Approach to the acute abdomen (pediatrics): Clinical sciences

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Introduction0:00–0:59

Acute abdomen refers to sudden, severe abdominal pain characterized by extreme abdominal tenderness, rebound, or guarding.
These signs suggest the presence of peritoneal inflammation or peritonitis, and an underlying cause that requires urgent surgical intervention.
Evaluation of a child with an acute abdomen depends on their age, the presence of an inguinal mass or bilious emesis, and the location of maximum abdominal tenderness.
Here’s a high yield fact! The acute abdomen is often referred to as a “surgical abdomen,” but some non-surgical conditions can mimic peritoneal signs.
Examples include acute bacterial peritonitis, diabetic ketoacidosis, pancreatitis, sickle cell crisis, familial Mediterranean fever, and lead poisoning.
When a pediatric patient presents with a chief concern suggesting an acute abdomen, your first step is to perform an ABCDE assessment to determine if the patient is stable or unstable.

Unstable0:59–1:43

Most patients with an acute abdomen are unstable, so be sure to stabilize their airway, breathing and circulation. Obtain IV access and start fluid resuscitation; continuous vital sign monitoring; and provide supplemental oxygen if needed.
Additionally, make your patient NPO in anticipation of surgical intervention, and consider placing a nasogastric tube. Finally, obtain an emergent surgical consultation and start broad spectrum IV antibiotics.
Now that you’ve stabilized your patient, perform a focused history and physical examination. Patients typically describe severe, acute abdominal pain with a sudden onset.

Focused H&P1:43–3:03

If the physical examination demonstrates abdominal tenderness with rebound and guarding; and possibly abdominal distension, or even a rigid abdomen; consider an acute abdomen.
Here’s a clinical pearl! It can be tricky to interpret exam findings when a child is experiencing pain or anxiety, but certain techniques can help you obtain a more reliable exam.
For instance, you might begin the exam by auscultating the heart and lungs, and then move your stethoscope to the abdomen to perform both auscultation and palpation using the stethoscope’s diaphragm.
Since most children don’t associate a stethoscope with discomfort, this method can reduce your patient’s anxiety and reveal signs like tenderness, rebound, or guarding!
Next, consider ordering a complete blood count or a complete metabolic panel, since patients with an acute abdomen may have leukocytosis, anemia, or electrolyte abnormalities.
Now, before you proceed with the evaluation, consider your patient’s age. First, let’s discuss patients under two months of age.

Less than 2 months3:03–3:14

In this case, you should also assess the gestational age at birth. If your patient was born premature, consider necrotizing enterocolitis.

Necrotizing enterocolitis3:14–3:49

Infants with this condition typically have feeding intolerance, lethargy, apnea and bradycardia, temperature instability, and in some cases, bilious vomiting.
The exam may reveal abdominal distension and bloody stools. Next, obtain an abdominal X-ray.
If it reveals pneumatosis intestinalis, which is visible air inside the bowel wall, diagnose necrotizing enterocolitis. Now let’s discuss patients who were born full term.

Full-term3:49–4:01

In this case, your next step is to assess for passage of meconium within 48 hours of birth. If your patient failed to pass meconium within this time frame, consider Hirschsprung disease.

Hirschsprung disease4:01–4:45

These infants demonstrate poor feeding and vomiting that is often bilious. Physical examination will reveal abdominal distension, and if you perform a rectal exam, you will find no stool in the rectal vault.
Next, obtain a contrast enema and consider a rectal suction biopsy. Imaging may demonstrate a funnel-shaped transitional zone between the dilated proximal colon and a narrow distal segment.
The biopsy will reveal an absence of ganglion cells in the colonic submucosa, which confirms Hirschsprung disease. Now, if your patient did pass meconium within 48 hours of birth, consider pyloric stenosis.

Pyloric stenosis4:45–5:31

These patients have immediate postprandial, non-bilious projectile vomiting, and appear perpetually hungry. Caregivers may report a sibling with a history of pyloric stenosis.
The physical exam might demonstrate a palpable olive-shaped mass in the epigastrium or right upper quadrant, and lab findings classically reveal hypochloremic, hypokalemic metabolic alkalosis.
Next, order an abdominal ultrasound, and if it reveals a hypertrophic pylorus, diagnose pyloric stenosis. Okay, now let’s go back and discuss children two months of age and older.

Incarcerated hernia5:31–6:16

In this case, assess for an inguinal mass. If you identify a mass, consider an incarcerated hernia.
These patients are usually diagnosed during infancy and present with vomiting, as well as abdominal and groin pain. If the physical exam demonstrates a non-reducible groin mass, diagnose incarcerated hernia.
Generally, this can be diagnosed clinically based on exam findings, if you’re uncertain, you can order an ultrasound or CT scan to confirm the presence of bowel within a hernia defect, and to look for signs of bowel obstruction.

Intestinal obstruction6:16–6:37

On the flip side, if you don’t find an inguinal mass, your next step is to assess for bilious emesis. The presence of bilious emesis should make you consider the possibility of intestinal obstruction, which is often caused by intestinal malrotation with volvulus, or intussusception.

