[Does persistent occiput posterior position increase the risk of severe perineal laceration?]. / Les présentations postérieures augmentent-elles le risque de déchirures périnéales sévères?

OBJECTIVE: To assess the risk of severe perineal lacerations (III and IV degrees) during vaginal deliveries in occiput posterior position. PATIENTS AND METHODS: We conducted a retrospective cohort study of 9097 vaginal deliveries in a teaching hospital's maternity between January 1st 2005 and December 31st 2008. Risk factors associated with tears of the 3rd or 4th degree were studied by a multivariate logistic regression. RESULTS: Severe perineal lacerations occurred in 1.69% of cases (n=152) and did not significantly vary between 2005 and 2008. Parity was a protective factor (OR 0.42; P<0.001; IC(95%) 0.29-0.60) whereas instrumental extraction was associated with an increased risk: vacuum (OR 3.95; P<0.001, IC(95%) 2.23-7.00) and forceps (OR 3.55; P<0.001, IC(95%) 2.33-5.42). macrosomia. Risks were also increased in fetal macrosomia and episiotomy did not protect the mother (respectively OR 1.41 P<0.001, IC(95%) 1.19-1.68 and OR 1.73; P<0.001, IC(95%) 1.16-2.57). Persistent occiput posterior position was not significantly associated with an anal sphincter injury (OR=1.70 P=0.059; IC(95%) 0.98-2.94). DISCUSSION AND CONCLUSION: In our series, occiput posterior position did not significantly impact the risk of severe perineal laceration. A manual rotation of the fetal head should be performed in case of associated risk factors.

Enhancement by pyridoxine of the action of diazepam on spinal presynaptic inhibition.

In spinal unanesthetized cats, pyridoxine pretreatment significantly enhanced the diazepam-induced increase in dorsal root potentials and dorsal root reflexes.