Sonographic Appearances of Common Gut Pathology in ... · Although plain radiography of the abdomen...

The Radiographer – vol. 51: 11-17

Sonographic Appearances of Common Gut Pathologyin Paediatric Patients:

Comparison with Plain Abdominal Radiography

Lino Piotto and Roger Gent

Division of Medical ImagingWomen’s and Children’s Hospital72 King William RoadNorth AdelaideSouth Australia 5006Telephone: +61 8 8161 6639Fax: +61 8 8161 6969e-mail: [email protected]

The Radiographer – vol. 51, no. 1, April 2004 11

INTRODUCTIONFor a long time now ultrasound has been used as the first exam-ination for suspected hypertrophic pyloric stenosis. Yet there isstill a widespread notion that ultrasound does not have a majordiagnostic role in evaluating other gut pathology, a role tradi-tionally undertaken by plain x-rays.

The signs and symptoms of abdominal pathology are verynon-specific. These include colicky abdominal pain, vomiting,diarrhoea, palpable abdominal mass, focal or generalised ten-derness, blood and mucus per rectum and fever. Patients withabdominal pathology may present with one or more of thesesigns and symptoms, making a specific clinical diagnosis verydifficult.

By far the most common investigation for abdominal pain isthe plain radiograph. These are often unhelpful, being normal inas many as one third of cases (unpublished data over a two yearperiod from WCH). They may, however, show evidence of asoft tissue mass or small bowel obstruction. Both of these radi-ographic signs, although suggestive of the presence of intussus-ception or ileus, are non-specific.

Ultrasound is valuable in the further assessment of thesepatients, and also in patients whose plain films are normal.

The most common gut conditions encountered are appen-dicitis, intussusception and gastroenteritis. Less common condi-tions that can be diagnosed with ultrasound include mesentericlymphadenopathy, midgut malrotation (with or without an asso-

ciated volvulus) and Crohn’s disease. Rarely, conditions such asduplication cysts, haemolytic uraemic syndrome, HenochSchonlein Purpura, bezoars and malignancies are diagnosedfrom the ultrasound examination.

INTUSSUSCEPTION

Intussusception is one of the most common causes of abdominalemergency in early childhood.1,2,3 In this condition, a segment ofthe bowel wall invaginates the lumen of the segment immediate-ly distal to it. Intussusception occurs most commonly in the firsttwo years of life, but is occasionally seen in older children andadults, associated with other conditions such as cystic fibrosis. Itis thought that most cases arise as a result of hyperplasia ofPeyer’s patches, the lymphoid tissue of the intestinal wall. Theresultant swelling of the intestinal wall is pushed distally by peri-stalsis, dragging the wall of the bowel with it, together with itsattached mesentery. Compromise of venous drainage then resultsin marked oedema of the involved bowel wall. The commonestlocation is at the ileocaecal junction, where the ileum invaginatesthe large bowel – this is termed an ileo-colic intussusception.Most commonly, the “head” of the intussusception is found inthe ascending or transverse colon. In advanced cases however,the invagination can extend as far as the sigmoid colon, almostto the anus. The main clinical features are intermittent attacks ofcolic with drawing up of the legs and the passage of blood andmucus per rectum. These patients often appear very flat. Asausage shaped tumour may be palpable in the abdomen. Later,there may be vomiting due to intestinal obstruction.

A review of patients with confirmed ileo-colic intussuscep-tion at our institution showed the plain radiographs were normalin 33 per cent of cases. In 57 per cent of cases, a soft tissue masswas apparent, while 19 per cent showed features of small bowelobstruction. On ultrasound examination, all intussusceptions dis-play a “concentric ring” or “doughnut” sign, with marked oede-ma of the bowel wall. The diameter of the intussusception is typ-ically 2.5cm or more.

ABSTRACTEven with the advent of more specialised imaging modalities such as fluoroscopic contrast examinations, CT and MRI, the plainabdominal radiograph remains the initial imaging modality in investigating the signs and symptoms of suspected gut pathology.However, ultrasound is playing an increasing part in the detection of gut pathology in paediatric patients.

