The Child with Acute Abdominal Pain

The most common diagnoses for (non-neonatal) paediatric abdominal pain in the ED, in order of frequency, higher to lower, are:

1. Gastroenteritis
2. Respiratory Tract Infection (RTI) — Otitis Media, Pharyngitis, and Pneumonia
3. Urinary tract infection (UTI)
4. Constipation
5. Appendicitis¹

High-­yield associations with Abdominal Pain:

• Intermittent pain with change in stools (esp. bloody) – intussusception
• Bilious vomiting in neonate – malrotation of the gut
• Scrotal swelling or discoloration – testicular torsion
• Polyuria and Polydipsia – Diabetic Ketoacidosis (DKA)
• Recent Mononucleosis – splenic rupture
• Petechial rash to buttocks and legs – Henoch Schönlein Purpura (HSP)
• Haematuria and proteinuria – HSP
• Sterile pyuria – appendicitis
• Glucosuria and ketonuria – DKA
• Occult blood in stools – intussusception or advanced volvulus²

“Adult” diagnoses, including cholecystitis, renal colic, and incarcerated hernia also all occur in children.

Gastroenteritis

Gastroenteritis occurs commonly but because a more sinister pathology may “hide behind” a gastric-like syndrome, best consider it a diagnosis of exclusion. Especially in cases of isolated vomiting, and where prolonged, consider alternate diagnoses: intracranial mass, meningitis, strep throat, pneumonia, myocarditis, appendicitis, UTI, etc.¹

Consider in the history any sick contacts, such as siblings, day care, travel, or relatives visiting from abroad, any contact with farm-­‐products (e.g., unpasteurized milk), any unclean water exposure, exposure to new animals or foods, or any prior episodes (if chronic or recurrent, may need outpatient work-up to rule out Inflammatory Bowel Disease).¹ On examination, dehydration is a highly sensitive but non-specific sign that is difficult to quantify accurately clinically, one which clinicians generally over-estimate the degree, leading to over-aggressive resuscitation.

Only three findings show a statistically significant positive likelihood ratio as good clinical indicators of degree of dehydration:

• Prolonged cap refill time (CRT)
• Abnormal skin turgor
• Tachypnoea³

Those three features help to classify the degree of dehydration and inform treatment:

1. No / Mild Dehydration: none of the three features. Diet as tolerated.
2. Moderate Dehydration: some component of an unwell general appearance (e.g., fussy, lethargic); dry mucous membranes, absence of tears, sunken eyes; prolonged capillary refill; abnormal skin turgor; and tachypnoea. Oral rehydration is indicated as it is safer than giving intravenous (IV) fluid therapy, which is not without risk of harm.
3. Severe Dehydration: most / all of the above features along with abnormal vital signs. IV or nasogastric (NG) rehydration is generally indicated.

The vast majority of children do not need investigations, except for a capillary BGL: if lethargic secondary to poor oral intake or, in combination with urinalysis, to rule out other diagnoses, such as DKA with polyuria and polydipsia or UTI in children with fever and prior UTI. Electrolyte abnormalities are usually minor and rarely impact management; however, if starting IV hydration, monitor serum to avoid the all-too-common iatrogenic electrolyte imbalance seen in patients receiving parenteral fluids. Indications for stool cultures, meanwhile, include: travel to endemic countries, > 10 diarrhoeal episodes in 24 hrs, > 5 days’ duration without resolution, blood and/or mucous in stools, or unremitting fever.

Hemolytic Uremic Syndrome (HUS): triad of microangiopathic hemolytic anaemia, thrombocytopenia, and renal insufficiency, caused by E. coli O157:H7 bacterial enteritis. Presenting features of HUS include bloody stool and abdominal pain, lethargy, low-grade fever, paleness and tachycardia due to anaemia, petechiae, tea-coloured urine due to haematuria, and periorbital edema (especially upon waking). Note that the haemolytic component may present after the diarrhea has resolved; do not give antibiotics on spec if you suspect HUS because it may worsen disease. [4]

Management of Gastroenteritis

Oral vs IV Rehydration:

Compared with IV rehydration, oral rehydration therapy is associated with a lower risk of complications, such as electrolyte imbalance and cerebral edema (and, obviously, phlebitis and cellulitis). Essentially, oral rehydration therapy (ORT) is the treatment of choice for children with acute gastroenteritis associated with any degree of dehydration bar shock.

