Small Bowel Obstruction, Perforation, and Other Bowel Pathology
Gunter Michael Krauthamer
John T. Moeller
1. An 87-year-old man is admitted to the intensive care unit (ICU) for ascending cholangitis. Two days after admission, he complains of worsening abdominal pain, nausea, and vomiting. His nurse notes that he hasn’t had a bowel movement in 48 hours. Point-of-care ultrasound of his abdomen reveals Figure 64.1.
 Figure 64.1 |
Which is the most appropriate next step in management?
A. Obtain a right upper quadrant ultrasound to evaluate for worsening biliary disease.
B. Obtain a surgical consult for bowel perforation.
C. Obtain a computed tomography (CT) scan to evaluate for gallstone ileus.
D. Obtain an abdominal X-ray to evaluate for pneumoperitoneum.
View Answer
1. Correct Answer: C. Obtain a CT scan to evaluate for gallstone ileus.
Rationale: Figure 64.1 shows dilated loops of small bowel with plicae circulares. These findings are concerning for a bowel obstruction, which could be due to gallstone ileus in the setting of his biliary disease. Plain films may be used in making this diagnosis, classically showing Rigler’s triad: air in the biliary tree (pneumobilia), signs of SBO, and ectopic radiopaque gallstones, but CT has improved sensitivity and may show alternative pathology. There is no evidence of bowel perforation on this image, which may manifest as peritoneal air or fluid. While medical management may be appropriate for functional ileus or adhesive bowel obstruction, gallstone ileus typically requires surgical treatment.
Selected References
1. Chang L, Chang M, Chang HM, Chang AI, Chang F. Clinical and radiological diagnosis of gallstone ileus: a mini review. Emerg Radiol. 2018;25(2):189-196.
2. Chuah PS, Curtis J, Misra N, Hikmat D, Chawla S. Pictorial review: the pearls and pitfalls of the radiological manifestations of gallstone ileus. Abdom Radiol. 2016;42(4):1169-1175.
3. Nuño-Guzmán CM, Marín-Contreras ME, Figueroa-Sánchez M, Corona JL. Gallstone ileus, clinical presentation, diagnostic and treatment approach. World J Gastrointest Surg. 2016;8(1):65-76.
2. A 70-year-old man with diabetes is admitted to the hospital for septic shock, attributed to severe cellulitis of his left upper extremity. He begins treatment with intravenous (IV) clindamycin. Three days after admission, the patient begins to complain of profuse, watery diarrhea. On examination, he is diffusely tender, and his abdomen is tense. His vital signs are: temperature 39.0°C, BP 80/50 mm Hg, HR 125 bpm, and SpO2 90% on room air. Abdominal ultrasound reveals Figure 64.2A and B.
 Figure 64.2 |
What is the most appropriate next step in his management?
A. Broaden antibiotic coverage to include Clostridium difficile.
B. Obtain a CT angiogram to evaluate for mesenteric ischemia.
C. Obtain an upright abdominal X-ray to evaluate for intraperitoneal free air.
D. Begin IV fluid resuscitation and emergently consult general surgery.
View Answer
2. Correct Answer: D. Begin IV fluid resuscitation and emergently consult general surgery.
Rationale: The patient has evidence of intraperitoneal free air on ultrasound (Figure 64.2) including a thickened peritoneal stripe with ring-down artifact. Portal venous gas is also noted (white arrows in liver). While ultrasound is not the diagnostic gold standard for intraperitoneal free air, it is a reasonable bedside test to evaluate patients who have acute-onset abdominal pain and hypotension. The ultrasonographic findings of free air in this clinical context should raise suspicion for toxic megacolon leading to colon perforation. The history of diarrhea and acute abdominal pain in the setting of recent antibiotic use makes sequela from C. difficile infection more likely than mesenteric ischemia. While the patient may need additional antibiotic coverage, intestinal perforation is typically an indication for emergent surgery. While radiographs may be useful to further evaluate for free air, resuscitation and surgical consult should not be delayed for additional imaging.
Selected References
1. Coppolino F, Gatta G, Di Grezia G, et al. Gastrointestinal perforation: ultrasonographic diagnosis. Crit Ultrasound J. 2013;5(suppl 1):S4. doi:10.1186/2036-7902-5-S1-S4.
2. Hefny AF, Abu-Zidan FM. Sonographic diagnosis of intraperitoneal free air. J Emerg Trauma Shock. 2011;4(4):511-513. doi:10.4103/0974-2700.86649.
3. Hoffmann B, Nürnberg D, Westergaard M. Focus on abnormal air. Eur J Emerg Med. 2012;19(5):284-291. doi:10.1097/mej.0b013e3283543cd3.
4. Ma O. Ma and Mateer’s Emergency Ultrasound. McGraw-Hill Education Medical; 2014.
3. Which of the following is most closely associated with an ultrasonographic diagnosis of appendicitis?
A. Compressibility
B. Intraluminal air
C. Anterior to posterior measurement of 5 mm
D. Appendicolith
View Answer
3. Correct Answer: D. Appendicolith
Rationale: Noncompressibility, a visualized appendicolith, and an anterior-posterior measurement >7 mm are all findings consistent with appendicitis. Intraluminal air is typically a normal finding, although the presence of air does not exclude the diagnosis of appendicitis.
Selected References
1. Jeffrey RB, Jain KA, Nghiem HV. Sonographic diagnosis of acute appendicitis: interpretive pitfalls. Am J Roentgenol. 1994;162(1):55-59.
2. Ma O. Ma and Mateer’s Emergency Ultrasound. McGraw-Hill Education Medical; 2014.
3. Mostbeck G, Adam EJ, Nielsen MB, et al. How to diagnose acute appendicitis: ultrasound first. Insights Imaging. 2016;7(2):255-263. doi:10.1007/s13244-016-0469-6.
