Ultrasound for Pediatric Appendicitis

Introduction:

Appendicitis is an inflammatory condition of the long slender projection of the colon called the appendix, which is an emergency situation and requires immediate attention. The treatment and diagnosis are made quickly because the appendix can rupture and can spread the infection to the whole abdomen and body. Ultrasound is a type of diagnostic test that uses sound waves to detect the structures present inside the body. The use of ultrasound can eliminate the harmful radiations that are caused by computed tomography (CT) scans.

What Is Pediatric Appendicitis?

Appendicitis is the infection of the appendix, which is a long narrow projection of the colon (part of the large intestine) that is present on the right side of the abdomen in pediatric patients who are between five to 19 years old. This condition requires urgent surgical treatment. If the appendix is not treated right away, it can get ruptured and can spread the bacteria throughout the abdominal area. The bacteria can also get into the bloodstream and trigger the body’s reaction to the infection called sepsis which is a life-threatening condition.

What Are the Causes of Pediatric Appendicitis?

The causes of pediatric appendicitis are:

• Obstruction of the appendix is the most common cause, which can occur due to fecalith (hard feces), appendicoliths (mineral or calcium deposits in the appendix), or lymphoid hyperplasia (presence of lymphocytes).

• Abdominal infection.

• Inflammatory bowel disease (chronic inflammation of the gastrointestinal tract).

• Infection of the digestive tract.

• Presence of parasite or stool inside the appendix.

What Are the Symptoms of Pediatric Appendicitis?

The symptoms of appendicitis are:

• Pain in the lower right side of the abdomen is the key sign. Mostly the pain starts around the center of the stomach and slowly spreads to the right side of the abdomen.

• Mild fever.

• Nausea.

• Vomiting.

• Loss of appetite.

• Dysuria (painful urination).

• Hematuria (presence of blood in the urine).

What Is the Pathogenesis of Appendicitis?

Appendicitis develops within 24 to 36 hours, and in children, it can even be quick. When the appendix is obstructed, it starts to distend and starts as a peri‐umbilical pain (pain around the belly button) due to stimulation of T8 to T10 visceral nerves (thoracic spinal nerves). The pressure inside the abdomen increases, and bacteria start invading the wall. The infection starts to spread and stimulate the nerves of the peritoneum, which causes pain on the right side. If this is not treated immediately, it can result in gangrene (loss of blood supply to the part of the appendix, which causes the death of tissue) and perforation. The perforation is inversely related to the kid’s age; the lesser the age quicker the rate of perforation.

What Is the Diagnosis of Pediatric Appendicitis?

The diagnosis of pediatric appendicitis includes:

• Appendicitis is diagnosed with the help of clinical symptoms, and a complete physical examination is done.

• Blood and urine tests are done to check for infections.

• Imaging modalities such as X-rays, ultrasound, and computed tomography (CT) scans can be used to detect the structure of appendicitis.

How Is Ultrasound Utilized in the Diagnosis of Pediatric Appendicitis?

Ultrasound scanning can be a challenging task since the child is already in pain, has undergone physical checkups, and often has undergone cannulation in which a cannula (thin tube) is placed inside the vein for administering medications or fluids. These all can limit the cooperation of the child affecting the success of the procedure. The ultrasound is done with the help of a graded compression technique with the help of a linear transducer (a sensor) that helps in applying gradual pressure to the ride side of the abdomen and displacing the bowel contents. The graded compression technique can prevent false positives but should contain a degree of repeatability. First, the ascending colon is identified due to its gassy look, the probe is slowly compressed inside, and the psoas and iliac vessels (which provides blood supply to the pelvic region) are detected. The appendix is detected anterior to these vessels. To get a better view of deeper appendices, the sonographer can provide anterior force in the right lower back of the child. A lower-frequency curvilinear transducer can be used in the case of obese children.

What Are the Sonographic Criteria for Detecting Pediatric Appendicitis?

The maximum outside diameter (MOD) is the commonly used sonographic criteria in which the hypoechoic tunica muscularis’(muscular layer of the appendix) outer border is measured. The sonographic criteria include:

• A normal appendix can be compressed and is less than 6 millimeters. Whereas, an inflamed appendix cannot be compressed and is more than 6 millimeters. A false positive diagnosis can occur in the case of cystic fibrosis due to an increase in the diameter of the appendix from the mucoid material or in the case of other right lower quadrant inflammation.

• The presence of an appendicolith which is highly reflective and projects a posterior acoustic shadow.

• Increased color Doppler flow which occurs due to increased blood flow, is another sign of appendicitis.

• The wall of the appendix can also be a useful diagnostic feature but sometimes it cannot be differentiated from the intra‐luminal pus.

The secondary sonographic signs are useful in the case of invisible appendicitis, which is:

• Echogenic mesenteric fat, in which the mesentery (a membrane that attaches the intestine to the abdominal wall) can become inflamed in case of acute appendicitis. An increased mesenteric echogenicity is related to the diagnosis of appendicitis.

• The presence of free intra‐peritoneal fluid in the right lower quadrant can indicate appendicitis.

• The presence of enlarged intra‐peritoneal lymph nodes indicates appendicitis.

• Thickened adjacent bowel wall and echogenic debris in the urinary bladder indicate ruptured appendicitis.

What Are the Advantages of Using Ultrasound Scanning in Pediatric Appendicitis?

The advantages of ultrasound scanning in pediatric appendicitis are:

• It reduces the risk of exposure to radiation. A CT scan can provide accurate results, but children are more sensitive to ionizing radiations than adults. The use of ultrasound can eliminate this disadvantage.

• The ultrasound helps in the visualization of a thick, non-pressable appendix with a diameter of more than six millimeters which is the diagnostic criteria of appendicitis.

• Cost-effective compared to CT scans.

What Are the Drawbacks of Ultrasound Scanning in Pediatric Appendicitis?

The drawbacks of ultrasound scanning in pediatric appendicitis are:

• Due to the pain, the child is experiencing, sufficient compression cannot be applied, which can cause difficulty in locating the appendix, and the success rate can go down up to 2 %.

• An incomplete investigation can result in failure to identify tip appendicitis (inflammation in the distal part).

• Overestimation can lead to false positive diagnoses.

• An ultrasound is difficult to diagnose at the retro‐caecal location (behind the first part of the large intestine) due to overlying bowel faces or gas.

Conclusion:

Therefore ultrasound is a useful diagnostic method, and with the help of secondary signs, appendicitis can be diagnosed more accurately. This can help in better clinical outcomes and can decrease the need for the use of CT scans or surgical procedures in case of negative results.