Getting to the bottom of constipation

MELBOURNE surgeons recently reported the unusual case of a man who was rushed to Footscray Hospital’s Emergency Department with such a severe bout of constipation that he was completely unable to walk. Diagnosed with the life-threatening abdominal compartment syndrome, the man underwent an intervention that involved removing a whopping two litres of faecal matter from the bowel. The case was duly written up and published in BMJ Case Reports.

Of course, constipation is rarely so extreme, and treatments tend to be lifestyle modifications and laxatives rather than surgery. But a new Review of the management of chronic idiopathic constipation, published in the MJA, points out that there are indeed rare cases when the condition proves so refractory that total colectomy is indicated. Even in the far more common, less severe cases, treatment often fails and it can have a significant impact on quality of life. Constipation is something to be taken seriously, but so often it is not.

Dr Michael Levitt, a Perth-based colorectal surgeon who has just published a book on bowel health, says that one major problem in constipation management is that not enough research has been done on it.

“It’s not a sexy subject. Only very rarely is it a life-threatening condition, and there aren’t people out there thinking they’re going to get the Nobel Prize if they crack the constipation problem. The end result is that doctors aren’t overly interested in the subject, and so many of the symptoms that are problematic if you’re constipated are hard to quantify in a way that appeals to the scientist.”

Dr Levitt says that another issue is that the majority of people with significant constipation are women, while most prescribers still tend to be men, with a male perspective on bowel function. But male and female bowel function is not the same, he says. He cites a well known trial in which men and women were given exactly the same solids and fluids to consume; the men had faster colonic transit, had their bowels open more frequently and produced a greater volume of stool.

“It is simply not a gender-equivalent condition, it’s predominantly a female problem. In my career, I’ve only done around 35 total colectomies for severe constipation, but never on a man, only women. There’s a fundamental gender difference in how the bowel works. That creates a problem where you have a large chunk of prescribers who essentially think if you eat enough fruit and vegetables your bowels should work, but [many] patients don’t respond that way.”

Dr Levitt says that there has nonetheless been a definite improvement in treatment, in particular with the ready availability of osmotic laxatives such as polyethelene glycol and lactulose.

“There is an increasing use of osmotic laxatives over the traditional herbal or stimulant laxatives, which are habit forming. That’s a good development. The trouble is we still tend to measure constipation in terms of stool frequency, when almost certainly that’s just a secondary marker for other things. In fact, the critical symptoms are things [such as] abdominal bloating, straining, anxiety and impact on quality of life.”

He says that this focus on stool frequency leads doctors to prescribe laxatives on a daily or twice daily basis.

“The problem is, if you’re prone to sluggish bowels, you need quite a large dose of laxative to get a response and you can’t give that daily. So, what happens is most people are taking laxatives at a lower dose on a daily basis but aren’t opening their bowels every day. As a result, there’s a lot of anxiety and dissatisfaction over laxative use. If we said, take enough to get your bowels to work and then take a break, that would be a much better strategy.”

Associate Professor Phil Dinning, a researcher in functional gut disorders and gastrointestinal motility at Flinders University, is one of a small band of scientists doing work on constipation using a manometry catheter to record muscular contractions in the colon.

“What we’ve found is that certain contractions are very irregular or are not there at all in patients with constipation, particularly if it’s slow transit constipation. When you go to the toilet, your whole colon is involved in a coordinated pattern of contraction and relaxation, and unless you’ve got this pattern, you’ll fail to empty your bowel.”

But Professor Dinning says that this might not be a question of the bowel itself not working; it might be that the bowel is getting the wrong, or no, signals from the central nervous system.

“We’ve done experiments with colons that have been removed from patients with severe constipation. And when we put the removed colon in an organ bath, it contracts perfectly, which suggests that the bowel itself works, but it’s the nerves coming to the bowel that don’t work.”

He says that the research he and other researchers are doing may help identify more clearly defined subtypes of constipation that can be targeted for treatment.

“I’m optimistic that we’ll have a better understanding that will start to guide treatment in certain patients. But I’d be very sceptical about saying we’ll have a cure. Because it doesn’t work that way. Constipation isn’t a single disorder, it’s very multifactorial and heterogeneous.”

He agrees with Dr Levitt that lack of research is a major problem in constipation.

“We apply for grants like everyone else, but you’ve got a condition that’s embarrassing and that rarely kills anyone, and it’s up against breast cancer or brain cancer in an environment with very limited funding. So, the studies that get done tend to be very limited with very small sample sizes, which makes it incredibly hard to build the big picture. We could theoretically get a big study done in a couple of years, but because of the drip, drip style of funding, it would actually take much longer.”

To find a doctor, or a job, to use GP Desktop and Doctors Health, book and track your CPD, and buy textbooks and guidelines, visit doctorportal.