Opioids and constipation
The bottom line
-Opioids are an illogical choice for treating pain associated with constipation
-Pain needs to be treated promptly and effectively
-Abdominal pain requiring opioids should raise suspicion of a surgical diagnosis
Why are we talking about opioids and constipation?
This post arose from a twitter conversation that began with the question “Is it ever OK to use opioids for treating the pain associated with constipation?” some people said “No, never!”
Why shouldn’t we use opioids to treat constipation?
A universal side effect of opioid medication is constipation. In the case of codeine this comes without a useful analgesic effect in a significant proportion of the population so that one is definitely best avoided. Essentially in using opioid medication to treat constipation associated pain you are exacerbating the underlying problem.
Why should we use opioids to treat constipation?
Gone are the days when it was considered OK to leave a patient in pain so as not to reduce the physical signs that would be used to diagnose surgical disease. Pain management is one of the things that we can and should do rapidly and effectively for any patient of any age coming to see us in the ED. Opioids are generally very effective analgesics and most staff in our departments will be comfortable with their use.
What are the alternatives?
Our usual go to medications, paracetamol and ibuprofen, are usually the first thing to try but simple interventions like hot packs are often helpful and underutilized.
How sure are we about the diagnosis?
Constipation can indeed be painful, sometimes dramatically so. It is also extremely common. We often work on the principle that if you have a single, strong diagnosis that explains a patient’s symptoms then it’s OK to stop investigating. There are of course exceptions to this rule. It’s an old joke that the hardest type of fracture to pick up is the second fracture and a subset of under-reporting errors in radiology has been assessed and published as being due to “search-satisfaction” or stopping looking because you have found one abnormality (1). This is relevant as although constipation can indeed cause pretty bad abdominal pain it is common enough that kids can be constipated and have appendicitis!!
What about enemas?
There are a few opinions about this but I think the role of enemas in managing constipation is extremely limited. Lots of constipated kids (indeed lots of kids in general) don’t like people putting things up their bottoms. Not only is it awkward even for fairly young children it is also often painful. Many constipated kids are in a vicious cycle of holding on because it hurts when they poo, which leads them to build up bigger and firmer stools, which makes it hurt even more when they do go to pass that stool. This not infrequently leads to anal fissures. These are exquisitely tender and do not respond well to being poked with plastic tubes. If constipation is an ongoing problem for a child then further visits to doctors or other health care professionals are likely and these become more difficult for the practitioner and, more importantly, distressing for the child if they come with a fear or even an expectation of someone hurting them.
Are enemas safe?
Microlax™ products are advertised for use in babies (they even have tips for use in infants on their website). Sodium phosphate or “fleet” enemas may be appropriate in older children but in smaller children and especially with repeat dosing the phosphate load carries a very real risk of causing hypocalcaemia with hypocalcaemic tetany having been reported after just 2 doses (2). It is hard to imagine many circumstances in which a phosphate enema is truly the best option for any child under 5. Certainly repeat dosing should be approached with extreme caution in any paediatric patient.
When should I call a surgeon?
The diagnosis of constipation really requires the consideration and exclusion of more sinister causes of abdominal pain. The usual red flags (bilious vomiting, significant abdominal distension, well localized pain, etc) should be actively sought and not overlooked should their presence be found. In this author’s opinion the repeated need for opiates to treat abdominal pain in children should be considered a red flag in itself and in most practice environments should prompt the involvement of the surgical team in the child’s care.
For more on constipation take a look at our week long series:-
- Berbaum KS et al satisfaction of search in diagnostic radiology. Invest radiol 1990 feb;25(2):133-40
- Craig JC et al. phosphate enema poisoning in children. Med J aust 1994 Mar 21;160(6):347-51