between subgroups by inspection of the subgroups’ confidence intervals; non‐overlapping confidence intervals indicate a statistically significant difference in treatment effect between the subgroups.
Sensitivity analysis
We will conduct sensitivity analyses by comparing the outcomes before and after exclusion of trials with inadequate or unclear sequence generation or allocation concealment.
