Printer Friendly

Pediatric gastrointestinal emergencies.

Gastrointestinal (GI) complaints are among the most frequent causes for emergency department visits in the pediatric population. Radiology plays an ever-increasing role in the diagnosis and treatment of these emergencies. This article describes the clinical presentation, epidemiology, and imaging findings of 5 GI emergencies that require surgical intervention: Malrotation and midgut volvulus; intussusception; hypertrophic pyloric stenosis; appendicitis; and Meckel's diverticulum.

Malrotation and midgut volvulus

Malrotation is any deviation from the normal 270[degrees] counterclockwise rotation of the bowel that occurs during embryogenesis. The resultant shortened mesenteric pedicle predisposes to midgut volvulus, a clockwise rotation around the superior mesenteric artery axis that can lead to bowel ischemia. A mnemonic for remembering the direction of rotation of volvulus and surgical devolvulus is: "the surgeon turns back the hands of time."

The incidence of malrotation is 1 in 500. (1) The male-to-female ratio is 2:1. Malrotation with midgut volvulus may become rapidly life-threatening. The previously healthy infant with bilious emesis is one of the few "drop everything else" presentations in pediatric imaging, as the stopwatch of ischemic bowel may be ticking. The older the child, however, the more atypical the symptoms; the teenager with chronic abdominal pain or malabsorption may be suffering from recurrent bouts of volvulus and devolvulus.


Conventional radiographs are neither sensitive nor specific for malrotation. On the upper GI series, it is crucial to locate the position of the duodenal jejunal junction (DJJ). The DJJ must be at least over (but more reassuringly lateral to) the left vertebral pedicle and at the same height as the duodenal bulb on a well-centered view. If the DJJ does not meet these two criteria, then malrotation is diagnosed (Figure 1). Signs of midgut volvulus include an abrupt termination, or beak, of the contrast column (Figure 2) and the corkscrew (apple peel, or barber pole (2)) sign (Figare 3).

On ultrasound (IJS) and computed tomography (CT), the superior mesenteric artery (SMA) and superior mesenteric vein (SMV) relationship may be reversed (Figure 4). Normally the SMV is to the right of the SMA; with malrotation, the SMV may occupy a position directly anterior or to the left of the SMA. Of critical importance, a normal SMA/SMV relationship does not exclude malrotation, and the upper GI remains the imaging gold standard. Conversely, some children without malrotation may have a vertical or inverted SMA/SMV relationship. (3) Several other US signs of midgut volvulus include: Hyperdynamic pulsating SMA (4); distal SMV dilation (5); whirlpool sign (6) (Figure 5); and a truncated SMA sign (7) (Figure 6). Two technical points should be kept in mind when evaluating the SMA/SMV relationship. First, scan as caudally as possible; at the portal confluence, the SMV occupies the most ventrally vertical position with respect to the SMA and may erroneously suggest malrotation. Second, place the transducer over the midline and not over the liver; rightward deviation will falsely "move" the SMV to the left and possibly ventral to or left of the SMA. (8)




Intussusception is the telescoping of a segment of bowel into an adjacent segment; the great majority of cases are ileocolic. In only 5% of cases is a pathologic lead point identified. (9) Lymphoid hyperplasia is the cause in the vast majority of the remaining 95%. The classic clinical triad is abdominal pain, currant-jelly stool, and palpable abdominal mass. However, in our experience, lethargy and drawing up of the legs are the most commonly reported signs, and a significant percentage of patients may be pain-free at presentation. (10) Most patients are between the ages of 6 months and 2 years.


Conventional radiographs are neither specific nor sensitive. (11,12) Findings include the meniscus (Figure 7) and target signs. The most important use for radiographs is excluding pneumoperitoneum. A gasfilled cecum on a left lateral decubitus film is a good negative predictor for Intussusception. However, determination of cecal position can be difficult; in 45% of children [less than or equal to]5 years of age, a gas-/stool-filled sigmoid colon is positioned in the right lower quadrant and may mimic a normal-appearing cecum. (13) One less well-known sign that the authors have found to be predictive of intussusception is "ileization" of the right lower quadrant, ie, visualization of gas-filled small-bowel loops in the right lower quadrant, filling the "vacuum" left by the intussuscepted cecwn and ascending colon (Figure 7).


