I have/had(?) hematometra and had a d&c to remove the blood. my obgyn doesn't know what caused it. no visible causes, should i be worried?

Hematometra: In many cases, the d&c is enough to cure the problem. Some people just have a narrow cervical opening which can be blocked by anything from inflammation to nothing at all. The d&c opens up this canal, which is the correct treatment if this occurred. Most of the time the hematometra does not come back, especially at your age. There is usually not a visible cause, just a narrow or blocked cervix.