Spontaneous bacterial peritonitis

Question 1

Define SBP

Answer 1

Bacterial infection of peritoneal fluid by mixed enteric flora

Question 2

Presentation of SBP

Answer 2

The answer on USMLE when they give you diffuse abdominal pain and fever in one of the three following scenarios: 1) cirrhosis; 2) recent peritoneal dialysis; 3) nephrotic syndrome.

Shifting dullness” or a “fluid wave” are buzzy for ascites, but questions will often omit these descriptors from stems

Question 3

patient has cirrhosis + abdo pain + fever

Answer 3

SBP

they don’t have to mention a fluid wave, but you just have to
infer, “Well he/she clearly has major risk factor for ascites, so this sounds like SBP.”

Question 4

kid with minimal change disease
(nephrotic syndrome) has abdo pain + fever

Answer 4

spontaneous bacterial peritonitis

Question 5

Diagnosis of SBP

Answer 5

abdominal paracentesis

This refers to aspiration of fluid from the peritoneal cavity. Do not confuse this with pericardiocentesis. “Paracentesis” as an answer shows up everywhere, and
I’ve seen students avoid it because they’re like, “What? I thought that meant pericardiocentesis.”

Question 6

After the paracentesis is done, USMLE wants a very specific order for what to do next for SBP

Answer 6

Choose “white cell count and differential” first if it’s listed, followed by “gram stain and culture of the fluid”

This order is important because “gram stain and culture of the fluid” is correct answer in one Q but wrong answer in another Q, where “white cell count and differential” is correct to do first.

The reason white cell count and differential is done first is because SBP is diagnosed when paracentesis shows >250 WBCs/µL

Question 7

Ascites in patient with cirrhosis, but do not mention fever or abdominal pain; However, they say paracentesis shows 900 WBC//µL. Dx and Tx?

Answer 7

SBP and “antibiotic therapy.”

It should be made clear though that ~6/7 SBP Qs will give abdo pain and fever.

Question 8

Treatment SBP

Answer 8

ceftriaxone