Several studies have reported 100% diagnostic accuracy rate for US, and US may be used to guide hydrostatic and air reduction. (14-17) A clear advantage is the lack of ionizing radiation. The technique is more widely used in Europe and Asia, but is gradually being adopted in the United States. Several US signs have been described: Doughnut; pseudokidney; crescent in doughnut (Figure 8A); sandwich (Figure 8B); and hay-fork. (16,18,19)

CT findings for intussusception are characteristic. The telescoping natare of the pathology is seen on axial images as an eccentric fat and soft-tissue density mass surrounded by bowel wall (Figare 9). The typically crescentic fatrepresents the mesentery drawn into the intussuscipiens, and the soft tissue is a combination of bowel, lymph nodes, and mesenteric vasculature.

In most institutions, a contrast enema remains the standard for diagnosis and initial treatment. Peritonitis and perforation are absolute contraindications. The major complication is perforation with potential tension pneumoperitoneum. Prior to performing the enema, a surgical consult is required, the patient must have an intravenous (IV) line in place (for emergency resuscitation), and a large-bore needle (eg, 14-g catheter needle) should be within close reach to decompress a tension pneumoperitoneum. If the patient cries during the procedure, it is expected and beneficial; crying simulates the Valsalva maneuver and protects against bowel perforation by reducing the transmural gradient. (20) Explaining this to the parents both reassures and deflects requests for sedation. Whether air orliquid is used to perform the enema is a matter of personal preference. The rates of reduction of intussusception are not statistically different when using air versus liquid contrast (21); however, air is faster, uses less radiation, causes significantly smaller perforations, and results in less peritoneal contamination if perforation does occur (20). Those who favor liquid point to the slightly lower perforation rate in large studies, superior visualization of pathologic lead points, and greater control over the lead pressure. (22)


The authors favor the air enema for speed, decreased radiation dose, and cleanliness, reserving the contrast enema for children with a higher pretest probably of a pathologic lead point based on age (<1 month old or >4 years old). A negative study goes quickly, with rapid filling of the colon and reflux into the terminal ileum. In a positive study, the intussusceptum is usually encountered in the transverse colon, and the initial reduction proceeds rapidly to the ileocecal valve (Figures 10A and 10B). Disappearance of the cecal mass and free reflux of air into the terminal ileum indicates successful reduction (Figure 10C). How long to persist is controversial, with some advocating 3 attempts, a maximum pressure of 120 mm Hg, and limiting the duration of maximal pressure to <3 minutes. (23) Others will try longer, reasoning that both perforation and incomplete reduction will result in surgery. We have had excellent success with delayed attempts after initial incomplete reduction; after waiting 15 to 20 minutes (to allow the edematous bowel and ileocecal valve to decrease in size), a subsequent reduction attempt may be successful. (24) If tension pneumoperitoneum occurs, insert a large-bore needle (eg, 14-g catheter needle) in the midline abdomen through the avascular linea alba, 2 cm above the umbilicus.






Hypertrophic pyloric stenosis

Several hypotheses have been proposed for hypertrophic pyloric stenosis (HPS), including those focused on the pyloric muscle and its innervation, hormones, and a molecular etiology. (25,26) The typical patient is a male infant with a previously normal feeding history who presents with nonbilious, projectile emesis. In the premature infant, the diagnosis may be made at an older age. (27) Palpation may reveal an "olive" in the right upper quadrant; however, in 15% of cases, even highly experienced pediatricians and surgeons cannot make this diagnosis on physical examination. (28) The incidence of HPS is 1 to 4 cases per 1000 live births, with a 2:1 to 5:1 male/female ratio. (29) Patients usually present between the ages of 2 and 8 weeks, with peak incidence at 3 to 5 weeks. (30) With delayed diagnosis, the infant shows signs of dehydration, lethargy, and a hypochloremic alkalosis due to loss of stomach acid.

