The Sonographic Double-Track Sign - Wiley Online Library

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ic double-track sign can be seen in cases of pylorospasm as well as ... Key words: double-track sign; hypertrophic ... children during the first 3 months of life.
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The Sonographic Double-Track Sign Not Pathognomonic for Hypertrophic Pyloric Stenosis; Can Be Seen in Pylorospasm Harris L. Cohen, MD, Steven L. Blumer, BS, William B. Zucconi, DO

Objective. The “double-track” sign has previously been reported as specific for hypertrophic pyloric stenosis when noted on an upper gastrointestinal series. The sign has been noted on sonographic examinations as well. We sought to determine whether this sign can also be seen in cases of pylorospasm diagnosed by sonography, proving it not to be pathognomonic for hypertrophic pyloric stenosis. Methods. The data obtained prospectively from 91 consecutive patients studied between 1999 and 2002 by sonography for projectile vomiting were retrospectively reviewed. Cases with diagnoses of hypertrophic pyloric stenosis or pylorospasm were reviewed for the imaging finding of the double-track sign. Results. Thirty-seven patients had a sonographic diagnosis of hypertrophic pyloric stenosis that was confirmed surgically. Twenty-six (70.2%) showed a sonographic double-track sign. Thirty-four patients had a sonographic diagnosis of pylorospasm that was confirmed by close clinical follow-up. Eighteen (52.9%) showed a sonographic double-track sign. Conclusions. The sonographic double-track sign can be seen in cases of pylorospasm as well as hypertrophic pyloric stenosis. It is not pathognomonic for hypertrophic pyloric stenosis. Key words: double-track sign; hypertrophic pyloric stenosis; pylorospasm.

T Abbreviations HPS, hypertrophic pyloric stenosis; PS, pylorospasm

Received December 1, 2003, from the Division of Abdominal Imaging, Department of Radiology (H.L.C.), School of Medicine (S.L.B.), and Department of Radiology (W.B.Z.), State University of New York–Stony Brook, Stony Brook, New York, USA. Revision requested December 11, 2003. Revised manuscript accepted for publication December 18, 2003. Address correspondence and reprint requests to Harris L. Cohen, MD, 78 Grove Ave, Cedarhurst, NY 11516-2311 USA. E-mail: [email protected].

here are several causes of nonbilious vomiting in children during the first 3 months of life. Aside from simulation of vomiting by idiopathic gastroesophageal reflux, the 2 most common causes of true vomiting are hypertrophic pyloric stenosis (HPS) and pylorospasm (PS).1 It is important to clinically and radiologically differentiate between HPS, which is treated by surgical pyloromyotomy, and PS, which is treated by observation and perhaps antispasmodics. Ultrasound has proved of great help in the diagnosis of HPS since Teele and Smith2 introduced it in 1977. Measurement criteria for the diagnosis of HPS have been published.3–5 It has been shown that measurements considered positive for the sonographic diagnosis of HPS may be overlapped by those obtained in patients with a diagnosis of PS.6 In addition to measurement criteria, imaging criteria have also been described and used to diagnose HPS. In 1966, Haran et al7 described the “double-track” sign of the upper gastrointestinal series as a “simple yet constant sign” that was “specific” for HPS. The sonographic equivalent of

© 2004 by the American Institute of Ultrasound in Medicine • J Ultrasound Med 23:641–646, 2004 • 0278-4297/04/$3.50

The Sonographic Double-Track Sign

this sign (Figure 1) was reported in 1987.8 However, we anecdotally have seen the doubletrack sign in cases of PS. This report is the result of an attempt to confirm the observation of the sonographic double-track sign in cases of PS.

Materials and Methods We reviewed the sonographic studies that were performed for projectile vomiting in 91 neonates between 3 and 8 weeks of age examined at Kings County Hospital from 1999 to 2000, Johns Hopkins Medical Institutions from 2000 through 2001, and State University of New York–Stony Brook in 2002. Patients who were sent for sonographic examination because of projectile vomiting were analyzed with either an HDI 5000 sonography machine with a linear L7-4 or a curved array C8-5 transducer (Philips Medical Systems, Bothell, WA) or an Acuson Sequoia sonography machine with a sector 8v5, a linear array 15L8w, or a curved linear array 8c4 transducer (Siemens AG, Munich, Germany). Transducer choices were made on an individual patient basis in an attempt to produce images that would allow a definitive diagnosis.

Figure 1. Longitudinal oblique sonogram through the pylorus of a 26-day-old male neonate with HPS showing the sonographic double-track sign. Two arrows point to echopenic parallel lines in a thick-walled and elongated pylorus. Crosses mark the pyloric channel, although the distal cross does not go to its farthest point. The findings were unchanged during the study. Debris and fluid are seen in the stomach (S).

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Some patients were studied with the residual fluid found in their stomach. However, in most cases, when the stomach antrum, the pyloric region, or both were obscured by gas, we evaluated the individual patient according to our published technique.9 A nasogastric tube (8F, 15 in) is placed into the stomach. Through that tube, 60 mL of sterile water (the equivalent of at least half a feeding) is placed into the stomach. The tube is then removed to prevent the gastroesophageal reflux that is known to occur when a tube crosses the gastroesophageal junction. The water acts as an echoless contrast agent within the stomach and duodenum. Fluid placement by tube, in our opinion, allows a quicker examination with a more exacting determination of delay in emptying or relative obstruction at the antropyloric region. Using the fluid to help show the antropyloric area, we study the area for the presence or absence of a pyloric mass and the alacrity of fluid flow, if any, from stomach to duodenum. A normal study is considered one without a pyloric mass (ie, little if any pyloric muscle wall thickness or pyloric canal length) and rapid egress of fluid from antrum to pylorus to duodenal bulb. An abnormal study is one with a pyloric mass and little if any egress of fluid. If a pyloric mass is imaged, we analyze it for length of the pyloric canal and thickness of the pyloric muscle wall surrounding the pyloric canal. We note whether there are 2 or more tracks of fluid within the pylorus, a finding that has been reported as the sonographic double-track sign of HPS.8 The pyloric mass is also studied for any changeability during the study. Cases of HPS show unchangeable pyloric masses and only minimal, if any, fluid exiting the antrum. Cases of PS show changeable pyloric masses that often disappear or become significantly smaller. When the mass is present, fluid egress from the antrum is limited. When the mass disappears, there is often concurrent egress of fluid into the pylorus, duodenal bulb, and distally. The measurement criteria we use for the definitive diagnosis of HPS9 include a pyloric length of 18 mm or greater and an individual wall thickness of 4 mm or greater. Cases can have positive findings for HPS with a thickness of 3 mm, especially in patients in whom symptoms present early (ie, in the first 4 weeks of life) or those who were born prematurely in whom symptoms present when they are really chronoJ Ultrasound Med 23:641–646, 2004

Cohen et al

logically younger. The abnormal image of HPS remains essentially unchangeable during a sonographic study, as do the abnormal measurements. Our criteria for the diagnosis of PS10 are the presence of a thick pyloric muscle wall (Figure 2) and/or an elongated pyloric length that change in size, usually to a normal measurement, during the course of the sonographic study. All patients with PS were followed closely by their clinicians because of our warning of the theoretical possibility that a diagnosis of PS might be made in a patient in whom HPS was developing, particularly if analyzed at a young age (