Ultrasonography of the acute abdomen

During the past decade, noninvasive imaging has assumed an increasingly prominent role in the evaluation of patients who have acute abdominal conditions. Ultrasonography is often the initial diagnostic imaging modality used to examine patients who are clinically suspected of having acute cholecystitis, choledocholithiasis, and acute appendicitis. This article focuses on the clinical considerations and the ultrasonographic findings that relate to each of these conditions. In addition to describing the ultrasonographic appearances for each of these entities, this article also emphasizes useful scanning techniques that will provide optimal images.

Sonographic diagnosis of perforation in patients with acute appendicitis

The sonographic diagnosis of appendicitis can be challenging in patients with perforation. In order to detect the accuracy of specific sonographic features of appendiceal perforation, graded compression sonograms in 100 patients with surgically confirmed acute appendicitis were reviewed retrospectively. Twenty-two of these patients had perforation. A statistically significant association was found between three sonographic findings and perforation: loculated pericecal fluid, prominent pericecal fat, and circumferential loss of the submucosal layer of the appendix. No single finding had a specificity greater than 59%. By using a combination of one or more findings, the overall sensitivity of sonography for the diagnosis of perforation was 86%. The specificity, however, was only 60%. Our results suggest that in patients without a sonographically visible appendix, recognition of loculated pericecal fluid and prominent pericecal fat may be a useful indirect clue to the diagnosis of perforating appendicitis.

Sonourethrography in the evaluation of urethral stricture disease

Ultrasonography of the anterior urethra offers a dynamic three-dimensional study that can easily be repeated. It holds the promise of defining accurately, not only the exact length and severity of the strictured urethral segment, but also the extent of urethral fibrosis and the anatomy of the periurethral structures. A significant reduction in the incidence of recurrent stricture may be obtained by selecting patients for treatment on the basis of the findings of sonourethrography. Moreover, the potential exists for the use of this imaging method during internal urethrotomy to ensure a more accurate and aggressive incision of the stricture.

Abdominal lymphoma in AIDS: evaluation with US

The sonographic findings in 38 patients with abdominal lymphomas related to acquired immunodeficiency syndrome (AIDS) were reviewed. Thirty-three patients had non-Hodgkin lymphoma, and five had Hodgkin disease. Abnormal masses were detected with sonography in 33 patients (87%). Focal hypoechoic liver lesions up to 10 cm in diameter were visible in 17 patients. Several lesions were anechoic and septated, mimicking fluid. Adenopathy (at the retroperitoneum, mesentery, or porta hepatis) was seen in 15 patients. Other involved areas included bowel, omentum, spleen, kidney, and adrenal gland. AIDS-related abdominal lymphomas frequently cause extranodal masses that can be readily imaged with ultrasound. Ultrasound-guided fine needle aspiration biopsy allows a specific diagnosis to be made in many cases.

Scrotal ultrasonography and the management of testicular trauma

The early surgical repair of testicular injuries has reduced morbidity and increased testicular salvage. Orchiectomy can be avoided in about 90 per cent of cases. Ultrasound has increased our ability to diagnose parenchymal injury preoperatively and thus to advise the frightened patient more authoritatively and assure ourselves of the necessity of surgical exploration. In most cases, the patient can expect a short convalescence and preservation of his injured gonad.

Sonography in patients with suspected acute appendicitis: value in establishing alternative diagnoses

We reviewed the clinical and sonographic findings in 297 patients who had graded compression sonography for suspected acute appendicitis. The purpose of the study was to determine the accuracy of sonography in detecting other diseases in the 174 patients in this group who proved not to have acute appendicitis. Of the 174 patients without acute appendicitis, 93 patients (53%) were ultimately discharged with a diagnosis of abdominal pain of unknown origin. Of the 81 patients in whom specific diagnoses were established, sonography suggested the correct diagnosis in 57 patients (70%). A broad spectrum of diseases was detected, including: gynecologic diseases (35); visceral diseases, including hollow viscera and diseases of liver, pancreas, or spleen (18); and urinary tract abnormalities (four). This study suggests that sonography is useful in establishing alternative diagnoses in patients undergoing sonography for suspected acute appendicitis.

