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Abdominal Pain

Michael A. Davis, MD

The evaluation of abdominal pain is problematic because the pain is often difficult to localize, and the history in children is often nonspecific. In children the differential diagnosis of abdominal pain is extensive.

Localization of Abdominal Pain

Generalized pain in the epigastrium usually comes from the stomach, duodenum, or the pancreas.

Pain in the midgut (small bowel and colon or spleen) usually localizes to the periumbilical region.

Inflammation (parietal pain) is usually well localized.

Referred abdominal pain occurs when poorly localized visceral pain is felt at a distant location.

Pancreatitis, cholecystitis, liver abscess, or a bleeding spleen cause diaphragmatic irritation, which is referred to the ipsilateral neck and shoulders.

Intraabdominal fluid may produce shoulder pain on reclining.

Gallbladder pain may be felt in the lower back or infrascapular area.

Pancreatic pain often is referred to the posterior flank.

A migrating ureteral stone often is felt as pain radiating toward the ipsilateral groin.

Rectal or gynecological pain often is perceived as sacral pain.

Right lower lobe pneumonia may be perceived as right upper quadrant abdominal pain.

Clinical Evaluation

History should include the quality, timing, and type of abdominal pain.

Pain of sudden onset often denotes colic, perforation or acute ischemia caused by torsion or volvulus.

Slower onset of pain suggests inflammatory conditions, such as appendicitis, pancreatitis, or cholecystitis.

Chronic pain can occur with non-surgical conditions or with early problems that are potentially surgical.

Colic results from spasms of a hollow viscus organ secondary to an obstruction. It is characterized by severe, intermittent cramping, followed by intervals when the pain is present but less intense. When spasms are present, the patient will appear agitated and restless, pale and diaphoretic. Colic pain usually originates from the biliary tree, pancreatic duct, gastrointestinal tract, urinary system, or uterus and tubes.

Inflammatory pain is caused by peritoneal irritation, and the patient presents quietly without much motion and appears ill. The pain is initially less severe and is exacerbated by movement.

Vomiting

The timing of the onset of vomiting is important. Usually abdominal pain will precede vomiting.

The interval between abdominal pain and vomiting is shorter when associated with colic.

Delayed vomiting for many hours is often associated with distal bowel obstruction or ileus secondary to peritonitis.

Diarrhea

Mild diarrhea with the onset of abdominal pain suggests acute gastroenteritis or early appendicitis.

Delayed onset of diarrhea may indicate a perforated appendicitis, with the inflamed mass causing irritation of the sigmoid colon.

Physical Examination

The abdomen should be observed, auscultated, and palpated for distention, localized tenderness, masses, and peritonitis. The groin must be examined to exclude an incarcerated hernia or ovary, or torsion of an ovary or testicle.

Rectal Examination

Gross blood in the stool suggests ectopic gastric mucosa, Meckel’s diverticula, or polyps.

Blood and mucus (currant jelly stool) suggests inflammatory bowel disease or intussusception.

Melena suggests upper gastrointestinal bleeding, necessitating gastric aspiration for blood.

Tests for occult blood in the stool should be performed.

Pelvic examinations are mandatory for postmenarchal and/or sexually active female patients. The rectal examination may also be used to evaluate the cervix, uterus, adnexa, and other pelvic masses.

Fever

Thoracic disease (eg, pneumonia) may be the cause of abdominal pain associated with fever.

Costovertebral angle tenderness with fever suggests pyelonephritis or a high retrocecal appendicitis.

Appendicitis

The history and physical exam, including rectal (and pelvic exam in females), are diagnostic of appendicitis in 80% of the cases. Perforation often follows the onset of symptoms in 24-48 hours. Beyond the neonatal period, but <2 years old, gastroenteritis and intussusception are also part of the differential diagnosis of abdominal pain.

Fever, vomiting, irritability, lethargy with right lower quadrant (RLQ) tenderness and guarding are diagnostic of appendicitis in the very young patient until proven otherwise.

Masses may be felt on rectal exam in 2-7% of younger patients with appendicitis.

Children Older than 2 years old present with a perforated appendix about 30-60% of the time. This incidence declines as the age of the child increases.

Lower abdominal pain in the adolescent female may be caused by pelvic inflammatory disease (PID), ovarian cysts, ovarian torsion, ectopic pregnancy, or mittelschmerz (pain with ovulation).

A WBC >15,000 supports the need for surgery, but a normal WBC and differential does not exclude appendicitis.

