2. Acute appendicitis
2.1. Prevalence and clinical implication
Acute appendicitis is the most common surgical disease in Western countries, with
a lifetime prevalence of 7 – 8 % [3]
[4]. In 1986, Puylaert introduced graded compression ultrasound in the workup of suspected
appendicitis [5]. Beside clinical examination and laboratory findings, imaging has become the third
component in the assessment of patients with suspected appendicitis [6]
[7]. The three main goals of the ultrasound examination are:
-
Exclusion of an alternative abdominal disease.
-
Confirmation of typical appendicitis or
-
Ruling out of acute appendicitis, by proving a normal appendix over its entire length.
The routine use of ultrasound in suspected appendicitis halves the rate of negative
appendectomies and reduces surgical complications and costs [6]
[8]
[9]
[10].
Recent studies evaluated antibiotic therapy as a possible alternative in selected
cases of uncomplicated appendicitis. For this, appendicitis must be verified by imaging
and complicated versus uncomplicated appendicitis should be distinguished [11]
[12]
[13].
The use of ultrasound imaging should be a routine procedure in every patient with
suspected appendicitis.
Consensus levels of agreement: A+ 16/18; A– 2/18
Routine sonography in all patients with suspected appendicitis halves the rate of
unnecessary surgery (negative laparotomy rate).
Consensus levels of agreement: A+ 14/18; A– 4/18
2.2. Examination technique
One way to detect an inflamed appendix is a simple search at the point of maximum
tenderness [5]. An alternative way involves systematic localization of the ascending colon, the
cecal pole, the terminal ileum and the origin of the appendix, 2 – 3 cm below the
medial contour of the cecum [14]
[15]. Examination is performed using the graded compression technique first described
by Puylaert [5]. Gentle compression eliminates disturbing gas and reduces the distance to the pathologic
process. Additions to this technique have been described, for example a left oblique
body position in obese patients or an upward graded compression technique in children
[16]
[17]
[18]
[19]. Ultrasound experience plays a role in the visualization of the appendix. Practical
training in normal and pathological conditions is mandatory to enable adequate appendix
evaluation.
The graded compression technique should be used for visualization of the appendix.
Consensus levels of agreement: A+ 18/18
Anatomical variations require a systematic examination technique for identification
of the appendix.
Consensus levels of agreement: A+ 17/18; A– 1/18
2.3. Sonography of uncomplicated appendicitis
Previously, acute appendicitis was diagnosed when a thickened vermiform appendix could
be visualized at the point of maximum tenderness [5]. However, increasing experience and technical improvements have made it possible
to demonstrate a normal appendix in more than half of adults and more than 70 % of
children [20]
[21]
[22]. Beside maximum diameter, several additional criteria that help to distinguish between
an inflamed and a normal appendix have been established. These criteria are the same
for children and adults [23].
Primary signs of acute appendicitis
-
Maximum outer diameter of more than 6 mm [14]
[17]
[24]
[25]
[26]
[27]
[28]
[29]
[30]. A diameter between 6 – 8 mm indicates an equivocal zone of uncertainty [27]
[31]
[32].
-
Maximal tenderness over the thickened appendix [5]
[15]
[29]
[33]
[34].
-
Incompressibility of the inflamed appendix [14]
[17]
[24]
[25]
[28]
[29]
[30]
[35].
-
(Large) appendicoliths [14]
[25]
[26]
[28]
[29]
[36].
-
Hypervascularity in color Doppler in uncomplicated cases [14]
[29]
[37]
[38].
-
Loss of stratification in gangrenous appendicitis [25]
[29]
[30]
[36].
Secondary signs of acute appendicitis (in the surroundings)
-
Hyperechoic periappendiceal tissue [14]
[15]
[17]
[24]
[25]
[29]
[30]
[34]
[39].
-
Complex fluid collection (pericecal abscess) [14]
[15]
[17]
[25]
[29]
[39].
-
Mesenteric lymphadenopathy [14]
[15]
[25]
[40]
[41].
