While the ultimate goal would be for most constipation to be prevented or managed by primary care physicians, the reality is that a lot of children are seen in the ER setting.  Particularly in the hospital setting, many practitioner’s have relied on abdominal xrays (AXRs) and this practice has been criticized previously (What’s Wrong with Ordering an AXR for Constipation in the …).

It is gratifying that efforts are underway to reverse this tendency.  A recent study (J Kurowski et al. J Pediatr 2015; 167: 706-10) document the effect that a 10 minute training session can have.

In this retrospective chart review, the researchers examined a 2 month baseline period and then a 2 month period after institution of a 10-min educational module for ER healthcare providers.  The module included the following:

1. Rome III criteria for constipation  -at least 2 criteria weekly for >2 months:
   • ≤2 defecations in the toilet per week
   • at least 1 episode of fecal incontinence per week
   • history of retentive posturing or excessive volitional stool retention
   • history of painful or hard bowel movements
   • presence of a large fecal mass in the rectum
   • history of large stools which may obstruct toilet
2. Review of the lack of utility of abdominal radiographs
3. Use of rectal exam

Patients were identified who were discharged from the ER (without hospital admission)  with a diagnosis of constipation and with a chief complaint of abdominal pain.  In the baseline period, there were 105 patients and in the followup period, there were 91 patients.

Key findings:

• Digital exams increased: 22.9% —>47.3%
• AXR decreased: 69.5% –>26.4%

This study has numerous limitations; these include retrospective study and patient selection. Nevertheless, it makes several useful points.  If constipation is suspected, better care at a lower cost can be achieved by including a digital exam.  The authors note that “there is no strong evidence to support the utility of radiographs for this diagnosis [constipation] or even reliable standards to evaluate the normal stool burden across different ages.”

My take: The lessons from this study are applicable to primary care physicians and gastroenterologists as well as to ER physicians.  While this educational module is a good start, if I were designing a module, I would include information on irritable bowel syndrome which is often confused with isolated constipation.

Related blog posts:

• Updated Pediatric Expert Constipation Guidelines …
• Diagnostic tests hardly ever help patients poop …
• Data Supporting Miralax | gutsandgrowth
• AGA Constipation Guidelines | gutsandgrowth
• Miralax Safety | gutsandgrowth

My understanding is that shortly before my twin and I were born, a nurse used a pencil test to predict our genders.  Though my mother is quite smart, she believed the nurse knew what she was doing.  However, shortly thereafter, it turned out that I had a twin brother not a twin sister.

ER doctors often perform a similar service to the pencil test when they use an abdominal radiograph (AXR) to determine if their patients have constipation.  A new pediatric study from Toronto highlights this phenomenon and current recommendations (J Pediatr 2014; 164: 83-8).

Background:  this retrospective cohort study of children <18 years took place between 2008-2010.  As part of the study, a single pediatric radiologist (blinded to participant classification, assigned Leech scores to all misdiagnosis AXRs along with 20% of the remaining AXRs.  From a total of 112,381 ER visits, the review identified 3987 where constipation was the discharge diagnosis (3.5% of all visits).  In the cohort diagnosed with constipation, the mean age was 6.6 years.

Key findings:

• Only 9% of children returned within 7 days.  20 of these (0.5%) had a significant misdiagnosis based on the authors definition, including 7 with perforated appendix, 2 with intussception, and 2 with bowel obstruction.  Other misdiagnosis included ovarian torsion, thalamic brain tumor, acute lymphoblastic leukemia, cardiomyopathy, ileal volvulus, and pancreatitis.
• Children with a misdiagnosis had similar amounts of stool on AXR as those who were not misdiagnosed.
• AXR was performed more frequently in those with a misdiagnosis (75% vs. 46%).
• Rectal examination was documented in only 9% of those with a diagnosis of constipation (low frequency rectal examination has been shown in other ED-based studies).
• Abdominal pain and tenderness were more common in those with a misdiagnosis.

Why I think this study is important:

While the authors point out that 1 in 200 children ultimately required a surgical or radiologic  intervention within 7 days, I do not think that this error rate or diagnostic delay is particularly high.  What is important is that this study reiterates the fact that AXRs are not useful for the diagnosis of constipation.  The authors note “reviews have concluded that there is no evidence of an association between clinical symptoms of constipation and fecal loading on AXR.”  Furthermore, AXRs may lead ER physicians to a cognitive diagnostic error.

Also, the misdiagnosis rate is much greater than reported in the study due to the definition adopted by the authors.  The authors did not include treatable infectious diseases (e.g.. pneumonia, urinary tract infection) as well as a large number of other medical diagnosis. Other “incipient” disease processes may have been missed including inflammatory bowel disease and celiac disease.

The authors imply that using a more standard definition of constipation would be useful, namely the Iowa criteria which requires the presence of 2 of the following:

• ❤ stools/week,
• ≥1 episoded of fecal incontinence/week
• large stool palpable on rectal/abdominal examination
• passing large stool which obstructs toilet
• withholding posturing
• painful defecation

The authors reference a study which indicated that AXRs should be restricted to patients with high-yield clinical features: prior abdominal surgery, foreign body ingestion, abnormal bowel sounds, addominal distention, and peritoneal signs.

Bottomline: AXRs do not establish a diagnosis of constipation.  Yet, after families have been told their child is constipated because of an AXR it is not easy to convince them that an AXR is about as useful as a pencil test for this diagnosis.

Related blog posts:

• Miralax Safety | gutsandgrowth
• Diagnostic tests hardly ever help patients poop | gutsandgrowth
• Updated Pediatric Expert Constipation Guidelines | gutsandgrowth
• AGA Constipation Guidelines | gutsandgrowth
• Data Supporting Miralax | gutsandgrowth
• Newsflash: constipation frequently causes … – gutsandgrowth