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286
8 Spleen and Pancreas
ab
c
Fig. 8.25 Simple ( a , b ) and complex ( c ) intraperitoneal ascites. ( a , c ) Sagittal section of lower
abdomen, empty bladder poorly distinguishable, the complex nature in ( c ) was due to haemor-
rhage (+ +). ( b ) Axial view through full urinary bladder demonstrating retrovesical free peritoneal
fl u i d
ab
Fig. 8.26 Peritoneal shunt with cyst. Cyst ( a ) around abdominal end of ventriculoperitoneal shunt
( b , arrow ) causing shunt dysfunction/obstruction
8.3 Retroperitoneum, Other Peritoneal and Retroperitoneal Structures
287
ab
cd
Fig. 8.27 Retroperitoneal masses. ( a ) Retroperitioneal lymph node metastasis/recurrence in a girl
after ovarian tumour at site of left ovarian vein junction with left renal vein. ( b ) Retroperitoneal
ganglioneuroma seen behind the bladder (axial section). ( c ) Neuroblastoma of left adrenal gland
region (actually originating from paravertebral plexus tissue) with invasion of the spinal neuroforamen, an obvious bridge of tissue to the neuroforamen (potentially entering the spinal canal) can be
seen in this slightly oblique axial section in the upper abdomen. ( d ) Retroperitoneal lymphatic
malformation in paremedian right upper abdomen (behind duodeneum and liver) with multiple
cysts, some of them exhibit echoes as sign of haemorrhage
8.3.7 Retroperitoneal Soft Tissues
8.3.7.1 Lymph Nodes
May be enlarged in infl ammatory (rare), but most commonly in malignant disease.
Sometimes diffi cult to visualise – actively search areas adjacent/in between abdom-
inal aorta and IVC, e.g. in patients with ovarian or testicular tumours (Fig. 8.27a ):
• Criteria resemble fi ndings in all other body compartments and in mesentery
(see above)
8.3.7.2 Retroperitoneal Tumours
A number of conditions exist: retroperitoneal fi brosis (Ormond’s disease – extremely
rare in childhood), neuroblastoma/ganglioneuroma, nerve sheath tumours, rhabdomyoma, teratoma, etc.
US fi ndings nonspecifi c and resemble aspects as described in principle locations
(see respective chapters) (Fig. 8.26b–d ):
• Sometimes meticulous US can help narrowing down DDx, e.g. spinal canal invasion in neuroblastoma, destruction/infi ltration of vertebral body in sarcomatous
tumours, ureteral obstruction in retroperitoneal fi brosis and continuity with nerve
routes in nerve sheath tumours/schwannoma/neurofi broma
288
8 Spleen and Pancreas
Fig. 8.28 Abdominal wall seroma after huge traumatic haematoma. Anechoic fl uid in the
abdominal wall with disrupted abdominal wall structures/muscles after trauma
ab
Fig. 8.29 Huge desmoid tumour of abdominal wall. ( a ) Split/dual image. ( b ) Extended fi eld of
view US
8.3.8 Abdominal Wall
Rarely focus of US in children.
Always use high-resolution linear transducers.
Imaging appearance same as in any other body area, US used as initial assessment
tool.
US Findings :
• Trauma: haematoma/seroma, muscle disruption – if large, dual image technique
or extended view US may improve documentation, demonstration and
measurements (Fig. 8.28 )
• Hernia and abdominal wall defects (postoperative, posttraumatic, etc.) – see above
• Hypotrophic or displaced muscles (e.g. rectus diastasis, missing rectus muscle
and diffuse a-/hypoplasia in prune belly syndrome)
• Vascular malformation of abdominal wall vessels, or extending from neighbouring areas
• Abdominal wall tumours – unspecifi c fi ndings:
– For example desmoids, neurofi broma, rhabdomyoma, lipoma and (neuro-)
fi broma (Fig. 8.29 )
US of the Gastrointestinal (GI) Tract
Michael Riccabona
Contents
9.1 Stomach ........................................................................................................................... 289
9.1.1 Requisites .......................................................................................................... 289
9.1.2 How to Investigate............................................................................................. 290
9.1.3 Normal Findings ............................................................................................... 291
9.1.4 Normal Variants ................................................................................................ 291
9.1.5 Malformations ................................................................................................... 292
9.1.6 Pathologic Findings ........................................................................................... 292
9.1.7 Role of US ......................................................................................................... 298
9.2 Bowel .............................................................................................................................. 298
9.2.1 Preparation and Requisites ................................................................................ 298
9.2.2 Course of Investigation ..................................................................................... 299
9.2.3 Normal US Findings ......................................................................................... 300
9.2.4 Pathology .......................................................................................................... 300
9.2.5 Acquired Obstructive Pathology ....................................................................... 306
9.2.6 Infl ammatory Conditions .................................................................................. 310
9
9.1 Stomach
9.1.1 Requisites
Indications
Mostly vomiting (non-bilious), part of other abdominal US.
