Sonography and the Acute Abdomen

AJR:168, January 1997 179

Perspective

Sonography and the Acute Abdomen: PracticalConsiderationsJulien B. C. M. Puylaert1, Friso M. van der Zant1, Arie M. Rijke2

O ver the past 10 years, sonography. . has gained acceptance for examin-

ing patients with acute abdominal

pain. Sonography is dynamic, noninvasive,

rapid, inexpensive, and readily accessible;

however, it has some serious drawbacks. Use is

limited in obese patients; the ultrasound beam

cannot penetrate bone or gas; and sonography,

more than other radiologic techniques, is oper-

ator-dependent and requires skill, dedication,

and experience.

In this perspective, several practical aspects

of using sonography on patients with acute

abdominal pain are highlighted. These aspects

include the choice between sonography and CT

as an initial examining technique, the timing of

the sonographic examination, sonographically

guided puncture, the value of indirect sono-

graphic findings, the significance of normal

findings on a sonogram, and, finally, commu-

nication with the clinician.

Indications

Traditionally, surgeons have accepted a high

negative laparotomy rate to avoid the risks of

ill-advised surgical delay. Nonetheless, serious

surgical delay inside the hospital is common. A

prospective study of patients with a suspected

appendicitis showed a negative laparotomy rate

of 27%; and concomitant serious therapeutic

delay in 14% of patients who needed surgery

[1]. Another prospective study dividing patients

into three categories (high, equivocal, and low

clinical suspicion) showed that even in the high-

suspicion group, 35% of the patients did not

have an appendicitis, whereas 5% of the

patients in the low-suspicion group had an

inflamed appendix [2]. In 30 patients with a

ruptured aortic aneurysm, treatment was

delayed more than 6 hr because of misdiagnosis

[3]. These figures show that the clinical diagno-

sis of an acute abdomen is unreliable and that

the threshold for radiologic imaging studies

should be low. The concept of sonography as

a helpful diagnostic tool used only in cases of

clinical doubt is and should be rejected.

The impact of sonography on clinical man-

agement of patients with an acute abdomen is

impressive. In a study of patients with sus-

pected appendicitis, sonographic findings sig-

nificantly changed the therapeutic management

in 26% of patients [4]. In three independent

studies using sonography, negative laparotomy

rates were 13%, 13%, and 7%, respectively,

[4-61 with a concomitant reduction in unneces-

sary surgical delay. In our institution, virtually

all patients with acute or subacute abdominal

pain are referred for a sonogram, including

patients for whom surgery seems definitely

required as well as patients with a remote possi-

bility ofrequiring surgery (Figs. 1 and 2).

Not surprisingly, sonography of the acute

abdomen has markedly affected routine prac-

tice in many institutions. Sonography per-

formed on indication of acute abdominal pain

makes up 25% of all abdominal sonographic

examinations at our institution, and nation-

wide, acute abdominal pain has become the

most frequent reason for radiologists to go in

to the hospital when they are on call.

Sonography or CT as Initial Technique?

Several acute abdominal conditions are more

easily detected on a CT scan than on a sono-

gram. They include a ruptured aortic aneurysm,

an aortic dissection, an esophageal rupture, a

mycotic aneurysm, an acute pancreatitis, an

incarcerated internal hernia, and perirenal and

hepatic abscesses. In addition, CT scans usually

provide better results in obese patients who

have retrocecal appendicitis, appendiceal

abscess, deeply located sigmoid diverticulitis,

closed-loop bowel obstruction, gastrointestinal

perforation to the retropetitoneum, and emphy-

sematous cholecystitis. However, in experi-

enced hands, the sonograrn can still be used to

reliably diagnose most acute abdominal condi-

tions in most patients [4]. Therefore, a reason-

Received June 1, 1995; accepted after revision July 23, 1996.

1 Department of Radiology, Westeinde Hospital. Ujnbaan 32, 2512 VA The Hague, the Netherlands. Address correspondence to J. B. C. M. Puylaert

2Department of Radiology. Health Sciences Center, University of Virginia. Lee St, Charlottesville, VA 22908.