-
Periappendiceal fluid [14]
[15]
[25].
2.4. Sonography of complicated appendicitis
Complicated appendicitis includes gangrenous appendicitis (focal or complete necrosis
of the wall) as well as perforation (inducing abscess, regional peritonitis and general
peritonitis). Confirmation of these complications has consequences for treatment and
usually rules out conservative treatment [13]
[42]
[43]. There is a continuous transition from severe uncomplicated (phlegmonous) to gangrenous
appendicitis.
The loss of the normally echogenic submucosal layer seems to be the best independent
indicator of gangrenous appendicitis [11]. Other indicators of necrosis may be the lack of vascularization on color Doppler
or an appendiceal wall enhancement defect, but these have not been sufficiently investigated
[44]
[45].
Signs of (sealed) perforation are extraluminal gas, localized collections of periappendiceal
fluid, extraluminal appendicoliths and abscess [14]
[15]
[24]
[25]
[39].
To distinguish non-complicated from complicated appendicitis, scoring systems based
on clinical and imaging features have been suggested [13]
[44]
[45]
[46]. However, they must still be confirmed in larger studies. Other features like intraluminal
appendicoliths do not implicate complicated appendicitis, but are associated with
perforation and recurrence under antibiotic therapy [42]
[47]
[48].
2.5. Value of the various sonographic criteria
In routine clinical examination, only the combination of as many different criteria
as possible guarantees the best results in the validation or ruling out of acute appendicitis
[14]
[15]
[24]
[25]
[29]
[30]
[33]
[34]
[39]. The three most important criteria in the confirmation of acute appendicitis are:
-
max. diameter of appendix > 6 mm
-
maximum pain over the appendix
-
hyperechoic periappendiceal tissue
Free fluid, mesenteric lymphadenopathy and vascularity of the appendiceal wall on
color Doppler are nonspecific signs and can be found in many other situations [14]
[15]
[25]. Definite exclusion of appendicitis requires visualization of the normal appendix
in its entire length [29].
A thickened appendix at the point of maximum tenderness and hyperechoic periappendiceal
tissue are the most important signs of appendicitis.
Consensus levels of agreement: A+ 15/17; A– 2/17
2.6. False-negative results
Non-visualization of the appendix is a problem and does not rule out acute appendicitis.
The most important reason for false-negative results is inexperience in GIUS and the
examination technique. In this case, an intensive search for indirect signs of appendicitis
should be performed as a first step [49]
[50]
[51].
However, some situations are challenging even for experienced investigators: in particular
when the appendix has a retrocecal or pelvic position or in very obese patients [33]
[52]
[53]
[54]. In these cases, adequate compression, scanning in a left lateral decubitus position
of the patient and use of a convex probe may be essential to visualize the appendix
[17]
[52]
[53]. Focal appendicitis confined to the tip has a frequency of about 5 % and is another
factor in misdiagnosis [25]
[37]. Therefore, demonstration of the entire length of the appendix is important [15]
[25]
[37].
Gas in the appendiceal wall in cases of gangrenous appendicitis may be misinterpreted
as a gas-containing bowel loop [15]
[55]. A perforated and completely destructed appendix in an abscess is another rare cause
of a false-negative result.
Adequate training is a precondition for sonographic diagnosis of acute appendicitis.
Consensus levels of agreement: A+ 18/18
Atypical positions of the appendix are the most frequent cause of false-negative results.
Consensus levels of agreement: A+ 12/18; A– 4/18; I 2/18
2.7. False-positive results
Soon after introducing ultrasound as a preoperative tool, cases of “spontaneously
resolving appendicitis” were observed [56]
[57]. Recent research confirms mild forms of appendicitis, which resolve spontaneously
or under antibiotic therapy [4]
[58]
[59]. Strictly speaking they are not false-positive, but rather mild courses that probably
would not require surgery.