At our hospital, when plain abdominal radiography does not provide a diagnosis, ultrasound is commonly requested to ruleout conditions that require urgent attention, such as intussusception, appendicitis and midgut malrotation and volvulus. Afterthese conditions have been excluded however, the ultrasound examination can frequently lead to the diagnosis of several otherconditions, including gastroenteritis, Crohn’s disease, mesenteric lymphadenopathy and less commonly, duplication cysts, bezoas,and haemolytic uraemic syndrome.

Although plain radiography of the abdomen may be suggestive of gut pathology, the additional information provided bysonography often provides a specific diagnosis, leading to better patient care.

This paper is a presentation of ten case studies demonstrating the use of ultrasound to augment plain X-ray findings, in orderto obtain a final diagnosis.

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12 The Radiographer – vol. 51, no. 1, April 2004

SONOGRAPHIC APPEARANCES OF COMMON GUT PATHOLOGY IN PAEDIATRIC PATIENTS:COMPARISON WITH PLAIN ABDOMINAL RADIOGRAPHY

Case 1This six-month-old boy presented with intermittent vomiting. His supine abdominalradiograph showed a normal gas pattern throughout, with no evidence of a soft tissuemass (Figure 1a). Due to the clinical presentation of bilious vomiting, further investiga-tion with a barium meal was performed to exclude a proximal small bowel obstruction.The barium study was normal. The subsequent ultrasound examination showed a welldefined, rounded mass in the left iliac fossa (Figure 1b), with the concentric ring signconsistent with an ileo-colic intussusception. The intussusception was thought to be atthe junction of the descending and sigmoid colons, subsequently confirmed with a bari-um enema.

Case 2A two-and-a-half-year-old boy with intermittent colicky abdominal pain for two days,associated with non-bilious vomiting. Plain radiography showed a rounded soft tissuemass to the right of the midline, possibly representing an intussusception. The bowel gaspattern was non-specific, with no suggestion of obstruction (Figure 2a). The ultrasoundexamination confirmed the presence of an intussusception in the ascending colon, corre-sponding to the position of the soft tissue mass seen in the radiograph (Figure 2b).

Case 3This three-year-old boy presented with colicky abdominal pain and bilious vomiting.The abdominal radiograph demonstrated numerous fluid levels within moderately distended bowel loops, extending down to the pelvis. The appearances suggest a distal small bowel obstruction (Figure 3a). The ultrasound study revealed an ileo-colic intussusception in the transverse colon (Figure 3b) and confirmed the presence of multiple dilated fluid-filled loops of small bowel, consistent with obstruction. Amoderate amount of free fluid was also demonstrated in the peritoneal cavity. Several lymph nodes and some echogenic mesentery were visible within the intussus-ception.

Figure 3b (right): Transverse ultrasound image of the transverse colon, showingan ileo-colic intussusception. The invaginating ileum and its associated mesenteryare indicated by arrows, within the colon (arrow heads).

Figure 1a (far right):Normal supine abdominalradiograph in 6-month oldmale.Figure 1b (right):Transverse ultrasoundimage from the left iliacfossa, showing an intussus-ception, with arrow headsindicating the outer marginof the invaginated bowel.

Figure 2a (far right):Supine abdominal radiograph, showing a softtissue mass (arrow heads) tothe right of the midline.Figure 2b (right):Transverse ultrasoundimage over the soft tissue mass seen on theradiograph, showing anintussusception in theascending colon.

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L. PIOTTO AND R. GENT


Case 4Not all intussusceptions are ileo-colic. Transient ileo-ileal intussusception is a com-mon finding in abdominal sonography of paediatric patients, most often seen to theleft of the midline. These are rarely symptomatic and resolve spontaneously. Theydo not cause any significant vascular compromise and therefore do not result inoedema of the bowel wall. Occasionally, two or even three separate segments of ileo-ileal intussusception may be present simultaneously. The sonographic appearance ofan ileo-ileal intussusception is that of a localised expansion of a part of the ileum,

with a concentric ringsign (Figure 4) corre-sponding to the invagi-nation of the bowel. Thediameter of these isinvariably much lessthan that of an ileo-colicintussusception.

