Minimising the risk of accidental dural puncture with epidural analgesia for labour: a retrospective review of risk factors

BACKGROUND

Accidental dural puncture has a quoted incidence of between 0.19% and 3.6% of obstetric epidurals and is associated with significant morbidity. We set out to determine possible factors associated with an increased risk of accidental dural puncture.

METHODS

We performed a retrospective review of 18385 epidurals, performed over a 15-year period. Factors analysed were: time of day of insertion, loss-of-resistance technique, maternal position, cervical dilatation, grade of anaesthetist and depth to the epidural space.

RESULTS

Using univariate analyses we found no association between the risk of accidental dural puncture and the following variables: time of day of insertion (P=0.71), loss-of-resistance technique (P=0.22), maternal position for insertion (P=0.83), degree of cervical dilatation (P=0.41) and grade of anaesthetist performing the epidural (P=0.34). Conversely, we found that the risk of accidental dural puncture increased with increasing depth to the epidural space. This was confirmed using a logistic regression analysis, from which it was estimated that, for every 1-cm increase in depth, the risk of accidental dural puncture increased by approximately 19% (P=0.019; 95% CI for OR: 1.029-1.38).

CONCLUSION

We conclude that the risk of accidental dural puncture increases with increasing depth to the epidural space. We suggest further study is required to correlate this risk with increasing body mass index.

Amplification and detection of transposon insertion flanking sequences using fluorescent muAFLP

The amplification of transposon insertionflanking sequences is the basis of a variety of techniques usedfor the detection and characterization of specific transposon insertion events. We have developed a method for the efficient size determination and quantification of amplified genomic sequences thatflank Mutator (Mu) transposon insertions in maize. Using this detection method, we have been able to optimize Mu insertion site amplification and to assess amplification from increasingly complex templates representing increasing numbers of Mu-active maize plants. This detection method should be applicablefor the characterization of transposon or transgene insertion events in a wide variety of organisms.