An Infant With Abdominal Distention, Pain, and Bloody Stools
A 10-week-old girl presented to the emergency department after having had several episodes of nonbloody, nonbilious emesis and irritability. On the night before presentation, she had refused to breastfeed, began vomiting, and was difficult to console. She had had 2 loose, nonbloody stools. The infant had been born prematurely via cesarean delivery at 35 weeks of gestation after the mother went into premature labor. The girl had had several meconium stools on her first day of life and had been discharged with her mother after a 3-day stay. She had no other medical problems and a negative family history for intestinal disorders. The mother denied recent travel, fever, respiratory symptoms, and rash.
On physical examination, the patient was alert and uncomfortable, with mottled skin. She cried immediately with light palpation of all quadrants of her abdomen. Bowel sounds were high-pitched and increased in frequency. Results of inguinal examination were unremarkable. The anus was patent, with normal tone and no lesions. A moderate amount of bright red blood mixed with soft stool was found in the rectal vault. The remaining physical findings were normal.
Results of a complete blood count and a comprehensive metabolic panel were normal. Supine and lateral abdominal radiographs (Figures) demonstrated markedly dilated loops of small bowel and air-fluid levels. There was no free air. Results of abdominal ultrasonography and barium enema were normal.
What is causing this infant’s symptoms?
Answer on next page
Answer: Meckel diverticulum
A pediatric surgeon was consulted for suspected bowel obstruction. The surgeon took the patient to operating room for an emergent exploratory laparotomy. The girl was found to have a 1 × 3-cm Meckel diverticulum and obstructing adhesive bands. She underwent segmental bowel resection and anastomosis. Pathology test results confirmed the diagnosis of Meckel diverticulum and revealed a combination of ileal and gastric mucosa. The patient recovered uneventfully.
Incidence and Pathophysiology
The incidence of Meckel diverticulum is 0.6% to 4%,1 making it the most common congenital malformation of the intestinal tract. Because it often is asymptomatic, it is not a condition for which most general pediatricians have a breadth of experience.
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A Meckel diverticulum is a blind pouch formed by the incomplete obliteration of the vitelline duct. In fetal life, the vitelline duct connects the yolk sac to the intestinal tract and typically obliterates by 7 weeks of gestation. If it fails to obliterate completely, several anomalies can form, including Meckel diverticulum and intestinal umbilical fistulas.2 A Meckel diverticulum often is lined with ectopic tissue, most commonly gastric mucosa.2 However, it may contain duodenal, colonic, pancreatic, hepatobiliary, or endometrial tissue.
The prevalence is similar in boys and girls, yet complications occur more often in boys.1 In textbooks, it is reported to follow the “rule of 2’s”: 2% of the population, 2 feet from the ileocecal valve, 2 inches long, and 2 types of mucosa. In reality, however, there are many variations.1
Clinical Manifestations
Meckel diverticula can be symptomatic (16%) but more commonly are discovered incidentally in the operating room (84%).2 In symptomatic cases, rectal bleeding is a common presentation in adolescents and adults. Bleeding may be caused by acid secretion and ulceration of adjacent tissue, or by recurrent intussusception leading to inflammation and injury.1,5 At times, the bleeding can be massive and may lead to iron-deficiency anemia.
In infants and children, Meckel diverticula most commonly present with obstruction.2 Complications include obstruction due to intussusception or adhesive bands, ulceration, diverticulitis, and perforation.Rare complications include tumor formation, foreign body obstruction, inversion or torsion, and active inflammatory bowel disease in the diverticulum.1
Differential Diagnosis
The differential diagnosis depends on the presentation. In infants with bowel obstruction, the differential diagnosis should include intussusception, malrotation and volvulus, annular pancreas, congenital megacolon, and an irreducible inguinal hernia. Therefore, it is very important to do a groin examination in vomiting infants.
Other less common considerations are duplication, mesenteric cysts, and intestinal hematomas secondary to abuse.3 Necrotizing enterocolitis is a possibility, particularly in premature infants; symptoms typically present in the first few weeks.4 There are many causes of vomiting in infants, but bilious vomiting, localized or asymmetric tenderness, and abdominal distension are features that suggest a surgical condition.3 In our patient, the distension, the severity of pain, and the bloody stools, coupled with radiographs suggesting obstruction, were worrisome features.