AJR 1997;168:179-186 0361-803X/97/1681-179 © American Roentgen Ray Society

Fig. 2-24-year-old previously healthy man was admittedwith classical presentation of acute appendicitis. No diar-rhea was present WBC was 16,500!mm3. Immediate ap-pendectomy was proposed.AD, Sonography shows mucosal inflammation ofterminal 1-eum in transverse (A) and longitudinal (B) planes as well asenlarged mesenteric lymph nodes (C). Appendix (arrows)was small and measured 2.1 mm during compression. Sur-gery was cancelled. Three days later, Salmonella paratyphi B(D) was cultured from stool. a = iliac artery , v = iliac vein.

Puylaert et al.

180 AJR:168, January 1997

able course of action is to begin with the least

expensive and least invasive technique and pro-

ceed to a CT scan only in cases of an inconclu-

sive sonogram.

Examination Technique

Examination of the entire abdomen, from

the axilla to the groin. in patients with acute

abdominal pain is more than a routine survey

of all abdominal organs. The examination

involves a sonographically guided. rational

approach to the clinical problem of that par-

ticular patient. During the examination, the

radiologist should continuously consider all

possible differential diagnoses depending on

the sonographic findings. This symptom-

directed sonographic examination requires

communication with the patient because spe-

cific findings may raise specific questions

and. conversely, information provided by the

patient may lead to a search for a specific

sonographic feature (Fig. 3).

Similarly. sonographic examination is closely

linked with physical examination. A dual exami-

Fig. 1-68-year-old man with acute appendicitis had 2-dayhistory of constipation and uncomfortable sensation in low-er abdomen. No local or rebound tenderness and no feverwere present Erythrocyte sedimentation rate was 32 mm!hr with normal leukocyte count Proposed managementwas conservative.A and B, Sonography showed inflamed appendix in longi-tudinal (A) and transverse (B) plane. Appendix was subse-quently removed.

nation is helpful when identifying what organ or

structure corresponds to the most painful area or

palpable mass. For example. if in women the

most tender region is deep in the pelvis, vaginal

sonography may help not only in detecting gyne-

cologic conditions but also in diagnosing sig-

moid diverticulitis 171or appendicitis [8] (Fig. 4).

Asking patients to point out the most tender

region can be especially important in conditions

that typically cause localized tenderness but do

not have conspicuous sonographic features. Seg-

mental omental infarction 19]. epiploic

Fig. 3-67-year-old woman with 10-year history of abdominal pain complained of recurrent urinary tract infec-tions.A, Sonography showed thickened small-bowel loops (b) with interloop fistula (black arrows). Adjacent bladderwall was locally irregular (white arrows).B, Small amount of air was found in dome of bladder (arrowhead). Only on specific questioning did patient recallepisode of urinating air. She was diagnosed with Crohns disease with fistulization to bladder.

Fig. 4.-25-year-old woman complained of lower ab-dominal pain in pelvic region for 1 day. Transabdomi-nal sonography was normal. Transvaginal sonographyrevealed inflamed appendix (arrow).

Fig. 5.-Infarcted epiploic appendix. 40-year-old manhad severe pain on pressure in left lower quadrant,suspect for sigmoid diverticulitis. Erythrocyte sedi-mentation rate was 36 mm!hr.A, At point of maximum tenderness, sonography showed2.5-cm ovoid area of inflamed fat (arrowheads).B, CT scan confirmed diagnosis of infarcted epiploicappendix (arrowheads).

Sonography and the Acute Abdomen


appendagitis f 10), an incarcerated spigelian or

epiga.stric hernia, a small rectus hematoma [I I],

or sigmoid diverticulitis [ I 2, 13j are a few such

conditions (Figs. 5 and 6).

On the other hand. diagnostic signs can be

found at a considerable distance from the most

tender region. In appendicitis. the pain is some-

times diffuse in the lower abdomen, a patient

may present with a perforated duodenal ulcer

that causes right lower quadrant pain because

the gastric contents track down the right pare-

colic gutter. small-bowel obstruction may cause

maximum pain at a marked distance from the

site of obstruction (Fig. 7), a stone in the distal

ureter may present with only flank pain, air in

the biliary system with small bowel obstniction

may indicate a gallstone ileus, or liver

metastases may indicate an underlying malig-

nancy in patients with an appendiceal mass.

