Purpose: The development of a metric fundus assessment and definition of the uterine fundus thickness (FTH) for supporting objective diagnosis and treatment of congenital uterine anomalies (CUAs). Materials and Methods: A) In a prospective cohort study, FTH was systematically assessed by 3 D transvaginal ultrasound (TVS) in patients, who presented a normal uterus. B) The mean normal FTH recorded was applied to uteri with fundal protrusions and septations, and compared to two CUA classification systems (ASF and ESHRE/ESGE). C) FTH was studied for preoperative metric planning and evaluation of the postoperative outcome. Results: A) From August 2013 to January 2014, FTH was assessed in 100 normal uteri. An FTH of 12.02 +/- 2.03 mm (mean +/- SD) was recorded. B) Evaluating the 8 detected abnormal uteri, excellent correlation with the new ESHRE/ESGE classification system was observed, taking an FTH of 12 mm as the overall normal FTH equivalent to the individual normal wall thickness (WTH) stipulated in the classification and an FTH of 18 mm as the WTH + 50 %, serving as a cut-off value of (abnormal) septation. C) Metric fundus assessment was initially applied before and after septum resection and the following pregnancy could be monitored. Conclusion: An FTH measurement in 3 D TVS paves the way for metric fundus diagnostics. This objectively distinguishes normal from abnormal fundi. It also has the potential to support accurate septum resection planning and objective postoperative evaluation. The value of the fundus assessment and metrics proposed in this study is not known. It should be investigated in prospective randomized controlled trials.