Madtown Sono

Middle-aged female with abdominal pain

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By Michael Kern, MD
Edited by Hani I. Kuttab, MD

Clinical Case

A middle-aged female with a history of hypertension presented to the emergency department (ED) with abdominal pain and onset of constipation approximately 10 days prior. Laxatives, enemas, and magnesium citrate only mildly alleviated symptoms. The patient reported her last bowel movement occurred one day prior, but was with very small amounts of firm, hard stool, and has continued to have left-sided abdominal pain. The patient denied a history of abdominal surgeries. She denied all other associated symptoms. She appears uncomfortable and with tenderness to palpation in all quadrants of the abdomen. A bedside bowel ultrasound was performed (Figures 1 and 2).

Bedside Bowel Ultrasound (LUQ, short)
Figure 1. Bedside Bowel Ultrasound (LUQ, short)

Bedside Bowel Ultrasound (LUQ, long)
Figure 2. Bedside Bowel Ultrasound (LUQ, long)

Diagnosis

Perforated Diverticulitis. Bedside ultrasound demonstrated thickening of the bowel wall and dilatation in the left upper/lower quadrant. In addition, free air was noted on ultrasound (indicated by the “lung curtain” on the leftward side of the screen of Figures 1 and 2), indicating pneumoperitoneum. Computed tomography (CT) imaging of the abdomen was performed, confirming this diagnosis and also revealing an organizing abscess. General surgery was consulted, who recommended initiation of broad spectrum antibiotics and hospitalization.

“Lawnmower” approach. Begin in the right upper quadrant and scan up and down the abdomen, until reaching the left lower quadrant.
Figure 3. “Lawnmower” approach. Begin in the right upper quadrant and scan up and down the abdomen, until reaching the left lower quadrant.

Performing the Exam

Point-of-care bowel ultrasound can be easily performed to assess for small bowel obstruction, appendicitis, or diverticulitis. Place the patient supine, but beware that the change in patient position may facilitate bowel gas movement. The curvilinear probe should be used, but in thinner patients (or pediatric patients), the linear probe can be used. The lawnmower method is the most common approach, in which you begin by placing the probe in the right upper quadrant and scanning downwards. Hold constant pressure as you migrate the probe into the right lower quadrant, as healthy bowel can usually be compressed and shifted with transducer pressure. Continue to move up and down the abdomen, ending in the left lower quadrant (Figure 3). Handing the probe to the patient and having them place the probe over the point of maximal tenderness can also be incredibly helpful!

Diverticulitis by Ultrasound

Evaluation of diverticulitis with ultrasound is a newer application for point-of-care ultrasound. Recent studies have demonstrated excellent sensitivity and specificity (92% and 97%, respectively) and is comparable to CT. Plus, ultrasound is cheap, can be performed at the bedside, and provides no radiation to the patient. When evaluating the left lower quadrant, the FABD approach should be considered. Use the mnemonic ‘Find Air B4 Diverticulum’ (FABD) to help you keep the findings in mind (taken from a recent SCUF 2020 presenter!):

  1. F: Fat Enhancement (brightness around the bowel)
  2. A: Air Pockets
  3. B4: Bowel Wall >4mm (thickened)
  4. D: Diverticulum (dark, outpouchings noted near the bowel)

However, ultrasound for the assessment of diverticulitis does have several limitations. This exam can be difficult because of pesky bowel gas. Obesity also makes the exam more difficult., Ultrasound may not be as helpful in identifying alternative causes of abdominal pain as CT may. There is quite a bit of operator dependence when performing this exam. There is also some concern that the sensitivity decreases when evaluating for any sort of complications of diverticulitis, such as abscess, perforation, etc.

The peak of the waveform is termed the E-point and is the point at which the mitral valve opens. This represents early diastolic filling and when flow across the mitral valve is maximal. There is a second peak called the A-point, which represents brief increased flow from atrial kick just prior to systole. A normally functioning left ventricle will squeeze down enough to get very close to the distal mitral valve when diastole begins, whereas a poorly functioning left ventricle is unable to contract enough, and thus are farther away from the valve. The distance between the E-point and the ventricular septum can be measured and used to estimate the LVEF. There is an inverse correlation between LVEF and EPSS—the greater the EPSS, the poorer the left ventricular function (Figure 4). An EPSS of greater than 10mm suggests a reduced ejection fraction, while values less than 7mm suggest a normal ejection fraction.

Teaching Points

Point-of-care ultrasound for the assessment of diverticulitis is a newer application of ultrasound. If you’re going to use it, practice, practice, practice! Remember the mnemonic ‘Find Air B4 Diverticulum’ to help you remember the sonographic signatures.

References

  1. Cohen A, Li T, Stankard B, et al. A Prospective Evaluation of Point-of-Care Ultrasonographic Diagnosis of Diverticulitis in the Emergency Department. Ann Emerg Med. 2020; 76(6): 757-766.
  2. Lameris W, van Randen A, Bipat S, et al. Graded compression ultrasonography and computed tomography in acute colonic diverticulitis: meta-analysis of test accuracy. Eur Radiol. 2008; 18:2498–251.

Acknowledgements

Additional information and figures created by Hani I. Kuttab, MD