Appendicitis, an inflammation of the appendix, represents a significant concern for children, often requiring urgent medical attention. It is the most common pediatric surgical emergency, affecting about 7% of healthy children. Accurate and quick diagnosis is important to prevent complications. Early diagnosis helps avoid a ruptured appendix, which can lead to serious, widespread infection within the abdomen.
Why Ultrasound for Children?
Ultrasound is the preferred initial imaging method for evaluating suspected appendicitis in children. It does not use ionizing radiation, unlike computed tomography (CT) scans, making it a safer option for young patients. This non-invasive technique costs less and requires minimal patient preparation, avoiding intravenous lines or sedation. Ultrasound offers dynamic information during the scan, allowing the sonographer to assess the area of pain directly. While CT scans can provide a broader overview and are less operator-dependent, the concern for radiation exposure in children often leads medical professionals to choose ultrasound first.
Ultrasound demonstrates high sensitivity and specificity in diagnosing appendicitis in children, with reported sensitivities between 85% and 100% and specificities from 89% to 98%. Despite some challenges in consistently visualizing the appendix in all cases, its performance supports routine use. Using ultrasound as a primary diagnostic tool helps to reduce unnecessary surgeries and the rate of appendix perforations.
The Ultrasound Procedure
During a pediatric appendicitis ultrasound, the child is positioned lying on their back, though adjustments like lying on their left side may be made to improve visualization if bowel gas is present or the appendix is in a difficult-to-see location. Pain medication may be given beforehand to ensure the child’s comfort and cooperation, important for obtaining clear images. The sonographer will apply a clear, water-based gel to the child’s lower right abdomen. This helps the ultrasound transducer glide smoothly and ensures good contact with the skin.
A high-frequency linear transducer, between 5 and 12 MHz depending on the child’s size and age, is used. The sonographer applies a technique called “graded compression,” gradually increasing pressure with the transducer to gently displace overlying bowel loops and gas, to allow for better visualization of the appendix. This process is generally painless, though some pressure may be felt, and the entire procedure usually takes about 15 to 30 minutes.
Interpreting Ultrasound Findings
Medical professionals examine specific features in ultrasound images to determine if the appendix is inflamed. A normal appendix appears as a compressible, blind-ending tubular structure with an outer diameter of 6 millimeters or less. Its wall is thin, usually less than 3 millimeters, and shows little to no blood flow. The lumen, or inner channel, of a normal appendix may appear empty or contain gas and fecal matter.
In cases of appendicitis, the appendix becomes non-compressible, meaning it does not flatten under pressure from the ultrasound probe. Its outer diameter typically exceeds 6 millimeters, and the wall thickness may be 3 millimeters or more. Increased blood flow within the inflamed appendiceal wall, known as hyperemia, is often visible with color Doppler ultrasound.
Other signs of inflammation around the appendix include increased echogenicity (brightness) of the surrounding fat, fluid collections or an abscess, and enlarged mesenteric lymph nodes. A “target sign” or “bull’s-eye” appearance can also be seen, which is characteristic of an inflamed appendix. Identifying these findings requires skilled technicians and radiologists with expertise in pediatric sonography.
Comprehensive Diagnosis and Next Steps
An ultrasound is one part of a comprehensive diagnostic process for appendicitis in children. Healthcare providers also consider the child’s symptoms, which often include abdominal pain that may start around the belly button and shift to the lower right side, nausea, vomiting, and a low-grade fever. A physical examination, checking for abdominal tenderness, is also a key part of the assessment.
Blood tests are commonly performed to check for signs of infection or inflammation, such as an elevated white blood cell count. A urine test may also be conducted to rule out bladder or kidney infections, which can present with similar symptoms. If ultrasound findings, combined with clinical symptoms and laboratory results, strongly suggest appendicitis, a surgical consultation for an appendectomy is typically the next step. In some mild cases, antibiotics alone may be considered, but surgical removal of the appendix is the standard treatment to prevent rupture and further complications.