What does a dent collector do if no credit card?

When I was first pregnant my husband (at the time fiance) had me go to an ER. I was in major stomach pains and tried telling him it was normal because my mother had the same problems with all four of her kids. But he was so afraid it was something else so I went. All they said was "yeah you're pregnant and about 6 weeks." they didnt' say anything about why i was in pain, and even stuck me with something. I actualy screamed out because it hurt so much and the lady was like "oh no, shhh shhh shh" shushing me. I remember something about saying useing a straw (im guessing to get urine although I dunno why i oculdnt just go to the bathroom and peei n a cup) and her saying "i'm glad we didn't use the big straw" ANYWAYS- we didn't have insurance at the time, I was techinially comepletely on my own. I dont have any credit cards or anything-been married to hubby for over a year now and we have our son. We were able to get insurance before baby was born (he's in military and they were going really slow. We were trying to get married even before I was pregnant and ended up having to call higher up to get the process going. Apparently the area he was workign in didn't want him to get married and was trying to hold it off . I guess thuinking if they held it off long enough we wouldn't marry at all.) Anyways, debt collectors have called his cell phone, we did make one payment once when we could afford it but we havn't been able to ever since then. Anyway, what can they do? Mother in law keeps saying they can't do anything. Any experience? thanks