Pneumoperitoneum – CXR

27 Pneumoperitoneum – CXR



image

Fig. 27.1A Pneumoperitoneum on an erect chest X-ray.



Background


The erect chest x-ray is the most important plain film for diagnosis of perforated abdominal viscus.


The patient needs to be erect for 5 minutes before a chest radiograph is taken. It does not matter if the radiograph is AP or PA. If there is a perforated viscus, air will rise and collect beneath one or both hemidiaphragms.


This technique is about 80% sensitive for perforation. Lateral films are reportedly more sensitive for detection of pneumoperitoneum [1] but rarely performed in practice.


The commonest causes of air under the diaphragm are perforated peptic ulcer (large volume of air), perforated diverticular disease (smaller amount of air) and perforation of obstructed bowel (small or large bowel).


The presence of pneumoperitoneum usually mandates an exploratory laparotomy. However, remember that there are causes of air under the diaphragm for which an operation is not necessary. These include recent laparotomy/laparoscopy, pneumatosis coli, peritoneal dialysis (look for a peritoneal dialysis tube and appropriate history), and entry through the female genital tract (again the history will determine this).



Clinical features



Symptoms


There is abdominal pain, of sudden onset. Because the pain of peritonitis irritates the parietal peritoneum, the patient will prefer to lie still and will experience pain on movement.


Pain may be referred to the shoulder tip due to diaphragmatic irritation.



Signs



• Signs of peritonism (guarding, rebound, rigid abdomen, silent abdomen).

• Shock. Beware the patient on steroids, who may have few signs or symptoms.


Radiological features



image

Fig. 27.1B Air collects under the hemidiaphragm (arrow 1). The upper border of the liver is outlined by free air superiorly (arrow 2). The thin diaphragmatic outline is seen, outlined by air underneath it (free air) and air above it in the lung (arrow 3).


The continuous diaphragm sign may be seen in pneumoperitoneum as well as pneumopericardium as free intraperitoneal air outlines the undersurface of the central diaphragm (see p. 104).

Only gold members can continue reading. Log In or Register to continue

Related posts:

Permanent pacemakers Gastric outlet obstruction Caecal volvulus Small bowel obstruction Pleural effusion Intussusception

Stay updated, free articles. Join our Telegram channel
Tags:
Aug 20, 2016 | Posted by in ULTRASONOGRAPHY | Comments Off on Pneumoperitoneum – CXR

Full access? Get Clinical Tree
Get Clinical Tree app for offline access