Early pregnancy complications: endovaginal sonographic findings correlated with human chorionic gonadotropin levels

Endovaginal sonography results were compared with quantitatively determined human chorionic gonadotropin (hCG) levels in 84 women referred for early pregnancy complications. Of the 27 with normal intrauterine pregnancies, an intrauterine gestational sac was prospectively identified in one of five cases (20%) in which hCG levels were below 500 IU/L (Second International Standard), four of five (80%) with hCG levels of 500-1,000 IU/L, and all 17 with hCG levels above 1,000 IU/L. In comparison, 17 of the 26 women with ectopic pregnancies (65%) had hCG levels greater than 1,000 IU/L, and none of the 26 had an intrauterine gestational sac. Endovaginal sonography demonstrated an adnexal mass and/or a gestational sac-like structure in 16 of the 17 cases (94%) in which hCG levels were above 1,000 IU/L, compared with only three of the nine (33%) with lower hCG levels (P less than .01). These findings indicate that an intrauterine gestational sac should be normally visualized with endovaginal sonography when the hCG level exceeds 1,000 IU/L, and that visualization of an extrauterine gestational sac and/or adnexal mass is significantly more likely in ectopic pregnancies when the hCG level exceeds 1,000 IU/L.

Acute appendicitis: sonographic criteria based on 250 cases

Two hundred and fifty consecutive patients with suspected appendicitis were examined with graded compression sonography. The initial diagnostic criterion for appendicitis was visualization of a noncompressible appendix; this was later modified to include the dimensions of the visualized appendix. The appendix was visualized in 91 of 250 patients (36%). Five adult patients with sonographically visible appendixes that were 6 mm or less in maximal diameter had either benign clinical follow-up (three patients) or a histologically normal appendix removed at surgery (two patients). However, two patients with appendixes measuring 6 mm in diameter and multiple appendicoliths had surgically confirmed acute appendicitis. Of 84 patients with visible appendixes measuring greater than 6 mm in maximal diameter, 78 had surgically confirmed acute appendicitis. In the remaining six, symptoms resolved spontaneously, and no surgery was required. In the absence of compelling clinical findings or an appendicolith, adult patients with maximal appendiceal diameters of 6 mm or less should undergo a period of close observation rather than immediate surgery. A diagnosis of appendicitis can be made in adult patients with persistent right lower quadrant pain and a visualized appendix greater than 6 mm in diameter.

Sonourethrography in the evaluation of urethral strictures: a preliminary report

A total of 17 patients with suspected stricture disease underwent conventional retrograde urethrography and sonourethrography. When the length of the stricture as assessed by each imaging modality was compared to measurements at open urethroplasty in 7 patients, sonourethrography was consistently more accurate. Distension of the urethra with saline during the ultrasound examination enabled classification of the degree of spongiofibrosis, which was confirmed by full depth biopsy in 5 patients. Sonourethrography cannot adequately image the posterior urethra, even when the transcrotal approach is used. However, because it is a dynamic 3-dimensional study and can be repeated without risk of radiation exposure, sonourethrography is preferable to radiographic retrograde urography to evaluate patients with suspected anterior urethral strictures.

Endovaginal sonographic evaluation of ectopic pregnancy: a prospective study

To determine the value of endovaginal sonography for evaluating women with a suspected ectopic gestation, we prospectively studied a group of 84 pregnant women in whom conventional transabdominal sonograms failed to show a living embryo. Of 84 patients studied, 25 had an ectopic gestation, 32 had a normal intrauterine pregnancy, and 27 had an abnormal (nonviable) intrauterine pregnancy. Endovaginal sonography, compared with transabdominal sonography, provided additional information in 50 cases (60%) and less information in only three cases (4%). Of 25 ectopic gestations, endovaginal sonography provided new information in 15 cases (60%) including detection of an extrauterine gestational sac (10 cases), extrauterine embryo (two cases), or adnexal mass (three cases) not observed on transabdominal sonography. Of 32 normal intrauterine pregnancies, endovaginal sonography provided additional information in 26 cases (81%) including detection of a yolk sac (14 cases), living embryo (11 cases), or small gestational sac (one case) not seen on transabdominal sonography. Of 27 abnormal intrauterine pregnancies, endovaginal sonography showed additional information in nine cases (33%) including detection of embryonic demise (three cases), retained intrauterine products (four cases), or a yolk sac (two cases) not seen on transabdominal sonography. Patient acceptance of endovaginal sonography was excellent; 82% of the patients preferred this method to transabdominal sonography, 13% expressed no preference, and 5% preferred transabdominal sonography. We conclude that endovaginal sonography can provide significant additional information in the majority of women who are referred for sonography with a suspected ectopic gestation. We believe that this method should become a integral part of sonographic evaluation in women who are suspected of having an ectopic gestation when conventional transabdominal sonography fails to show a living embryo.

