Pain of sudden onset is likely associated with colic, perforations,
and acute ischemia (eg, torsions, volvulus). Slower onset of pain
generally is associated with inflammatory conditions such as appendicitis,
pancreatitis, and cholecystitis. Colic results from spasms of a hollow
muscular viscus (eg, biliary tree, pancreatic duct, gastrointestinal
tract, urinary system, uterus and fallopian tubes) and is usually
secondary to an obstructive process. In general, children with visceral
pain due to colic have episodic severe cramping with intervals when
the pain is absent or markedly reduced. During the painful episodes,
the patient is usually writhing, agitated, restless, and often pale
and diaphoretic. Inflammatory pain secondary to peritoneal irritation usually results
in a quiet, motionless, ill-appearing patient in whom pain is exacerbated
with movement.
The approach to differential diagnosis in a child with abdominal
pain is shown in Figure 383-1.
The differential diagnosis of acute abdominal pain varies depending
on the age of the patient and the location and duration of the pain
(new onset of pain or exacerbation of existing pain). Causes of
acute abdominal pain in children are shown in Table
383-1. Abdominal pain in the newborn manifests with incessant
crying, drawing up of the legs, and other nonspecific symptoms such
as feeding refusal. Diagnoses such as incarcerated hernia, bowel
obstruction, urinary tract infection, and volvulus must be considered.2 In
all ages, the presence of red flags such as bilious vomiting and
abdominal distension suggesting bowel obstruction; signs of impending
shock such as hypotension, confusion, and diaphoresis; hematemesis or
melena; or features of peritonitis demand immediate evaluation for
the specific presenting symptom or sign. Fever is associated with
gastrointestinal infections, bowel ischemia, and perforation but
may also occur in many of the other disorders associated with abdominal
pain. A history of possible trauma or abuse may be associated with
visceral injury and/or pancreatitis. A history of colicky
episodes with lethargy suggests possible intussusception. Previous
intra-abdominal surgery suggests a possibility of bowel obstruction
due to adhesions, intussusception, or intra-abdominal hernia. Other
medical conditions, such as a history of hemolytic disease, cystic
fibrosis, or inflammatory bowel disease, may also alter the likelihood
of various diagnoses. A history of heartburn or epigastric tenderness
may suggest acid-peptic disease. Associated symptoms and signs such
as dysuria (urinary tract infection), polyuria (diabetes mellitus),
hematuria (renal stone), purpura (Henoch-Schönlein purpura),
or diarrhea (gastroenteritis, colitis) may narrow the differential
diagnosis. In females, the gynecologic history is important. A history
of sexual activity may suggest pelvic inflammatory disease or pregnancy.
Midcycle pain of short duration may suggest mittelschmerz. Extra-abdominal
causes of perceived abdominal pain include rectus muscle hematoma,
testicular torsion, herpes zoster, diabetic ketoacidosis, porphyria,
sickle cell disease, myocardial infarction, pneumonia, pulmonary
embolus, radiculitis, spider and scorpion stings, and poisoning
(heavy metals, methanol). Pain out of proportion to the physical
findings can suggest ischemic pain, which is uncommon in pediatric
patients, or may be behavioral and associated with attention seeking.