Several other pitfalls can lead to a false-positive US diagnosis of acute appendicitis:
-
Incorrect classification of the terminal ileum as an inflamed appendix [15]
[60]
[61]
[62]
[63]
[64].
-
Other tubular structures in the right lower abdomen simulating an inflamed appendix:
-
e. g. Meckel’s diverticulitis
-
right-sided colonic diverticulitis
-
dilated Fallopian tube
-
gonadal vein thrombosis
-
muscle fibers of psoas [15]
[61]
[62]
[64]
-
Appendiceal thickening can also be produced by other conditions [65]
[66]
[67]
[68]
[69]
[70]
[71]:
Systematic search for signs that suggest differential diagnoses of appendicitis should
be implemented.
Consensus levels of agreement: A+ 17/18; A– 1/18
2.8. Comparison of US with others imaging methods
The diagnostic accuracy of high-end ultrasound in suspected appendicitis has clearly
improved over the last decades. Meanwhile the sensitivity, specificity, and accuracy
of ultrasound have reached values above 90 % and are equivalent to CT or MRI [72]
[73]
[74]
[75]
[76]
[77]
[78].
However, ultrasound is a highly operator-dependent tool, and its sensitivity fluctuates
greatly in the case of inexperienced operators or inadequate equipment. Institutions
using US regularly have a higher sensitivity, and the sensitivity increases with an
increased rate of visualization of the appendix [79]
[80]
[81]. In addition, patient characteristics (e. g. obesity) may influence the sensitivity
of US [82].
Point-of-care ultrasonography (POCUS) is increasingly performed by emergency physicians
to diagnose acute appendicitis and is available around the clock. If adequate equipment
and training are provided, the results will reach accuracy nearly equal to that of
ultrasound performed by radiologists, gastroenterologists and pediatricians [83]
[84]
[85]
[86].
Ultrasound for suspected appendicitis may be challenging among pregnant women: if
the appendix can be visualized, the specificity of US is good. In equivocal cases,
MRI has a higher sensitivity and is considered the method of choice in pregnant women
[85]
[87].
In the hands of well-trained operators and with adequate equipment, the sensitivity
and specificity of ultrasound in acute appendicitis are similar to CT and MRI.
Consensus levels of agreement: A+ 15/18; A– 2/18; I 1/18
2.9. Diagnostic strategy
Preoperative imaging has become routine in the workup of suspected appendicitis for
both medical and legal reasons. Ultrasound is available in almost every emergency
department as a point-of-care procedure 24/7 hours without delay. It is cheap, noninvasive
and without ionizing radiation [88].
Based on this data, an “ultrasound first and always” strategy has proved to be reasonable
in both children and adults [89]
[90]
[91]
[92]
[93]. Primary ultrasound supports the ALARA principle (radiation as low as reasonably
achievable), thereby avoiding radiation exposure, especially in children and women
of childbearing age [94]
[95]. Consistent use of ultrasound in right lower quadrant pain can reduce the need for
additional CT or MRI imaging to a small fraction [76]
[96]
[97]
[98]
[99]. Cases of inconclusive ultrasonography should lead to clinical reassessment. A second
ultrasound after an observation period [100]
[101] or a complementary MRI or CT examination should be considered.
Diagnostic scoring systems are recommended in some guidelines as a part of a diagnostic
algorithm for suspected appendicitis [87]
[102]. There are several competing scores [e. g. the Alvarado Score, Pediatric Appendicitis
Score (PAS), and Appendicitis Inflammatory Response score (AIR)] but these do not
always perform satisfactorily. Even the cut-off values are not clear. Scores may be
used for roughly estimating the likelihood, but not for proving appendicitis [103]
[104]
[105]. In accordance with the Dutch guidelines [92], we recommend routine use of ultrasound in all cases of suspected appendicitis and
do not consider the use of scoring groups obligatory ([Table 1]).