Intussusception

Intussusception is the most common cause of bowel obstruction between 2 months and 5 years of age. The most vulnerable age group is 4-10 months old, but children up to 7 years old may be at risk.

Intussusception is characterized by vomiting, colicky abdominal pain (85%) with drawing up of the legs, and currant jelly stools (60%). Fever is common. Lethargy, dehydration, obtundation and/or coma may occur in younger infants.

The abdomen may be soft and nontender between episodes of colicky pain, but eventually it becomes distended. A sausage-shaped mass in the right upper quadrant (RUQ) may be palpable.

Intussusception may sometimes be palpated during rectal examination, and three percent of intussusceptions may prolapse.

Ninety-five percent of intussusceptions are located at the ileocecal junction, 5% are found elsewhere in the GI tract.

Abdominal X-ray

The leading edge of the intussusception is usually outlined with air, which will establish the diagnosis. Often there are radiographic signs of bowel obstruction.

When the plain abdominal x-ray is normal, intussusception cannot be excluded without a barium enema.

Treatment usually consists of radiologic reduction using air and fluoroscopy, which is effective in 80-90%. Radiographic reduction is contraindicated if the patient has evidence of peritoneal irritation or toxicity. Under these conditions, surgery must be considered.

Midgut Volvulus

Midgut volvulus results from the improper rotation and fixation of the duodenum and colon (malrotation) resulting in a long, narrow mesenteric base. Obstruction of the superior mesenteric artery may cause ischemic necrosis of the gut, which may be fatal.

Infants in the first month constitute the majority of the cases. Symptoms usually begin about 5 days before diagnosis. The first sign of volvulus is bilious vomiting, followed by abdominal distention and GI bleeding. Peritonitis, hypovolemia, and shock follow as the ischemia continues.

Abdominal x-ray reveals a classic double bubble caused by duodenal obstruction, but this finding is nonspecific. Pneumatosis intestinalis or distal bowel obstruction may also be apparent.

Infants with rapid deterioration and obstructed loops of bowel require immediate surgery.

If the infant is not critically ill, an UGI series with water-soluble, non-ionic, isoosmolar contrast will confirm midgut volvulus. If malrotation or volvulus (suggested by a beak, spiral or corkscrew sign) is found, an immediate laparotomy is necessary.

Thirty to sixty percent of malrotations are associated with other anomalies, described below.

Gallbladder Disease

Cholecystitis in children occurs most commonly in the adolescent female, but it may affect infants who are only a few weeks of age. Cholecystitis is suggested by RUQ pain, back pain, or epigastric pain, radiating to the right subscapular area, bilious vomiting, fever, RUQ tenderness, and a RUQ mass. Jaundice is present in 25-55%, usually in association with hemolytic disease.

Hydrops of the gallbladder is characterized by massive gallbladder distention in the absence of stones, infection, or congenital malformations. It usually is preceded by another systemic disease (viral syndrome), and it is often associated with dehydration (bile thickening) or lymphadenopathy (partial obstruction). The usual treatment is a cholecystectomy.

Acalculous cholecystitis accounts for about 10-30% of gallbladder disease in children. It may occur with severe illnesses, such as burns, sepsis, or trauma.

Cholelithiasis may be a concomitant of hemolytic diseases in children. Fifty percent of children with spherocytosis develop gallstones. Sickle cell anemia and Thalassemia are the next most common causes. In adolescent females cholelithiasis can be found in the absence of hemolytic disease. Risk factors include obesity and pregnancy. Pregnancy is associated with 50% of all adolescent cholelithiasis.

Ultrasonography delineates gallstones and is the study of choice to screen for gallbladder disease.

Radioisotopic scanning evaluates biliary and gallbladder function. Nonvisualization of the gallbladder with no progression of isotope indicates acute cholecystitis.

Ectopic Pregnancy

Ectopic pregnancy must be considered in any postmenarchal, sexually active adolescent with abdominal pain. It is uncommon and usually seen in late adolescence. Ectopic pregnancy occurs in 0.5-3% of all pregnancies.

Signs of ectopic pregnancy include abdominal pain in any location, vaginal bleeding, and/or amenorrhea. Nausea and vomiting, other symptoms of pregnancy, and lightheadedness may also be present.

Abdominal, adnexal, and/or cervical tenderness are often found on pelvic examination, but occasionally abdominal tenderness is absent. The cervix may be soft (Godell’s sign) and bluish in color (Chadwick’s sign). The examination may reveal adnexal fullness and uterine enlargement. Some patients present with blood loss and hypotension or unexplained anemia. Ten percent will be in shock.

