We've all had moments when a sudden flood of emotion threatens to overwhelm us. And then, for most of us, those moments pass. What distinguish the postpartum blues from true postpartum depression (which is a much more serious situation and actually classified as an illness) are severity as well as persistence of symptoms. It's difficult to make an accurate diagnosis of postpartum depression, given how prevalent the more common blues can be right now.
When a woman comes to me for a six-week appointment, in addition to performing a physical exam I'll also try to give the once-over with regard to her emotional state. Of course this is hard to do in a 20-minute office visit, but some details might raise a red flag for me, such as excessive tearfulness and a heightened emotional state, as we talk. Her degree of grooming can give me a sense of how well she's taking care of herself; depressed mothers often have a hard time managing to comb their hair or take a shower. If she's brought the baby with her, as I peek into the carriage and coo and compliment, I'll make sure the baby looks clean and well-cared-for too.
I once had a patient who became convinced, in the hospital, that the nurses were manhandling her baby. She tearfully told me, "They throw my baby around the nursery. I can't believe they treat him like this." I knew that the nursing staff was gentle and competent, and I felt my patient's view was untrue, a distortion. Her response did not seem normal to me, and I had someone from Psychiatry come down to talk to her and make sure it was safe to release her. In the end she turned out to be fine, but I needed to make sure. In its most dramatic (but rare) forms, postpartum depression can develop into actual psychosis, in which women are at risk of harming themselves or their babies.