APPENDICITIS

Appendicitis is another common abdominal emergency in childhood, and the mostcommon condition requiring emergency surgery.4 It is thought that most cases resultfrom obstruction of the lumen of the appendix by faecal impaction or a faecolith,which then results in bacterial infection within the obstructed segment. In somecases, the appendix ruptures, resulting in a peri-appendiceal abscess easily demon-strable on ultrasound images. Clinically, patients with appendicitis have focal(rebound) tenderness over the appendix, with associated fever and leukocytosis. Aninflamed appendix typically has a diameter of 6mm or more, is non-compressible,blind ending, hyperaemic and may be fluid-filled. When present, an appendicolithappears as a focus of increased echogenicity, not necessarily casting an acousticshadow. The inflammatory reaction often results in increased echogenicity of theadjacent meso-appendix and omentum. It is also not uncommon to see a smallamount of free fluid adjacent to the caecal pole. An inflamed appendix is more dif-ficult to detect with ultrasound when in a retrocaecal position and when it is deepwithin the pelvis. Ultrasound is frequently useful when the clinical findings do notstrongly support appendicitis. This can occur when the appendix is in a relativelyhigh position, near the tip of the liver, or when there is negligible tenderness becausethe appendix is wrapped in a “cushion” of oedematous omentum. It is useful to ini-tially concentrate on the region of maximum tenderness.

Figure 3a (above): Supine abdominal radiograph, showing multiple distendedbowel loops.

Figure 4 (left):Transverse ultrasound imageof an ileo-ilealintussusception(arrow heads) inthe left flank of a3-year old child.

Case 5This 13-year-old boy presented with onset of severe right sided abdominalpain especially in the right flank. On his abdominal radiograph, apart from aprominent loop of small bowel in the right iliac fossa the radiographic appear-ances are non specific but raise the possibility of a localised ileus (Figure 5a).Suspicious of appendicitis, an ultrasound examination was performed whichrevealed a relatively long and swollen retrocaecal appendix (Figure 5b). Thethick walled appendix also demonstrated noncompressibility, rather causingindentation of the posterior psoas when pressure was applied from the trans-ducer (Figure 5c).Figure 5a (above): Supine abdominal radiograph suggestive of alocalised ileus in the right iliac fossa.Figure 5b (left): Longitudinal ultrasound image in the right iliac fossa,showing a distended and inflamed appendix (arrow heads), lying anterior to the psoas muscle.



Case 6A nine-year-old boy with a two week history of fever and right iliac fossa pain wasthought to have appendicitis. The A-P abdominal radiograph demonstrated a calcific den-sity projected over the right edge of the lower sacrum (Figure 6a), but which was pro-jected clear of the sacrum in the oblique view (Figure 6b). This was assumed to be anappendicolith. The A-P viewshowed a normal bowel gas pat-tern, with a mild scoliosis con-cave to the right. An ultrasoundexamination revealed a fluidcollection in the pelvis behindthe bladder, anterior to the rec-tum, and containing a smallechogenic structure, likely to bethe density visible on the radi-ographs (Figure 6c). The infect-ed nature of the collection isapparent from the reactive oede-ma of the adjacent posteriorbladder wall (Figure 6d). Moresuperiorly was an inflammatorymass of bowel that showedhyperaemia on power Dopplerimages. A separate appendixcould not be identified.

MALROTATION

Another condition that can pre-sent with these symptoms ismalrotation of the intestine,resulting from failure of the gutto undergo its normal 270º anti-clockwise rotation in the firsttrimester. Malrotation causesshortening of the root of the mesentery, predisposing the jejunum and ileum to twistaround the narrow base. The twisting is referred to as a volvulus (of the midgut),and is a surgical emergency. The signs and symptoms of malrotation include bilious vomiting, abdominal pain and failure to thrive.