Table 1
Based on clinical assessment, laboratory results, and possibly scoring results, three
scenarios are common in the daily routine.
|
risk of appendicitis
|
Alvarado or AIR points
|
impact of sonography
|
|
low
|
0 – 4
|
visualization of the normal appendix in its full length definitively rules out appendicitis
|
|
complete ultrasound is helpful in finding an alternative diagnosis
|
|
intermediate
|
5 – 8
|
validation of an inflamed appendix confirms the need for surgery
|
|
if the diagnosis remains unclear, complementary CT, MRI or serial ultrasound performed
by an experienced operator may be helpful
|
|
high
|
> 8
|
confirmation of acute appendicitis
|
|
diagnosis of complications, e. g. abscess
|
In any case of suspected appendicitis, an “ultrasound first” strategy should be used
in both children and adults.
Consensus levels of agreement: A+ 18/18
Complementary CT or MRI should be limited to inconclusive findings and difficult conditions,
e. g. in very obese patients or in pregnant women (MRI).
Consensus levels of agreement: A+ 14/18; A– 3/18; I 2/18; D– 1/18
2.10. Education and quality management
In more cases than in other imaging modalities, GIUS depends on individual skills
and adequate ultrasound equipment. So-called “non-diagnostic ultrasound” represents
a problem especially among less experienced operators. Non-diagnostic ultrasound is
caused either by borderline results (e. g. borderline thickening of the appendix to
7 mm) or if the appendix could not be visualized. Non-visualization should be minimized
by training and ultrasound experience [106]
[107]. If the appendix cannot be visualized, the report should include information as
to whether secondary findings in the right lower abdomen were present or not [108].
Visualization of the appendix and especially the search for secondary sonographic
features can be taught even to less experienced investigators [83]
[109]
[110]
[111]
[112]. A structured training program, the use of standardized ultrasound reporting templates
and regular feedback enhance the accuracy of ultrasound and dramatically reduce the
number of non-diagnostic ultrasound scans [8]
[77]
[108]
[113]
[114]
[115]
[116]
[117]
[118]. In this way, the use of CT for patients with an equivocal ultrasound result, costs
and admission for observation can be reduced [114].
Structured training programs, quality controls and the use of standardized ultrasound
reporting templates should be integrated in the training of emergency physicians for
point-of-care ultrasound (POCUS) in appendicitis.
Consensus levels of agreement: A+ 17/18; D+ 1/18
3. Acute diverticulitis
3.1. Prevalence and clinical spectrum of acute diverticulitis
Colonic diverticula are a common condition, especially in elderly people in Western
populations. Complications such as diverticulitis and diverticular bleeding are a
frequent cause of hospital admission [119]. Acute diverticulitis occurs in approximately 5 % of people with diverticula, sometimes
in recurrent episodes [120]
[121]. The incidence of acute diverticulitis seems to have increased during the last years,
especially in young and obese subjects [119].
For many years the diagnosis of acute diverticulitis was made clinically, by the triad
of left-sided abdominal pain, fever and laboratory markers of inflammation. However,
systematic evaluation revealed a high rate of incorrect diagnosis [122]
[123], and additional imaging was recommended in cases of suspected diverticulitis [124]
[125]
[126]
[127]
[128]. Furthermore, imaging procedures enable us to differentiate uncomplicated from complicated
diverticulitis. Roughly, 15 % of patients have complicated disease, defined as an
abscess, perforation, fistula, or stenosis [124].
Ultrasound imaging should be a routine procedure in all patients with suspected diverticulitis.
Consensus levels of agreement: A+ 17/18; I 1/18
Sonography can confirm the diagnosis of acute diverticulitis and allows early risk
stratification.
Consensus levels of agreement: A+ 16/18; A– 1/18; I 1/18
3.2. Examination technique
The scanning techniques for evaluating the colon are described in detail in part 1
of the EFSUMB recommendations for GIUS [1] and in the WFUMB position papers [117]
[118]. The graded compression technique is used as described in appendicitis. The easiest
way to start your search is at the point of maximum tenderness pointed out by the
patient [129]
[130]. Alternatively, the sigmoid colon could be localized ventral to the left iliac artery
in a cross section and from there be tracked distally and orally to the descending
colon. Particularly, for the lower sigmoid, a moderately filled urinary bladder may
be beneficial.
