PP patients may have a medical history of gastrointestinal disease or recent surgery, and corresponding anamnestic data should be considered when interpreting clinical signs, before deciding on a therapeutic approach. While the presence of free air in the peritoneal cavity cannot be diagnosed during a general examination, abdominal distension, intense pain, rigidity and rebound tenderness are indicative of peritonitis and possibly GIT perforation. In these cases, bowel sounds are usually absent and patients present constitutive symptoms like fever, volume depletion, hypotension and tachycardia; they may suffer from nausea and vomiting. Furthermore, patients may report not to have passed stools or gasses since symptom onset [1].

In contrast, postoperative PP doesn't generally cause major complaints, and mild to moderate abdominal distension and pain may merely result from the underlying disease or surgery. This condition should normalize within a week.

• Pain

  CASE EXAMPLE: A typically young, otherwise healthy woman comes into the emergency department of Stanford University, California, complaining of recurrent chest pain. [ncbi.nlm.nih.gov]

  A 56-year-old man presented to the emergency department with a 3-day history of diarrhea and dull epigastric pain. The diarrhea had responded to antidiarrheal agents. [nejm.org]

  Conclusions US can be a useful bedside screening test for pneumoperitoneum in patients with acute abdominal pain. [dx.doi.org]

• Asymptomatic

  INTRODUCTION: Benign pneumoperitoneum (BPPT) is defined as asymptomatic free intraabdominal air or as pneumoperitoneum without peritonitis. [ncbi.nlm.nih.gov]

  The management dilemma is when the pneumoperitoneum is asymptomatic without signs of peritonitis. [emjreviews.com]

  The incidence of spontaneous air leaks is not fully evaluated since the presentation can be asymptomatic, but the incidence has been shown to be increasing. [omicsonline.org]

  The asymptomatic and stable patient should be kept under surveillance and usually no intervention is needed.1,5 However, in the presence of abdominal pain, tenderness, rigidity, progressive distension, fever, hemodynamic instability, leucocytosis or evidence [elsevier.es]

  We present a case report of a patient with benign asymptomatic pneumoperitoneum and review the causes of this uncommon entity. [aafp.org]

• Fever

  Patients with small bowel perforation may present with a prolonged history of fever followed by the appearance of pain in lower abdomen. [ncbi.nlm.nih.gov]

  After 4 days of hospitalisation, the patient developed low-grade fever of (38.5 oC), while the patient’s abdominal physical exam was normal except for distention. [emjreviews.com]

• Inflammation

  An explorative laparotomy revealed a cecal perforation caused by bowel-wall inflammation due to enteritis, as well as severe bowel dilatation. After repair of the perforation, the patient was discharged in good health 1 month later. [nejm.org]

  Blood studies showed only slight abnormalities, in particular, inflammation parameters were not significantly increased. Finally, obtained CTs showed free abdominal gas of unknown origin in both cases. [ncbi.nlm.nih.gov]

  The ability to produce ex vivo cytokines was less hampered in the early postoperative period when low pressure was present, and there was less hypoxia and inflammation at the surgical site. [physiciansweekly.com]

  Rarely, emphysematous inflammation of abdominal organs may give rise to PP. PP may also occur after penetrating abdominal trauma or abdominal surgery. [symptoma.com]

  Apart from direct bowel wall inflammation by SARS-CoV-2, intestinal dysbiosis, as well as immunological alteration in lung via gut-lung axis, local disseminated intravascular coagulation, vasculitis secondary to hypercoaguable state in COVID-19 infection [anncaserep.com]

• Surgical Procedure

  If the free air is due to recent surgical procedure it should resolve within 3-7 days and serial films should show decreasing amounts of free air. [med-ed.virginia.edu]

  Pneumoperitoneum may be Iatrogenic in nature or which that results from surgical procedures and other medical procedures or activity such as: Laparoscopy Laparoscopy is a surgical procedure intended for the abdomen or pelvis and which is performed with [hubpages.com]

  Pneumoperitoneum is usually seen after bowel perforations and surgical procedures. An increasing number of cases of non-surgical pneumoperitoneum related to sexual activity has been reported worldwide over the last years. [ncbi.nlm.nih.gov]

  Non-surgical causes of pneumo-peritoneum can be categorized as postoperative, thoracic, abdominal, gynecologic and idiopathic. Abdominal surgical procedures either open or laparoscopic leads to free intra-peritoneal air. [ispub.com]

• Dyspnea

  This approach dramatically relieved the tension pneumoperitoneum and dyspnea. Our patient then recovered smoothly; the catheter was removed on postoperative 24, and she was discharged on postoperative day 28. [ncbi.nlm.nih.gov]

  Three days after admission, he reported sudden severe dyspnea, nausea, and abdominal distension. [ajtmh.org]

