Technical factors responsible for "placental migration": sonographic assessment

Whether placental migration occurs is debatable. To determine the incidence of placenta previa in early pregnancy and the frequency of placental migration, a retrospective analysis was undertaken of 2,087 consecutive obstetrical sonograms obtained during a 23-month period. Among 849 patients scanned between 14 and 26 weeks after conception, placenta previa was diagnosed using ultrasonography (US) in 53 patients (6.2%). This diagnosis was confirmed at surgery in 15 patients (1.8%); there were 12 cases of central previa and three cases of partial previa. Retrospective analysis revealed that in 25 cases, technical factors, such as an overly distended urinary bladder (19 cases) or focal uterine contractions (six cases), were responsible for the false-positive diagnoses. In the 13 remaining patients, however, there were no obvious technical difficulties to account for the diagnosis of previa. Migration did not occur in any of the patients with central previa. It appears that placental migration may occur, although less frequently than has previously been reported. Furthermore, this study suggests that migration does not occur in patients with central previa.

Extrapancreatic spread of acute pancreatitis: new observations with real-time US

Real-time ultrasonography (US) was compared with abdominal computed tomography (CT) in 40 patients with moderate to severe acute pancreatitis. Emphasis was placed on the ability of US to disclose peripancreatic involvement of the anterior pararenal spaces, lesser sac, and transverse mesocolon. When a realtime US scanning technique emphasizing semierect patient positioning and coronal views was used, 20 of 26 lesions in the anterior pararenal space (77%) and 14 of 14 abnormalities in the lesser sac (100%) were visualized. Abnormalities in the transverse mesocolon, however, were poorly detected on US scans. Ten patients (25%) in the study had extrapancreatic abnormalities missed by US. CT remains the imaging method of choice in patients with clinically moderate to severe pancreatitis. In patients with mild pancreatitis, the real-time US technique we describe improved extra-pancreatic visualization compared with previous studies using static scanners. A new US observation of perivascular spread of acute pancreatitis around the splenic and portal veins is described.

CT in the management of periappendiceal abscess

Abdominal CT was the primary diagnostic method used to evaluate 40 patients with suspected periappendiceal abscess. Its subsequent impact on patient management was then analyzed for several categories of clinical presentation, including patients with and without a palpable right-lower-quadrant mass and postoperative patients. CT was reliable in distinguishing periappendiceal abscesses from phlegmons; 17 of 18 patients with phlegmons responded promptly to antibiotic therapy alone without need for surgery. Patients with larger, poorly localized abscesses underwent early surgical drainage. CT was successful in guiding percutaneous catheter drainage (nine patients) or aspiration (one patient) of well-localized periappendiceal abscesses in 10 of 11 patients. One attempted catheter drainage guided by sonography was technically unsuccessful. In patients without a palpable right-lower-quadrant mass, CT was helpful in establishing the diagnosis of periappendiceal inflammation. However, there were three false-positive diagnoses in patients with pericecal fluid collections including a ruptured cecal lymphoma, a ruptured cecal diverticulum, and a ruptured corpus luteum cyst. A diagnostic approach with CT is presented in patients with suspected periappendiceal abscess.

Threatened abortion: sonographic distinction of normal and abnormal gestation sacs

In an attempt to determine whether sonographic evaluation alone can distinguish normal from abnormal gestation sacs, a retrospective analysis was performed of ultrasound (US) scans from 168 women with threatened abortion. Gestation sacs were judged to be abnormal on the basis of specific sonographic criteria including large size (greater than or equal to 25 mm mean sac diameter) without an embryo; distorted shape; thin (less than or equal to 2 mm), weakly echogenic, or irregular choriodecidual reaction; absence of a double decidual sac; and low position. Two criteria - large sac and distorted shape - had 100% specificity and were called major criteria. The remaining criteria were individually less specific, although 100% specificity was achieved when three or more of these minor criteria were demonstrated. When one major or three minor criteria were present, 53% of abnormal gestations were correctly identified without any false-positive diagnoses. The authors conclude that experienced sonographers can reliably identify many abnormal gestation sacs on a single examination.

