Endoscopic sellar surgery, especially for adenomas, is a relatively safe, straightforward surgery with (mostly) reproducible results and few complications. One of the commonest complications is the creation of a CSF leak with the subsequent need for repair (there is usually no need for sellar repair). A way to deal with such a defect is to prepare a nasoseptal flap. However, the low incidence of CSF leaks does not warrant the routine elevation of such a flap (albeit, a rescue flap may be an option). Hence, it is important to be able to select high-risk patients, where CSF leaks are more likely to happen. This is exactly the point of this very important paper – the authors collected data from seven centres over a period of 12 years. The authors gathered data on more than 1000 adenomas (5.1% CSF leak rate) and 50 craniopharyngiomas (20.8% CSF leak rate). What they found was partly expected. In multivariate analysis, increased BMI, decreased age, female gender and being African-American, as well as craniopharyngioma, recurrent tumour and extension into anterior cranial fossa and intraventricular extension were all associated with a higher risk of leaking. Importantly, the use of nasoseptal flap was clearly associated with a reduced overall risk of CSF leak.