Pediatricians evaluating children with signs and symptoms that they believe could be consistent with either UC or CD are ideally positioned to initiate the workup necessary to expedite subspecialty referral and more definitive testing (). Initial laboratory studies should assess for signs of inflammation, including elevations in white blood cell and platelet counts, erythrocyte sedimentation rate (ESR), or C-reactive protein (CRP). Gastrointestinal blood loss and anemia can be assessed with a hemoglobin or hematocrit, and a mean cell volume (MCV) can help discriminate patients with chronic disease (low MCV) from those with more acute processes (normal MCV), including infection. Serum albumin is often low in patients with newly diagnosed IBD or those experiencing a flare in their condition. Liver function tests (alanine transaminase [ALT], alkaline phosphatase, bilirubin, and γ-glutamyltransferase [GGT]) can be elevated in patients with IBD and may be related to disease activity or an extraintestinal complication, including primary sclerosing cholangitis, autoimmune hepatitis, or biliary tract disease. Children presenting with abdominal pain should be screened for pancreatitis with a serum amylase and/or lipase. Although a number of serologic assays are commercially available to assist physicians in screening their patients for suspected UC or CD, these commercially available serologic assays may fail to detect CD in at least 30% of children with this disorder and may wrongly suggest a diagnosis of IBD that is not supported by subsequent and more definitive (endoscopic study) testing. As such, it may be most prudent for primary care providers to avoid ordering these tests and instead pursue referral and more conclusive specialty testing. Nonetheless, more recent studies suggest that these serologic assays may play a role in providing relevant diagnostic and/or prognostic information after more definitive biochemical, radiologic, and endoscopic information has been collected and reviewed.
FIGURE 1 Office management of children presenting with suspected IBD. ALT =alanine aminotransferase; CBC = complete blood cell count; CRP = C-reactive protein; ESR = erythrocyte sedimentation rate; GGT = γ-glutamyl-transferase; IPV =inactivated polio vaccine; (more ...)
Stool studies are essential in the initial evaluation of any child suspected as having IBD. Given that these tests are typically parent dependent, labor intensive, and time-consuming, there is a premium on providers requesting them as early as possible in the workup. In many cases, stool studies may point away from a chronic inflammatory process and instead identify a pathogen that can be readily addressed with either observation and support (Escherichia coli
0157) or definitive antibiotic therapy (Shigella). Stool should be tested for the presence of occult blood. It is important to note that although the absence of visible or occult blood makes a diagnosis of active colitis unlikely, many children with CD may present without any evidence of GI blood loss. Children with suspected IBD, especially those with hematochezia, should provide a fresh stool sample for assessment of routine pathogens including Salmonella
, Shigella, Campylobacter, Yersinia
, and Escherichia coli
0157, and Clostridium difficile
. Ova and parasite testing can also be considered. Although fecal leukocyte (FL) stain has been used for many years to assist clinician in determining whether or not a patient’s symptoms are more likely to be the result of an inflammatory (FL positive) versus a noninflammatory (FL negative) process, this test relies on the provision of a fresh stool sample, is not quantitative, and is operator dependent. A number of newer assays are now commercially available to detect the presence of intestinal inflammation, as assessed by the presence of white blood cell proteins (lactoferrin and calprotectin) in the stool; however, it is important to note that these studies do not discriminate patients with infectious versus inflammatory processes and the results of parallel stool cultures are essential. Nonetheless, a number of studies have confirmed the utility of fecal lactoferrin and calprotectin measurements to distinguish patients with inflammatory gastrointestinal disease from those with irritable bowel syndrome, and serial measurements of these fecal proteins can be used to assess interval disease activity in patients with IBD (16