These examples all emphasize the importance

of examining the entire abdomen.

If the anatomy is aberrant. especially in the

case of an inflamed appendix far removed

from the point where the gridiron incision is

normally made. The appendix should be

marked on the skin with an indelible pencil

(Fig. 8). Sonography in patients with an acute

abdomen should be performed with graded

compression similar to gentle palpation [ 14).

Compression shortens the distance from the

transducer to the abnormal structure and allows

the use of a high-frequency probe. It is also

used to compress or displace gas-containing

bowel. thereby reducing the disturbing effect of

gas on the sonographic images. Compression

also involves determining the extent an organ

and its surrounding tissues can be compressed.

For instance, compression allows identification

of gallbladder hydrops as well as assessment of

appendiceal rigidity in appendicitis (Fig. 9).

Finally, compression should always be applied

in a graded manner to minimize pain.

If. despite compression. gas continues to

hamper the sonographic examination, the

patient can be scanned with the transducer

positioned posterolaterally over the flank. In

this manner. ventrally located gas in partially

fluid-filled bowel loops or gas-containing

abscesses can be avoided (Fig. 10). With the

patient in a left lateral decubitus position, free

air should specifically be looked for between

the lateral abdominal wall and the liver.

Timing of the Sonographic Examination

Many acute abdominal conditions show a

tendency toward spontaneous resolution;

however, symptoms may recur later. Inter-

mittent episodes of abdominal pain are pre-

dominantly seen in cases of obstruction.

When the obstruction is relieved, the symp-

toms resolve. and when the obstruction

recurs, the symptoms reappear.

This scenario is seen in biliary and urinary

stone disease. appendicitis. intussusception,

incarcerated hernia, and small-bowel obstruc-

tion from adhesions. Sonographic findings dur-

ing an episode of pain may differ significantly

Puylaert et al.


Fig. 8.-Inflamed appendix in unusually high position.A, Sonogram shows inflamed appendix in right upper quadrant.B. In view of its unusual position, location of appendix was drawn on skin with indelible pencil.C. This location influenced site, size, and direction of incision.

Fig. 6.-Otherwise healthy middle-aged woman pre-sented with severe localized pain in right lower quad-rant. She was suspected of having appendicitis.A, Sonography showed small, impalpable rectus he-matoma (arrowheads).B, Rectus hematoma (arrowheads) was confirmed byCT scan. Appendectomy was cancelled.

Fig. 1.-Incarcerated obturator hernia. 86-year-oldwoman presented with small-bowel obstruction.A, Left-sided groin sonography revealed small, impalpableherniated bowel loop (asterisk) behind pectineus muscle.B, T2-weighted MR imaging confirms incarcerated ob-turator hernia (asterisk). Also note contralateral asymp-tomatic hernia. a = femoral artery, v = femoral vein.

Fig. 9.-Acute gallbladder hydrops.A and B, On compression of gallbladder, in longitudinal (A) and transverse (B) plane mild bulging (arrowheads)of anterior abdominal wall was noted, indicating hydrops with high pressure in lumen. No gallstones were visu-alized. At surgery, 3-mm obstructing stone in distal cystic duct was found.

Fig. 10.-Small-bowel obstruction with partially gas-filled loops. Fig. 11.-50-year-oldwomanwith classic signs of chole-A and B, Ventral scanning yielded only air(A), whereas posterolateral scanning clearly showed dilated loops (B). cystitis 2 days earlier was completely free of symptoms

when this sonogram was obtained. Gallbladder stillshowed considerable residual changes.



from findings immediately after such an epi-

sode and from the findings several days after

such an episode. For instance, if a patient is

examined during an episode of biliary colic, a

sonogram may show hydrops, thickening of the

gallbladder wall, a sonographic Murphy’s sign,

and an impacted stone. A few days later, when

the symptoms have subsided, all that is found is

a morphologically normal gallbladder contain-

ing a mobile stone. Sonographic findings

should always be correlated with the course of

the symptoms in time. Dilatation due to an

obstruction ofthe gallbladder, kidney, bowel, or

appendix may disappear quickly after relief of

the obstruction. However, the inflammatory

changes associated with the process of obstruc-

tion often remain sonographically visible for

days or weeks even when the symptoms have

long since subsided. These residual changes

explain why an impressive cholecystitis or

appendicitis can be documented sonographi-

cally in a patient free ofsymptoms at the time of

the sonogram 16](Fig. I1).

