Pneumoperitoneum due to splenic abscess rupture

Clinical History

This 56-year-old male known diabetic patient presented with lethargy, a low grade fever and left hypochondrial pain of 2 weeks duration. On examination his abdomen was a little distended and he had a temperature of 37.5C. Plain abdominal radiograph, ultrasound and CT were subsequently performed.

Imaging Findings

A plain abdominal radiograph was performed on admission showing a relative paucity of bowel gas within the left upper quadrant. The large bowel was gaseous, with an apparent calibre change at the level of the splenic flexure (Fig. 1).

This demonstrated a large, single, but extensive splenic abscess, with foci of gas within (Fig. 2a). A perisplenic collection and foci of gas adjacent to the splenic capsule suggested splenic rupture (Fig. 2b). Multiple foci of free gas were present within the upper abdomen, consistent with pneumoperitoneum (Fig. 3).

Ultrasound guided percutaneous drain insertion was performed, yielding thick brown pus (Fig. 4). After a short period the drain became non-functional despite a persistent collection and the drain was upsized using the Selginger technique. Soon after this the drain content was bloody and CT was performed (Fig. 5).

Discussion

Splenic abscesses are uncommon. Gas-containing splenic abscesses are rare. Perforated gas-containing splenic abscesses are exceptional [1].
In our region, the commonest cause of splenic abscess is Burkholdia pseudomalleoi, in the clinical condition melioidosis. These, however, virtually never contain gas. The usual gas organisms responsible for gas containing splenic abscesses are Klebsiella and E Coli.

Pneumoperitoneum secondary to splenic abscess rupture is rare, but there have been several reported cases [1, 2, 3]. Invariably the patient is immunosupressed, it being particularly common in those with diabetes mellitus. However, there have been reports of pneumoperitoneum caused by a gas-forming splenic abscess in a patient with AIDS, presenting with an acute abdomen [2].

Pathology in the spleen is more limited than many other intra-abdominal organs. Although usually well visualised on ultrasound it can be challenging to accurately see the spleen in its entirety. However, CT offers superb images with splenic abscesses well delineated in the portal venous phase. Abscesses may be fluid, solid-cystic or solid appearing. Rarely they contain foci of gas due to gas forming organisms. Large and peripherally located abscesses may perforate the splenic capsule causing both a perisplenic collection and even a pneumoperitoneum. Cautious image guided percutaneous drain insertion may be considered on a case by case basis. It is advisable that the surgical team are aware before the procedure is performed, in case of any complication, in particular bleeding.

The patient's pyrexia discontinued with 48 hours of the insertion of the percutaneous drain. Multiple further ultrasounds demonstrated that despite an improving clinical condition, the abscess had not fully resolved. Repeat CT confirmed a large persistent abscess but no evidence of a fistulous communication. In view of this the decision to upsize the drain to 8F was taken, along the existing tract. Initially, frank pus drained, but this was promptly followed by venous blood. In view of this, limited CT was performed confirming fresh blood within the abscess cavity. The patient remained haemodynamically stable and the drain was removed 4 days later.

Gas-forming splenic abscesses are rare, but may perforate causing a pneumoperitoneum.

Caution with splenic/perisplenic drain insertion, given the spleen's vascular nature.

Even with frank pus, a micro-organism is not always identified.

Differential Diagnosis List

Final Diagnosis

Pneumoperitoneum secondary to splenic abscess rupture.

URL:	https://eurorad.org/case/9350
DOI:	10.1594/EURORAD/CASE.9350
ISSN:	1563-4086