The approach to the radiologic assessment of children with suspected IBD must be individualized. Upper gastrointestinal study with small bowel follow-through (SBFT) has long been the mainstay for evaluating mucosal disease in the small intestine and ileum, but these modalities provide limited information about the presence or extent of extramural or mesenteric disease. During the course of the last decade, significant advancements in cross-sectional imaging of the small bowel with computed tomography (CT) and magnetic resonance imaging (MRI) enterography have occurred. Both CT and MRI have a major advantage over fluoroscopic techniques because they provide direct visualization of the extent of bowel wall inflammation and peri-intestinal involvement in multiple imaging planes. This type of information is especially useful to clinicians when there is concern for disease relapse or complications such as abscess, fistula, or obstruction, or when evaluating a patient’s response to medical therapy. Prospective studies in adults have shown improved diagnostic performance of both CT and MRI as compared with SBFT in evaluating extent of small bowel disease (21
). Both CT and MRI have equivalent and excellent sensitivity for detecting active small bowel inflammation as compared with ileocolonoscopy (22
). MRI has the added advantage of not subjecting patients to ionizing radiation. Pelvic MRI is the best imaging choice for evaluation of the extent of perianal disease including fistulas (23
). MRI, especially when used in conjunction with gadolinium enhancement, may provide additional information when clinicians are attempting to discern whether a patient’s IBD is more likely to be CD or UC (24
Technological advances in abdominal ultrasound (US) have improved spatial resolution for visualization of the bowel and mesentery and permit identification of wall thickening or abdominal and pelvic abscesses more readily in children and adolescents who typically have a small body habitus as compared with adults (25
). When compared with MRI, US has the best diagnostic performance when evaluating terminal ileal disease over proximal small bowel or colonic disease (26
). Although US examinations tend to be more readily available and are less expensive than MRI, appropriate technique necessitates a focused examination of the entire bowel and a radiologist who is experienced and comfortable with the use of this imaging modality for this particular clinical indication.
Increasing consideration is being given to the use of MRI or US, which do not expose patients to ionizing radiation, especially young children. New data suggest that the lifetime risk of cancer in children undergoing CT scanning may be considerably more than previously thought (27
). Radiation resulting from abdominal CT may be especially relevant and could account for up to 50% of radiation-related malignancy (28
). This issue is especially relevant to pediatric patients with IBD for 2 reasons. First, children with IBD require diagnostic studies at a time when their bodies are still growing and developing and therefore may be more sensitive to short- and long-term risks of ionizing diagnostic radiation. Second, children with IBD are likely to require repeated imaging during the course of their lives, leaving them vulnerable to accrue a higher lifetime radiation exposure than patients diagnosed with IBD as adults. An abdominal CT study exposes children to the equivalent of multiple individual abdominal radiographs, and carries at least a 2-fold higher radiation dose than SBFT (29
). To this end, MRI is increasingly being used for initial diagnosis and follow-up examinations to assess response to medical therapy; however, CT is logistically more available in most centers, provides clinical information more quickly for patients presenting with severe acute symptoms when there is concern about an abdominal abscess or fistula or obstruction, and does not typically require physical or chemical restraint. In general, the choice of which imaging study would be most useful for a particular patient depends on their clinical symptoms, relative cost and availability, and local imaging expertise. As such, primary care providers should work in close collaboration with available subspecialty and radiologic colleagues to choose the most appropriate study to request in their patients with IBD with an objective to keeping acute and long-term radiation exposure to a minimum.
Routine health maintenance issues also take on new relevance in children being evaluated for IBD. Primary care providers should consider placing a purified protein derivative (PPD) to assess a patient’s earlier tuberculosis (TB) exposure, especially if one has not been completed in the last year. Many patients with IBD require long-term immunosuppressive therapy, and initiation of these agents is contraindicated in patients in whom latent TB status has not been assessed by PPD or chest film. It is also important for primary care providers to review their patient’s immunization status early in the IBD evaluation. The administration of live virus vaccines is contraindicated in patients receiving immunosuppressive therapy. As such, documenting (and when necessary completing) a patient’s measles, mumps, and rubella (MMR) and Varicella series may expedite care down the road. It may also be useful to review and document immunization to hepatitis A and B.