Ultrasound is the imaging modality of choice because it enables direct visualization of the pyloric muscle and avoids ionizing radiation. The pylorus is a hypoechoic structure with echogemc mucosa/ submucosa and serosa on either side (Figure 11). Although a narrow range of diagnostic measurement criteria have been published, the authors use the mnemonic [pi] (3.14) to remember 3-mm thickness and 14-mm channel length. Practically, the appearance of HPS is characteristic, independent of measurements. A high-frequency linear transducer should be used. Allowing the infant to bottle-feed with glucose solution (NOT echogexric formula) will provide an acoustic window through the antrum and facilitate evaluation for liquid shuttling across the pylorus. A right posterior oblique position may displace air into the fundus and liquid against the pylorus, which will now lie in a more dependent position. An important component of the complete US evaluation is inclusion of the SMA/SMV relationship and the kidneys to assess the possibility of malrotation or renal pathology as the cause of the child's symptoms.


Although once the diagnostic standard for HPS, the upper GI series is now virtually never performed as an initial study for this indication; the diagnosis may be revealed during a fluoroscopic examination for another indication, such as possible malrotation. In a positive study, one may observe "shouldering" of the hypertrophic pyloric muscle at the antrum and the string or double-track sign, representing barium squeezed between folds of mucosa pressed together by the hypertrophied muscularis layer (Figare 12). (31)


Luminal obstruction is the usual initial insult in appendicitis. Obstruction may be caused by a fecolith, appendicolith, lymphoid follicle, or foreign body. Lifetime risk in males is approximately 9% and in females 7%. (32) It has been estimated that 1 % to 8 % of children who present to the emergency department with abdominal pain will be diagnosed with appendicitis. (33,34) Appendectomy is the most common emergency surgical procedure performed in children. (26)


Abdominal radiographs are frequently normal in appendicitis. However, one or more of the following signs may be present: Calcified appendicolith (occurs in <10% of cases) (Figure 13); obliteration of the right psoas margin; splinting leading to a lumbar dextroscoliosis; and right lower quadrant air-fluid levels (localized ileus). A perforated appendix may produce pneumoperitoneum.

There is significant and ongoing controversy over which imaging modality, US or CT, should be used for initial evaluation in children with suspected appendicitis. Ultrasound advantages include low cost, lack of ionization radiation, and ability to evaluate compressibility and vasculariry. A sensitivity of 85% and a specificity of 92% have been reported for US using meta-analysis of all studies published between 1986 and 1994. (35) Ultrasound evaluation using graded compression is performed with a high-frequency linear array transducer. Gentle pressure is applied to the right lower quadrant to compress and displace normal bowel loops. Technically adequate studies can be achieved in >95% of patients. (36) An abnormal appendix measures [greater than or equal to]6 mm in maximal outer diameter, is not compressible, reveals adjacent inflammatory changes, and is hyperemic with Doppler imaging. Other US findings include: Echogexric submucosa in early acute appendicitis; a target sign if the appendix is fluid-filled (hypoechoic fluid layer, echogexric mucosa/submucosa, and hypoechoic muscularis); an appendicolith; pericecal or periappendiceal fluid; increased periappendiceal echogemciry (from inflamed fat); and enlarged mesenteric nodes (Figare 14).

Advantages of CT over US include: Reduced operator dependence; enhanced visualization of soft tissues, bones, gas, and fluid; and superior evaluation for complicating phlegmon and abscess formation. CT is also superior in obese patients. Sivit et al (37) showed that CT had a significantly higher sensitivity (95% versus 78%, P = 0.009) and accuracy (94% versus 89%, P = 0.05) than that of graded compression US for the diagnosis of appendicitis in children, adolescents, and young adults. Specificity was 93% for both. CT was especially useful when the US examination was normal. (37) The optimal CT technique is controversial. The highest reported diagnostic efficacy has been with rectal contrast only and thin collimation through the lower abdomen and pelvis, with sensitivities of 97% to 100% and specificities of 94% to 98%. (37) We prefer IV contrast without oral or rectal contrast to decrease preparation time and for enhanced evaluation of inflammatory changes, complicating abscesses, and evaluation of other infra-abdominal and pelvic structures. CT features of acute appendicitis include: Appendix diameter >6 mm; appendiceal wall thickening and enhancement; an appendicolith; apical cecal thickening; periappendiceal or pericecal fat stranding; mesenteric lymphadenopathy; phlegmon or abscess (Figare 15). (37)