Abnormal pregnancy: early diagnosis by US and serum chorionic gonadotropin levels

Simultaneous sonography and quantitative serum human chorionic gonadotropin (HCG) levels from 126 women with threatened abortion were compared. Of 56 women with normal outcome, 39 (70%) had a gestation sac greater than or equal to 5 mm in mean sac diameter, and in each case the HCG level was 1,800 milli-international units (mIU/ml) or greater. The serum HCG levels strongly correlated with the gestation sac sizes to a mean sac diameter of 25 mm. Of 70 abnormal pregnancies, 31 demonstrated a gestation sac. Of these, 20 women (65%) had disproportionately low HCG levels relative to sac size, including 12 in whom the HCG level was less than 1,800 mIU/ml. One woman with an early molar pregnancy had a disproportionately elevated HCG level. Correlation of sonograms with a simultaneous measurement of serum HCG level is a useful method for evaluating threatened spontaneous abortion. A disproportionately low HCG level relative to gestation sac size is evidence for an abnormal pregnancy.

Computed tomography of thick-walled gallbladder mimicking pericholecystic fluid

We have recently encountered four patients in whom pericholecystic fluid was suspected on CT. However, sonography revealed only a thick-walled gallbladder. Helpful clues to avoid this potential interpretive pitfall are described.

Abdominal CT in acquired immunodeficiency syndrome

Acquired immunodeficiency syndrome (AIDS) is a lethal infectious disease that has reached epidemic proportions in urban centers of the United States. Intraabdominal opportunistic infections and malignancies are common features of this syndrome. A prodromal phase or possibly milder form of infection is known as the AIDS-related complex. Abdominal computed tomography (CT) in patients with AIDS-related complex often demonstrates a triad of mild retroperitoneal and mesenteric adenopathy, splenomegaly, and perirectal inflammation. Lymph node enlargement greater than 1.5 cm is unusual in the AIDS-related complex and should prompt CT-guided biopsy. Abdominal adenopathy (greater than 1.5 cm) in AIDS, in our experience, is most commonly related to non-Hodgkin lymphoma, Kaposi sarcoma, or infection with Mycobacterium avium-intracellulare. In most instances, CT-guided biopsy with appropriate staining technique can readily distinguish these entities. However, the subtyping of non-Hodgkin lymphoma by fine-needle aspiration biopsy alone remains controversial. Unusual features of abdominal malignancies are common in AIDS. These include a purely lymphadenopathic form of AIDS-related Kaposi sarcoma and a predilection for extranodal sites of lymphoma in AIDS. In general, patients with AIDS-related lymphoma present with advanced stages of disease with highly malignant histologic subtypes. Abdominal CT may be useful clinically for diagnosing intraabdominal complications of AIDS.

Ultrasound in acute pancreatic trauma

The ultrasound findings are reviewed in 4 patients with surgically proven acute pancreatic trauma. Despite technically adequate sonograms, pancreatic injuries were not prospectively diagnosed in any of the patients. Computed tomography (CT) performed shortly after ultrasound demonstrated changes of traumatic pancreatitis in each case. Because of the subtlety of the ultrasound findings, CT appears to be the preferred method for evaluating suspected pancreatic trauma.

High resolution scrotal ultrasonography: a highly sensitive but nonspecific diagnostic technique

We compared surgical and pathological findings to those of preoperative scrotal ultrasonography in 50 consecutive patients undergoing surgical exploration for testicular trauma, tumors or benign atraumatic conditions. An inhomogeneous parenchymal echo pattern was the single most reliable predictor of a parenchymal abnormality. Large scrotal hematomas may preclude adequate visualization of the parenchyma and early testicular torsion may exhibit a normal parenchymal echo pattern. Except for early torsion, no false negative predictions of the state of the parenchyma were made.

Sonographic differentiation of enlarged hepatic arteries from dilated intrahepatic bile ducts

Identifying parallel tubular structures within the liver by sonography has been regarded as a sensitive and specific sign of intrahepatic duct dilatation. Eight cases are reported in which parallel tubes within the liver were shown not to represent dilated ducts on computed tomography, but rather enlarged hepatic arteries due to increased blood flow. All eight patients had a history of alcoholism and/or cirrhosis and had at least one ancillary sign of portal hypertension. The sonographic findings in these eight patients were compared with similar findings in 12 other patients who were subsequently found to have true intrahepatic bile duct dilatation. Sonographic features that were helpful in distinguishing these two groups are described.

Sonography of ovarian fibromas

Sonographic findings are described in four women with ovarian fibromas. Three of the four women were postmenopausal. Three had only minimal symptoms; the other presented with acute right lower quadrant pain caused by torsion of the tumor. The tumors were large, ranging from 9 to 16 cm in diameter. A distinctive sonographic appearance was found, with a predominantly hypoechoic, solid mass producing striking sound attenuation.