Preferably, the examination should be done

during an episode of pain for two reasons. Not

only is the chance of a diagnostic sonographic

finding greater but it also guarantees optimal tim-

ing of possible surgery. In case of intennirtent

episodes ofpain, the patient should be warned to

seek immediate medical attention during the next

episode so that sonography, and possibly sur-

gery, can be performed without delay (Fig. 12).

Sonographically Guided Puncture

In patients with an acute abdomen, a small

amount of free fluid may occur in both surgi-

cal and nonsurgical conditions and, as such,

is nonspecific. Identifying the nature of the

fluid, however, can be helpful. Sonographi-

cally guided puncture carries virtually no

risk and allows rapid differentiation between

blood, pus, and bile, and additional labora-

tory investigation can distinguish further

between gastric fluid, pancreatic fluid, and

malignant ascites (Fig. 13).

Indirect Sonographic Findings

Many sonographic diagnoses such as appen-

dicitis, renal colic, or cholecystitis are fairly

straightfoaward and can be made with confi-

dence. However, sometimes the primary condi-tion is not well, or not at all, recognizable by

sonography. In such cases, indirect sonographic

findings may be of help.

Fig. 12.-Over 3 months, 59-year-old woman suffered from severe colicky attacks lasting 1-2 hr. Two earliersonographic examinations performed during symptom-free intervals showed no abnormalities. Present ex-amination, performed during attack, revealed intussusception.

Puylaert et al.


primary bowel wall diseases as infectious ile-

ocolitis. Crohn’s disease, or ischemia I 15).

Other useful indirect findings are associ-

ated with abscesses, which occur when a

gastrointestinal perforation is not effectively

sealed off. Often the underlying cause-

appendicitis, diverticulitis, Crohn’s disease,

or a malignancy-can be determined. In

cases of large, gas-containing abscesses, this

determination may be difficult I 16, 17). An

abscessogram done some days after percuta-

neous drainage and a repeated sonogram

may, as yet, reveal the underlying condition.

Another indirect sonographic sign is

related to free perforation. If the process of

sealing the bowel has been completely inef-

fective and the bowel contents are spilling

into the peritoneal cavity. first a local and

then a generalized peritonitis with paralytic

ileus will ensue. The presence of dilated

fluid-filled bowel loops with absent peristal-

sis is an important clue and. in most cases,

indicates a gastrointestinal perforation requir-

ing surgical treatment (Fig. 15).

The most helpful indirect findings are related

to gastrointestinal pert�ration. such as may

occur in appendicitis, diverticulitis. Crohn’s dis-

ease, peptic ulcer disease, and bowel cancer. In

all of these conditions, protective migration of

omentum, inesenteiy, and bowel loops to the

site of imminent perThration occurs in an

attempt to seal offand prevent spillage of howel

contents into the peritoneal cavity. The migrat-

ing, inflamed fatty mesentery and omentum are

recognized as amorphous masses of hypere-

choic, noncompressible tissue. This inflamed

fat is usually concentrated around the diseased

organ and, although often prominent, can easily

be overlooked on a sonogram. The most con-

spicuous feature of inflamed fat is its noncom-

pressibility, which is best observed by applying

intermittent graded compression with the trans-

ducer. Inflamed fat, especially in advanced

cases, is well recognized on a CT scan as hyper-

attenuating streaky (dirty) areas in the abdomi-

nal fat(dirtyfat)(Fig. 14).

