What laboratory tests are indicated for pediatric patients presenting with abdominal pain?

From the Guidelines

Laboratory tests for pediatric abdominal pain should be tailored to the clinical presentation, including complete blood count (CBC), C-reactive protein (CRP), urinalysis, and liver function tests, as these tests help distinguish between surgical emergencies and medical conditions that can be managed conservatively, guiding appropriate treatment decisions while minimizing unnecessary testing in children. When evaluating pediatric abdominal pain, it is essential to consider the clinical presentation and tailor laboratory tests accordingly. For suspected appendicitis, a CBC with differential can detect leukocytosis (elevated white blood cells) and left shift, while CRP helps assess inflammation 1. Urinalysis is essential to rule out urinary tract infections, which commonly present as abdominal pain in children. Liver enzymes (AST, ALT), amylase, and lipase should be ordered when hepatobiliary or pancreatic disease is suspected. In adolescent females, consider pregnancy testing. Stool studies including culture, ova and parasites, and occult blood may be appropriate for children with diarrhea or suspected inflammatory bowel disease. Abdominal imaging often complements laboratory evaluation, with ultrasound being the preferred initial imaging modality due to lack of radiation exposure, as shown by Saucier et al, who demonstrated that ultrasound has 93% accuracy with 86% sensitivity and 97% specificity in patients with an intermediate clinical risk for acute appendicitis 1. The use of clinical scoring systems, such as the Pediatric Appendicitis Score (PAS) and the Alvarado score, can be helpful in evaluating pediatric patients with suspected acute appendicitis, but they should be used in conjunction with laboratory tests and imaging, as they have been shown to have limitations, including over-diagnosis and under-diagnosis of appendicitis 1. For example, the PAS has been shown to be useful in ruling out or in appendicitis in pediatric female patients, but it has poor positive predictive values 1. Recently, the new Pediatric Appendicitis Laboratory Score (PALabS) has been shown to accurately predict which children are at low risk of appendicitis and could be safely managed with close observation 1. Overall, a comprehensive approach that includes laboratory tests, imaging, and clinical evaluation is necessary to accurately diagnose and manage pediatric abdominal pain. Some key points to consider when evaluating pediatric abdominal pain include:

• The clinical presentation and medical history of the patient
• The results of laboratory tests, such as CBC, CRP, and urinalysis
• The results of imaging studies, such as ultrasound
• The use of clinical scoring systems, such as the PAS and the Alvarado score
• The need for prompt surgical intervention in cases of suspected appendicitis or other surgical emergencies.

From the Research

Laboratory Evaluation for Pediatric Abdominal Pain

The laboratory evaluation for pediatric abdominal pain may include:

• Urinalysis to check for urinary tract infections or other conditions 2, 3
• Complete blood cell count to check for signs of infection or inflammation 2, 3
• Human chorionic gonadotropin, lactate, and C-reactive protein levels to check for pregnancy, infection, or inflammation 2
• Comprehensive metabolic profile to check for any underlying metabolic conditions 2

Imaging Studies for Pediatric Abdominal Pain

Imaging studies may be used to further evaluate the cause of abdominal pain in children, including:

• Ultrasonography, which is the preferred initial imaging modality due to its low cost, ease of use, and lack of ionizing radiation 2, 3
• Abdominal radiography to diagnose constipation or obstruction 3
• Computed tomography or magnetic resonance imaging to confirm the diagnosis of appendicitis or other conditions if the appendix is not clearly visible on ultrasonography 3

Diagnostic Approach for Pediatric Abdominal Pain

The diagnostic approach for pediatric abdominal pain varies by age and may include:

• Considering congenital anomalies and other causes in infants and toddlers 3
• Considering constipation and infectious causes in school-aged children 3
• Considering pelvic inflammatory disease, pregnancy, ruptured ovarian cysts, or ovarian torsion in female adolescents 3
• Using validated scoring systems, such as the Pediatric Appendicitis Score, to help determine the patient's risk of appendicitis 2