Prilocaine theoretically could provide faster onset because of its lower pKa (7,7) compared to bupivacaine (8,1). The primary objective of this prospective double blind randomized trial is to determine block onset of spinal hyperbaric prilocaine compared to bupivacaine, both with a small dose of sufentanyl as an additive.The primary hypothesis is that a significant larger amount of patients will gain surgical readiness within 8 minutes after spinal injection of prilocaine with sufentanyl compared to bupivacaine with sufentanyl. Surgical readiness is defined as a sensory block level of T5 tested by loss of cold sensation.

This study is designed as a randomised prospective double blind multi centre study.

Following approval by the Hospital Ethics committee of the University Hospital Antwerp and all participating hospitals, all-in term (37-42 weeks of gestation) pregnant women planned for a caesarean section will be asked to participate in this trial.

Patients will be randomised to receive either spinal prilocaine with sufentanyl or spinal bupivacaine with sufentanyl.The patient, the anaesthetist performing the CSE and the observer are not aware of the local anaesthetic solution administered.

Preoperative a combined spinal epidural puncture will be performed in the sitting position at the level of L2-L3 or L3-L4 . Vital parameters will be registered at regular intervals. Block characteristics ( onset, duration and intensity of the sensory block and motor block) will be measured at regular intervals.

Patients with insufficient analgesia will receive a top up dose of 5 ml lidocaine 2 % via the epidural catheter.

Time of birth, neonatal outcome (Apgar score 1 min, 5 min and 10 minutes after birth) and admission to the nicu as well as umbilicus venous and arterial blood gasses are recorded.

Patients will be discharged from the PACU when motor block reached a Bromage score 1 Time intervals of discharge to the ward will be registered.At the maternity ward the time of first contact of the baby and the mother and first breast feed (if applicable) will be registered.

One week postoperative patients will be called and asked if they experienced any postoperative symptoms like headache, micturition problems or symptoms resembling Transient Neurological Symptoms

Inclusion Criteria:

• A term Pregnant women (37-42 weeks)scheduled for caesarian section

Exclusion Criteria:

• Patient refusal
• Twin or multiple pregnancy
• Preeclampsia
• Contraindication neuraxial technique
• Indication general anaesthesia
• BMI before pregnancy >35
• Maternal height <155 cm

The spinal solution will be prepared by an independent anaesthetist, anaesthetist trainee or research nurse on a sterile table after opening the sealed envelope with the appointed study group. The patient, the anaesthetist performing the CSE and the observer are not aware of the local anaesthetic solution administered.