Pneumoperitoneum: ED Presentation, Evaluation, and Management

Authors: Rebecca O’Neill, DO (TY, PGY-1, David Grant Medical Center, Travis AFB, CA) and Lane Thaut, DO (EM Attending Physician, David Grant Medical Center, Travis AFB, CA) // Reviewed by: Erica Simon, DO, MPH, MHA (@E_M_Simon); Alex Koyfman, MD (@EMHighAK); Brit Long, MD (@long_brit)

Case:

A 43-year-old obese female presents to the ED with sudden onset abdominal pain. The pain began one hour prior while eating dinner. The patient reports nausea, but denies vomiting, diarrhea, dark or bloody stools, fevers, recent travel, and sick contacts. Surgical history is significant for a Roux-En-Y procedure performed two weeks prior. The patient called her surgeon immediately following the onset of her abdominal pain, and was directed to the ED for evaluation.

Vitals: BP 138/82, HR 112, RR 18, T 37℃, SpO2 97% RA
The patient is anxious, tearful, and holding her abdomen in pain.

What is your differential diagnosis? What are the next steps in your evaluation and treatment?

 

Differential Diagnosis 

Time Sensitive: AAA, aortic dissection, mesenteric ischemia, perforated hollow viscous, and acute myocardial infarction.

Roux-En-Y complications: Anastomotic leak, marginal ulcer, cholecystitis, choledocholithiasis, dumping syndrome, small bowel obstruction.1

Other: Lower lobe pneumonia, pancreatitis, cirrhosis, hepatitis, GI bleed, appendicitis, diverticulitis, ischemic colitis, mesenteric ischemia, renal colic, and constipation.2

 

Background

Pneumoperitoneum is defined as extra-luminal “free” air or fluid collection found on diagnostic imaging. Perforated viscus is the most common etiology in adults (85%–95% of cases); more specifically a perforated peptic ulcer (75% of cases).3 Operative intervention is required for the majority of patients.3

 

Etiologies of pneumoperitoneum include:

  • Physical perforation of a hollow viscus secondary to: endoscopy, NG intubation, esophageal dilation, paracentesis, peritoneal dialysis, surgery,4 toothpicks, chicken bones, fish bones,5 or recent CPR.6 Tumors in the GI tract may cause hollow viscus perforation proximal to site of obstruction due to increase intraluminal pressures.7
  • Physical and/or chemical perforation of a hollow viscus such as in the case of button battery ingestion.8
  • Medication-related perforations (e.g. NSAID use leading to peptic ulcer disease).9
  • Perforations secondary to inflammatory processes: inflammatory bowel disease, diverticulitis, and appendicitis.10
  • Perforations due to ischemia or pressure necrosis: bowel strangulation from a hernia or volvulus.11
  • Gynecologic etiologies: pelvic inflammatory disease, sexual abuse, pelvic examination and instrumentation, and rarely, sexual intercourse.6
  • Recreational activities: diving with decompression sickness.

Complications may arise as free gas accumulates in the peritoneal cavity. Diaphragmatic function may be compromised, resulting in a tension pneumoperitoneum, or abdominal compartment syndrome, the manifestations of which may be hypoxia, hypercarbia, high peak inspiratory pressures (if intubated), bowel ischemia, oliguria, and renal failure.2

 

Patient Presentation

Depending upon the underlying etiology and volume of free air/fluid, patients with pneumoperitoneum may range from asymptomatic to critically ill.12 Adult patients commonly report symptoms such as abdominal pain, chest pain, dyspnea, nausea, or vomiting. Some may present with fever. If the perforation is along the esophagus, dyspnea may occur.3 Diaphragmatic irritation can lead to referred pain to the shoulder as well (Kehr sign).13

 

Evaluation

Assess the ABCs and establish your safety net.