3.3. Classification of acute diverticulitis
Various classifications of acute and chronic diverticulitis have been published and
modified during the last 55 years [128]
[131]. The first of these classifications was based on clinical and surgical findings
[132]. In 1978, Hinchey’s original classification [133] divided complicated diverticulitis into four stages (from local abscess to generalized
fecal peritonitis). Hinchey’s classification was refined and amended several times
and, until today, in various modifications, it remains the basis of most classifications.
Most of the current classifications are based on CT findings [134], but, to this day, not even the use of intravenous or rectal contrast agents is
standardized. Ultrasound as a “point-of-care” method that is available in almost every
emergency department proved to be able to confirm and classify acute diverticulitis
as well [130]
[135]
[136].
In 2014, the German Society of Gastroenterology (DGVS) and the Society of Visceral
Surgery (DGAV) agreed on another classification as part of the new German S2k guidelines:
Classification of Diverticular Disease (CDD) [125]. This classification is not linked to a specific diagnostic preference, such as
CT versus ultrasonography [137]
[138]. However, all guidelines distinguish between uncomplicated and complicated diverticulitis.
Complications are generally defined as abscess, perforation, fistula or stenosis [128] ([Table 2]).
Table 2
Classification of Diverticular Disease (CDD) 2014.
|
type 0
|
asymptomatic diverticulosis
|
|
type 1
|
acute uncomplicated diverticulitis
|
|
type 2
|
acute complicated diverticulitis
-
2a Microabscess (< 1 cm)
-
2b Macroabscess
-
2c Free perforation
|
|
type 3
|
chronic diverticular disease
|
|
type 4
|
diverticular bleeding
|
3.4. Sonography in uncomplicated diverticulitis
Uninflamed colonic diverticula can be detected as outpouchings of the colonic wall,
often containing gaseous feces or fecaliths, sometimes associated with acoustic shadowing
[136]
[139]
[140]. Particularly, sigmoid colon diverticulosis may be associated with slight thickening
of the muscularis propria (the outer hypoechoic layer), caused by a hypertrophied
circular smooth muscle.
The following three criteria allow the sonographic diagnosis of acute diverticulitis
[130]
[136]
[139]
[141]:
-
Short segmental colonic wall thickening (> 5 mm).
-
Demonstration of the inflamed diverticulum in the wall-thickened area (in contrast
to normal diverticula, they are often hypoechoic and are surrounded by hyperechoic
fatty tissue).
-
Pericolic tissue changes (non-compressible, hyperechoic).
All three signs correlate very well with the point of maximum tenderness and can be
evoked by the graded compression, with the ultrasound transducer (dynamic examination).
These criteria have been confirmed by prospective studies and two meta-analyses, providing
high diagnostic accuracy, with a sensitivity and positive predictive value above 90 %
[7]
[135]
[142]
[143]
[144]
[145]. The diagnostic accuracy remains slightly inferior to that of CT scan, particularly
in obese patients and in deeply seated lesions in the pelvis. In contrast to the United
States, sonography is used as the first-line imaging modality in some European countries
and most developing countries [125]
[137]
[146]
[147]
[148]
[149]. A step-up strategy with US as the first-line method followed by CT whenever US
is inconclusive or unreliable seems to represent the most effective approach [150].
GIUS accurately assesses acute diverticulitis by detecting short segmental colonic
wall thickening (> 5 mm), an inflamed diverticulum and pericolic tissue changes.
Consensus levels of agreement: A+ 15/17; A– 2/17
GIUS should be the first-line diagnostic procedure followed by additional CT scan
only in the case of inconclusive sonographic findings.
