A manifold assembly for a peritoneal dialysis apparatus, comprising: a casing having a flattened shape and delimiting internally a first compartment and a second compartment; a yielding pump tube having a first end connected to the first compartment and a second end connected to the second compartment, wherein the yielding pump tube extends outside the casing to be coupled to a peristaltic pump of a cycler of a peritoneal dialysis apparatus; a patient line tube having a first end connected to the second compartment and a second end connectable to a peritoneal cavity of a patient; at least one fluid line tube (59, 61, 63, 65; 63, 65) having a first end connected to the first compartment and a second end connected or connectable to a fluid source (60, 62, 64; 64) and/or to a drain; optionally, at least one fluid line tube (59, 61) having a first end connected or connectable to the second compartment and a second end connected or connectable to a fluid source (60, 62); wherein the first compartment, the yielding pump tube and the second compartment delimit together a fluid path extending between said at least one fluid line tube (59, 61, 63, 65; 63, 65), having the first end connected to the first compartment, and the patient line tube, to allow fluid flow at least from said at least one fluid line tube (59, 61, 63, 65; 63, 65), having the first end connected to the first compartment, to the patient line tube or from the patient line tube to said at least one fluid line tube (59, 61, 63, 65; 63, 65), having the first end connected to the first compartment, when the peristaltic pump of the cycler is actuated; characterized in that the second compartment delimits at least one expansion chamber (24a, 24b, 24c) configured to attenuate pressure pulsations from the peristaltic pump, wherein the at least one expansion chamber (24a, 24b, 24c) is at least in part delimited by one soft membrane; wherein the casing comprises at least one recess/protrusion (25a, 25b, 25c) delimiting said at least one expansion chamber (24a, 24b, 24c) such that said at least one expansion chamber (24a, 24b, 24c) has a depth greater than a depth of a remaining part of the second compartment; optionally wherein a plurality of expansion chambers (24a, 24b, 24c) are delimited in the second compartment. a casing having a flattened shape and delimiting internally a first compartment and a second compartment; a yielding pump tube having a first end connected to the first compartment and a second end connected to the second compartment, wherein the yielding pump tube extends outside the casing to be coupled to a peristaltic pump of a cycler of a peritoneal dialysis apparatus; a patient line tube having a first end connected to the second compartment and a second end connectable to a peritoneal cavity of a patient; at least one fluid line tube (59, 61, 63, 65; 63, 65) having a first end connected to the first compartment and a second end connected or connectable to a fluid source (60, 62, 64; 64) and/or to a drain; optionally, at least one fluid line tube (59, 61) having a first end connected or connectable to the second compartment and a second end connected or connectable to a fluid source (60, 62); wherein the first compartment, the yielding pump tube and the second compartment delimit together a fluid path extending between said at least one fluid line tube (59, 61, 63, 65; 63, 65), having the first end connected to the first compartment, and the patient line tube, to allow fluid flow at least from said at least one fluid line tube (59, 61, 63, 65; 63, 65), having the first end connected to the first compartment, to the patient line tube or from the patient line tube to said at least one fluid line tube (59, 61, 63, 65; 63, 65), having the first end connected to the first compartment, when the peristaltic pump of the cycler is actuated; characterized in that the second compartment delimits at least one expansion chamber (24a, 24b, 24c) configured to attenuate pressure pulsations from the peristaltic pump, wherein the at least one expansion chamber (24a, 24b, 24c) is at least in part delimited by one soft membrane; wherein the casing comprises at least one recess/protrusion (25a, 25b, 25c) delimiting said at least one expansion chamber (24a, 24b, 24c) such that said at least one expansion chamber (24a, 24b, 24c) has a depth greater than a depth of a remaining part of the second compartment; optionally wherein a plurality of expansion chambers (24a, 24b, 24c) are delimited in the second compartment.