Case 7A two-day-old (38 week gestation) twin, vomiting, with large stomach residue andabsence of bowel sounds was thought to have an intussusception. A supine radiograph revealed dilated bowel loops, most marked in the left upper quadrant.Bowel gas pattern in the right lower quadrant was normal, but showed some separation of the loops. In the clinical setting, meconium inspissation was thought


Figure 5c (left): Transverse ultrasound image of the inflamedappendix (arrow heads). With transducer pressure applied, theappendix is seen to be non-compressible as it indents the marginof the underlying psoas muscle (arrows).

Figure 6a (below right): Supine abdominal radiograph showing asuspected calculus (arrow head) projected over the right edge ofthe lower sacrum.

Figure 6b (below):Oblique pelvic radi-ograph demonstratingthe calculus (arrows).

Figure 6c (above left): Transverse ultrasoundimage showing a fluid collection (arrow heads)posterior to a distended bladder and contain-ing a calculus (arrow).

Figure 6d (above): Longitudinal ultrasoundimage showing an inflammatory mass ofbowel, superior to the hypoechoic collection,with localised thickening (arrow heads) of theposterior bladder wall. The calculus is againvisible within the inferior part of the collection.




to be a possibility (Figure 7a). An ultrasound examination showed no intussusception, butdid reveal reversal of the normal arrangement of the superior mesenteric vessels, with theSMV positioned on the patient’s left of the SMA (Figure 7b). This is indicative of amidgut malrotation. Further scanning revealed the ultrasonic “whirlpool” sign, pathogno-monic of a volvulus.5 The whirlpool sign is elicited by moving the transducer cranially andcaudally while scanning in the transverse plane. This movement demonstrates a corkscrewarrangement of the mesenteric vessels which simulates a whirlpool as the transducer ismoved back and forth. A barium meal con-firmed the ultrasonic diagnosis of midgutmalrotation with associated volvulus.

Figure 7a (far right): Supine abdomi-nal radiograph showing some dilatedbowel loops in the left upper quadrant.

Figure 7b (right): Transverse ultra-sound image in the mid abdomenshowing reversal of the normal superi-or mesenteric artery/vein relationship.The artery (long arrow) is seen to lie tothe patient’s left of the vein (shortarrow), anterior to the abdominalaorta (arrow heads).

GASTROENTERITIS

Patients with gastroenteritis, of viral or bacterial origin, maypresent with abdominal pain, bilious vomiting and diarrhoea.Ultrasound is not normally used to diagnose gastroenteritis.However, findings consistent with this condition are often foundwhen the examination is being done to exclude the conditionsthat require intervention. Features of gastroenteritis on ultra-sound images include multiple fluid-filled small bowel loops,often with slightly thickened walls and hyperperistalsis.Frequently, a fluid-distended colon is also apparent.

Case 8An 18-month-old girl presented with severe attacks of colic,thought to be due to intussusception. The erect abdominal radi-ograph demonstrated several air-fluid levels in the right iliacfossa, possibly representing a localised ileus due to an inflam-matory process (Figure 8a). An abdominal ultrasound con-

firmed the pres-ence of multiplefluid-filled loopsof small bowel(Figure 8b),together with adistended andfluid-filled colon.In the absence ofany other findings,these features areconsistent with adiagnosis of gas-troenteritis

CROHN’S DISEASE

Crohn’s Disease is the most common inflammatory disease ofthe bowel, usually affecting the terminal ileum and proximalcolon. Clinically, Crohn’s disease affects children over the ageof ten years, who may present with abdominal pain, diarrhoea,fever and weight loss. The disease appears as symmetricallythickened (greater than 5mm), hypoechoic, hypoperistalticbowel wall.6 Inflammatory bowel masses may also be seen in children with this condition, resulting in the formation offistulae.