Consensus levels of agreement: A+ 13/18; A– 2/18; D– 2/18; D+ 1/18
3.5. Sonography in complicated diverticulitis
In cases of severe diverticulitis, greater thickening of the colonic wall and increasing
paracolic tissue changes can be found. The typical complications of acute diverticulitis
include abscess formation, fistulas, perforation and stenosis (CDD type 2).
The US morphology of diverticular abscesses varies widely: they usually appear as
hypoechoic fluid collections, sometimes containing echogenic debris and gas bubbles.
Hyperechoic, gas-containing abscesses are sometimes difficult to differentiate from
bowel loops [151]. In unclear cases with a suspected abscess deep in the pelvis or a gas-containing
abscess, additional CT should be performed.
Contrast-enhanced ultrasound (CEUS) is an accurate method for differentiating between
intra-abdominal phlegmon and abscess, which both may manifest as hypoechoic masses
[152]. CEUS may help to better define the size of the fluid collections and guide sonographic
intervention.
Fistulas may present as hypoechoic bands with or without central gas bubbles. Fistulas
can involve an adjacent bowel loop, the bladder, or the uterus [140]. Gas in the urinary bladder is an indirect sign of a sigmoid-vesical fistula.
The typical signs of perforation are gas bubbles outside the bowel loops. Contained
perforations, fistulas and abscesses are characterized by air bubbles in the mesenterium
or in an echo-poor fluid collection. Free peritoneal air or air bubbles in the retroperitoneal
space, indicate free or retroperitoneal perforation [137]
[153].
CEUS can be used in cases of acute diverticulitis to differentiate between periintestinal
phlegmon and abscess.
Consensus levels of agreement: A+ 18/18
3.6. Unusual locations of diverticulitis
Right-sided diverticulitis tends to occur in younger patients and is more frequent
in the Far East. The sonographic signs are identical to those of left-sided diverticulitis
and ultrasound usually allows differentiation from acute appendicitis [40]
[154].
The lower sigmoid colon may be difficult to assess by transabdominal ultrasound and
represents a blind spot of GIUS. Especially if the bladder is empty, lower diverticulitis
in the deep pelvic region cannot be ruled out by ultrasound. As an alternative to
CT or MRI imaging, additional transvaginal or transrectal ultrasound can be used [155]
[156] but its use is not widespread.
3.7. The role of US in the treatment of diverticular abscesses
GIUS is a versatile tool for diagnosing paracolic abscesses in complicated diverticulitis.
In some special cases, such as distant mesenteric or deep pelvic abscesses, CT has
definite advantages for detection. For estimation of the real extension, CEUS may
be helpful before intervention [152]
[157]
[158]
[159]. Microabscesses (CDD 2a) and other small abscesses (up to 3 cm) can be treated successfully
with antibiotics alone [125]
[146]
[149]
[160]
[161]
[162]. For large abscesses (> 3 cm) percutaneous drainage combined with antibiotics is
the first choice and can significantly reduce the risk of death compared to patients
undergoing acute surgery [160]. In borderline abscess, single puncture (or repeated puncture) with aspiration may
be sufficient, while drainage with small catheters (7 – 10 Ch) is more effective in
larger abscesses [163]
[164]
[165]. Percutaneous drainage can be performed with ultrasound or CT guidance. If visible
by sonography and technically feasible, ultrasound guidance allows real-time control
of the puncture [158]. Drains are flushed several times daily and may be removed after imaging control
when purulent production has ceased [149]. Injecting an ultrasound contrast agent (SonoVue, some drops diluted in saline)
into the cavity through a needle or catheter can prove communication with the bowel
lumen or display complex abscess systems [159]
[166].
Ultrasound-guided puncture/drainage is the first-line option in the therapy of abscesses
larger than 3 cm.
Consensus levels of agreement: A+ 13/17; A– 3/17; D– 1/17
Drainage of diverticular abscesses using the trocar technique (single step) is easy
to perform and is usually successful.
Consensus levels of agreement: A+ 16/17; A– 1/17
CEUS before intervention may be helpful to demonstrate the real extension of the abscess.