 

History

The amount of history obtained will depend upon the acuity of the patient. Where is the pain? Ask the patient to point to it. Keep in mind that retroperitoneal perforations often lead to back pain, and young children and the elderly frequently have atypical or vague symptoms.2 Has this patient had pain like this prior to presentation? Has he been vomiting?14 Could she have ingested a foreign body while eating?5 If it is a small child, could the child have ingested a small object while unattended?8,15

What is the medical history? Medications? NSAIDS and glucocorticoids decrease the inflammatory response, delaying detection of symptoms.9,17 History of peptic ulcer disease, irritable bowel disease, diverticular disease?10 Risk factors for cardiovascular disease? Mental illness (ingestion of foreign bodies)? Any recent procedures or surgeries?3

 

Physical Exam

  • General: These patients may or may not be ill appearing.
  • HEENT, Pulmonary: Always perform a thorough physical exam of these areas as perforations can occur anywhere along the GI tract, and pneumoperitoneum may be accompanied by pneumomediastinum as well (see this emDocs post).
  • Abdomen: The abdomen may or may not be distended. Distention is common in patients with perforation secondary to small bowel obstruction. Evaluate for peritoneal signs and palpate for masses (malignancy, intra-abdominal abscess). Mild focal abdominal tenderness is common with retroperitoneal perforations.2
  • Rectal: Evaluate for a palpable or painful mass, which could be a phlegmon or abscess.2

 

Obtain an EKG if indicated.

 

Labs

Laboratory testing should be guided by the history, physical examination, and differential diganosis:2

  • Complete Blood Count, Basic Metabolic Profile, Liver Function Tests, Lipase, BhCG, UA17,18

In acutely ill or unstable patients add: Coagulation studies, type and screen/cross, lactate2

 

Imaging

With high suspicion of perforation: STAT Upright Chest Radiograph (up to 80% sensitivity).2  If possible, direct the patient to sit fully upright or in a left lateral decubitus position for 10-20 min prior to imaging. If unable to sit upright: supine and lateral decubitus films should be
obtained.20,21

What am I looking for on the radiograph?

  • Free air under the diaphragm in upright abdominal films.
  • Cupola sign (inverted cup): an arcuate lucency over the lower thoracic spine.22
  • For patients who receive a supine radiograph: visualization of both the inner and outer walls of bowel, known as the “Rigler sign,” is indicative of free air, and can be easily overlooked.3

 

Ultrasound: In skilled hands, ultrasound may be utilized for rapid assessment, but is frequently limited by patient body habitus and bowel gas.2 In order to assess for free air, the patient should be scanned in the supine and left lateral decubitus positions with a linear array transducer directed towards the epigastrium and right upper quadrants.23

What am I looking for on ultrasound?

  • Enhancement of the peritoneal stripe.24
  • Presence of air in abnormal locations (Figure 2: gastrohepatic ligament).25
  • In the patient with ascites: hyperechoic gas bubbles, often referred to as comet tails/ ring down artifacts,22 or floating echogenic foci in the ascitic fluid.23

 

If you are having difficulty differentiating between intraperitoneal free air and intraluminal bowel gas, consider using dynamic maneuvers:26

  • Free intraperitoneal air will move with patient position, or with deep breaths.
  • Free air in the epigastrium, detected during supine evaluation, will shift to the right upper quadrant when the patient transitions to the left lateral recumbent position.23
  • You may be able to displace the air with caudal pressure on the ultrasound probe. This air will reappear after pressure is removed.26

 

CT abdomen with oral contrast:

  • Extra-luminal air or oral contrast, free fluid, discontinuity of the intestinal wall, fistulas, or abscesses.28 Extravasation of oral contrast is associated with increased mortality.2

 

Management

If imaging is positive for free air/fluid: consult surgery. If there is a large amount of free air on plain abdominal films,24-26 or an increase in the amount of free air from previous imaging,29-31 and the patient reports abdominal tenderness, he/she will go directly to the operating room.32