Secondary mural thickening of the neigh-

boring bowel loops, such as seen in appendi-

citis, is another indirect sign. This finding can

be confusing and may be interpreted as such

Normal Sonographic Findings

It is not unusual to find no sonographic

abnormalities whatsoever in patients with an

acute abdomen. In patients with a low clinical

suspicion of disease requiring surgery, a nega-

tive sonographic examination can usually be

taken as confirmation that no condition requir-

ing surgery exists. lf� however, clinical findings

and laboratory tests suggest a serious abnormal-

ity, further workup is required. This problem

occurs frequently in young women in whom

appendicitis must be differentiated from adnexi-

Fig. 13.-61-year-old woman was admitted with rapidly increasing pain over entire abdomen. She had suffered no trauma.A and B, Sonograms show free fluid around liver and inhomogeneous spleen.C, Sonography-guided puncture yielded blood. Surgery confirmed spontaneously ruptured spleen.

Fig. 14.-Inflamed fat in sigmoid diverticulitis.A, Sonogram shows wall thickening of contracted sigmoid (5) and diverticulum surrounded by large areas of hy-perechoic, noncompressible tissue (asterisks).B, This tissue represents fatty mesentery and migrated omentum, which was confirmed by CT scan.

A B

Fig. 15.-i 1-year-old girl presented with right lower quadrant pain.A and B, Sonograms show dilated fluid-filled bowel loops over entire abdomen with complete absence of pen-stalsis during 10 mm of examination. No other abnormality was shown. Surgery by median incision showed gen-eralized purulent peritonitis from perforated appendicitis.



tis. Normal sonographic findings do not exclude

appendicitis or adnexitis. In this context, the

role of the erythrocyte sedimentation rate must

be emphasized, because in adnexitis it is usually

high at the time of admission. If the etythrocyte

sedimentation rate is markedly elevated in a

young and not too obese woman with normal

sonographic findings. adnexitis is strongly

favored. The reasoning is as follows: if the high

erythrocyte sedimentation rate had been caused

by appendicitis, conspicuous and extensive

inflammatory periappendiceal changes would

be present that would not have gone unnoticed

during sonography.

Another condition in which no sonographic

abnormalities are found in the presence ofa high

erythrocyte sedimentation rate is pyelonephritis;

however, this diagnosis is usually made on clini-

cal presentation. It can, however, masquerade as

a condition requiting surgery and lead to an

unnecessary laparotomy. Thickening ofthe pye-

localiceal wall and local tenderness over the kid-

ney may provide clues to the diagnosis [ I 8J.

Two other diseases that initially do not give

rise to abnormal sonographic findings are pan-

creatitis and mesenteric ischemia [19). Pan-

creatitis is usually diagnosed by an elevated

amylase level in both urine and serum.

Mesenteric ischemia, however, can be a diag-

nostic nightmare.

When no sonographic abnormalities are

found in a patient with severe epigastric or

upper quadrant symptoms, a myocardial inf-

arction or a pulmonary cause should be con-

sidered. A subtle amount of pleural fluid or a

region of pulmonary consolidation may be

the first clue to the diagnosis of pulmonary

embolism or early pneumonia (Fig. 16).

If, in a patient with severe abdominal

symptoms, both sonographic and laboratory

findings are repeatedly normal. a psychogenic

cause or functional bowel disorder should be

suspected. If the sonographic examination is

not conclusive, the most useful complemen-

tary study is a CT scan, especially if the

patient is obese or is not suitable for sonogra-

phy in other respects.

Communication with the Clinician

For mote than a century, surgeons have been

taught to rely on their clinical impression in their

decision between surgery and conservative man-

agement of patients with an acute abdomen.

Understandably, surgeons have viewed the ad-

vance ofsonography in this field with caution and

perhaps even some distrust. The realization that

clinical astuteness is being challenged by technol-

ogy has c&tsed both excitement and confusion

[20}; therefore, radiologists must have a good rela-

tionship with surgeons. A good relationship starts

with mutual confidence and good communica-

tion. Radiologist and surgeon should speak acorn-

mon language. Tenns such as “phlegmon”,

“perforation”, “walled-offperforation”, “pseudoa-

neulysm”, and “ileus”can mean differentthings to

a surgeon and a radiologist In difficult cases,

therefore, a morphologic description of the intni-

abdominal situation based on the sonographic

findings should be given, and a single-term diag-

nosis should be avoided. ln such cases, the radiolo-

gisi should ask the surgeon to be present at the

sonographic examination.