Diagnosis
The precise etiology is often not known preoperatively in patients presenting with obstruction. In one large study of patients with a Meckel diverticulum, the correct preoperative diagnosis was made in 88% of patients presenting with bleeding but only in 11% of patients presenting with other symptoms.1 Conventional radiographs may demonstrate the obstruction but not its etiology. Sonography may demonstrate a fluid-filled structure in the right lower quadrant but often is of limited value.6 With abdominal computed tomography, it is difficult to distinguish normal bowel from the Meckel diverticulum, except in cases causing intussusception.6
A technetium-99m pertechnetate scan (Meckel scan) is the most accurate test for patients who do not require emergent surgery. In children, its sensitivity is between 80% and 90% and its specificity is 95%.1 The scan is less reliable in adults, perhaps because it detects gastric mucosa, which is more common in children with bleeding a Meckel diverticulum.2
Management
The treatment approach for patients with a Meckel diverticulum depends on the presentation and presence of complications. Initial treatment is directed toward stabilization: fluid resuscitation, nasogastric decompression, and transfusion in cases of significant bleeding. For symptomatic patients, the treatment approach is always surgical resection via laparoscopy or laparotomy.
The results of recent studies have shown that the laparoscopic technique is safe and effective for definitive diagnosis and treatment, even in complicated cases.5,7 Diverticulectomy or segmental bowel resection with anastomosis are the two procedures indicated. The latter is favored in cases with palpable ectopic tissue, intestinal ischemia, or intestinal perforation. Conversion from laparoscopy to laparotomy may be necessary in complicated cases with small bowel obstruction requiring hemicolectomy or in cases of intussusception where pneumatic reduction is necessary.7
Prognosis
Prognosis generally is excellent. A recent series of 20 pediatric patients with complicated Meckel diverticula demonstrated that all had an uneventful recovery, except for one patient with a postoperative a wound infection.7 Cases of postoperative adhesions also have been reported.
Controversy surrounds whether to excise a Meckel diverticulum in an asymptomatic patient. Factors to consider are whether complications from surgery are greater than the lifetime complication risk from the diverticulum, which is estimated at 16%.1 For pediatric patients, nearly all studies favor prophylactic removal.1,2
A comprehensive review of Mayo Clinic patients with Meckel diverticula suggested removal in asymptomatic patients younger than 50 years, in male patients, in patients with a diverticulum greater than 2 cm, and in cases with ectopic or abnormal features within the diverticulum.2
The Take-Home Message
Meckel diverticulum is the most common congenital anomaly of the intestinal tract, but most cases are asymptomatic. In young patients, obstruction is a common presentation.
In patients with an acute abdomen, an exploratory laparoscopy or laparotomy is necessary for diagnosis and treatment, whereas a technetium-99m pertechnetate scan usually is diagnostic for patients with rectal bleeding.
For nearly all pediatric patients, the treatment is surgical resection.
References:
1. Sagar J, Kumar V, Shah DK. Meckel’s diverticulum: a systematic review. J R Soc Med. 2006;99(10):501-505.
2. Park JJ, Wolff BG, Tollefson MK, Walsh EE, Larson DR. Meckel diverticulum: the Mayo Clinic experience with 1476 Patients (1950-2002). Ann Surg. 2005;241(3):529-533.
3. Davenport M. ABC of general surgery in children: surgically correctable causes of vomiting in infancy. BMJ. 1996;312(7025):236-239.
4. McCollough M, Sharieff GQ. Abdominal pain in children. Pediatr Clin North Am. 2006;53(1):107-137.
5. Brown RL, Azizkhan RG. Gastrointestinal bleeding in infants and children: Meckel’s diverticulum and intestinal duplication. Semin Pediatr Surg. 1999;8(4):202-209.
6. Sumer A, Kemik O, Olmez A, et al. Small bowel obstruction due to mesodiverticular band of Meckel’s diverticulum: a case report. Case Rep Med. 2010;doi:10.1155/2010/901456.
7. Chan KW, Lee KH, Mou JW, Cheung ST, Tan YH. Laparoscopic management of complicated Meckel’s diverticulum in children: a 10-year review. Surg Endosc. 2008;22(6):1509-1512.
Drs Samaddar and Celleri are pediatricians at St. Joseph’s Hospital and Medical Center in Phoenix, Arizona.
William Yaakob, MD—Series Editor:Dr Yaakob is a radiologist in Tallahassee, Florida.