occurs as a result of Budd–Chiari syndrome, CHF, or constrictive pericarditis The liver is engorged, resulting in hepatomegaly and right upper quadrant tenderness in each of these entities Nonalcoholic fatty liver disease (NAFLD), usually associated with obesity and type diabetes, is the most common cause of liver disease in children and may lead to fibrosis and cirrhosis later in life If there is associated liver disease and ascites, NAFLD may cause abdominal discomfort and distension Finally, a diseased peritoneum from infectious, inflammatory, or malignant causes can also cause an intra-abdominal effusion A history of recent trauma and signs of shock point to intraperitoneal bleeding, usually due to a splenic or hepatic laceration An ileus secondary to both peritoneal inflammation and shock likely contributes to the abdominal distension Trauma in the recent past suggests chylous ascites Finally, a diffusely tender abdomen suggests infectious peritonitis, pancreatitis, or bile peritonitis Extreme hepatomegaly that develops acutely occurs secondary to inflammation, congestion due to increased central venous pressure or vascular obstruction, or trauma (see Chapter 91 Gastrointestinal Emergencies ) There will be marked right upper quadrant tenderness and general systemic toxicity Causes include hepatitis, CHF, constrictive pericarditis, and congenital enzyme deficiencies Neoplastic disease, especially the proliferative blood cell disorders (leukemia, lymphoma), commonly causes significant hepatomegaly and splenomegaly Extreme splenomegaly without marked hepatomegaly in the toxic-appearing child suggests intraparenchymal bleeding with an intact capsule, sickle cell sequestration crisis, or malaria (see Chapters 93 Hematologic Emergencies and 94 Infectious Disease Emergencies ) In the nontoxic child, portal hypertension, neoplastic disease, and chronic hemolysis should be suspected Neoplastic disease often results in a spleen with an irregular surface Chronic hemolysis secondary to sickle cell disease, β-thalassemia, and hereditary spherocytosis may also result in a very large spleen In the case of hemoglobin “SS” disease, but not hemoglobin “SC” disease or sickle-thalassemia, splenic enlargement is followed by splenic atrophy beyond years of age A peripheral blood smear generally identifies this group of causes of massive splenomegaly (see Chapter 93 Hematologic Emergencies ) Other causes of abdominal distension include cysts, masses, tumors, uterine enlargement, obstructive uropathy, bowel duplication, and inflammation Cystic lesions include ovarian cysts; mesenteric, omental, or peritoneal cysts; choledochal cysts; and polycystic kidneys These conditions generally present with a subacute history and physical examination The exception is torsion of the large ovarian cyst, which produces vomiting and marked abdominal pain Abdominal ultrasound generally identifies intra-abdominal cysts readily Renal abnormalities are probably the most common cause of abdominal masses in early infancy Renal cystic disease is the most common cause of flank mass in the neonate Hydronephrosis due to ureteral–pelvic junction obstruction or posterior urethral valves may also cause abdominal distension in the neonate Confirmation of renal anomalies is made by ultrasound Tumors such as neuroblastoma, Wilms tumor, an ovarian tumor, and a teratoma generally can be palpated easily as firm, discrete abdominal masses by the time they are causing frank abdominal distension (see Chapter 98 Oncologic Emergencies ) Bowel duplication can be a subtle diagnosis until a complication such as mechanical bowel obstruction or hematochezia develops Finally, a midline pelvic mass should suggest pregnancy or hematocolpos EVALUATION AND DECISION History The history should attempt first to differentiate acute from chronic symptomatology by focusing on the rate of progression, recent trauma, weight loss, or weight gain Progressive distension suggests accumulating ascites, intraabdominal tumor, or increasing hepatosplenomegaly Parents may note early, subtle changes in these symptoms before they become apparent to the clinician Next, systemic signs such as fever, anorexia, edema, and lethargy further define the acuteness of the problem and, to some degree, narrow the diagnostic possibilities One must always be on alert, however, for an acute complication superimposed on a more subtle chronic condition Next, symptoms relative to specific organs, including the GI, renal, cardiac, and gynecologic systems, should be pursued These include questions about nausea, vomiting (bilious or nonbilious), abdominal pain, change in bowel habits, stool history (color, consistency), shortness of breath, cough, hemoptysis, urine output (including strength of stream and any abnormality of urinary color or foamy urine), menstrual history, and sexual activity Other important historical information includes stress or anxiety (associated with aerophagia), previous abdominal surgery, and recent medication use (including laxatives and antidiarrheal agents) Finally, a family history of anemia, early infant death among relatives or metabolic disease, a travel history, and a careful newborn history may be revealing Physical Examination After ruling out life-threatening respiratory embarrassment and shock, the physical examination should focus on determining whether the cause of the abdominal distension is related to bowel (air or stool) ( Fig 12.1 ), free fluid ( Fig 12.2 ), extreme hepatomegaly ( Fig 12.3 ), extreme splenomegaly ( Fig 12.4 ), inspissated stool, or a discrete mass ( Fig 12.5 ) A tympanitic abdomen suggests bowel distension (either by a mechanical obstruction or an ileus) or, especially in a toxic- appearing child, free air However, bowel distension may also be deceptive as it may overlie organomegaly or a solid tumor A fluid wave or shifting dullness (more reliable in younger children) suggests ascites Palpable loops of bowel or a palpable descending colon suggests stool Extreme hepatomegaly and splenomegaly generally are defined easily by palpation However, care should be taken to begin palpation in the pelvic area and advance superiorly so as not to overlook the liver edge Furthermore, the examiner must be cautious since other masses may mimic hepatomegaly and, in particular, splenomegaly Thus, it is important to note not only the location of the mass, but also whether it is firm, fixed (suggesting retroperitoneal origin), cystic, smooth, or nodular Rebound tenderness, pain with percussion and involuntary guarding should raise concern for a surgical etiology Other key physical findings include signs of CHF, abdominal tenderness, peripheral edema, signs of trauma or easy bruising, lymphadenopathy, pallor, and jaundice A rectal examination for a mass, tenderness, gross (frank blood, currant jelly stool) or occult blood, and the presence or absence of stool is also helpful More specific findings may be pursued once an initial hypothesis is made based on the algorithms in this chapter Laboratory The initial laboratory evaluation of abdominal distension is determined by the clinical findings and may include complete blood count with smear, reticulocyte count, erythrocyte sedimentation rate, and C-reactive protein; liver function tests, including serum albumin and clotting studies; electrolytes with BUN, creatinine, lipase, and amylase; a urinalysis with reducing substances; and an upright chest radiograph and a two-view abdomen plain radiograph The radiographs are helpful in determining the intestinal gas pattern, presence of free intra-abdominal air, and presence of intra-abdominal calcifications If intestinal obstruction is suspected, one of the plain radiographs should be a prone cross-table lateral view to determine the presence or absence of air in the rectum and sigmoid colon The addition of a left lateral decubitus view to the supine radiograph of the abdomen adds to the diagnostic utility if an intussusception is suspected, although ultrasonography has a higher overall sensitivity FIGURE 12.1 Bowel distension TE, tracheoesophageal