The patient should be made NPO. Broad-spectrum antibiotics which target anaerobes and facultative, aerobic, gram negative bacteria are indicated for suspected abdominal sepsis and peritonitis. Recommended regimens include: Piperacillin-Tazobactam 3.375mg IV q6hr, Imipenem-cilastatin, Ertapenem, Meropenem, Cefepime + Metronidazole, Ceftriaxone + Metronidazole, Ciprofloxacin/Levofloxacin + Metronidazole. Piperacillin-Tazobactam 3.375mg IV q6hr or a carbapenem is often utilized in patients with suspected biliary sepsis. A proton pump inhibitor should be added if there is suspicion of an upper GI tract perforation.2

Opioid analgesics will not obscure abdominal findings and should be administered for analgesia, as well as antiemetics for nausea/vomiting.2

A quick word regarding the postoperative period: Demonstration of free intra-abdominal air may be seen on a radiograph for up to a week postoperatively, however, the volume of the intra-abdominal air should gradually decrease with time. Always consider serial images or admission for observation in a patient reporting increased pain or new onset symptoms.1

 What if the CT is negative for air/fluid? Who gets admitted? If the CT is negative, but the patient has intractable vomiting and pain, is elderly, immunocompromised, unable to communicate, cognitively impaired, or lacks social support, admission should be considered.2

 

Back to the Case

The patient’s abdominal examination was absent rebound and guarding. Laboratory studies were significant for a WBC of 17 x 109 cells/L. Lipase was within normal range. BhCG and UA were negative. CT of the abdomen with PO contrast revealed pneumoperitoneum and contrast extravasation at the gastrojejunostomy anastomosis, the most common site of a leak following a Roux-En-Y (Figure 3).

IV antibiotics were given, and general surgery was consulted. The patient was ultimately taken to the OR for repair of the anastomotic leak.

 

Key Points:

-The elderly, children, and immunosuppressed may have perforated viscus with only mild abdominal tenderness to palpation on exam.

-When the anatomy of the gastrointestinal tract has been altered, pneumoperitoneum should always be on your differential.

-The yield of an upright chest x-ray to detect free air may be improved by having the patient sit fully upright or in a left lateral decubitus position for 10 to 20 minutes (if possible) prior to imaging.

 

References/Further Reading:

