Structured hysteroscopic examination of uterine niches: a modified Delphi procedure.

Background: Uterine niches in the Caesarean section scar are seen in approximately half of women with a history of caesarean delivery. Whilst a structured ultrasound assessment of caesarean defects has been described, there is no consensus on a structured hysteroscopic evaluation.
Objectives: To propose a methodology for a structured hysteroscopic evaluation of uterine niches.
Materials and Methods: We conducted a modified Delphi procedure, including two online rounds and two face-to-face meetings of the members of the ESGE Uterine Niches Working Group. The taskforce members have extensive experience in hysteroscopic niche evaluation. The consensus was predefined as a Rate of Agreement of at least 75%.
Results: Thirteen experts participated in this modified Delphi procedure. There was consensus on the need for a standardised methodology and the hysteroscopic definition of a niche as any indentation in the myometrium at the site of a previous CS. There was consensus that a hysteroscopic evaluation of a niche must be combined with ultrasound to measure the residual myometrial thickness. In addition, it was agreed that niches should be subclassified as 'simple', 'simple with one branch', or 'complex'. There was consensus that the following items should be described during a hysteroscopic niche evaluation: the number of niches, the size in relation to the size of cervical canal, the presence of polyps, crypts, cysts, fibrotic tissue, blood, mucus, placental remnants, a dynamic valve, the appearance of the endometrium, the number of blood vessels and bleeding from blood vessels within the defect.
Conclusion: Using a modified Delphi procedure with international experts, consensus was achieved on the hysteroscopic evaluation and classification of niches in the uterine caesarean section scar.
What Is New?: A structured registration form was developed to aid consistency in hysteroscopic niche reporting.