Intestinal malrotation with volvulus6:37–7:32

First up is intestinal malrotation with volvulus. These infants typically present during infancy with bilious vomiting, and bright red blood per rectum; the exam will reveal abdominal distension and tenderness.
Now, bilious vomiting in an infant is a warning sign that should immediately make you consider intestinal malrotation with volvulus!
This can’t-miss condition results from defective embryonic rotation of the gut, which causes the intestines to twist around their mesenteric root.
Consequently, these infants can quickly develop vascular compromise and bowel ischemia, so order an emergent upper GI contrast study.
Imaging will show a spiral appearance of the duodenum and jejunum called the “corkscrew sign,” confirming the diagnosis of intestinal malrotation with volvulus.
Okay, let’s discuss intussusception. These patients typically present between the ages of 6 and 36 months, with lethargy, irritability, and colicky abdominal pain.

Intussusception7:32–8:22

Some patients pass stool containing blood and mucus, giving it an appearance resembling “red currant jelly.” The abdominal exam often reveals tenderness and a sausage-shaped mass in the right upper quadrant.
With these findings, consider intussusception and promptly obtain an abdominal ultrasound. Findings will reveal a proximal segment of bowel telescoping into a distal segment, as well as concentric bands alternating in echogenicity, creating the “target sign.” At this point, diagnose intussusception.
Now let’s go back and discuss patients who do not have bilious emesis. As a next step, assess the point of maximum tenderness during the abdominal examination, since its location will provide clues about the underlying cause.

Point of maximum tenderness8:22–8:38

If the point of maximum tenderness is periumbilical or in the right lower quadrant, consider appendicitis. These patients often report periumbilical pain that migrates to the right lower quadrant, with anorexia, nausea, and vomiting.

Appendicitis8:38–10:29

The exam will confirm tenderness at McBurney point; and positive psoas and obturator signs. You can elicit the psoas sign by assisting your patient lie supine; placing your hand against their thigh; and asking them to lift their leg against resistance.
If this causes pain, that’s a positive psoas sign! On the flip side, check for the obturator sign by passively flexing the right knee and then internally rotating it.
If rotation causes pain, that’s a positive obturator sign! Next, order an abdominal and pelvic ultrasound, but if you can’t visualize the appendix with ultrasound, consider an abdominal CT scan.
Ultrasound will demonstrate a thickened, enlarged appendix with peritoneal fluid; occasionally with an abscess or fecalith in the right lower quadrant.
If you ordered a CT scan, it will also reveal a thickened, enlarged appendix, as well as evidence of inflammation, like periappendiceal fat stranding.
These imaging findings confirm a diagnosis of appendicitis. Here’s another high yield fact!
Appendicitis is the most common cause of an acute surgical abdomen in pediatric patients, so consider appendicitis in all previously healthy children who present with abdominal pain, nausea and vomiting!
Okay, now let’s discuss cases where the point of maximum tenderness is in the pelvis. Pain in this location should make you consider gonadal torsion.

Gonadal torsion10:29–10:39

Ovarian torsion10:39–11:50

First let’s discuss ovarian torsion. Patients are biologically female and often present during adolescence, although it can occur at any age.
Symptoms include sudden onset of colicky pelvic pain, and possibly nausea or vomiting. If the exam demonstrates unilateral pelvic tenderness and possibly a pelvic mass, consider ovarian torsion.
Then, obtain a urine human chorionic gonadotropin, or hCG, to rule out pregnancy, a pelvic or transvaginal ultrasound; and color-flow Doppler.
The hCG will be negative, and the imaging commonly reveals an enlarged ovary with diminished or absent Doppler flow. You might see the presence of a twisted pedicle, known as the “whirlpool sign.” These findings confirm ovarian torsion.
Here’s a clinical pearl! Ectopic pregnancy can cause life-threatening hemorrhage, so don’t forget to perform a pregnancy test on all biologically female, post-menarcheal patients, with an acute abdomen!

Testicular torsion11:50–12:31

Now, let’s talk about testicular torsion. These patients are biologically male with sudden onset of severe scrotal pain.
Exam findings of testicular tenderness, scrotal erythema, induration, or edema; and an absent cremasteric reflex. These findings should make you consider testicular torsion.
Obtain a color-flow Doppler ultrasound of the scrotum to assess blood flow to the testicle, and if it reveals absent or diminished blood flow to the testicle or coiling of the spermatic cord, known as the “whirlpool sign,” diagnose testicular torsion.

Acute cholecystitis12:31–13:37

Finally, let’s discuss cases where the point of maximum tenderness is in the right upper quadrant or epigastrium. Pain in this location should make you consider acute cholecystitis.
Affected patients may report that their pain radiates to the right shoulder, scapula or chest. Many patients also report fever, nausea, and vomiting; and occasionally, a history of gallstones.
The physical exam will reveal mild jaundice; and you might elicit a positive Murphy sign. To check for this sign, ask your patient to take a deep breath and hold it; then press below the right subcostal margin as they exhale.
If they report pain, the Murphy sign is positive. Next, obtain an ultrasound, which will show a dilated and thickened gallbladder wall; pericolic fluid; and possibly a dilated common bile duct or gallstones.
These findings confirm acute cholecystitis. Alright, as a quick recap… Acute abdomen refers to severe acute abdominal pain associated with signs of peritonitis such as abdominal tenderness, rebound, and guarding.

Review13:37–14:23

The underlying causes of an acute abdomen often require prompt surgical intervention. For patients under two months of age, possible causes include necrotizing enterocolitis, Hirschsprung disease, and pyloric stenosis.
On the flip side, for children over two months, possible causes include incarcerated hernia; intestinal malrotation with volvulus; intussusception; as well as appendicitis; ovarian or testicular torsion; and acute cholecystitis.