  1. Seeras K, Lopez P. Roux-en-Y gastric bypass. StatPearls[Internet]. 2019. Accessed 4 Nov 2019. Available from https://www.ncbi.nlm.nih.gov/books/NBK519489/.
  2. Tintinalli, J, Stapczynski, J, Ma, O, Yealy, D, Meckler, G and Cline, D. (2016). Tintinalli’s emergency medicine. 8th ed. McGraw-Hill Education, pp.182, 481-489.
  3. Tanner TN, Hall BR, Oran J. Pneumoperitoneum. Surgical Clinics of North America. 2018;98(5):915-932.
  4. Nassour I, Fang SH. Gastrointestinal perforation. JAMA Surg 2015; 150:177.
  5. Katsetos MC, Tagbo AC, Lindberg MP, Rosson RS. Esophageal perforation and mediastinitis from fish bone ingestion. South Med J 2003; 96:516.
  6. Tallant C, Tallant A, Nirgiotis J, Meller J. Spontaneous pneumoperitoneum in pediatric patients: A case series. International Journal of Surgery Case Reports. 2016;22:55-58. doi:10.1016/j.ijscr.2016.03.017.
  7. Kang MH, Kim SN, Kim NK, et al. Clinical outcomes and prognostic factors of metastatic gastric carcinoma patients who experience gastrointestinal perforation during palliative chemotherapy. Ann Surg Oncol 2010; 17:3163.
  8. Fuentes S, Cano I, Benavent MI, Gómez A. Severe esophageal injuries caused by accidental button battery ingestion in children. J Emerg Trauma Shock 2014; 7:316.
  9. Morris CR, Harvey IM, Stebbings WS, et al. Anti-inflammatory drugs, analgesics and the risk of perforated colonic diverticular disease. Br J Surg 2003; 90:1267.
  10. West AB, NDSG. The pathology of diverticulitis. J Clin Gastroenterol 2008; 42:1137.
  11. Case courtesy of Dr Vikas Shah, https://radiopaedia.org/”>Radiopaedia.org</a>. From the case <a href=”https://radiopaedia.org/cases/56066″>rID: 56066</a>
  12. Moore LJ, Moore FA. Early diagnosis and evidence-based care of surgical sepsis. J Intensive Care Med 2013; 28:107.
  13. Moore, K., Agur, A. and Dalley II, A. (2015). Essential clinical anatomy. 5th ed. Philadelphia, Pa: Wolters Kluwer, pp.111-194.
  14. Wu JT, Mattox KL, Wall MJ Jr. Esophageal perforations: new perspectives and treatment paradigms. J Trauma 2007; 63:1173.
  15. Peters NJ, Mahajan JK, Bawa M, et al. Esophageal perforations due to foreign body impaction in children. J Pediatr Surg 2015; 50:1260.
  16. Spoormans I, Van Hoorenbeeck K, Balliu L, Jorens PG. Gastric perforation after cardiopulmonary resuscitation: review of the literature. Resuscitation 2010; 81:272.
  17. Abid S, Mumtaz K, Jafri W, et al. Pill-induced esophageal injury: endoscopic features and clinical outcomes. Endoscopy 2005; 37:740.
  18. Wu Z, Freek D, Lange J. Do normal clinical signs and laboratory tests exclude anastomotic leakage? J Am Coll Surg 2014; 219:164.
  19. Singh PP, Zeng IS, Srinivasa S, et al. Systematic review and meta-analysis of use of serum C-reactive protein levels to predict anastomotic leak after colorectal surgery. Br J Surg 2014; 101:339.
  20. Cho KC, Baker SR. Extraluminal air. Diagnosis and significance. Radiol Clin North Am 1994; 32:829.
  21. Ghahremani GG. Radiologic evaluation of suspected gastrointestinal perforations. Radiol Clin North Am 1993; 31:1219.
  22. Marshall Geoffrey B. “The Cupola Sign.” Radiology 241, no. 2 (November 1, 2006): 623-624.
  23. Hanbidge A, Khalili K, Wilson S. “The Peritoneum.” In Diagnostic Ultrasound. 5th Philadelphia, PA: Elsevier: 2018.14:504.
  24. Gaillard F. Pneumoperitoneum (A Summary). rID 17957. Radiopaedia.org. Available at: https://radiopaedia.org/cases/17957. Accessed August 27, 2019.
  25. D’Anverrs. P. Pneumoperitoneum. rID: 46608. Radiopaedia.org. Available at: https://radiopaedia.org/cases/46608. Accessed August 27, 2019.
  26. Patel, MS. Pneumoperitoneum. rID: 14804. Radiopaedia.org. Available at: https://radiopaedia.org/cases/14804/. Accessed August 27, 2019.
  27. Hefny AF, Abu-Zidan FM. Sonographic diagnosis of intraperitoneal free air. Journal of Emergency Trauma Shock. 2012;4 (4): 511-3.
  28. Shah, V. Small Bowel Infarction and Perforation. rID: 56066. Radiopaedia.org. Available at: https://radiopaedia.org/cases/56066. Accessed August 27, 2019.
  29. Zissin R, Osadchy A, Gayer G. Abdominal CT findings in small bowel perforation. British Journal of Radiology 2009; 82:162.
  30. Peirce GS, Swisher JP, Freemyer JD, et al. Postoperative Pneumoperitoneum on Computed Tomography: is the operation to blame? American Journal of Surgery 2014; 208:949.
  31. Gayer G, Jonas T, Apter S, et al. Postoperative pneumoperitoneum as detected by CT: prevalence, duration, and relevant factors affecting its possible significance. Abdominal Imaging 2000; 25:301.
  32. Farooqui MO, Bazzoli JM. Significance of radiologic evidence of free air following laparoscopy. Journal of Reproductive Medicine. 1976; 16:119.
  33. Jacobsen HJ, Nergard BJ, Leifsson BG, et al. Management of suspected anastomotic leak after bariatric laparoscopic Roux-en-y gastric bypass. British Journal of Surgery 2014; 101:417.

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