Patient Preparation
Optimal initially fasted + feeding tea/formula during investigation.
M. Riccabona
Division of Pediatric Radiology, Department of Radiology,
University Hospital Graz, Auenbruggerplatz 34,
Graz 8036, Austria
e-mail: michael.riccabona@klinikum-graz.at
M. Riccabona, Pediatric Ultrasound,
DOI 10.1007/978-3-642-39156-9_9, © Springer Berlin Heidelberg 2014
289
290
9 US of the Gastrointestinal (GI) Tract
Positioning
• Commonly starts in supine position, positioning manoeuvres helpful (changing
to right/left/lateral decubitus).
• Sometimes posterior access may improve assessment, particularly of dorsal parts
or if gas impairs access.
Transducers
• Near fi eld (pylorus, ventral wall) – high-resolution linear (or curved array)
transducers.
• Deeper parts – curved linear arrays/sector transducers.
• Frequency depends on age and necessary penetration/depth.
9.1.2 How to Investigate
9.1.2.1 Access
Subxiphoid, median/upper left quadrant:
• For pylorus – upper right quadrant. Use left liver lobe as access.
• How to orient: try to localise either entrance or outlet in organo-axial section;
follow in organo-axial section before turning into longitudinal plane for outlet
(pylorus) or inlet (gastro-oesophageal junction).
• If fasted: assess residual volume (often best seen from transsplenic approach to
view greater curvature and posterior fundus).
Subsequently fi ll stomach with fl uid/formula – assess entire stomach including all
visible wall parts in two orthogonal planes:
• Assess peristalsis.
• Assess for refl ux or intermittent herniation towards thoracic space.
• Assess pylorus and its function (clearance of stomach contents into duodenal
bulb).
• Always observe paragastric area for potential changes (e.g. large veins at gastrooesophageal junction in portal hypertension with collaterals).
9.1.2.2 Functional Assessment of Bowel and Stomach
Observation and documentation of peristalsis (M-Mode, video clip).
Quantifi cation of stomach content using ellipsoid equations (correct factor varies
with shape from 0.5 in spherical shape to 1 in more rectangular shape):
• Intermittent volume assessment allows estimation of gastric clearance (e.g.
measurements every 15 min for 1–1.5 h, depending on fi lling and clearance
dynamics).
Observe clearance to duodenum, potential refl ux into oesophagus.
CDS can be useful for documenting (direction of) gastro-oesophageal refl ux,
patency of pylorus and duodeno-gastric refl ux (Fig. 9.1 ).
Remarks on oesophagus : visualised at cervical part (see US of the neck, Chap.
4 ), at median part, provided suffi cient mediastinal access (e.g. by large tumour); at
9.1 Stomach
Fig. 9.1 CDS for
documentation. CDS
demonstrates patency of
pyloric canal after feeding:
red coded infl ux of stomach
content into duodenum (note
colour map in left upper
corner of US image: red
encodes direction away from
transducer, thus from
stomach into duodenum).
Colour box angulated for
better Doppler angle
distal part, gastro-oesophageal junction (visible via paramedian left, slightly tilted
sagittal view), observe relation to aorta and diaphragmatic hiatus.
NOTE : Typical structure defi ned by serosa, muscle and mucosa, as well as content
and wall thickness.
291
9.1.3 Normal Findings
Collapsed distal oesophagus and gastro-oesophageal junction should not measure
more than 7 mm in infants.
