Post-operative nausea and vomiting are the major complications after spinal anesthesia with intrathecal morphine, therefore antiemetic drugs should be administered for best satisfaction of anesthesia to prevent these complication.

Furthermore, administration of a combination of antiemetic drugs with different mechanisms of action appears reasonable and synergistic effect of drugs.

In conclusion, we study efficacy of antiemetic effect of single antiemetic drug compare with combination antiemetic drugs.

In this study : a randomized, double-blind, placebo-controlled, clinical trial comparing single doses of Metoclopramide 10 mg and Ondansetron 8 mg alone and a combination of Dexamethasone 5 mg and Metoclopramide 10 mg or a combination of Dexamethasone 5 mg and Ondansetron 8 mg for prevention of PONV after spinal morphine for cesarean section.

Inclusion criteria

1. Patient undergoes elective cesarean section age more than 18 years
2. Patient accepted in spinal anesthesia technique
3. ASA classification I-II
4. Patient understand question and evaluation process

Exclusion criteria

1. Hyperemesis gravidarum
2. Patient with ongoing antiemetic drugs treatment
3. Patient with history of drug allergy in Metoclopramide,Ondansetron and Dexamethasone

Outcome measurement By oral interview and nurse notification in 24 hr. post-operatively.

Detail of outcome measurement

1. Nausea and vomiting score
2. Pain score
3. Sedation score
4. Itch symptom
5. Patient satisfaction

Inclusion Criteria:

• Pregnancy patients undergo Elective cesarean section age more than 18 years
• Patient accept spinal anesthesia technique
• ASA classification I-II
• Patient understand question and evaluation process

Exclusion criteria:

• Hyperemesis gravidarum
• Patient ongoing treatment with antiemetic drugs
• Allergy to Metoclopramide,Ondansetron and Dexamethasone