Otherwise well children (without chronic renal failure or a cardiac condition) older than 6 months of age presenting within 48 hours of symptom onset can be rehydrated rapidly with 50ml/kg oral rehydration solution (ORS) over 4 hours (or via NGT with kangaroo pump). Ongoing vomiting is no contraindication to oral rehydration; fluid can be given orally via cup, spoon, or syringe. But ORT is intensive and dependent upon the child’s caregiver.

For simplicity, one teaspoon per minute is an adequate starting rate for the infant or younger child.

Oral rehydration with Pedialyte ORS:

Pedialyte q 5 min dose for a goal of approximately 30 cc / kg per hour, for the first 3-4 hours. That is:

• 5 mL: < 6 months old
• 10 mL: 6 months to 3 years old
• 15 mL: > 3 years old

Or start slower, during the first 30-60 minutes, to minimize the chance of emesis. [5] Continue to breastfeed at the same time, and add 10 cc/kg per stool for fluid loss from diarrhoea.

Where oral or nasogastric fluids are not tolerated, commence IV 0.9% sodium chloride + 5% glucose at 10 ml/kg per hour for four hours (do not add maintenance fluid to this volume).

Patients who do not fit the criteria for rapid rehydration should be rehydrated more slowly over 24 hours by summation of deficit with maintenance and ongoing losses.

Calculate the Fluid deficit (ml) = % dehydration x weight (kg) x 10. Give this over eight hours or more slowly. Ongoing losses can be estimated to be 2ml/kg per hour in acute rotavirus. Review the patient at 4 hours and after the rehydration volume has been given. Once the child is rehydrated, continue fluids at maintenance plus ongoing losses. Potassium may be added to IV solutions once the child has passed urine and the serum potassium is known. Feeding, including full-strength milk or formula in infants, may commence once oral fluids are tolerated or the child is hungry. Commence instead a starch-based, reduced-milk (low-lactose) diet for cases with persistent diarrhoea.

Compared with placebo, oral ondansetron (Zofran) stops vomiting more frequently (NNT 5) preventing the need for IVC insertion (NNT 5) and reducing the rate of immediate admission without masking serious disease or leading to worse outcomes; without, however, any change to rates of hospitalization at 72 hrs, as children with missed serious pathology return. [6]

Give a single oral disintegrating dose of ondansetron and wait 15 minutes before starting bubble-gum Pedialyte. Perhaps avoid giving any prescription to take home as thereafter ondansetron accrues no benefit but increases diarrhea, and the child with worsening vomiting needs formal reassessment nonetheless.[7] Do not use ondansetron as a diagnostic tool – i.e. if a child stops vomiting with ondansetron, that clearly does not rule out alternate, more sinister, diagnoses such as appendicitis. Moreover, ondansetron may prolong QTc interval and should be avoided in patients with known prolonged QTc, hypokalemia or hypomagnesemia, congenital heart disease and congestive heart failure, in whom it may provoke arrhythmia.[8]

Antibiotics are rarely required, even for bacterial gastroenteritis; consider antibiotics only where the child is persistently ill and high-risk, such as immunocompromised, has sickle cell disease, or is using corticosteroids or chemotherapy, or with risk factors for C. difficile (neonates and graduates of NICU, IBD patients, or immunosuppressed recently on antibiotics). Antibiotics are contraindicated in enterotoxigenic E. coli (O157:H7) gastroenteritis: they increase the risk of HUS. Return to care if child has bloody stool, increasing pain or fever, is lethargic (“too sleepy”), or behaves unusually for them.

Do not use loperamide (may cause lethargy, paralytic ileus, case reports of death), and bismuth is not recommended. Avoid also probiotics in children with central lines, congenital heart disease, or short gut, as probiotics lead to higher infection rates in these patients. Otherwise, probiotics may reduce the duration of diarrhea by one day in more severe cases.[9]

Intussusception

Intussusception occurs when a section of bowel invaginates (telescopes) into and incarcerates within the lumen of the immediately distal bowel, resulting in infarction and gangrene of the inner bowel segment. It most commonly occurs at the ileocaecal junction.

Sixty percent of cases are < 1 year old, most (80-90%) under 2; so while it can present at any age between six months and 6 years old (3 months to 5 year old), it is the most common cause of acute intestinal obstruction—the most common surgical emergency—in children 6-36 months old.

