A clinical case is described of a patient diagnosed of prostate cancer under treatment with brachytherapy in the last three months. Due to this, the patient presents urinary retention and secondary acute renal failure. This case occurred during the COVID-19 confinament period. Appointments requested by the patient were by telephone and the family doctor, based on each case, decided and scheduled the in-person appointment. Considering this exceptional situation, we want to stress, first of all, the importance of a telephone interview as a filter to decide on the in-person care of the patient. On the other hand, the important role of the ultrasound as a tool to help in the primary care study, which, in the case of this patient, was fundamental to establish the diagnosis and send the patient without delay to the second care level