I had a hysterectomy and they gave me a couple pairs of these at the hospital. I immediately bought these upon getting home.

Some help with measurements: I bought a small as I am of average build (5'5", ~145). I have a small waist but wide hips and big butt (waist 27, hips 40) but these did not bunch up as other full-coverage underwear often do, due to the mesh material being flexible. They were tighter than the hospital ones (hospital must use medium/larges) but didn't cut into my stomach or disappear into my butt, so I was happy.

I didn't end up needing them all - they were to accommodate a large pad, and I didn't have any bleeding issues. I'm still glad I had them when I needed them and will save the unused ones in case any friends or family need them.