For this month’s ultrasound blog, we decided to focus on a relatively different application for ultrasound. However, it would be false to label this a “new” ultrasound application as it is used very commonly in many other countries. However, given our nation’s preference for other diagnostic examinations, specifically computed tomography, for the diagnosis of acute diverticulitis, we have essentially “missed the boat” on using sonography as the first line diagnostic tool. This article was recently published in the Journal of Ultrasound in Medicine as part of their Sound Judgment Series. The purpose of these series of articles is to highlight the clinical value of using ultrasound first in specific clinical diagnoses where ultrasound has shown comparative or superior value to other diagnostic examinations.
Here are a few key points presented in the article:
- Diverticulitis presents in 10% of the general younger than 40 years and 60% in those over 80 years
- It is the second leading cause of abdominal pain but roughly 1/3 of patients are clinically missed on clinical presentation
- Primary modalities for detecting diverticulitis include radiography, endoscopy, barium contrast enema, computed tomography, sonogrophay and MRI
- In contrast to the United States, sonography is used as the first imaging modality in some European countries and most developing countries
- Graded compression is used in scanning the GI tract
- Examination is ideally performed with the curvilinear 3.5-5.0 MHz probe but can be done with the high frequency linear 5-12 MHz probe (mostly in pediatric, thin and elderly patients with decreased muscular mass)
- It is critical to focus on the patient’s most painful area
- Recommended to perform a systemic evaluation of the abdomen by starting in the RUQ with the ascending colon to the RLQ quadrant to examine the terminal ileum and appendix to the transverse and descending colon leading then to the small bowel
- Normal colon rarely recognized on sonography (thickness <3mm)
- Suspect underlying disease if colonic wall thickness >5mm
- To differentiate sigmoid colon from small bowel:
- Sigmoid colon has stable location
- Colonic lumen lacks vulvulae conniventes
- There is no peristalsis in colon
Sonographic Features of Acute Diverticulitis:
- Thick, hypoechoic wall with central hyperechoic center (target phenomena); though nonspecific sign
- Diverticula, seen in up to 50% cases
- Changes in pericolic fat
- Enlarged fluid-filled loops of bowel
- Air-containing diverticula manifesting as hyperechoic areas within the lumen
- Abscess presenting primarily as a cystic mass with hyperechoic debris
- Local pain and tenderness on compression
- Using sonography first also allows for immediate assessment of peristalsis and blood flow on color Doppler imaging
- Area may be obscured by overlying gas
- Disease confined to distal colon may be difficult to visualize
- Highly operator dependent
- Sonography is safe, widely available, easily accessible, portable and affordable
- Allows for rapid and accurate diagnoses in trained hands
Other Articles on Topic:
Vijayaraghavan SB. High-resolution sonographic spectrum of diverticulosis, diverticulitis, and their complications. J Ultrasound Med 2006; 25:75-85.
Puylaert JB. Ultrasound of colon diverticulitis. Dig Dis 2012; 30:56-59.
Hollerweger A, Rettenbacher T, Macheiner P. Sigmoid diverticulitis: value of transrectal sonography in addition to transabdominal sonography. AJR Am J Roentgenol 2000; 175:1155-1160.
Chaubal N, Dighe M, Shah M. Sonography of the gastrointestinal tract. J Ultrasound Med 2006; 25:87-97.