Patient description: A 45-year-old woman was referred to the emergency department with abdominal pain lasting about 4 days accompanied by nausea and 2 episodes of vomiting. The pain is localized to the epigastric region and radiates to the right upper quadrant. The pain is worsening after eating fatty food. The patient experienced similar pain twice in the past year. Her past medical history is remarkable for hypercholesterolemia and two C/sections. She has 2 children, and she is menopausal. She doesn't smoke, drink alcohol, or use illicit drugs. She is mildly febrile. Her BP is 150/85, HR 115, RR 15, T 38.2, SpO2 98% on RA. On palpation, she experiences epigastric tenderness and tenderness in the right upper quadrant without rebound. Bowel sounds are normal. Laboratory analysis is remarkable for elevated ESR and leukocytosis with a left shift. The ultrasound revealed several gallstones and biliary sludge. The largest gallstone is 0.7cm. Surgery consultation recommends elective cholecystectomy.

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Acute Pain Female subjects ≥ 18 years on the day of consent. 2. Willing and able to provide written informed consent for this study. 3. Subjects are scheduled to have a total or subtotal abdominal hysterectomy under general anasethesia via a Pfannenstiel incision. 4. The elective procedure (total or subtotal hysterectomy with or without salpingo-oophorectomy) must be for benign conditions within 28 days of screening. Subjects with stage 0 carcinoma in situ of cervix, endometrial hyperplasia or clinically staged 1A or 1B endometrial cancer are allowed to participate. 5. American Society Anaesthesiology physical status of I or II. 6. If a female is of child-bearing potential, she must be using highly effective methods of contraception throughout the study, not breastfeeding, and have negative pregnancy tests prior to receiving IMP. A highly effective method of birth control is defined as one which results in a low failure rate (i.e. less than 1% per year) when used consistently and correctly such as sterilisation, implants, injectables, combined oral contraceptives, some IUDs (Intrauterine Device, hormonal), sexual abstinence or vasectomised partner). 7. Good general health as judged by Investigators on the basis of medical history and physical examination. 8. Willingness to comply with the study procedures and requirements. Additional after Surgery: 1. Abdominal hysterectomy completed without any immediate complication. 2. Tolerating oral fluids, no uncontrolled nausea/vomiting and ready to take oral analgesia. 3. The subject is alert and calm, spontaneously pays attention to caregiver, e.g. RASS = 0 (Sessler et al., 2002 & Ely et al., 2003). 4. Subjects will be capable to sit up from supine, stand up from a sitting position and walk 10 meters without assistance in the morning of the day following surgery. 5. Subjects with moderate or severe pain (qualifying PI-VAS score ≥ 45mm and < 70mm or ≥ 70mm and ≤ 90mm) as a result of a surgical procedure (abdominal hysterectomy) under general anaesthesia. This must be measured within a maximum of 24 hours after leaving the recovery room and subjects can only be randomised on the day after surgery, after cessation of the post-operative analgesia  Any abnormal laboratory value that is clinically significant in the opinion of Investigator that would compromise the safety of the subject in the study. 2. Any recent history of frequent nausea or vomiting, dizziness within the last 3 months regardless of etiology. 3. Subjects having any medical condition or treatment that is either a warning or contraindication as per the SmPC of tramadol (e.g. selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants, MAO inhibitors (within 14 days before taking IMP), antipsychotics, anticonvulsant and other seizure threshold-lowering medicinal products), celecoxib (e.g. increased risk of post-operative bleeding, active peptic ulceration, GI bleeding or inflammatory bowel disease) or paracetamol. 4. Known sensitivity and/or contraindication to tramadol, celecoxib, paracetamol, sulfonamides, opioids, COX-2 inhibitors, or related compounds or formulation excipients as well as severe hypersensitivity reactions (e.g. anaphylactic shock, bronchospasm, angioedema) to any drugs. 5. Subjects who are known to have had inadequate pain relief from paracetamol, tramadol or celecoxib. 6. Subjects requiring any medication which is prohibited as per section prohibited medication. 7. Subjects who are in the Investigator's opinion considered at increased risk of operative (those associated with the surgical procedure and general anaesthesia) and post-operative complications, e.g. excessive post-operative bleeding, infection. 8. Any history of drug or alcohol abuse, misuse, physical or psychological dependence, mood changes, sleep disturbance and functional capacity which have an impact on pain perception. 9. Significant neurological or psychiatric disorders including mental instability (unrelated to the pain) that could interfere with pain assessment; other pre-existing or new non-abdominal/pelvic pain that might impair the assessment of the nociceptive pain. 10. Any medical history of significant and/or inadequately controlled cardiovascular (uncontrolled high blood pressure, high risk of cardiovascular events, severe heart failure), pulmonary, hematologic, (including coagulopathy/bleeding disorders), neurological (e.g. subjects with epilepsy or those susceptible to seizures), liver disease (e.g. severe hepatic impairment), kidney disease (e.g. serum creatinine level greater than 1.5 times the upper limit of normal, impaired renal function in subjects taking diuretics, ACE-inhibitors, or angiotensin II antagonists), endocrine, immunologic, dermatologic painful conditions or any other conditions that may compromise the ability of the subject to participate in the study or might interfere with drug absorption, distribution, metabolism or excretion. 11. Previous randomisation in this study. 12. Subjects who participated in a clinical research study involving a new chemical entity or an experimental drug within 30 days of study entry (defined as the start of the Screening Period). 13. Subjects who were treated regularly with opioid analgesic or NSAIDs within 30 days prior to screening or who have received a long-acting NSAID within three days prior to the start of the surgery. 14. Subjects who are incapable of complying with the protocol. 15. Epidural or spinal anaesthesia or infiltration of the wound with an infusion of a local anaesthetic agent is not allowed. A single perioperative dose is allowed. 16. History or ongoing chronic pelvic inflammatory disease or painful endometriosis. 17. History of advanced gynaecological cancers. Additional after Surgery: 1. Serious complication during surgery and up to randomisation, including Post-operative primary and secondary bleed that cannot be controlled Subjects who have not had the abdominal hysterectomy surgery completed as planned. 2. If in the Investigator's opinion, there are any factors that may affect compliance with the protocol. 3. Subject clinical need for antiemetics (apart from standard perioperative practice as defined in the protocol) or any other medication which is prohibited as per section prohibited medication. 4. Subjects who have received any analgesic medication other than perioperative analgesia as described in the protocol. 5. Any concerns that renal function has deteriorated, e.g. a laboratory parameter, profound hypotension, poor urine output or excessive bleeding during surgery