The classic triad of intermittent crying (pain), bloody stools, and sausage-shaped mass in the abdomen is seen in less than 40% of cases: several-minute long episodes, recurring at 5-20 minute intervals, of sudden intense pain with screaming and flexion of the legs, often associated with pallor yet a well-looking infant in between episodes. Rather, intussusception more often presents in one of two ways: either vomiting (perhaps pain-related) and bilious if prolonged, with or without abdominal pain in the older child, or lethargy with paleness, especially in younger infants where parents say child looked as if “all the life got sucked out of them.” Be alert then to this less common presentation of intussusception, the child who appears floppy and obtunded – i.e. episodes of lethargy or irritability and altered mental status and which may be mistaken for a post-ictal or septic/meningitic child. [10]

Crying with intussusception is often severe and different than usual crying, the child dropping into a fetal or knee-chest position one moment yet behaving normally moments later. One-third of cases present with a history of recent viral illness as the intussusceptus often reflects the presence of a lead point from which the bowel can invaginate, such as enlarged lymph glands (e.g., Peyer’s patch), Meckel’s diverticulum, or mesenteric duct remnant. A history of recent vaccination may itself reflect the small risk of intussusception in infants following rotavirus vaccination.

Classic currant-jelly stool (loose stool with mucous and blood) is a late finding present in only 10% of cases. Indeed, a rectal exam for faecal occult blood will precede this later, more ominous, gross sign of bowel ischemia. Not infrequently, a disconcertingly “empty” RLQ or, conversely, sausage-shaped mass in the RUQ (just below the liver but often difficult to appreciate), is noted.

Examination should focus on ruling out inguinal hernia, testicular torsion, midgut volvulus (80% present with bilious vomiting in first year of life), as well as child abuse, sepsis, meningitis, bacterial gastroenteritis, and UTI (crying on urination).

On examination, then, the child with intussusception can present with any of the following features:

• relatively well-looking
• pale, lethargic, and hypovolemic
• distended, tender abdomen
• palpable abdominal mass (sausage shaped) in the right upper quadrant
• dehydrated or shocked
• vomiting, that may become bile-stained if bowel obstruction has occurred
• “red currant jelly” stool, a late sign [11]

In other words, the diagnosis of intussusception requires a high index of suspicion.

An Abdominal X­-ray will rule out other or indeed concomitant diagnoses (bowel obstruction, perforated viscus), but look for the subtle target (or “doughnut”) sign in the RUQ, perceive a paucity of air in the RLQ, or note a crescent sign in the LUQ, present in 23% of cases. [12]

AXR signs of intussusception:

• paucity of bowel gas on the right side of the abdomen
• distended loops of small bowel with air/fluid level
• obscured liver edge, crescent and target signs
• free gas, if perforated

Albeit operator-dependant, abdominal ultrasound scan (USS) is the diagnostic test of choice for intussusception; it is highly specific with a sensitivity of 99%. It is less painful than the centre-dependent air- or barium-contrast enema (performed under IV sedation) which, however, although therapeutic, may cause compartment syndrome (tension pneumoperitoneum) in case of perforation from high pressures. The leaked barium also occasions a chemical peritonitis. Otherwise, direct the very young patient, those with symptoms of greater than 15 hours duration, the acidotic child, the child with evidence of ongoing ischemia, the child with worsening gross blood per rectum, or the hemodynamically unstable child, immediately to the operating room (OR).[13] Administer antibiotics prior to either air enema or surgical reduction. [14]

Complications:

• Perforation of bowel, with peritonitis
• Necrosis of bowel requiring bowel resection
• Shock and sepsis
• Re-intussusception after spontaneous or active reduction

Management:

• Insert intravenous (IV) cannula and obtain bloods
• Correct shock with 20 mL/kg of 0.9% saline IV boluses
• Nil by mouth ± Nasogastric tube (NGT) on free drainage if signs of bowel obstruction
• Analgesia: IV morphine 0.05 mg/kg to 0.1 mg/kg titrated
• Urgent abdominal ultrasound and urgent surgical review
  • positive abdominal ultrasound is followed directly by attempted non-operative reduction via air enema unless surgeon and radiologist agree that air reduction is unsafe and operative treatment is require
• Air Enema
  • contraindications: peritonitis/perforation
  • IV Antibiotics prior
  • IV morphine analgesia prior/during
  • surgical registrar in attendance
  • performed by experienced radiologist (up to 95% success rate)
  • adjuvant dexamethasone may have a role
• Surgical reduction is necessary if there are signs of peritonitis / perforation, or if air enema fails to reduce the intussusception [15]

Constipation

Per Rome III criteria, constipation is ≤ 2 stools per week for 2 months in patients > 2 years old and for a duration of 4 months in patients < 2 years old or with evidence of overflow incontinence (seemingly fluctuating between constipation and diarrhoea), or simply stools that clog the toilet. Functional constipation is the most common cause of abdominal pain in children, but severe underlying disease should first be excluded before labelling the abdominal pain as functional. [16]