Gastric wall has fi ve layers; wall thickness smaller than 3–4 mm, depending on
fi lling and age.
Inner mucosa and echogenic layer thin. Contour of inner mucosa and gastric
folds can be visualised, if stomach suffi ciently fi lled with anechoic fl uid.
US appearance of stomach contents varies depending on kind of food and amount
of air (Fig. 9.2a ).
Pylorus/gastric outlet usually shows only slight thickening of wall in relation to
stomach wall. In infants muscle thickness should measure <3 mm, length should be
<15 mm and diameter <10 mm (Fig. 9.2b ).
After feeding unhindered passage of stomach content into duodenum can be
observed (Fig. 9.2c ).
NOTE : In newborns wall thickness physiologically less; length of pyloric canal
shorter. Pyloric length only assessable if stomach suffi ciently fi lled.
9.1.4 Normal Variants
Not reliably assessable by US.
292
ab c
Fig. 9.2 Normal stomach and pylorus. ( a ) Fluid-fi lled stomach, adjacent spleen. ( b ) Normal pylo-
rus (+ +) while stomach empty. Wall narrow, though pylorus appears long. Wall layers, particularly
prominent echogenic mucosal inner layer, nicely appreciated. ( c ) Open normal pylorus after feed-
ing tea – unhindered passage of anechoic fl uid from stomach into duodenum
9 US of the Gastrointestinal (GI) Tract
9.1.5 Malformations
9.1.5.1 Microgastria
Small content, easier to visualise on fetal scans than postnatally.
9.1.5.2 Pyloric Atresia
Rare condition, usually diagnosed prenatally.
Diffi cult to differentiate from high-grade pyloric stenosis and gastric webs.
9.1.5.3 Congenital Hiatal Hernia
Variant from diaphragmatic hernia (see Chap. 6 ), can be depicted by US if large.
TIP : Fill stomach and observe dynamically.
9.1.6 Pathologic Findings
9.1.6.1 Gastro-Oesophageal Reflux (GOER)
Defi nition
Refl ux of stomach contents to oesophagus – small amounts of intermittent regurgitation physiologic in fi rst 3 months of life. To be distinguished from intermittent
regurgitation during swallowing which may be physiologic.
Grading :
• Mild, intermediate and severe (Table 9.1 ).
Criteria :
• Frequency, duration, dilatation of distal oesophagus and oesophageal clearance.
Provocation :
• Drinking (water siphon test), left decubitus position with slight pressure on
abdomen with transducer, similar to fl uoroscopy.
US Findings
Regurgitation of fl uid from stomach into oesophagus with variable widening of the
gastric inlet (Fig. 9.3a, b ). Details depend on kind of food, stomach and gastric wall
thickness + severity of GOER. Assess number and duration of refl ux episodes, grade
9.1 Stomach
Table 9.1 Grading of gastro-oesophageal refl ux (GOER) in infants
Grade
No refl ux Thin Prompt clearance into
Up to four refl ux
episodes
More than four
refl ux episodes
Numerous refl ux
episodes
Continuous refl ux Constantly open
US criteria of grading GOER in infants, based on correlation to pHmetry
Oesophagus Function
stomach, during swallowing
no refl ux after feeding
No dilatation Prompt clearance after
GOER
Mild dilatation Slightly delayed clearance
after GOER
Signifi cant dilatation Signifi cant delay Intermittent
gastro-oesophageal
junction
Yo-yo phenomenon of
stomach content to distal
oesophagus
Diagnosis
Normal
Physiological
GOER
Mild GOER
GOER
Severe GOER
/ hiatal hernia
293
of dilatation of distal oesophagus, oesophageal clearance and wall thickness.
Observe for potential intermittent herniation of gastric parts to thoracic cavity in
intermittent sliding hiatal hernia, particularly after fi lling stomach (Fig. 9.3c, d ).
Document GOER – best achieved by video clips or CDS (documents direction of
fl ow) using adapted settings.
NOTE : Use standard meal, avoid ingredients that cause or provoke GOER.
Role of US
• In infancy good correlation with pH monitoring and fl uoroscopy. The older the
child, the poorer US performs.