Meckel's diverticulum

Meckel's diverticulum occurs in 2% to 3% of the population and is the most common developmental anomaly of the GI tract. (38) The diverticulum occurs at the antimesenteric border of the distal ileum and is caused by incomplete obliteration of the omphalomesenteric duct. The diverticulum often contains ectopic gastric and pancreatic mucosa. Complications include peptic ulceration with hemorrhage, intestinal obstruction from diverticular inversion, diverticulitis, and intussusception.

Conventional radiographs may reveal calcified stones in a lamellated pattern in the lower right quadrant. Meckel's diverticulum is notoriously difficult to detect with fluoroscopy, and a barium study to evaluate for Meckel's diverticulum is usually performed only if clinical suspicion remains high after negative cross-sectional imaging.

Hemorrhage is the most frequent complication. Technetium-99m (Tc-99m) pertechnetate scintigraphy is the imaging study of choice when a child presents with GI bleeding and a Meckel's diverticulum is suspected. After IV administration of the radiotracer, ectopic gastric mucosa in the diverticulum will appear as a focus of increased activity usually within 30 minutes of injection (Figure 16). (39) Normal activity will occur concurrently in the stomach. In children, the sensitivity, specificity, and accuracy of Tc-99m pertechnetate scintigraphy is 85%, 95%, and 90%, respectively. (40,41) Causes of a false-positive scan include: Gastric or small intestine duplication, heterotopic gastric mucosa in an otherwise normal small intestine, and inflammatory bowel disease that causes intestinal hyperemia. (42) A false-negative scan will result if the diverticulum contains too few or no gastric mucosa.




The second most common complication is intestinal obstruction, but identifying a Meckel's diverticulum as the cause is often difficult preoperatively. The most useful radiographic-finding that suggests Meckel's diverticulum as the cause of obstruction is lamellated calcification in the right lower quadrant. (43) When the diverticulum causes obstruction, it is usually secondary to inversion that causes luminal obstruction or forms an intussusception lead point.

CT is a superb modality for diagnosing bowel obstruction, but identification of a Meckel's diverticulum is often difficult. A third presentation is right lower quadrant pain and fever mimicking appendicitis. The US findings of a tubular, hyperemic structure can mimic appendicitis; however, a Meckel's diverticulum will typically be larger, have more irregular mucosal layers, and have associated anomalous vessels (Figare 17). (44)


Gastrointestinal emergencies continue to be a frequent cause of morbidity in the pediatric population, and several diseases requiring surgical intervention can lead to mortality if not rapidly diagnosed and treated Radiologists are at the critical front line of diagnosis for surgical decision making and, in the case of intussusception, have a vital therapeutic role as well.


(1.) Torres AM, Ziegler MM. Malrotation of the intestine. World J Surg. 1993;17:326-331.

(2.) Buranasiri SI, Baum S, Nusbaum M, Tumen H. The angiographic diagnosis of mid-gut malrotation with volvulus in adults. Radiology 1973;109:555-556.

(3.) Zerin JM, DiPietro MA. Superior mesenteric vascular anatomy at US in patients with surgically proved malrotation of the midgut. Radiology 1992;183:693-694.

(4.) Smet MH, Marchal G, Ceulemans R, Eggermont E. The solitary hyperdynamic pulsating superior mesenteric artery: An additional dynamic sonographic feature of midgutvolvulus. Pediatr Radiol. 1991;21:156-157.

(5.) Chao HC, Kong MS, Chen JY, et al. Sonographic features related to volvulus in neonatal intestinal malrotation. J Ultrasound Med. 2000;19;371-376.

(6.) Pracros JP, Sann L, Genin G, et al. Ultrasound diagnosis of midgut volvulus: The "whirlpool" sign. Pediatr Radiol. 1992;22:18-20.

(7.) Sze RW, Guillerman RP, Krauter D, Evans AS. A possible new ancillary sign for diagnosing midgut volvulus: The truncated superior mesenteric artery. J Ultrasound Med. 2002;21:477-480.

