Here is the design of a clinical trial:

Official Title: Endometrial Scratch Effect on Pregnancy Rates When Performed During the Previous Cycle of Embryo Transfer in Patients Undergoing Egg-donation IVF

Included conditions:
- EMBRYO IMPLANTATION

Study Armgroups:
- {'label': 'GROUP A: intervention group', 'type': 'EXPERIMENTAL', 'description': 'Patients will be performed an endometrial scratch with Pipelle Cournier 3 to 4 weeks before the embryo transfer and then they will follow the conventional preparation protocol to receive embryos coming from an egg donation treatment.', 'interventionNames': ['Procedure: Endometrial scratch']}
- {'label': 'GROUP B: no intervention group', 'type': 'NO_INTERVENTION', 'description': 'Patients will receive the conventional preparation protocol to receive embryos coming from an egg donation treatment.'}

Interventions:
- {'type': 'PROCEDURE', 'name': 'Endometrial scratch', 'description': 'Patients included in the study group will be performed an endometrial scratch with Pipelle Cournier 3 to 4 weeks before embryo transfer.', 'armGroupLabels': ['GROUP A: intervention group'], 'otherNames': ['Scratching']}

Primary Outcomes:
- {'measure': 'Positive Pregnancy Test', 'description': 'Positive test (hcG\\>10 UI/ml)', 'timeFrame': '12 to 14 days after embryo transfer'}
- {'measure': 'Clinical Pregnancy', 'description': 'Ultrasound confirmation of intrauterine pregnancy', 'timeFrame': '5 weeks of pregnancy'}

Please estimate the sample size based on the assumption: 
80% statistical power, two-sided alpha of 0.05, and a 5% dropout rate.
Sample size calculation
        The average CPR after embryo transfer in egg donor IVF cycles is 60% at our centre. Based on previous studies, where the difference in CPR for IVF cycles varied between 10 to 30% [9, 11, 12, 19, 20, 23â25], we estimated that a 15% difference in CPR would be clinically relevant. According to that percentage, a total of 332 patients will be needed to detect a 15% difference between the two groups, with 80% statistical power and two-sided alpha of 0,05. Considering a 5% dropout rate, we will include 176 patients per study arm, 352 patients in total.