Several alternatives are possible. What was your PSA value before your prostatectomy? Gleason 3+4 or 4+3?

It is unusual to have a PSA test 30 days after a prostatectomy. Why was a PSA test done so soon after your operation? What were the tumor pathology (e.g. margins) report results? Confirmed 3+4 or 4+3?

I presume that your PSA will be measured again 60 days after surgery. At that time, you will have two data points and know whether the PSA value after your prostatectomy is decreasing, constant, or increasing. That information will guide you and your medical team on likely reasons for the PSA value: decreasing - first test too early, constant - possible some prostate tissue remained in the prostate bed after surgery, increasing - likely prostate cancer cells outside of prostate.

It takes a bit of time for the PSA to get removed from your blood. If memory serves, my doc told me it has a three day half life, you can do the math.

Also, if your PSA was 18 at last check, it was still most likely climbing, how long before the operation was it 18? If it was a month or so, it was likely higher when you had the operation. If it was longer, well, we don't really know that number.

for example, my alarm bell went off on 3/1 at 11.5, biopsy showed cancer, retested at 7/1 that was 13.8, the operation was on 9/2 so likely around 15-16(ish) by then. I wouldn't read too much into anything until you see the trend as suggested prior. That's the most important factor at this point.