(8.) Weinberger E, Winters WD, Liddell RM, et al. Sonographic diagnosis of intestinal malrotation in infants: Importance of the relative positions of the superior mesenteric vein and artery. AJR Am J Roentgenol. 1992;159:825-828. Erratum in: AJR Am J Roentgenol. 1997;169:1755.

(9.) Ein SH. Leading points in childhood intussusception. J Pediatr Surg. 1976;11:209-211.

(10.) Daneman A, Navarro O. Intussusception Part 1: A review of diagnostic approaches. Pediatr Radiol. 2003;33:79-85.

(11.) Ein SH, Stephens CA. Intussusception: 354 cases in 10 years. J Pediatr Surg. 1971;6:16-27.

(12.) Sargent MA, Babyn P, Alton DJ. Plain abdominal radiography in suspected intussusception: A reassessment. PediatrRadiol.1994;24:17-20.

(13.) Fiorella DJ, Donnelly LF. Frequency of right lower quadrant position of the sigmoid colon in infants and young children. Radiology.2001;219:91-94.

(14.) Pracros JP, Tran-Minh VA, Morin DFCH, et al. Acute intestinal intussusception in children: Contribution of ultrasonography (145 cases). Ann Radiol. 1987;30:525-530.

(15.) Verschelden P, Fliatraut D, Garel L, et al. Intussusception in children: Reliabiluy of US in diagnosis--A prospective study. Radiology.1992;184:741-744.

(16.) Wang G, Liu S. Enema reduction of intussusception by hydrostatic pressure under ultrasound guidance. A report of 377 cases. J Pediatr Surg. 1988;23:814-818.

(17.) Riebel TW, Nasir R, Weber K. US-guided hydrostatic reduction of intussusception in children. Radiology. 1993;188:513-516.

(18.) Swischuk LE, Hayden CK, Boulden T. Intussusception: Indications for ultrasonography and an explanation of the doughnut and pseudokidney signs. Pediatr Radiol.1985;15:388-391.

(19.) Del-Pozo G, Albillos JC, Tejedor D. Intussusception: US findings with pathologic correlation--The crescent-in-doughnut sign. Radiology.1996;199:688-692.

(20.) Shiels WE II, Kirks DR, Keller GL, et al. Colonic perforation by air and liquid enemas: Comparison study in young pigs. AJR Am J Roentgeno1.1993;160:931-935.

(21.) MeyerJ, Dangman B, Buonomo C, et al. Air and liquid contrast agents in the management of intussusception: A controlled, randomized trial. Radiology. 1993;188:507-511.

(22.) Poznanski AK. Why I still use barium for intussusception. Pediatr Radiol. 1995;25:92-93.

(23.) Shiels WE II, Maves CK, Hedlund GL, Kirks DR. Air enema for diagnosis and reduction of intussusception: Clinical experience and pressure correlates. Radiology. 1991;181:169-172.

(24.) Gorenstein A, Raucher A, Serour F, et al. Intussusception in children: Reduction with repeated, delayed airenema. Radiology 1998;206:721-724.

(25.) Friesen SR, Boley JO, Miller DR. The myenteric plexus of the pylorus: Rs early normal development and its changes in hypertrophic pyloric stenosis. Surgery. 1956;39:21-29.

(26.) JonaJ. Electron microscopic observation in infantile hypertrophic pyloric stenosis (IHPS). J Pediatr Surg. 1978;13:17-20.

(27.) Schechter R, Torfs CP, Bateson TF. The epidemiology of infantile hypertrophic pyloric stenosis. Paediatr Perinat Epidemiol. 1997;11:407-427.

(28.) Scharli A, Sieber WK, Kiesewetter WB. Hypertrophic pyloric stenosis at the Children's Hospital of Pittsburgh from 1912 to 1967. A critical review of current problems and complications. J Pediatr Surg. 1969;4:108-114.

(29.) Mitchell LE, Risch N. The genetics of infantile hypertrophic pyloric stenosis: A reanalysis. Am J Dis Child. 1993;147:1203-1211.