• Evaluation of oesophagus and its mucosa for secondary infl ammation not
possible.
NOTE : Reliability for assessment of sliding hernias and anatomic stomach anoma-
lies restricted.
Additional Imaging : pH monitoring for GOER (only useful in acid refl ux), oesopha-
geal manometry and fl uoroscopy (barium swallow).
9.1.6.2 Hypertrophic Pyloric Stenosis (HPS)
Defi nition
• HPS best diagnosed sonographically.
• Cramps with propulsive non-bilious vomiting. Typically occurs in boys aged
4–12 weeks.
• Treatment usually by surgery, though medical conservative treatment may be an
option in early and mild disease with high surgical risk.
DDx
Pyloric atresia, gastric web, pylorospasm and gastric outlet tumours.
US Findings :
• Enlargement of pylorus and particularly pylorus muscle consistently throughout
investigation. Length >15 mm, muscle >3 mm, axial diameter ≥12 mm and wall
lumen ratio >2:1 (Fig. 9.4a , b ).
• No or only minimal opening of pyloric canal (Fig. 9.4c ).
294
9 US of the Gastrointestinal (GI) Tract
ab
cd
Fig. 9.3 Gastro-oesophageal refl ux (GOER). ( a ) Parasagittal paramedian view in upper abdo-
men: GOER of air mixed stomach content into distal oesophagus without dilatation (+ +),
normal wall of hiatal structures. NOTE : Similar images seen during feeding (then normal
direction of food going into stomach/not inverse as in GOER). ( b ) Same section as in ( a ):
stomach fi lled with fl uid – regurgitation into slightly dilated distal oesophagus, normal wall of
hiatal structures. ( c ) Axial median section, upper abdomen, transducer tilted cranially:
(pseudo-)tumorous structure (+ +) with thick wall and inhomogeneous echoes at gastrooesophageal junction. ( d ) Same patient and same US section as in ( c ): after feeding tea
“tumour” fi lls with fl uid and air confi rming hiatal hernia with parts of stomach herniated into
chest
• Change in wall thickness from stomach to pylorus with typical shoulder-like
contour at pyloric entrance.
• Often displacement of pylorus, gastric enlargement with residual volume in
fasted children.
• Particularly after feeding, hyperperistalsis and secondary GOER.
• In late stages hypotonic enlarged stomach.
NOTE : In early stages an very young infants/preterm babies fi ndings may be subtle,
only functional observation + follow- up will establish diagnosis; sometimes diffi cult
to differentiate from pylorospasm (Fig. 9.4d ).
9.1 Stomach
295
a
c
Fig. 9.4 HPSt. ( a ) Longitudinal section through pylorus, right paramedian upper abdomen:
enlarged pylorus, thickened wall ( arrowheads ), enlarged diameter (+ +) and length (× ×) and nar-
row canal ( arrow ). ( b ) Axial section through pylorus, right paramedian upper abdomen: enlarged
pylorus appearing as a round pseudotumorous lesion ( arrow ) with a central target sign. Thickened
wall ( arrowheads ) enlarged diameter (+ +). ( c ) Longitudinal section through pylorus, right para-
median upper abdomen: elongated pylorus within thick wall and ”pyloric shoulder” appearance of
gastric outlet with heavy peristalsis. Narrow canal, only minimal fl uid in duodenal bulb. ( d )
Pylorospasm: longitudinal section through pylorus in right paramedian upper abdomen depicts
HPSt-like appearance, only beginning and end of pylorus intermittently open. Central spastic part
resolved after some time – then relatively normal passage into duodenum could observed
b
d
Follow-up under medical treatment:
• First no morphologic changes, but improvement of gastric clearance and content
passage to duodenum.
• Thickening and elongation may persist for several weeks (as also after surgery).
• Documentation of pyloric passage best by CDS and video clips.
Role of US
Main method for diagnosis, rarely in equivocal fi ndings fl uoroscopic UGI or MRI
for gastric tumours may become indicated.
9.1.6.3 Other Stomach Conditions
Gastritis/Ulcers
Not diagnosed by US, sometimes contour alterations can be seen in thickened stomach wall, provided suffi cient fi lling without overlying gas/air. More easily visible if
adjacent deep abscess.