Approach to pneumoperitoneum and peritonitis (perforated viscus): Clinical sciences

Pneumoperitoneum, or the presence of air or gas within the peritoneal cavity, is considered a surgical emergency because it often indicates perforation of the gastrointestinal tract. On the other hand, peritonitis refers to the inflammation of the peritoneum. Depending on the etiology, peritonitis can be divided into primary, secondary, and tertiary.

Here is a clinical pearl! Even a small amount of bacterial seeding within the peritoneal space can progress quickly and become life-threatening. Keep in mind that bacterial infections can be spontaneous if there are preexisting ascites from liver or kidney failure or come from the GI tract through transmural infection or perforation.

When approaching a patient with signs and symptoms suggestive of peritonitis and pneumoperitoneum, first perform an ABCDE assessment to determine if the patient is unstable or stable. If the patient is unstable, stabilize their airway, breathing, and circulation by providing supplemental oxygen, obtaining IV access, and continuously monitoring their hemodynamics.

Alright, now that unstable patients are taken care of, let’s talk about stable ones. Your first step here is to obtain a focused history and physical examination and assess for an acute abdomen. Patients with acute abdomen usually report severe abdominal pain, nausea, vomiting, and bowel changes, as well as fever, chills, and generalized malaise. On a physical exam, you’ll find abdominal distension, tenderness, rigidity, rebound, guarding, decreased/absent bowel sounds. Now, when your clinical exam indicates an acute abdomen, the first thing you want to do is to find and treat the underlying cause.

Let's first look at pneupoeritoneum. When your clinical exam indicates an acute abdomen, your next step is to assess for pneumoperitoneum by obtaining an upright chest or 3 view abdominal x-ray. When it comes to the x-ray, air under the diaphragm is pathognomonic of pneumoperitoneum. Because pneumoperitoneum of any source is a surgical emergency, you need to use specific elements of the patient’s history to guide your differential diagnosis instead of ordering additional tests which can delay operative management.

Alright, if the patient reports the acute onset of severe postprandial epigastric pain, is unable to lie in a supine position, and has a history of GERD you should consider a perforated peptic ulcer. Call the surgical team for emergent operative intervention. The definitive diagnosis will be made intraoperatively.

Another cause of pneumoperitoneum is perforated appendicitis. History might reveal a young otherwise healthy patient with several days of worsening periumbilical or right lower quadrant pain. Call the surgical team for emergent operative intervention. Again, the diagnosis of perforated appendicitis will be confirmed intraoperatively.

Now, if a middle-aged or older patient with a history of diverticulosis and chronic constipation reports left lower quadrant pain, you should consider perforated diverticulitis. This patient will need an emergent operation, which will confirm the diagnosis.

On the other hand, if a patient above the age of 60 with a history of smoking reports anorexia, unintended weight loss, fatigue, as well as a personal or family history of cancer, you need to consider gastrointestinal malignancy like colon cancer as the cause of the perforation. These patients need to be taken to the operating room right away for resection of the mass and diversion of the bowel such as colostomy or ileostomy. A tissue sample of the mass should be sent for pathologic confirmation of the diagnosis.

Finally, in an elderly patient with a history of previous abdominopelvic operation who presents with bilious vomiting, PO intolerance, and bowel changes like constipation, obstipation, or overflow diarrhea, you need to consider small bowel perforation secondary to small bowel obstruction. This happens when the obstruction causes proximal dilatation so much that the bowel wall becomes ischemic. Operative management in this case is to identify the obstruction and resect the ischemic or necrotic segment.