Although the causes of abdominal pain in children are frequently benign (e.g., constipation), there is always the potential for life- or organ-threatening conditions, which require urgent intervention.
Acute appendicitis resulting in perforation
Untreated acute appendicitis may progresses to ischemia, necrosis, and eventually perforation. The clinician may encounter a range of presentations. Patients often complain of abdominal pain localized to the RLQ; in more severe cases the pain may be diffuse (e.g., if a large perforation results in generalized peritonitis). Perforation should be considered when a patient presents with a long duration of symptoms and/or suspected appendicitis with marked systemic signs of illness (e.g., high fever [>101°F, 38.3°C]), tachycardia, and anorexia). Evidence A A CT scan of the abdomen may be useful in determining the extent of the inflammatory response as well as the presence of any collections that may be amenable to percutaneous drainage. Appendectomy is commonly performed for perforated appendicitis, although nonoperative management is also practiced in some centers. The procedure can be done with an open approach or laparoscopically. Referral to a children’s hospital or a pediatric surgeon should be considered for children younger than 5 years of age. 
Urgency of intervention is dependent on the clinical severity of the obstruction. Nonstrangulated obstructions involve a loop of bowel that is partially or completely obstructed, but has adequate blood supply and is not necrotic. This type of obstruction is usually not associated with peritonitis, fever, or leukocytosis, but may be associated with abdominal distension, nausea, and vomiting. Although surgical intervention may be necessary, it is usually not urgent. However, prolonged delay may progress to strangulation. Strangulated obstructions are usually complete obstructions in which the blood supply to the bowel is cut off as a result of edema, twisting of the bowel, or adhesions. These usually demonstrate diffuse or local peritonitis, fever, and leukocytosis. Untreated, they progress to intestinal necrosis and/or perforation. Urgent surgical treatment is mandatory.
May lead to venous obstruction and bowel-wall edema and can progress, if untreated, to bowel necrosis, perforation, and, rarely, death.   Treatment should be initiated at the time of diagnosis. The goal is correction of hypovolemia and electrolyte abnormalities, and antibiotic administration, followed by urgent reduction. Reduction can be accomplished with contrast enema (air or contrast reagent) or by surgery.
Malrotation with midgut volvulus is a surgical emergency, and bilious vomiting in any child should prompt concern for this condition until confirmed otherwise. With a corresponding history and physical exam (bilious vomiting and feeding difficulty, especially in infants during the first month of life), no further diagnostic intervention is necessary and prompt surgical exploration is recommended. Ambiguous cases may proceed to an upper GI contrast study or abdominal CT scan. However, this should not preclude surgical intervention if clinical suspicion is high.
Prompt attention should be paid to an incarcerated inguinal or umbilical hernia due to the danger of bowel strangulation (compromise of blood flow to the bowel with consequent bowel ischemia and gangrene). Incarceration, with or without strangulation, occurs if intra-abdominal contents become trapped in the protruding hernia sac. Clinically, the hernia is irreducible and tender. Associated symptoms may include nausea, vomiting, and generalized abdominal pain. In severe cases, fever, abdominal distension, and skin changes may be present. If strangulation is evident, surgery is required urgently to resect the gangrenous segment of bowel.
The most common medical/surgical emergency affecting neonates, particularly premature infants, especially those weighing less than 1500 g. Early intervention is mandatory to prevent morbidity and mortality due to multiple organ impairment. Signs and symptoms include feeding intolerance, apnea, lethargy, bloody stools, abdominal distension, tenderness, abdominal wall erythema, and bradycardia. Treatment may be medical or surgical, and is determined by severity of the clinical presentation. [ ]
The third leading cause of death in pediatric trauma patients.  It is generally classified as penetrating or blunt. Most cases of blunt injury to the liver and spleen are managed nonoperatively. Indications for urgent surgery include hemodynamic instability despite adequate resuscitation, free air in the abdomen, penetrating injuries with fascial penetration, and peritonitis.  
Ruptured ectopic pregnancy
If undiagnosed or incorrectly managed, a ruptured ectopic pregnancy may lead to maternal death due to rupture of the implantation site and intraperitoneal hemorrhage. The classic presentation includes lower abdominal pain, amenorrhea, and vaginal bleeding. Patients with a positive urine pregnancy test and the absence of an intrauterine pregnancy on transvaginal ultrasound are considered to have an ectopic pregnancy until confirmed otherwise. It is important not to delay care while waiting for an ultrasound. A quick and focused ultrasonographic exam to assess for the presence of free fluid or blood may be helpful when this diagnosis is suspected. Urgent laparoscopy with salpingectomy or salpingostomy is performed for a ruptured ectopic pregnancy.
Twisting or torsion of the ovary compromises the arterial inflow and venous outflow, producing ischemia, which, if not relieved, can affect the viability of the ovary. It presents with acute-onset lower abdominal pain and, frequently, nausea and vomiting. Symptoms may be intermittent and fluctuate in severity. It is not known how long an ovary can withstand ischemia without permanent damage (it may be up to 72 hours or even longer), but definitive operative intervention should be undertaken as soon as possible.  
Should be ruled out in any male child presenting with abdominal pain.   The twisting of the testis and spermatic cord causes obstruction of arterial inflow and venous drainage from the testis. It typically presents with sudden-onset testicular pain; however, younger boys may only complain of abdominal tenderness, nausea, and/or vomiting. Physical findings suggestive of testicular torsion include loss of the cremasteric reflex, diffuse testicular tenderness, elevated testes, and a horizontal rather than vertical position of the testes. Prompt recognition and early surgical intervention are necessary to prevent testicular loss. Manual detorsion may be attempted while preparations for surgery are being made. Diagnostic studies should not preclude operative intervention.
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