An abstract noun would be 'hospitalisation'.

The abstract noun form of the concrete noun 'hospital' is hospitalization.

Extreme morning sickness Can result in dehydration and hospitalisation, only occurs in 1 in 100 pregnancies and can last for the duration in extreme cases.

not sure about indigestion but yes! it causes back ache.

Hospitalists provide services such as keeping a close eye on a hospitalised patient, answering a patient's questions and enabling care for patients when they are unable to see their general physician due to hospitalisation.