help! My father was just diagnosed 4 months ago.

After radical prostatectomy the PSA should be zero. Results of PSA test below 0.03 ng/ml are expected to occur at one month after surgery. This is the threshold indicating a successful outcome of the therapy. The 1.9 ng/ml level contradicts the pathologist’s report, which indicates an "all clean" status. This value could be due to a laboratory error, but it could also be due to the presence of a worse diagnosis that was not found in the tissue slices analysed by the pathologist. This is not common to occur but the pathologist only analysis a small portion of the prostate tissue. They do the cutting at critical regions leaving unstained other less common areas, which samples in your father’s case could have been “clean”.

You can always repeat the PSA test at a different reliable laboratory and can also request for a second opinion on the slides of the prostate gland. Hospitals usually keep the samples for a long period of time.
The assays used in PSA testing in guys without the prostate should also have LLD (low limits of detections) of two decimal places (PSA= 0.0X ng/ml) because the levels are expected to become very low. I recommend you for requesting they use ultra sensitive assays.

Welcome to the board.

VG