Case 9A 14-year-old boy with abdominal pain for a two week period.Plain radiography showed multiple prominent loops of smallbowel that do not appear particularly dilated, but do demon-strate thickened mucosal folds. (Figure 9a). An ultrasoundexamination demonstrated thickened loops of bowel in both

Figure 8a: Erectabdominal radi-ograph showingseveral air-fluidlevels.

Figure 8b: Longitudinal image of the right flank showingmultiple fluid-filled loops of small bowel, consistent withgastroenteritis.




iliac fossae, corresponding to areas of ileal wall thickening, sub-sequently proven to be due to Crohn’s disease (Figure 9b).

MESENTERIC ADENITIS

Mesenteric lymph node enlargement is commonly seen inpatients presenting with acute abdominal pain. The enlargednodes are most commonly identified in the root of the mesenteryand are thought to represent a non-specific finding.7 This appear-ance is commonly called mesenteric adenitis. This is essentiallya benign condition, although it should be noted that nodeenlargement can also occur in response to a local inflammatorycondition such as appendicitis or neoplastic infiltration.

Case 10A one-year-old boy presented with episodes of grunting and

screaming, possi-bly due to intus-susception. Therewas a normal gaspattern throughoutsmall and largebowel on the plainradiograph. Noabnormal loops orsoft tissue masseswere evident. Theprominent gas-filled stomach isnon-specific andprobably repre-sents swallowedair from crying

(Figure 10a). Ultrasound examination showed no evidence of anintussusception, but did show several enlarged lymph nodes onthe right side, the largest measuring 15mm in length (Figure10b). In the absence of other findings, the appearances are like-ly to represent mesenteric adenitis.

CONCLUSIONUltrasound is very valuable in the investigation of paediatricpatients with acute abdominal pain. With a careful scanning tech-nique, ultrasound can quite often detect a range of gut pathology.Importantly, ultrasound has been very useful in the detection ofthose conditions that require urgent intervention such as intus-susception, appendicitis and malrotation with volvulus. In ourhospital, all cases of suspected intussusception have an ultra-sound study before any treatment is instituted. In the event thatthe ultrasound examination does not reveal one of these condi-tions, it often provides an alternative diagnosis, which can then

Figure 9a: Supine abdominal radi-ograph showing small bowel loops withthickened mucosal folds.Figure 9b: Transverse image of a loop ofileum, which has a thickened wall (out-lined by arrow heads) due to Crohn’sdisease.

Figure 10a:Normal supineabdominal radiograph.

Figure 10b: Transverse ultrasound image from the midabdomen, showing prominent lymph nodes (arrowheads).




allow appropriate treatment. These examinations sometimesrequire considerable time and patience, particularly if the child isuncooperative or in pain. Analgesia prior to the ultrasound exam-ination is very advantageous.

REFERENCES1. Lim, H.K., Bae, S.H., Seo, G.S., Yoon, G.S. Assessment of

reducibility of ileocolic intussusception in children: useful-ness of color doppler sonography. Radiology 1994; 191:781-785.

2. Woo, S.K., Kim ,J.S., Paik, T.W., Choi, S.O. Childhoodintussusception: US-guided hydrostatic reduction.Radiology 1992; 182:77-80.

3. Shiels, W.E. Editorial Childhood Intussusception:Management Perspectives in 1995. J Pediatr GastroenterolNutr 1995; 21:15-17.

4. Siegel, M.J. 2002, Pediatric Sonography, LippincottWilliams & Wilkins, Philadelphia, USA.

5. Pracros, J.P., Sann, L., Genin, G. et al. Ultrasound diagnosisof midgut volvulus: the “whirlpool” sign. Pediatr Radiol1992; 22:18-20.

6. Siegel, M.J., Friedland, J.A., Hildebolt, C.F. Bowel WallThickening in Children: Differentiation with US. Radiology1997; 203:631-635.

7. Sivit, C.J., Newman, K.D., Chandra, R.S. Visualization ofenlarged mesenteric lymph nodes at US examination.Pediatr Radiol 1993; 23:471-475.

Peer ReviewedSubmitted: October 2003Accepted: February 2004


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