In the final report, the sonographic find-

ings should be integrated with the patient’s

history, physical signs, and laboratory data

as well as the results of a possible CT scan

Puylaert et al.


Fig. 16.-2O-year-old woman presentedwith severe right upper quadrant painand marked leukocytosis. Patient wassuspected of having cholecystitis or gen-eralized pelvic inflammatory disease.A, Sonographically. abdomen was normal.Only abnormalities observed were someecholucent areas above diaphragm.B, On lateral chest radiograph, small pos-terobasal consolidation wasfound. Final di-agnosis was right-sided basal pneumonia.

and other radiologic examinations. Liberal

use and a clinical approach are the key points

in sonography of the acute abdomen. Sonog-

raphy is a valuable tool to lower both the

number of unnecessary laparotomies and the

technique related to surgical delay.

References

I. Pieper R. Kager L, Nesman P. Acute appendicitis:a clinical study of 1028 cases of emergencyappendectomy. Acw Chir Scand 1982; 140:51-62

2. Schwerk WB, Wicktrup B, Rothmund M, Rus-

choffi. Ultrasonography in the diagnosis of acute

appendicitis: a prospective study. Gastroenterol-

ogv 1989:97:630-6393. Marston WA, Ahlquist R, Johnson G, Meyer AA.

J VascSurg 1992:16:17-22

4. Puylaert JBCM. Rutgers PH. Lalisang RI, et al. A

prospective study of ultrasonography in the diag-

nosis of appendicitis. N Engi J Med 1987;317:666-669

5. Braun B, Blank W. Ultraschall-Diagnostik der

Akuten Appendizitis. Ultraschall 1989: 10: 17()-l76

6. Ooms HWA. Ho Kang You PJ, Koumans RKJ,

Puylaert JBCM. Ultrasound and appendicitis. Br

JSurg 1991:78:315-3 18

7. Broekman BAMW, Puylaert JBCM, Van Dessel

1. Sigmoid diverticulitis in the female: transvagi-

nal sonographic findings. J C/in Ultrasound

1993; 2 1:393-395

8. Puylaert JBCM. Transvaginal sonography for

appendicitis (letter). AJR 1994:163:746

9. Puylaert JBCM. Rightsided segmental omental

infarction: clinical, US and CT findings. Radiol-

Og)� 1992;l84: 169-172

10. Rioux M, Langis P. Primary epiploic appendici-

tis: clinical, US and CT findings in 14 cases.

Radiolog% 1994:191:523-526

I I . Lohle P. Coerkamp EG. Puylaert JBCM. Her-

mans E. Nonpalpable rectus sheath hematoma

clinically masquerading as appendicitis: US and

CT diagnosis. Abdom Imaging 1995:20:152-154

12. Schwerk WB, Schwarz 5, Rothmund M. Sonog-

raphy in acute colonic diverticulitis: a prospective

study. Dis Colon Rectum 1992:35:1077-1084

I 3. Wilson SR. The value of sonography in the diag-

nosis of acute diverticulitis of the colon. AiR

1990:154:1199-120214. Puylaert JBCM. Acute appendicitis: US evalua-

tion using graded compression. Radiology 1986:

158:355-360

IS. Puylaert JBCM. Vermeijden Ri, Van der WerfSDJ,Doornhos L, Koumans RKJ. Incidence and sono-

graphic diagnosis of bacterial ileocaecitis masquer-

ading as appendicitis. Lrnicet l989:ii:84-86

16. Jeffrey RB. The pancreas. In: Jeffrey RB. ed. CT

and sonographv of the acute abdomen, 1St ed.

New York: Raven. 1989:111-14817. Balthazar El. Gordon RB. CT of appendicitis.

Semin Ultrasound CT MR 1989; 10:326-340

18. Avni EF. Van Gansheke D, Thona Y. et al. US

demonstration of pyelitis and ureteritis in chil-

dren. Pediatr Radio! 1988:18:134-139

19. Jeffrey RB. Management of the periappendical

inflammatory mass. Seinin Ultrasound CT MR

1989;10:341-34720. Schwartz SI. Tempering the technological diagnosis

ofappendicius. N EnglJ Med 1987:317:703-704

Sonography and the Acute Abdomen

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