The Twelfth House
The twelfth house is often said to be a difficult house for it is the house of hidden matter and issues that have been brushed aside and left undone, skeletons in the closest if you will. It is traditionally associated with prisons, hospitals and places that are out of view of the general public. These places are isolated or unknown and work in ways that most would not uncover. Working behind the scenes is a general theme for people who have strong planetary links to this house.
It is also considered a secret house and an occult house where the subconscious tends to work relentlessly to uncover unknown factor that lie beneath the surface. It is the house of self-undoing and in many cases, it can signify how someone stands in their own way. We can gain knowledge with inner reflection and open channels to the subconscious and recognizing that they are part of the collective consciousness that envelops us all.
Karma is also known to have its domain linked to this house along with charity work and the ultimate understanding of our sub-conscious connection. The sixth and twelfth house deal with service and they constitute service to others. While the sixth house may reflect service to others and the rewards it may bring, the twelfth house speaks of service without rewards, selfless service if you will.
It is also linked to secret affairs as well as progressive illnesses and weaknesses within the body that can build over time and be the eventual cause of death. The aspects to the planets within this house and the house cusp ruler can provide information in this regard. You also have to look at the ascendant and the aspects to it as well as the Sun to get a clear picture of chronic health conditions that are suggested in a chart.