4. What combination of ultrasonographic findings would be most consistent with bowel perforation?
A. Enhanced echogenicity of the peritoneal stripe and thickened bowel loops
B. Target sign and surrounding localized free fluid
C. Dilated loops of bowel with keyboard sign
D. Thin peritoneal strip and dirty shadowing
View Answer
4. Correct Answer: A. Enhanced echogenicity of the peritoneal stripe and thickened bowel loops
Rationale: Enhanced echogenicity of the peritoneal stripe and thickened bowel loops would be most consistent with bowel perforation. These findings are primary and secondary findings of bowel perforation, respectively. Scattering of sound waves at the interface of soft tissue and air causes a reverberation artifact that enhances the echogenicity of the peritoneal stripe and causes the appearance of A-lines. Thickened bowel loops suggest bowel edema, which often accompanies underlying bowel pathology leading to perforation. A target sign with surrounding free fluid would be more consistent with appendicitis. A thin peritoneal stripe and dirty shadowing are normal ultrasonographic findings.
Selected References
1. Coppolino F, Gatta G, Di Grezia G, et al. Gastrointestinal perforation: ultrasonographic diagnosis. Crit Ultrasound J. 2013;5(suppl 1):S4. doi:10.1186/2036-7902-5-S1-S4.
2. Hefny AF, Abu-Zidan FM. Sonographic diagnosis of intraperitoneal free air. J Emerg Trauma Shock. 2011;4(4):511-513. doi:10.4103/0974-2700.86649.
3. Hoffmann B, Nürnberg D, Westergaard M. Focus on abnormal air. Eur J Emerg Med. 2012;19(5):284-291. doi:10.1097/mej.0b013e3283543cd3.
4. Ma O. Ma and Mateer’s Emergency Ultrasound. McGraw-Hill Education Medical; 2014.
5. A 46-year-old man sustained deep partial-thickness burns to his back and legs. He has a prolonged ICU course complicated by sepsis. Three weeks after admission, he abruptly develops epigastric abdominal pain and dyspnea. His abdomen is not distended, but is exquisitely tender. Ultrasound of his abdomen reveals Figure 64.3.
 Figure 64.3 |
What is the most appropriate next step in his management?
A. Start stool softeners and encourage physical activity
B. Obtain a right upper quadrant ultrasound to evaluate for cholecystitis
C. Obtain a chest CT to further evaluate the pleural effusion
D. Begin resuscitation and get an emergent surgery consult
View Answer
5. Correct Answer: D. Begin resuscitation and get an emergent surgery consult
Rationale: While current recommendations advocate against the use of ulcer prophylaxis in all hospitalized patients, this patient has multiple risk factors for stress ulcers including burns and sepsis requiring a prolonged ICU stay. His ultrasound (Figure 64.3) demonstrates free fluid in Morison’s pouch, which raises suspicion for a stress ulcer with perforation, and an emergent surgery consult would be the preferred next step in management. Cholecystitis is not apparent on this image and the gallbladder is not visualized. This fluid is not a pleural effusion and a chest CT is unnecessary.
Selected References
1. Fashner J, Gitu AC. Diagnosis and treatment of peptic ulcer disease and H. pylori infection. Am Fam Physician. 2015;91(4):236-242.
2. Ma O. Ma and Mateer’s Emergency Ultrasound. McGraw-Hill Education Medical; 2014.
3. Pruitt BA, Goodwin CW. Stress ulcer disease in the burned patient. World J Surg. 1981;5:209-220. doi:10.1007/BF01658293.
6. While working in a rural hospital, a nurse informs you that your patient is complaining of severe abdominal pain, nausea, and vomiting. On physical examination, the patient’s abdomen is tense and diffusely tender. You are concerned about small bowel obstruction (SBO) and start evaluating the patient’s abdomen with ultrasound. The patient’s nurse asks if it would be better to obtain an acute abdominal series. You explain that ultrasound is preferable because:
A. While an acute abdominal series may have a higher sensitivity for diagnosing SBO, ultrasound has a higher specificity.
B. While an acute abdominal series may have a higher specificity for diagnosing SBO, ultrasound has a higher sensitivity.
C. X-ray and ultrasound have comparable sensitivity and specificity for diagnosing SBO, but ultrasound does not expose the patient to ionizing radiation.
D. Ultrasound is both more sensitive and specific for diagnosing SBO compared to an acute abdominal series.
View Answer
6. Correct Answer: D. Ultrasound is both more sensitive and specific for diagnosing SBO compared to an acute abdominal series.
Rationale/Critique: While CT imaging remains the gold standard for diagnosing SBO, multiple studies have demonstrated the superiority of ultrasound compared to radiographs as an early, rapid diagnostic modality for diagnosing SBO, particularly in situations where CT is not available or delayed. Compared to radiographs, ultrasound is both more sensitive and specific for diagnosing SBO. Findings consistent with SBO include dilated loops of bowel >25 mm, abnormal peristalsis, bowel wall edema (normal bowel wall is typically <3 mm), and plicae circulares, also known as “keyboard sign” (see Figure 64.7).
 Figure 64.7 |
Selected References
1. Becker BA, Lahham S, Gonzales MA, et al. A prospective, multicenter evaluation of point-of-care ultrasound for small-bowel obstruction in the emergency department. Acad Emerg Med. 2019;26(8):921-930.
2. Gottlieb M, Peksa GD, Pandurangadu AV, Nakitende D, Takhar S, Seethala RR. Utilization of ultrasound for the evaluation of small bowel obstruction: a systematic review and meta-analysis. Am J Emerg Med. 2018;36(2):234-242.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