  Three of them had clinical signs of tension pneumoperitoneum including vital compromise (dyspnea, hypotension and congested jugular veins) in addition to abdominal pain and distension. [bmcgastroenterol.biomedcentral.com]

  Four days after PEG tube placement, the patient developed abdominal distension and dyspnea. Complications with feeding, hygiene and PEG tube mobilization were denied by the caregivers. [elsevier.es]

• Abdominal Pain

  Hollow organ perforation is a surgical life-threatening emergency that presents with acute abdominal pain. [ncbi.nlm.nih.gov]

  A 4-year-old girl presented to the hospital with progressive abdominal pain and distention after a 1-week history of watery diarrhea. [nejm.org]

• Abdominal Distension

  Blood pressure returned to normal, and peripheral pulse became palpable as abdominal distension subsided. [dx.doi.org]

  distension following the insertion of a rectal thermometer. [europeanmedical.info]

  Polypnea and subcutaneous emphysema in the upper and lower left quadrants were noticed, as well as abdominal distension and diffuse tenderness with peritoneal signs. [elsevier.es]

• Acute Abdomen

  The patient presented with chronic pain abdomen and fever which later evolved to acute abdomen during the course of hospital stay. [ncbi.nlm.nih.gov]

  Pyometra is an unusual cause of peritonitis, but it must be considered as a possible diagnosis in elderly women presenting with an acute abdomen. [dx.doi.org]

  ACUTE ABDOMEN WITH PNEUMOPERITONEUM. J Family Community Med 2004 May-Aug;11(2):71-2. 9. Campos Canelas AL, Fernandez HM, Crociati Meguins L, Silva Barros S, Crociati Meguins EM, Ishak G, Rodrigues De Moraes LA. [oadoi.org]

• Abdominal Tenderness

  Five months later he was admitted with abdominal pain and cloudy CAPD bags. On admission he was afebrile but tachycardic with generalized abdominal tenderness. [ncbi.nlm.nih.gov]

  tenderness in 4, and leukocytosis in 4. [dx.doi.org]

• Diarrhea

  A 56-year-old man presented to the emergency department with a 3-day history of diarrhea and dull epigastric pain. The diarrhea had responded to antidiarrheal agents. [nejm.org]

  Patients were all admitted to hospital with the major clinical symptom of abdominal distension, including 2 cases accompanied by tachypnea, 2 cases with vomiting, 1 case with diarrhea, and 2 cases with fever. [ncbi.nlm.nih.gov]

  GI symptoms like anorexia, nausea, vomiting, and diarrhea are encountered in patients and these end up being more critical than expected in normal scenario. [anncaserep.com]

• Jaundice

  Symptoms include pain related to the gallbladder (biliary colic), inflammation of the gallbladder (cholecystitis), obstruction to the flow of bile from the liver and gallbladder into the small bowel resulting in jaundice (yellowish discolouration of the [cochrane.org]

• Tachycardia

  Normal heart rhythm, with transient tachycardia, recurred after a short cardiac massage, intravenous atropine and epinephrine administration as well as pneumoperitoneum decompression. ECG after the episode showed nonspecific ST segment changes. [ncbi.nlm.nih.gov]

  She had sinus tachycardia (130 beats per min) and tachypnoea (28 breaths per min) but was normotensive with normal peripheral oxygenation saturations. [thelancet.com]

  In these cases, bowel sounds are usually absent and patients present constitutive symptoms like fever, volume depletion, hypotension and tachycardia; they may suffer from nausea and vomiting. [symptoma.com]

  With prolonged procedures, CO2 retention is possible as evidenced by tachycardia and acidosis. [laparoscopy.blogs.com]

• Ulcer

  A) B) A) CT from a patient with a duodenal ulcer (arrows) B) Left lateral decubitus film from the same patient demonstrating pneumoperitoneum (A) resulting from perforation on duodenal ulcer after patient received steroids for treatment of COPD. [med-ed.virginia.edu]

  Causes The most common cause is a perforated abdominal viscus, generally a perforated ulcer, although any part of the bowel may perforate from a benign ulcer, tumor or trauma. A perforated appendix seldom causes a pneumoperitoneum. [wikidoc.org]

  Perforated gastric and duodenal ulcers; an analysis of 73 cases. Calif Med. 1951 Apr; 74 (4):250–252. [ PMC free article ] [ PubMed ] [ Google Scholar ] WINHAM AJ, PECHSTEIN GR. Clinical and roentgen observations of a newly perforated peptic ulcer. [ncbi.nlm.nih.gov]

  The most common cause is a perforation of the abdominal viscus—most commonly, a perforated ulcer, although a pneumoperitoneum may occur as a result of perforation of any part of the bowel; other causes include a benign ulcer, a tumor, or trauma. [emedicine.medscape.com]