Percutaneous drainage of periappendiceal abscesses: review of 20 patients

Twenty patients with periappendiceal abscesses diagnosed by CT underwent percutaneous catheter drainage. Eighteen (90%) of the 20 patients were successfully treated by percutaneous drainage and antibiotic therapy alone. In two of these patients, however, small recurrent abscesses were diagnosed by CT 4 and 6 weeks after drainage, but these abscesses resolved with additional antibiotic therapy. Surgery was performed in two patients in whom percutaneous drainage failed. One was a diabetic patient who had a gas-forming abscess that extended into the posterior pararenal space. Surgery was necessary in a second patient because of a technical failure of catheter insertion, which resulted in perforation of the abscess cavity and peritonitis. Abscess sinograms in eight (44%) of 18 patients showed fistulas between the abscess cavity and the base of the cecum or appendix. However, the fistulas did not pose a problem in clinical management, and all closed within 14 days. Percutaneous drainage is an effective alternative to surgery in selected patients with periappendiceal abscesses.

Deep venous thrombosis of the lower extremity: US evaluation

The sensitivity of duplex ultrasonography (US) for detecting deep venous thrombosis of the lower extremity was compared with that of venography in a prospective study of 54 patients. Doppler analysis of the common femoral vein and US imaging of the deep venous system from the common femoral vein to the popliteal vein was performed. Common femoral vein response to the Valsalva maneuver was recorded. Sonographically visible thrombi and abnormal vein compressibility were 91% sensitive for the common femoral vein, and 94% sensitive for the superficial femoral or popliteal veins, with no false-positive examinations. Abnormal Doppler flow and abnormal response of the common femoral vein to the Valsalva maneuver enabled thrombi to be detected only in the common femoral and iliac veins. Combined data allowed accurate diagnoses in all patients with deep venous thrombosis proximal to the deep calf veins. US should be the screening examination of choice for evaluating patients with suspected lower extremity deep venous thrombosis.

AIDS-related cholangitis: radiographic findings in nine patients

Acalculous inflammation of the biliary tract is a recently reported complication of the acquired immunodeficiency syndrome (AIDS). In a 33-month period, nine men with AIDS were evaluated because of right upper quadrant and/or epigastric pain, jaundice, or abnormal liver function test results. Each patient underwent ultrasonography and endoscopic retrograde cholangiopancreatography; seven also underwent computed tomography. In eight of nine patients the imaging studies disclosed intrahepatic and extrahepatic bile duct changes identical to those seen in sclerosing cholangitis (strictures, focal dilatation, thickened duct walls). Isolated papillary stenosis and ductal dilatation were present in one patient, while eight patients had some stricturing of the distal common duct. The combination of papillary stenosis and intrahepatic ductal strictures appears unique to AIDS-related cholangitis. Endoscopic papillotomy provided variable relief to symptoms and biochemical abnormalities. Cholangitis caused by cytomegalovirus and/or Cryptosporidium infection is the proposed pathophysiologic mechanism.

Acute appendicitis: high-resolution real-time US findings

High-resolution, real-time ultrasonography (US) with graded compression was used to evaluate 90 patients with clinically suspected acute appendicitis. US visualization of a noncompressible appendix was the primary criterion for a diagnosis of acute appendicitis. The overall sensitivity was 89%, the specificity was 95%, and the accuracy was 93%. When the results in women were analyzed separately (n = 49), the overall accuracy was 96%. Several important limitations of US scanning were encountered. There were three false-positive examinations in patients with a sonographically visible appendix whose symptoms spontaneously resolved. Another patient had a normal compressible appendix with a thin (2-mm), symmetric wall surrounded by ascites. There were three nondiagnostic studies (3%) due to inability to compress the cecum and right lower quadrant adequately because of exquisite tenderness (two patients) or massive ascites (one patient). When interpreted in light of the clinical examination, sonography should significantly reduce the rate of false-negative appendectomies, particularly in women.

