Differential Diagnosis for Vomiting and Peritoneal Signs in a 6-year-old
Single Most Likely Diagnosis
- Appendicitis: This is the most common cause of acute abdominal pain and peritoneal signs in children, often presenting with vomiting, abdominal pain (initially diffuse, then localized to the right lower quadrant), and fever. The combination of vomiting and peritoneal signs (such as tenderness, guarding, and rebound tenderness) strongly suggests appendicitis.
Other Likely Diagnoses
- Gastroenteritis: Although it primarily causes vomiting and diarrhea, severe cases can lead to dehydration and abdominal pain. Peritoneal signs might be present if there's significant inflammation of the bowel wall.
- Intussusception: A condition where a part of the intestine telescopes into another, causing bowel obstruction. It can present with vomiting, abdominal pain, and sometimes peritoneal signs if the bowel becomes ischemic.
- Mesenteric Lymphadenitis: Inflammation of the lymph nodes in the mesentery can mimic appendicitis, causing abdominal pain, vomiting, and sometimes peritoneal signs.
Do Not Miss Diagnoses
- Perforated Visculitis or Vasculitis: Conditions like Henoch-Schönlein purpura can cause abdominal pain and vomiting due to vasculitis affecting the bowel. Perforation can lead to peritoneal signs.
- Ectopic Pregnancy (in post-pubertal girls): Although rare in this age group, it's crucial to consider in post-pubertal girls presenting with abdominal pain and vomiting, as it can lead to severe consequences if missed.
- Intra-abdominal Shunt Infection or Malfunction (in patients with shunts): Patients with ventriculoperitoneal shunts can develop shunt infections or malfunctions, leading to peritoneal signs and vomiting.
Rare Diagnoses
- Meckel's Diverticulitis: Inflammation of a Meckel's diverticulum, a congenital anomaly of the small intestine, can cause abdominal pain, vomiting, and peritoneal signs if it becomes inflamed or perforated.
- Primary Peritonitis: Spontaneous bacterial peritonitis without an apparent source of infection, more common in patients with ascites or immunocompromised states.
- Ovarian Torsion: Twisting of the ovary can cause severe abdominal pain, vomiting, and sometimes peritoneal signs if there's associated bowel involvement or ischemia.