Differential diagnoses:

• Hirschsprung’s disease: severe obstipation with overflow diarrhea and abdominal distention in non-thriving, unsettled child which may present with toxic megacolon
• Cystic fibrosis and Hypothyroidism: assess family history, and whether screening was performed
• Others:
  • Down syndrome
  • Myelomeningocele or neuromuscular problem – slow to walk, walking “funny”
  • Coeliac disease – seek a family history
  • Child abuse

Oral medications administered in the ED work better when combined with enemas, but explain to parents that it takes time to retrain the bowel (sometimes years). For a child < 2 years old, use a 20 cc/kg saline enema. For an older child (> 20-25 kg), use an adult Fleet enema. For the outpatient, suggest an over-the-counter PEG 3350 preparation (e.g. Laxaday) at a dose of 1.5g/kg per day (rounded to nearest ½ cup of 17 g) dissolved in a cup of juice; and then titrate the dose up or down for one soft stool per day, and then slowly taper. [17]

Acute Appendicitis

Because of delay in diagnosis, the majority of cases of appendicitis in the younger child (< 4 years) have viscus perforation. This delay reflects an atypical history in many children: the absence of the classic history of anorexia and vague periumbilical pain followed by migration of pain to the right lower quadrant and onset of fever and vomiting. In contradistinction to a “typical” appendicitis, the younger child may present with diarrhea, constipation, and dysuria and their pain may localize to the back or psoas muscle, as many children have a retrocaecal appendix. Vomiting may declare itself before the younger child voices any complaint about abdominal pain.

Percuss the abdomen for focal tenderness. Look for discomfort on rolling the patient’s hips. Pyuria and haematuria can be consistent with a diagnosis of appendicitis. Abdominal USS comes with (an operator-dependent) > 95% sensitivity and specificity. Except in obese patients, consider giving analgesic/anxiolytic and repeating the ultrasound in 12hrs for improved diagnostic accuracy and because abdominal CT carries a life‐time cancer risk of about 1 in 1,000 in children (the younger the child, the higher the risk). Pediatric appendicitis decision rules also help reduce the use of CT scans by about 20%.[18] Where clinical index of suspicion (pre-test probability) is high, bypassing imaging studies in preference for direct surgical referral reduces the risk of appendiceal perforation.[19]

Alvarado Appendicitis Score: Yes = 1, No = 2 [20]

A score > 6: sensitivity = 72%

• Migration of pain to RLQ
• Anorexia or acetone in urine
• Nausea/Vomiting
• RLQ tenderness
• Rebound Pain
• Fever
• WCC > 10,000
• Left shift – neutrophils > 75%

< 5	Appendicitis less likely
5-6	Possible
7-8	Probable
> 8	Very probable

Broad-spectrum antibiotics are given to septic patients, while a prophylactic dose of antibiotics pre‐operatively, on call to the OR, is given to all appendicitis patients to reduce risk of post-operative complications. Meanwhile, the time-honoured approach to a perforated appendix presenting subacutely remains: manage conservatively with antibiotics, percutaneous drainage, and interval surgery (after 8‐12wks). [21]