  Lesions predisposing to this accident are as follows: gastric or duodenal ulcer; ileal ulcer complicating typhoid fever; rupture of the urinary bladder, and perforating abdominal wounds. [pubs.rsna.org]

• Irritability

  Causes of acute abdomen in children Constipation Prescription Did you ever think feeling angry and irritable could be a symptom of constipation? A horrible fullness and pressing sharp pains against the bladders can’t help but affect your mood. [europeanmedical.info]

  Conclusion Our experience, which coincides with others’, suggests that in absence of peritoneal irritation, a conservative management should be chosen. However, if the patient deteriorates with conservative management, one should proceed to surgery. [ghrnet.org]

  During the physical exam, the patient’s vitals were stable, with soft but distended abdomen with hypoactive bowel sound and no signs of peritoneal irritation. In addition, decreased bilateral air entry was noted over the lung field on auscultation. [emjreviews.com]

  On admission, the patient was alert with normal vital signs, and his abdomen was soft with no signs of peritoneal irritation. [dx.doi.org]

Abdominal imaging is the mainstay of PP diagnosis. To this effect, plain radiography has long since been the technique of first choice. Very small volumes of free gas - as little as 1 ml - can be observed in images obtained by means of this technique. Upright, anterior-posterior chest radiographs are most suited and typically depict a translucent, crescent area below the diaphragm [7]. The Rigler's sign may be observed; it corresponds to the display of both sides of the intestinal wall [8]. Similarly, the telltale triangle sign implies PP: A triangle of gas may be visualized between three adjoining bowel loops, or two loops and the peritoneal wall [9]. In emergency settings, radiographs may be obtained from a patient in the supine decubitus position.

Computed tomography scans may be reserved for doubtful cases. Its superior spatial resolution is helpful to localize minimum quantities of free gas and to distinguish PP from pseudo- pneumoperitoneum. The latter term refers to any condition that mimics PP, such as pneumatosis cystoides intestinalis and interposition of viscera [10].

• Pneumoperitoneum

  Pneumoperitoneum Treatment of Pneumoperitoneum Continuing Medical Education (CME) CME Programs on Pneumoperitoneum International Pneumoperitoneum en Espanol Pneumoperitoneum en Francais Business Pneumoperitoneum in the Marketplace Patents on Pneumoperitoneum [wikidoc.org]

  Progressive pneumoperitoneum increased the length of abdominal muscles. Hernia. 2009 Apr; 13(2): 183–7. Piskin T, Cemalettin A, Barut B, Dirican A, Kayaalp C. Preoperative progressive pneumoperitoneum for giant inguinal hernias. [facs.org]

  Figure 1: Pneumothorax and pneumoperitoneum. Figure 2: Bowel loop of normal calibres with a large pneumoperitoneum and air fluid levels. [emjreviews.com]

• X-Ray Abnormal

  Abdominal X-ray - Abnormal bowel gas pattern Free gas/pneumoperitoneum Key points Bowel perforation is a surgical emergency An ERECT chest X-ray should be requested if perforation is suspected Be familiar with Rigler's sign Free gas, or pneumoperitoneum [radiologymasterclass.co.uk]

• Leukocytosis

  Laboratory evaluation showed leukocytosis, with a white-cell count of 20,400 per cubic millimeter and 82% segmented neutrophils. No anemia was found. [nejm.org]

  Pneumoperitoneum observed up to 48 d status post laparoscopic hysterectomy, in the absence of peritoneal signs, fever, leukocytosis, or hemodynamic instability, may be considered for expectant management and serial inspection for clinical change. [ncbi.nlm.nih.gov]

Once the fistula is diagnosed, treatment options are several. Conservative versus operative treatment is currently a matter of debate generally regarding timing, patient's condition and fistula's size. [ncbi.nlm.nih.gov]

[…] patient#4 Image courtesy of RadsWiki and copylefted Large pneumoperitoneum after indomethicin treatment patient#4 Image courtesy of RadsWiki and copylefted CT CT can visualize quantities as small as 5 cm³ of air or gas. [wikidoc.org]

Conservative treatment is usually preferred mode of treatment. Laparotomy is usually performed if signs are suggestive of peritonitis and the patient deteriorates on conservative treatment. [ispub.com]

Delay in recognizing and treatment can significantly worsen prognosis. In neonate with intestinal perforation one should consider Hirschsprung's disease. [ncbi.nlm.nih.gov]

In 1957 Wolcott and Murphy 1 stated that the prognosis and management of lung abscess has changed dramatically in the past 15 years. They reported on 70 patients treated since 1941. [jamanetwork.com]

Asymptomatic pneumomediastinum has good prognosis and it resolves spontaneously. Pneumopericardium and pneumoperitoneum are rare event. But when pneumomediastinum is accompanied with pneumopericardium and symptomatic, the prognosis gets worse. [omicsonline.org]

