Please assess the completion status of the following clinical trial:

Trial Title: Effect of S-ketamine in Cesarean Section Combined Anesthesia

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: CROSSOVER
- Observational Model: None
- Primary Purpose: PREVENTION
- Time Perspective: None
- Masking: TRIPLE
- Phase: PHASE4
- Number of Arms: 4.0

Eligibility Criteria:
Inclusion Criteria:~* ASA status I-III~* Age 20 to 45~* 37-42 weeks gestation~* undergo elective cesarean section with subarachnoid anesthesia~* participate in this study and sign informed consent~Exclusion Criteria:~* Patients with contraindications for cesarean section~* Patients with contraindications of combined spinal and epidural anesthesia~* Patients with severe systemic disease~* Alcoholism and long-term use of anti-inflammatory and analgesic drugs~* Patients who were unable to cooperate or refused to participate in the trial~* Patients with contraindications to esketamine and hydromorphone

- Gender: FEMALE
- Minimum Age: 20 Years
- Maximum Age: 45 Years
- Healthy Volunteers: f

Study Arms:
- Group E1 (Type: EXPERIMENTAL): S-ketamine was administered intravenously after delivery，patient controlled epidural analgesia（PCEA）was administered postoperatively PCEA formula：（10μg/ml hydromorphone+0.11% ropivacaine) 200ml
- Group E2 (Type: EXPERIMENTAL): S-ketamine was administered intravenously after delivery，patient controlled intravenous analgesia（PCIA) was administered postoperatively PCIA formula：（100μg/ml hydromorphone) 100ml
- Group C1 (Type: PLACEBO_COMPARATOR): placebo was administered intravenously after delivery，patient controlled epidural analgesia（PCEA) was administered postoperatively PCEA formula：（10μg/ml hydromorphone+0.11% ropivacaine) 200ml
- Group C2 (Type: PLACEBO_COMPARATOR): placebo was administered intravenously after delivery，patient controlled intravenous analgesia（PCIA） was administered postoperatively PCIA formula：（100μg/ml hydromorphone) 100ml

Based on this trial design, predict the completion outcome and termination type (if applicable).