Objective: On prenatal diagnostics, 3D/4D ultrasound has had a significant influence. Although the technique is often identified with surface imaging, it enables one to obtain a large amount of additional information by means of processing of a volume data set. Furthermore, this opens up new possibilities in the diagnostics of internal organs. One method offered in 3D/4D ultrasound is processing in minimum mode. In this mode fluid-filled organs are displayed in black. Materials and Methods: This is a prospective observational study conducted during the period 1 Jan 2005-31 Aug 2007 using a 3D-static volume data set of the thorax and the abdomen in abnormal screening population in the second trimester. Additionally fetuses with various malformations in combination with fluid filled organs were analyzed. Results: The use of minimum mode in the 22th gestational week (gw) is easy, especially when the fetus is in a dorsoposterior position. We were able to demonstrate the typical signs in fetuses with various malformations (lung, diaphragmatic hernia, kidney, bladder, neck, heart). Because of using the volume ultrasound the method allows us often a much better spatial visualization of the organs. Discussion: Minimum mode is an additional tool in 3D/4D ultrasound, enabling the visualization of fluid-filled organs in a volume data set. This makes it possible to obtain information about the spatial relationship of the organs. [ABSTRACT FROM AUTHOR]