(30.) Letton RW Jr. Pyloric stenosis. Pediatr Ann. 2001; 30:745-750.

(31.) Haran PJ Jr, Darling DB, Sciammas F. The value of the double-track sign as a differentiating factor between pylorospasm and hypertrophic pyloric stenosis in infants. Radiology 1966;86:723-725.

(32.) Addiss DG, Shaffer N, Fowler BS, Tauxe RV. The epidemiology of appendicitis and appendectomy in the United States. Am J Epidemiol. 1990;132:910-925.

(33.) Reynolds SL, Jaffe DM. Diagnosing abdominal pain in a pediatric emergency department. Pediatr Emerg Care.1992;8:126-128.

(34.) Scholer SJ, Pituch K, Orr DP, Dittus RS. Clinical outcomes of children with acute abdominal pain. Pediatrics.1996;98:680-685.

(35.) Orr RK, Porter D, Hartman D. Ultrasonography to evaluate adults for appendicitis: Decision making based on meta-analysis and probabilistic reasoning. Acad Emerg Med.1995;2:644-650.

(36.) Sivit CJ, Siegel MJ, Applegate KE, Newman KD. When appendicitis is suspected in children. Radio-Graphics.2001;21:247-262.

(37.) Sivit CJ, Applegate KE, Stallion A, et al. Imaging evaluation of suspected appendicitis in a pediatric population: Effectiveness of sonography versus CT. AJR Am J Roentgenol. 2000;175:977-980.

(38.) Moore TC. Omphalomesenteric duct malformations. Semin Pediatr Surg. 1996;5:116-123.

(39.) Sty JR, Starshak RJ. The role of radionuclide studies in pediatric gastrointestinal disorders. Semin Nucl Med. 1982;12:156-172.

(40.) Cooney DR, Duszynski DO, Camboa E, et al. The abdominal technetium scan (a decade of experience). J PediatrSurg.1982;17:611-619.

(41.) Sfakianakis G N, Conway JJ. Detection of ectopic gastric mucosa in Meckel's diverticulum and in other aberrations by scintigraphy. 1. Indications and methods: A 10-yearexperience. J Nucl Med.1981;22:732-738.

(42.) Sty JR, Starshak RJ. The role of radionuclide studies in pediatric gastrointestinal disorders. Semin Nucl Med. 1982;12:156-172.

(43.) Pantongrag-Brown L, Levine MS, Buetow PC, et al. Meckel's enteroliths: Clinical, radiologic, and pathologic findings. AJR Am J Roentgenol. 1996;167:1447-1450.

(44.) Baldisserotto M, Maffazzoni DR, Dora MD. Sonographic findings of Meckel's diverticulitis in children. AJRAm J Roentgenol. 2003;180:425-428.

Mahesh Thapa, MD and Raymond W. Sze, MD

Dr. Thapa is a Radiology Resident, University of Washington Medical Center, and Dr. Sze is an Assistant Professor of Radiology, University of Washington Medical Center, and a Staff Radiologist, Children's Hospital & Regional Medical Center, Seattle, WA.
COPYRIGHT 2005 Anderson Publishing Ltd.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2005 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:Thapa, Mahesh; Sze, Raymond W.
Publication:Applied Radiology
Article Type:Clinical report
Geographic Code:1USA
Date:Apr 1, 2005
Previous Article:Imaging the obstructed bowel and other intestinal emergencies.
Next Article:Osteoporosis assessment.

Related Articles
Pediatric Gastrointestinal Disease: Pathophysiology, Diagnosis, Management, 4th ed; 2v. (CD-ROM included).
The Hospital for Sick Children handbook of pediatric emergency medicine.
GI disorders far more common in children with autism.
Antidepressant found to be just as effective as placebo in child pain relief.
Telehealth Ontario detection of gastrointestinal illness outbreaks.
Antidepressant found to be just as effective as placebo in child pain relief.
Kids with inflammatory bowel disease have high folate levels: Study.
Paediatric gastroenterology; an atlas of investigation and management.

Terms of use | Privacy policy | Copyright © 2018 Farlex, Inc. | Feedback | For webmasters