Early gestation: correlation of HCG levels and sonographic identification

Previous reports have indicated that an intrauterine gestational sac is not usually detected when the maternal serum human chorionic gonadotropin (HCG) is less than 6000 mIU/ml. In order to evaluate this observation, maternal serum HCG concentrations were correlated with sonographic uterine findings in 49 patients with normal early intrauterine pregnancies. Of 37 patients in whom a gestational sac was seen, simultaneous HCG levels were 1800 mIU/ml or more in 36 cases and 357 mlU/ml in one case. In 12 cases in which a gestational sac was not detected, the serum HCG levels were 1400 mIU/ml or less. Thirteen patients had HCG levels of less than 6000 mlU/ml. A linear relation was found between gestational sac size and the exponential rise of HCG levels in early pregnancy (p less than 0.001). Of the 13 patients in whom HCG levels were less than 6000 mIU/ml, the gestational sac measured 10 mm or less in each case. Currently, a gestational sac is always seen when the HCG level is greater than 1800 mIU/ml. Comparison of serum HCG levels with sonographic detection of the gestational sac seems to be a useful method of evaluating early pregnancy.

Ultrasound versus excretory urography in evaluating acute flank pain

To determine the role of ultrasound (US) in patients with acute flank pain and suspected acute urinary tract obstruction, a prospective study was performed on 20 patients comparing US with emergency excretory urography. US was not as sensitive as excretory urography for diagnosing hydronephrosis, for detecting ureteral or renal calcification, or for diagnosing forniceal rupture. Although US is an effective screening modality for hydronephrosis in patients with chronic renal obstruction, it is not useful for evaluating patients with acute flank pain in whom acute obstruction may be present. In this group of patients, excretory urography remains the examination of choice.

Sensitivity of sonography in pyonephrosis: a reevaluation

OFF sonographic features distinguishing randomly selected cases of simple hydronephrosis (34 patients) from pyonephrosis (16 patients) were reviewed in 50 patients. Fluid-fluid levels and coarse medium-intensity echoes within the renal collecting system were highly reliable findings for pyonephrosis in 10 patients. However, in six patients with proven pyonephrosis, the renal collecting system either was anechoic (four patients) or contained low-level echoes (two) that were difficult to distinguish from artifacts. Although the specificity for diagnosing pyonephrosis was 100%, the sensitivity was only 62%. Because of the consequences of misdiagnosis, sonographically guided diagnostic needle aspiration may still be required in patients with urosepsis and significant hydronephrosis.

Improved visualization of choledocholithiasis by sonography

During a 20 month period, real-time sonography performed on 26 patients achieved an overall sensitivity of 75% for detecting choledocholithiasis. Although previous publications have stressed very low sensitivities for diagnosing choledocholithiasis (13%-55%), it was postulated that the reasons for these disappointing results are primarily related to technique. Most laboratories evaluate the distal common bile duct (where most calculi are located) by obtaining parasagittal scans. Detection of choledocholithiasis can be substantially improved by scanning the intrapancreatic part of the bile duct in a transverse fashion with the patient in an erect position. Advantages of the transverse view include the ability to demonstrate the distal common bile duct in a high percentage of patients and to differentiate shadowing caused by duodenal gas from ductal calculi. The proximal duct is best imaged by obtaining parasagittal scans with the patient in a supine left posterior oblique position. Using these scanning techniques, eight (89%) of nine proximal and 16 (70%) of 23 distal calculi were visualized.

Sonography of the fetal duplex kidney

The sonographic features of the fetal duplex kidney are reviewed in five cases. Four cases had proven obstruction of either an upper (3 cases) or lower pole (1 case) moiety. Identification of two separate collecting systems may be difficult in utero. Therefore, the key to the sonographic diagnosis is recognition of asymmetric hydronephrosis between the dilated and nondilated moieties.

Hepatocellular carcinoma: assessment of resectability by computed tomography and ultrasound

A retrospective review of the CT and ultrasound scans from examinations of 30 patients who had hepatocellular carcinoma (hepatoma) was undertaken with special emphasis placed on evaluation of hepatic distribution of tumor, vascular invasion, and extrahepatic spread. Although both CT and ultrasound detected hepatoma in 29 of 30 patients (96%), CT showed more extensive hepatic parenchymal involvement in eight of the patients. Vascular invasion was seen more frequently with ultrasound than with CT. Invasion into the main portal vein was seen by ultrasound in 11 of 30 patients (37%). Extrahepatic spread of tumor was much more frequently detected by CT and was present in 21 of 30 patients (70%). A reasoned approach to the diagnostic workup of hepatomas that will minimize invasive procedures and unnecessary surgery is presented.