Evaluation includes a pregnancy test and ultrasound.

Treatment consists of removal of the ectopic pregnancy by laparoscopy or exploratory laparotomy.

Gonadal Pain in Males

In males with lower abdominal pain, the scrotum and its contents must be examined. Testicular torsion is a surgical emergency and must be treated within 6 hours of the onset of the pain to save the testicle.

Testicular torsion may present as lower abdominal pain, which may be associated with recent trauma or cold The gonad is tender and elevated in the scrotum, with a transverse orientation. Although testicular torsion may occur at any age, it usually occurs in adolescent males at puberty or shortly afterwards. It may occur in neonates. If the scrotum is empty, then torsion of a testicle located in the groin or in the abdomen should be ruled out. Torsion of undescended testicles occurs more frequent than in normally descended ones.

Torsion of an appendix testis may cause testicular pain, which occasionally be visualized as a "blue dot" beneath the scrotal surface on the testicle, associated with point tenderness. This disorder requires only analgesics and bedrest.

Laboratory Studies.

Ultrasound can sometimes help to localize an intraabdominal torsion. Doppler US may distinguish torsion (testes without blood flow) from epididymitis (where blood flow is normal or increased).

Gonadal Pain in Females

The leading causes of gonadal pain in females are ovarian cysts and torsion of uterine adnexal structures. Ovarian tumors are often associated with precocious puberty or virilization.

Ovarian cysts are responsible for 25% of childhood ovarian tumors. They are most common in adolescents. Bleeding into the cyst or cystic rupture causes pain, which usually subsides within 12-24 hours.

An ultrasound, performed after a cyst ruptures, may show pelvic fluid and the cyst.

Surgery is required if bleeding is uncontrolled. Growing cysts >5 cm should be considered for surgical enucleation.

Torsion of Uterine Adnexal Structures

Torsion is associated with unilateral, sudden, severe pain with nausea and vomiting. However, the patient may have subacute or chronic symptoms, with intermittent pain for days. The pain is usually diffuse and periumbilical in younger patients, but in older children and adolescents, the pain may radiate initially to the anterior thigh or ipsilateral groin. Torsion is more commonly right-sided.

Fever and leucocytosis are usually present. Physical exam may reveal muscle rigidity and fixation of the mass on pelvic examination.

Ultrasound will identify the mass accurately.

Surgical exploration may sometimes salvage the ovary. Malignant neoplasms may cause torsion in 35% of cases.

Abdominal Pain From Abdominal Scars

Adhesive small bowel obstruction occurs in 2-15% of children following a laparotomy. Seventy five percent of such patients present with adhesive obstruction between 2 weeks and 3 months after their operation. Eighty percent will occur within 2 years of operation. The disorder is treated with nasogastric decompression.

Postoperative intussusception occurs most commonly after major abdominal operations. Usually it is seen around age 26 months, but any age child may be affected. Postoperative intussusception presents with emesis, increased nasogastric drainage, abdominal distention, and irritability. Severe colicky pain and bloody stools are unusual. Ninety percent of the patients present within 2 weeks following surgery. Postoperative intussusception is managed with repeat laparotomy.

Meckel Diverticulum

Meckel diverticulum are present in 2% of the population. It presents as a tender left lower quadrant mass, associated with blood in the stool. Occasionally, technetium nuclear scans are positive for Meckel’s in the symptomatic patient.

Vague abdominal pain with hemoccult positive stools suggests a Meckel Diverticulum. Bleeding is seen in 35-40% of childhood cases. RLQ pain, suggestive of appendicitis, is the usual complaint of children with bleeding.

Meckel diverticulum may cause intestinal obstruction or diverticulitis, which cannot be distinguished from appendicitis.

Pancreatitis

Pancreatitis is a rare cause of abdominal pain in children. Trauma is the most frequent cause of this disorder in children.

Symptoms include mid-epigastric abdominal pain, nausea and vomiting, jaundice, and acholic stools.

Signs include epigastric tenderness, abdominal distention, decreased bowel sounds, and an epigastric mass may be detected.

An elevated serum amylase or serum lipase level is diagnostic.

Abdominal x-ray may show an epigastric sentinel loop or pancreatic calcifications. US is very sensitive and shows an enlarged, hypoechoic pancreas. A pseudocyst or an enlarged pancreatic duct may also be seen. §