• 1)Pain intensity 2)"Rescue" analgesia requirements [ Time Frame: 24 hours ] [ Designated as safety issue: Yes ]
  

Study Objective: To assess the analgesic efficacy of diclofenac or ropivacaine when administered via wound instillation.

Design: Prospective, randomized, double-blind, placebo-controlled study. Setting: Large referral hospital. Patients: 75 women recovering from Cesarean section performed via a Pfannenstiel incision.

Interventions: On completion of the surgical procedure, a 15 cm 19G instillation catheter (PAINfusor™, Baxter) will be placed below the fascia. Postoperatively, the catheter will be attached to a patient controlled analgesia (PCA) device programmed to deliver 9 mL with a 60 min lockout time and no basal infusion. According to a computer generated randomization schedule, patients will be divided into one of three treatment groups (n = 25).

• In Group Control a bolus dose of 10 mL of water for injection will be administered.
• In Group Ropivacaine a bolus dose of 10 mL 0.2 % ropivacaine will be administered.
• In Group Diclofenac a bolus dose of 10 mL diclofenac (300 mg/240 ml of water for injection) will be administered.

During the first 6 postoperative hours, a co-investigator will administer "rescue" analgesia. Thereafter, the catheter will be connected to an elastometric pump (LV 10 Infusor, Baxter) filled with either water for injection, ropivacaine 0.2 %, or diclofenac (300 mg/240 ml water for injection). The fluid will be administered as a constant instillation at a rate set of 10 mL/hr. Continuous wound instillation will be continued for the subsequent 18 postoperative hours. During this 18 hour period, subcutaneous morphine 4 mg will be administered on patient request for additional analgesia.

Measurements and Main Results: The following parameters will be assessed and recorded:

1. Demographic data
2. Surgical milestones(Anesthetic time, surgical time, readiness for PACU discharge etc).
3. Incidence of failed intrathecal anesthesia
4. VAS for pain every 15 min during first 6 postoperative hours
5. Time to first pain (intrathecal anesthesia to VAS > 60 mm)
6. Time to instillation onset (instillation to 50 % decrease in VAS for pain)
7. Number of instillations performed (10 mL and 5 mL)
8. Incidence of failed instillation (rescue morphine administration during first postoperative hours)
9. Subcutaneous morphine
10. VAS for pain at rest, on coughing and following leg raise on PACU admission, and at 6,12,18 and 24 hours postoperatively. The incidence of nausea and vomiting as well as uterine contractions will be assessed (yes/no) at these time intervals.
11. Patient satisfaction at 24 hours, postoperatively.