Postpartum evaluation of fetal hydronephrosis: optimal timing for follow-up sonography

Although intrauterine hydronephrosis can be detected readily by ultrasound, follow-up ultrasound evaluation on the first day of life may show a falsely normal-appearing kidney. The authors present three infants in whom subsequent studies confirmed the presence of upper urinary tract obstruction. It is postulated that the normal-appearing kidneys are probably due to a relative state of dehydration during the first 24 hours of life and a relatively low glomerular filtration rate. It is recommended that the initial postpartum ultrasound examination be performed several days after delivery in neonates diagnosed as having intrauterine hydronephrosis.

Sonographic detection of subtle pelvic fluid collections

The sonographic demonstration of small quantities of free intraperitoneal fluid often indicates significant pelvic pathology. In a review of pelvic fluid collections in 146 female patients, however, it became apparent that an overly distended urinary bladder may mask small quantities of free intraperitoneal fluid. The "mass effect" of a distended bladder may cause fluid in the pouch of Douglas to migrate to other parts of the peritoneal cavity, such as the peritoneal reflection over the fundus of the uterus. Fluid in this location produces a characteristic triangular "cap" and was present in 42 patients (29% of the study group). In 10 patients (6.9%) this was the only visible fluid collection. In addition, sonograms obtained after partial voiding demonstrated small quantities of free pelvic fluid in 14 patients (9.6% of the study group) that were not detected on routine full bladder scans. The sonographic appearance of small amounts of intraperitoneal fluid seen over the uterine fundus and the value of post-void scans are stressed in the demonstration of small quantities of intraperitoneal fluid.

Ultrasound localization of occult breast lesions

High-resolution real-time ultrasound with either a 7.5- or 10-MHz transducer was used to localize 7/9 nonpalpable breast masses previously detected by mammography and to determine where the biopsy needle should be inserted.

Major traumatic and septic genital injuries

Major injuries to the testicles, penis, and genital skin from trauma and infection were seen in 62 patients over a 6-year period (1977 to 1983). Urethral injuries were excluded. In the past blunt testicle injuries were infrequently diagnosed and surgically ignored because of large surrounding hematomas. With the use of real-time ultrasound, 17 of 18 cases of testicle rupture were correctly diagnosed preoperatively. Surgical repair resulted in testicle salvage in 16 patients. Penetrating testicle injuries resulted in a high orchiectomy rate secondary to the infrequently described but recognized entity of self-emasculation in transsexuals. Penile rupture from blunt injuries (8) was successfully repaired and complete function was recovered. Penetrating penile injuries (4) were extensive and involved the urethra in two cases; full function returned after reconstruction. Major skin loss of the penis and/or scrotum (19) occurred from necrotizing fasciitis, burns, avulsion and penetrating injuries. Early debridement, bowel and urinary diversion followed by penile skin grafting, thigh pouches to protect testicles, and scrotal reconstruction resulted in acceptable cosmetic and functional results in all cases of major skin loss.

Hemorrhagic pancreatic fluid collections examined by ultrasound

Ultrasound examination of nine patients revealed that the appearance of their hemorrhagic pancreatic fluid collections varied depending on the age of the hemorrhage. Acute hemorrhage was visualized as a well-defined homogeneous mass, while subacute hemorrhage (studied about a week after the bleeding episode) appeared as a mass that contained cystic and solid elements or was septated. Remote hemorrhage, studied several weeks after the acute event, was visualized as a simple cyst. Findings of CT, which were available for correlation in eight patients, revealed that acute hemorrhagic collections had CT numbers between 45 and 65 HU: older collections had CT numbers between 14 and 25 HU. The ultrasonographic evolution of hemorrhagic pancreatic fluid collections followed a pattern similar to that described by in vitro studies, which determined that hemorrhage and clotted blood may appear either echogenic or sonolucent, depending on the age of the hemorrhage and the transducer used. Factors that affect the echogenicity of hemorrhagic collections and the difficulties encountered in recognizing them by ultrasound are discussed.