From the Digestive Health Center, Medical College of Georgia, Georgia Regents University, Augusta, GA
Defecation is a coordinated process that involves generation of sufficient propulsive forces in the abdomen and rectum together with relaxation of the puborectalis and external anal sphincter. Likewise, continence involves conscious retention of bowel contents until stool or gas can be voluntarily eliminated in an appropriate fashion. A failure of these processes leads to altered bowel function and disorders of defecation that are commonly encountered in clinical practice. They include a diverse group of maladies that result in altered defecation. Among them are functional disorders, such as dyssynergic defecation, and mechanical/structural disorders, such as rectocele, solitary rectal ulcer syndrome (SRUS), excessive perineal descent, and rectal prolapse. This article discusses 3 cases that illustrate the clinical features and management approaches to dyssynergic defecation, SRUS, and fecal incontinence.
Case Study 1
Presentation and History
A 26-year-old white woman with a 10-year history of constipation presents to a gastroenterologist after referral from her primary care physician. She reports spontaneous bowel movements once every 2 weeks, and often she has to induce stools by using enemas or suppositories. Stooling became progressively more difficult for her during her teenage years, with infrequent bowel movements and hard stools (type 1–2 on Bristol stool scale). She also reports having to strain excessively during bowel movements, and on average she spends 30 minutes in the bathroom. She denies experiencing any perianal pain or bleeding or using manual maneuvers to defecate, but she often feels a sense of incomplete evacuation. She also describes intermittent abdominal pain and bloating.
She has tried several over-the-counter laxatives, includ-ing milk of magnesia, senna, and magnesium citrate. Most recently, she tried lubiprostone and polyethylene glycol without improvement. Her past medical history is significant for endometriosis, exploratory laparotomy, and 1 vaginal delivery. There is no family history of colorectal cancer or inflammatory bowel disease. She works as a truck driver and does not use alcohol, illicit drugs, or tobacco. There is no history of physical or sexual abuse. Her current medications include lubiprostone 24 µg twice daily, polyethylene glycol 17 g twice daily, and a birth control pill.
Physical Examination
On physical examination, the patient appears healthy without any distress. Her body mass index is 26 kg/m 2, and vital signs are normal. General examination is normal. Abdomen is flat, and bowel sounds are normal. Mild tenderness is noted in both lower quadrants. Rectal examination reveals normal anal skin folds. Digital exam-ination reveals a normal resting tone with pellet-like stool that is heme-negative. When asked to attempt defecation, she shows poor perineal descent and paradoxical contraction of the anal sphincter.
Laboratory Evaluation
Laboratory testing reveals normal levels of thyrotropin and thyroxine, no anemia on complete blood count, and normal levels of calcium, glucose, and electrolytes.
What are the possible causes for this patient’s altered bowel habits?
What is the approach to physical examination in patients with constipation?
Causes of Constipation
Constipation is a common digestive disorder, affecting up to 20% of the world’s population [1]. Primary or idiopathic constipation consists of 3 common overlapping subtypes: slow-transit constipation, dyssynergic defecation, and constipation-predominant irritable bowel syndrome. Slow-transit constipation involves the slow movement of stool through the colon. This is usually seen on a colonic transit study or with wireless motility capsule study. Dyssynergia in general is caused by functional outlet obstruction with or without normal colonic transit. Patients with dyssynergia often complain of incomplete evacuation, excessive straining, bloating, and blockage [2]. Often patients with dyssynergia resort to manual disimpaction/vaginal splinting and/or abdominal pressure to facilitate bowel movements. Secondary constipation may result from metabolic disorders (eg, hypercalcemia and hypokalemia, disorders associated with renal failure, hypothyroidism, and diabetes) as well as medications, including narcotics, anticholinergics, and antidepressants.