Correct answer:

(1) Organic obstruction:
(a) carcinoma of the colon;
(b) diverticular disease.
(2) Painful anal conditions:
(a) fissure in ano;
(b) prolapsed piles.
(3) Adynamic bowel:
(a) Hirschsprung’s disease;
(b) senility;
(c) spinal cord injuries and disease;
(d) myxoedema;
(e) Parkinson’s disease.
(4) Drugs:
(a) aspirin;
(b) opiate analgesics;
(c) anticholinergics;
(d) ganglion blockers.
(5) Habit and diet:
(a) dyschezia (rectal stasis due to faulty bowel habit);
(b) dehydration;
(c) starvation;
(d) lack of bulk in diet.