Save of the Month – July 2020

It’s 6:32 am and the last 28 minutes, 56 seconds of your CCT shift (but who’s counting?). A concerned triage nurse approaches you stating “Doc, I have a patient here that looks very uncomfortable, and his abdomen is really distended.” At the bedside, you find a 62-year-old male with no significant PMH presenting with 4 days of severe abdominal pain, subjective fevers/chills, and one episode of non-bloody/non-bilious emesis.

HR 111/min BP 92/43 mm Hg RR 20/min T 98.3 F SpO2 97% RA

The patient is confused, diaphoretic, and toxic-appearing. His abdomen is distended, firm, and diffusely tender with rebound.

This patient is exhibiting peritonitis and evidence of shock. Your differential diagnosis includes perforated viscus, ruptured AAA, and mesenteric ischemia.

Gastrointestinal tract perforation refers to a full-thickness wall injury occurring anywhere from the esophagus to the large bowel. Etiologies are numerous and include iatrogenic (e.g instrumentation), blunt or penetrating trauma, neoplasm (secondary to obstruction or invasion of the bowel wall), bowel obstruction, ingestion of foreign bodies or corrosive agents, and peptic ulcer disease.¹ Definitive management will vary based on etiology and ranges from conservative care to emergent surgery.

“ABC” assessment, IV access, and cardiac monitoring. Address respiratory status with supplemental oxygen. Resuscitate initially with intravenous fluids and add vasopressors to maintain perfusion prior to ET intubation if needed. Pain management is also essential – consider fentanyl or subdissociative-dose ketamine. Additional early interventions in this patient would include empiric antibiotic coverage for intra-abdominal bacteria – streptococci, enterobacteriaceae, and anaerobes. Finally, imaging should be obtained expeditiously.

Consider point-of-care ultrasound (POCUS) as a first-line modality in hemodynamically unstable patients. In addition to a FAST exam and aorta evaluation, you can look for evidence of viscus perforation. Use either the linear or curvilinear probe, depending on body habitus. The higher frequency linear probe is typically best suited for evaluating the more superficial peritoneal layer.² With the patient in the supine position, begin scanning in the right upper quadrant, superficial to the liver. Scan in a lawnmower-like fashion, evaluating all four quadrants of the abdomen for evidence of free air.

On your POCUS, look for:

(1) Enhanced peritoneal stripe sign (EPSS, the non-cardiac kind) – the result of disruption of the ultrasound waves as they pass through the anterior abdominal wall to underlying organs or peritoneal fluid by intra-abdominal air.³

(2) Reverberation artifacts – repeated reflections through the POCUS image caused by an initial reflection at a highly reflective interface–in this case, the gas (free air) and soft tissue interface.⁴ This is similar to the A-lines seen in normal lung tissue.

Several studies have investigated the value of POCUS in the diagnosis of viscus perforation. In one prospective, observational study (n=484), the sensitivity of POCUS for gastrointestinal perforation was 85% (95% CI, 72% to 93%), specificity 99% (95% CI, 98% to 100%), LR- 0.15 (95% CI, 0.08 to 0.28), and LR+ 366 (95% CI, 52 to 2,603).⁵ By comparison, a prospective analysis (n=1,723), found that 89% (95% CI, 88% to 91%) of upright chest or abdominal plain films were positive in admitted patients with confirmed pneumoperitoneum.⁶

Comparing the two modalities head-to-head, another prospective, observational study (n=188) calculated a sensitivity of 92% (95% CI, 87% to 96%) and specificity of 56% (95% CI, 31% to 78%) for the diagnosis of gastrointestinal perforation with POCUS compared to upright plain films: sensitivity 78% (95% CI, 72% to 85%) and specificity 56% (95% CI, 31% to 78%).⁷