Footnotes

1. Anton Helman and Lucas Chartier, “Episode 19, Part 2: Pediatric Gastroenteritis, Constipation and Bowel Obstruction,” Emergency Medicine Cases (EMC). Available at https://emergencymedicinecases.com/episode-19-part-2-pediatric-gastroenteritis-acute-constipation-bowel-obstruction/.
2. Helman and Chartier, “Episode 19, Part 2: Pediatric Gastroenteritis, Constipation and Bowel Obstruction,” EMC.
3. M. J. Steiner et al., JAMA 291(22); 2004: 2746-54. DOI:10.1001/jama.291.22.2746
4. Helman and Chartier, “Episode 19, Part 2: Pediatric Gastroenteritis, Constipation and Bowel Obstruction,” EMC.
5. Anna Jarvis (University of Toronto), in Helman and Chartier, “Episode 19, Part 2: Pediatric Gastroenteritis, Constipation and Bowel Obstruction,” EMC.
6. Helman and Chartier, “Episode 19, Part 2: Pediatric Gastroenteritis, Constipation and Bowel Obstruction,” EMC.
7. Stephen Freedman in Helman and Chartier, “Episode 19, Part 2: Pediatric Gastroenteritis, Constipation and Bowel Obstruction,” EMC.
8. Freedman, NEJM (2006); Fedorowicz, Cochrane Review (2011).
9. Anton Helman and Lucas Charter, “Episode 19, Part 1: Pediatric Abdominal Pain and Appendicitis,” Emergency Medicine Cases.
10. PCH Emergency Department. “Intussusception.” Perth Children’s Hospital. Child and Adolescent Health Service, Government of Western Australia. Mar 2018. https://pch.health.wa.gov.au/For-health-professionals/Emergency-Department-Guidelines/Intussusception.
11. PCH Emergency Department. “Intussusception.” Perth Children’s Hospital. Mar 2018.
12. Helman and Chartier, “Episode 19, Part 2: Pediatric Gastroenteritis, Constipation and Bowel Obstruction,” EMC.
13. Helman and Chartier, “Episode 19, Part 2: Pediatric Gastroenteritis, Constipation and Bowel Obstruction,” EMC.
14. PCH Emergency Department. “Intussusception.” Perth Children’s Hospital. Mar 2018.
15. John M. Hutson, Michael O’Brien, Spencer W. Beasley, Warwick J. Eague, Sebastian K. King (Eds), Jones’ Clinical Paediatric Surgery 7th Edn. (2015). PCH Emergency Department. “Intussusception.” Perth Children’s Hospital. Mar 2018. Gluckman S, Karpelowsky J, Webster AC, McGee RG. Management for intussusception in children. Cochrane Database of Systematic Reviews 2017, Issue 6. Art. No.: CD006476. DOI: 10.1002/14651858.CD006476.pub3
16. Helman and Chartier, “Episode 19, Part 2: Pediatric Gastroenteritis, Constipation and Bowel Obstruction,” EMC.
17. Helman and Chartier, “Episode 19, Part 2: Pediatric Gastroenteritis, Constipation and Bowel Obstruction,” EMC.
18. Ann Emerg Med 49; 2007: 778-784. Ann Emerg Med 74(4); 2019:471-480. doi:10.1016/j.annemergmed.2019.04.023.
19. Anton Helman and Lucas Charter, “Episode 19, Part 1: Pediatric Abdominal Pain and Appendicitis,” Emergency Medicine Cases. https://emergencymedicinecases.com/episode-19-part-1-pediatric-abdominal-pain-appendicitis/.
20. BMC Med. 2011;9:139.
21. Anton Helman and Lucas Charter, “Episode 19, Part 1: Pediatric Abdominal Pain and Appendicitis,” Emergency Medicine Cases.

References

Gluckman S., Karpelowsky J., Webster A. C. and McGee R. G. “Management for intussusception in children.” Cochrane Database of Systematic Reviews 2017, Issue 6. Art. No.: CD006476. DOI: 10.1002/14651858.CD006476.pub3.

Helman, Anton and Chartier, Lucas. “Episode 19, Part 1: Pediatric Abdominal Pain and Appendicitis.” Emergency Medicine Cases. Available at https://emergencymedicinecases.com/episode-19-part-1-pediatric-abdominal-pain-appendicitis/.

Helman, Anton and Chartier, Lucas. “Episode 19, Part 2: Pediatric Gastroenteritis, Constipation and Bowel Obstruction.” Emergency Medicine Cases. Available at https://emergencymedicinecases.com/episode-19-part-2-pediatric-gastroenteritis-acute-constipation-bowel-obstruction/.

Hutson, John M., O’Brien, Michael; Beasley, Spencer W., Eague, Warwick J. and King, Sebastian K. (Eds). In Jones’ Clinical Paediatric Surgery 7th Edn. (2015).

PCH Emergency Department. “Intussusception.” Perth Children’s Hospital. Child and Adolescent Health Service, Government of Western Australia. Mar 2018. https://pch.health.wa.gov.au/For-health-professionals/Emergency-Department-Guidelines/Intussusception.

Steiner M. J., DeWalt D. A., Byerley J. S. “Is This Child Dehydrated?” JAMA 291(22); 2004: 2746–2754. doi:10.1001/jama.291.22.2746.

Further

“Clinical practice Guidelines: Intussusception.” The Royal Children’s Hospital, Melbourne. Available at https://www.rch.org.au/clinicalguide/guideline_index/Intussusception_Guideline/.

Newman RK, Dayal N, Dominique E. “Abdominal Compartment Syndrome.” 2021 Apr 22. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan–. PMID: 28613682.

Niknejad, Mohammad Taghi  and Amini, Behrang et al. “Intussusception.” Revision 102. Radiopaedia. Available at https://radiopaedia.org/articles/intussusception/revisions?lang=us.