Article History
Received: 21 August 2018
Accepted: 27 March 2019
First Online: 3 April 2019
Compliance with ethical standards
:
: Wolf HW received financial support and technical equipment from Karl Storz GmbH, Tuttlingen, Germany.
: The authors Runkel N and Grumbeck B declare that thy have no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
: This article does not contain any studies with animals performed by any of the authors. As this study is designed as a retrospective study, formal consent is not required.
: As data were collected as part of a regular hospital stay and analyzed retrospectively, informed consent was not obtained. The study was approved by the local ethics committee and registered at the German trial register. Trial registration number: DRKS00009840.