Papillary stenosis and sclerosing cholangitis in the acquired immunodeficiency syndrome

Eight homosexual men with the acquired immunodeficiency syndrome (AIDS) presented with clinical, biochemical, and radiologic features of stenosis of the papilla of Vater and sclerosing cholangitis. This newly recognized complication of AIDS produces abdominal pain, nausea, and vomiting and may predispose patients to superimposed bacterial cholangitis. Marked elevation of serum alkaline phosphatase levels and lesser changes in hepatic aminotransferase levels are common. Although abdominal ultrasonography and computed tomography detect ductal abnormalities, endoscopic retrograde cholangiography best shows precise ductal irregularities and provides therapeutic intervention. Prompt relief of symptoms follows endoscopic sphincterotomy, often with resolution of biochemical evidence of cholestasis. Biliary tract infection with cytomegalovirus or cryptosporidia and resultant viral or coccidial cholangitis are the proposed pathophysiologic mechanisms.

Acute suppurative tenosynovitis of the hand: diagnosis with US

The sonographic findings in seven patients with surgically proved acute tenosynovitis of the hand (bacterial in six cases, of presumed viral origin in one) were reviewed. In the six patients with bacterial tenosynovitis the affected flexor tendon was larger than that of the contralateral normal digit. In five patients hypoechoic areas were identified surrounding the flexor tendon that proved to be pus at surgery. Sonography failed to depict a small amount of pus in the tendon sheath in one patient. The affected tendon of the single patient with tenosynovitis thought to be of viral origin was normal in size, but a focal tendon sheath fluid collection was detected that proved to be sterile at surgery. Sonography appears to be a useful imaging technique in the early diagnosis of acute suppurative tenosynovitis of the hand.

Pancreatic abscess: predictive value of early abdominal CT

The value of a recently reported grading system of early abdominal computed tomography (CT) for predicting development of pancreatic abscess in patients with acute pancreatitis was reassessed. When the previously described CT grading system was used in another patient population, it did not demonstrate the same degree of prognostic value of baseline CT. In this series pancreatic abscess occurred in only eight of 29 patients (28%) with grade E CT scans (with grade E representing the most severe involvement), compared with 60% in the previous series. Of 44 patients with either grade D or E baseline CT scans, abscesses developed in only 30%, with a minimum clinical follow-up of 3 months. A second grading system, which used a semiquantitative analysis of the degree of peripancreatic inflammation (a "CT severity score"), also did not strongly correlate with the future risk of abscess, The authors conclude that early abdominal CT should be performed selectively in patients with acute pancreatitis and reserved for patients who are either diagnostic dilemmas or who fail to respond to supportive treatment and have clinically suspected surgical complications such as pancreatic abscess.

Plastic wrap for US transducer sterility or sanitization

Commercially available plastic wrap can be used to encase an ultrasound transducer for sanitization purposes. If sterility is required, an individual piece of plastic wrap can be gas sterilized before the transducer is covered with it. This technique does not degrade or temporally limit the use of the transducer, it is easy to perform, and the materials are readily available.

Computed tomography of blunt trauma to the gallbladder

The CT findings are reviewed in two patients with injuries to the gallbladder following blunt abdominal trauma. In one patient with a laceration of the cystic artery a large intraluminal clot was identified within the gallbladder associated with extensive hemoperitoneum. Another patient presented with extensive bile leakage into the peritoneal cavity 72 h after blunt trauma due to laceration of the fundus of the gallbladder. The clinical features of blunt trauma to the gallbladder and the utility of CT in this entity are reviewed.

Biliary dilatation: defining the level and cause by real-time US

In a 15-month period, 110 patients with subsequently proved biliary dilatation were evaluated with ultrasound (US). The level of dilatation was defined as pancreatic, suprapancreatic, or at the level of the porta hepatis. Causes of dilatation included pancreatitis, choledocholithiasis, neoplasm, and stricture. The distal duct was examined initially on transverse scans obtained with the patient in a semierect right posterior oblique position; the proximal duct was then examined on longitudinal scans obtained with the patient in a supine left posterior oblique position. When this scanning technique was used, US indicated the level of dilatation in 91.8% of cases and suggested the correct cause in 70.9%. Because this approach markedly improves US visualization of the intrapancreatic bile duct, distal obstructing lesions, which are the most common, can be optimally examined.