Fig. 4

Dip slides used in the study. OR = operating room, UR = ultrasound room, prior to surgery = during preparations for the surgery, post-surgery = immediately after the surgery finished, prior to the first patient = before the first patient of the day, post ultrasound examinations = after the ultrasound examination of each patient including before and after decontamination of the abdominal position cushion, post-lunch = when the UR had been empty during lunch time and before the next patient arrived