Treatment The treatment and prognosis of pneumoperitoneum depend on its cause. The initial step of treatment is identifying the underlying condition that causes the air retention within the peritoneal cavity. [hubpages.com]

The most well-accepted etiology is an increase in arterial and venous pressures causing the rupture of subcutaneous capillaries, although the exact etiology remains unclear. [ncbi.nlm.nih.gov]

Etiology TP has several etiologies (Table). Gastrointestinal perforation —Gastrointestinal perforation is the most common etiology of TP. [hcplive.com]

"Systematic review: the epidemiology of ischaemic colitis". Alimentary Pharmacology & Therapeutics. 19 (7): 729–38. doi:10.1111/j.1365-2036.2004.01903.x. hdl:2027.42/74164. PMID 15043513. S2CID 9575677. ^ Brandt LJ, Boley SJ (May 2000). [en.wikipedia.org]

Stroup DF, Berlin JA, Morton SC, et al; Meta-analysis of Observational Studies in Epidemiology (MOOSE) Group. Meta-analysis of observational studies in epidemiology: a proposal for reporting. JAMA. 2000;283(15):2008-2012. [jamanetwork.com]

In cases of atypical non-surgical pneumoperitoneum in sexually active women, a careful inquiry into the medical-sexual history can reveal the cause of pathophysiology without comprehensive, painful and unnecessary diagnostics. [ncbi.nlm.nih.gov]

[…] dysbiosis, as well as immunological alteration in lung via gut-lung axis, local disseminated intravascular coagulation, vasculitis secondary to hypercoaguable state in COVID-19 infection, bowel edema leading to over distension of bowel all, play important pathophysiology [anncaserep.com]

Neonatal pneumoperitoneum is a surgical emergency indicative of gastrointestinal perforation that requires immediate treatment to prevent death. [ncbi.nlm.nih.gov]

To prevent pneumatic perforation during upper GI endoscopy, patients should be well prepared and fasted prior to the examination. [dx.doi.org]

The term pneumoperitoneum (PP) refers to the presence of gas within the peritoneal cavity. Most commonly, this gas originates from the gastrointestinal tract (GIT) and thus indicates a disruption of its physical integrity. Any part of the GIT may be affected and PP may complicate diseases like gastric ulcer, mesenteric infarction, toxic megacolon, and abdominal cancer. Interestingly, perforated appendicitis seldom entails PP [1]. Rarely, emphysematous inflammation of abdominal organs may give rise to PP [2]. PP may also occur after penetrating abdominal trauma or abdominal surgery. Postoperative PP may or may not indicate leaking anastomoses, since air may be introduced into the peritoneal cavity during surgery [3]. Indeed, PP may be induced intentionally by insufflation of carbon dioxide or helium to facilitate laparoscopic procedures and intraperitoneal chemotherapy [4]. Although such a measure may be contraindicated in patients suffering from cardiorespiratory disorders and increased intracranial pressure [5] [6], the presence of gas within the abdominal cavity per se is not detrimental. However, pathological PP as described above is virtually always associated with the presence of pathogens and toxins in the peritoneal cavity. Therefore, it is an indicator of a life-threatening situation that requires emergency surgery.

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2. Hateley C, Alcada J, Park M, Vaid N, Buckley J. Pneumoperitoneum, a urological source. Lancet. 2016;387(10015):284.
3. Lee CH, Kim JH, Lee MR. Postoperative pneumoperitoneum: guilty or not guilty? J Korean Surg Soc. 2012;82(4):227-231.
4. Henretta MS, Anderson CL, Angle JF, Duska LR. It's not just for laparoscopy anymore: use of insufflation under ultrasound and fluoroscopic guidance by Interventional Radiologists for percutaneous placement of intraperitoneal chemotherapy catheters. Gynecol Oncol. 2011;123(2):342-345.
5. Neuhaus SJ, Gupta A, Watson DI. Helium and other alternative insufflation gases for laparoscopy. Surg Endosc. 2001;15(6):553-560.
6. Kamine TH, Elmadhun NY, Kasper EM, Papavassiliou E, Schneider BE. Abdominal insufflation for laparoscopy increases intracranial and intrathoracic pressure in human subjects. Surg Endosc. 2016;30(9):4029-4032.
7. Pinto A, Miele V, Schilliro ML, et al. Spectrum of Signs of Pneumoperitoneum. Semin Ultrasound CT MR. 2016;37(1):3-9.
8. Rigler LG. Spontaneous pneumoperitoneum: A roentgenologic sign found in the supine position. Radiology. 1941;37:604–607.
9. Huang MY, Chang WH. Images in clinical medicine. Telltale triangle of pneumoperitoneum. N Engl J Med. 2009;361(1):73.
10. Lo BM. Radiographic look-alikes: distinguishing between pneumoperitoneum and pseudopneumoperitoneum. J Emerg Med. 2010;38(1):36-39.