CT remains the gold standard for diagnosing perforated viscus in hemodynamically stable patients.⁸ Evidence of perforation on CT includes extraluminal air, bowel wall thickening, and even direct visualization of focal wall defects. These findings can be identified without IV or intraluminal (oral, rectal) contrast.⁹ However, the addition of IV contrast can provide additional information such as evidence of bowel ischemia, active mesenteric bleeding, contusion, or hematoma.¹⁰

Ultimately, this patient will likely require emergent surgical evaluation and intervention (i.e laparotomy) for definitive management. One recent, retrospective cohort study (n=3,809) highlighted the necessity of rapid surgical source control, showing an increased risk-adjusted odds of mortality per hour associated with the delay in time to OR in patients with perforated peptic ulcer disease.¹¹

The patient was taken emergently to the operating room for exploratory laparotomy. He was found to have a large, obstructing, descending colon mass with necrosis and perforation at the cecum. He underwent subtotal colectomy and omentectomy.

1. 1. Consider viscus perforation in a patient presenting with abdominal pain/distension and shock.
2. 2. In addition to ordering upright plain films, consider ultrasound as a bedside tool to obtain information that can support your diagnosis.
3. 3. Definitive management is often surgical and early consultation is crucial for improving outcomes.

1. Rosen P, Marx JA, Walls RM, et al. Rosen’s emergency medicine: Concepts and Clinical Practice. 9th ed. Philadelphia, PA: Elsevier/Saunders; 2018.

2. Hoffmann B, Nürnberg D, Westergaard MC. Focus on abnormal air: diagnostic ultrasonography for the acute abdomen. Eur J Emerg Med. 2012;19(5):284-291. doi:10.1097/MEJ.0b013e3283543cd3

3. Peh WM, Lok TJ. Detecting Pneumoperitoneum via Point-of-Care Abdominal Ultrasound: To See Beyond Touch. Eur J Case Rep Intern Med. 2019;6(8):001193. Published 2019 Jul 29. doi:10.12890/2019_001193

4. Stone MB, and Papanagnou D: Emergency ultrasound identification of pneumoperitoneum. Acad Emerg Med 2011; 18: pp. e30

5. Moriwaki Y, Sugiyama M, Toyoda H, et al. Ultrasonography for the diagnosis of intraperitoneal free air in chest-abdominal-pelvic blunt trauma and critical acute abdominal pain. Arch Surg. 2009;144(2):137-142. doi:10.1001/archsurg.2008.553

6. Bansal J, Jenaw RK, Rao J, Kankaria J, Agrawal NN. Effectiveness of plain radiography in diagnosing hollow viscus perforation: study of 1,723 patients of perforation peritonitis. Emerg Radiol. 2012;19(2):115-119. doi:10.1007/s10140-011-1007-y

7. Chen SC, Yen ZS, Wang HP, Lin FY, Hsu CY, Chen WJ. Ultrasonography is superior to plain radiography in the diagnosis of pneumoperitoneum. Br J Surg. 2002;89(3):351-354. doi:10.1046/j.0007-1323.2001.02013.x

8. Stapakis JC, Thickman D. Diagnosis of pneumoperitoneum: abdominal CT vs. upright chest film. J Comput Assist Tomogr. 1992;16(5):713-716.

9. Hainaux B, Agneessens E, Bertinotti R, et al. Accuracy of MDCT in predicting site of gastrointestinal tract perforation. AJR Am J Roentgenol. 2006;187(5):1179-1183. doi:10.2214/AJR.05.1179Shanmuganathan K,

10. Mirvis SE, Chiu WC, Killeen KL, Scalea TM. Triple-contrast helical CT in penetrating torso trauma: a prospective study to determine peritoneal violation and the need for laparotomy. AJR Am J Roentgenol. 2001;177(6):1247-1256. doi:10.2214/ajr.177.6.1771247

11. Boyd-Carson H, Doleman B, Cromwell D, et al. Delay in Source Control in Perforated Peptic Ulcer Leads to 6% Increased Risk of Death Per Hour: A Nationwide Cohort Study. World J Surg. 2020;44(3):869-875. doi:10.1007/s00268-019-05254-x