What is the key difference between hemodialysis and peritoneal dialysis?

The key difference between hemodialysis and peritoneal dialysis lies in the method of filtration used to remove waste products and excess fluid from the blood. Hemodialysis specifically utilizes a machine known as a dialyzer, which acts as an artificial kidney to filter blood outside of the body. During this process, blood is drawn from the patient, circulated through the dialyzer where it encounters a dialysate solution, and then returned to the patient.

This method involves several procedures and requires the patient to visit a dialysis unit, typically multiple times a week. In contrast, peritoneal dialysis occurs within the body, using the peritoneal membrane as the semi-permeable membrane for filtration, and does not rely on a dialysis machine for the actual filtration process. Therefore, option B accurately describes the use of a machine and a dialyzer as the distinctive aspect of hemodialysis compared to the self-conducted nature of peritoneal dialysis.