A 52 year old woman presents with constipation for 3 years. She has attempted a high fiber diet, drinking large amounts of water, and numerous over-the-counter laxatives to no avail. She complains of having to strain excessively, and of experiencing a feeling of incomplete emptying every time she defecates, even on the rare occasions when her stools are soft. At times, digital manipulation is required. Her medical, surgical and family histories are unremarkable. She has 3 children, all delivered vaginally, while her menopause was 4 years ago. She is not on hormone replacement therapy. She drinks socially, does not smoke and is not on any medications currently.
Serum Na+, K+, Mg++, Ca++: all within normal parameters. Blood Urea, Serum Creatinine: all within normal parameters Fasting Plasma Glucose: normal
TSH: 2.9 mU/L (0.4- 4.5) Free T4: 16.1 pmol/L (9- 25) Free T3: 5.6 pmol/L (3.5- 7.8)
There is a paradoxical increase in anal sphincter pressure during attempted defecation. The pushing force is normal and adequate. The balloon could not be expelled. The rectoanal inhibitory reflex is present.
Colonoscopy reveals no abnormalities.