Consensus levels of agreement: A+ 14/18; A– 1/18; I 2/18; D– 1/18
3.8. Comparison of GIUS with other imaging methods
Overall, there are a limited number of published studies reporting the direct comparison
of different imaging procedures, considering the large number of affected patients.
Two systematic reviews and meta-analyses demonstrated a similar accuracy of CT and
ultrasound for the diagnosis of acute diverticulitis [142]
[144] ([Table 3]).
Table 3
Comparison between GIUS, CT and MRI in two metanalyses [142]
[144].
|
method
|
summary sensitivity
|
summary specificity
|
metanalysis
|
|
US
|
92 %
|
90 %
|
Lameris 2008
|
|
90 %
|
90 %
|
Andeweg 2014
|
|
CT
|
94 %
|
99 %
|
Lameris 2008
|
|
95 %
|
96 %
|
Andeweg 2014
|
|
MRI
|
–
|
–
|
Lameris 2008
|
|
98 %
|
70 – 78 %
|
Andeweg 2014
|
In both metanalyses and most head-to-head studies, ultrasound and CT were comparable
with respect to the diagnosis of diverticulitis and were superior to other modalities.
CT had the advantage of higher specificity and the ability to identify alternative
diagnoses [144]. The role of MRI in diagnosing acute diverticulitis is not yet clear and it is not
recommended as a first-line diagnostic procedure [128]
[144]. Studies comparing CT staging with intraoperative and histologic findings raise
doubts as to whether CT is really the “gold standard”. In phlegmonous diverticulitis
(CDD 1b; Hinchey IIa), CT resulted in overstaging in 33 % of the patients [167]. Another comparison to surgery revealed considerable inaccuracy of CT in complicated
diverticulitis: patients with Hinchey type III (purulent peritonitis) were understaged
as Hinchey type I or II [168].
Similar studies between ultrasound and intraoperative findings are still lacking.
In addition, there is only minimal data regarding ultrasound in major complications,
such as distant mesenteric and pelvic abscesses or free perforation.
However, as with any artform or advanced skill, there is a large learning curve. It
must be clear that little experience with GIUS inevitably yields unsatisfactory results
and it has been shown that less than 500 completed examinations is insufficient [169]
[170].
GIUS and CT have proved to have similar sensitivity and specificity in the assessment
of acute diverticulitis.
Consensus levels of agreement: A+ 14/18; A– 2/18; D– 1/18; D+ 1/18
3.9. Diagnostic strategy
Current guidelines suggest that the diagnosis in all patients with a clinical suspicion
of acute diverticulitis must be confirmed by imaging on admission. As treatment strategies
have become less aggressive and more tailored to the stage of diverticulitis, accurate
staging of the disease has become increasingly important [127]
[171]
[172]. Due to the similar sensitivity and specificity of US and CT, EFSUMB recommends
GIUS as the first-line imaging modality in suspected acute diverticulitis. Common
advantages are bedside availability, low costs and the absence of radiation and contrast-induced
nephropathy. Especially in cases of uncomplicated diverticulitis, GIUS is the only
imaging method needed in acute assessment. If there is no evidence of early and significant
clinical improvement, a “second look” 72 hours later may be helpful to rule out the
need for intervention or surgery [170]. This second assessment can easily be done by GIUS in most cases.
CT may work as a backup after inconclusive or negative US examinations and has particular
advantages for disease located in the distal sigmoid, inflammation deep in the small
pelvis or insufficient US scanning conditions (e. g. in obesity). Additional CT may
be helpful in planning drainage or immediate surgery in complicated cases. This step-up-approach
(ultrasound first and CT only in case of a negative or inconclusive ultrasound examination)
has proven to yield the best accuracy [126]
[169]
[173]. Ultrasound first has been incorporated in more and more European guidelines [124]
[125]
[128]
[174]. Advantages in ultrasound technology and specific training in GIUS (e. g. in emergency
medicine) will even strengthen this position in the coming years.
