QuestionSBA
QuestionChoice
This is correct. Neutrophils will be raised in bacterial peritonitis due to the localised inflammatory response. Positive ascitic fluid bacterial cultures will also confirm. E.coli is the most common bacteria grown
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a
Neutrophil count of more than 250/mm3
QuestionChoice
This is associated with malignancy or haemorrhagic pancreatitis. In SBP, the ascitic fluid may appear cloudy, but there should not be any visible blood
31929
b
Bloody appearance to ascitic fluid
QuestionChoice
Ascitic amylase is typically raised in pancreatic ascites and is usually normal in SBP
31932
e
Raised amylase
QuestionChoice
Ascitic glucose is typically normal in SBP and low in secondary bacterial peritonitis. However, a normal glucose would not **confirm** a diagnosis of SBP
31930
c
Low glucose
QuestionChoice
An ascitic pH of <7.0 suggests bacterial infection but will not confirm a diagnosis
31931
d
pH 7.1
QuestionComment
SBP: High neutrophils, normal glucose
CSF: Low Glucose - bacteria eats the sugar
Secondary Peritonitis due to e.g. dialysis or something: Low glucose
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# Summary

Ascites is the accumulation of fluid within the peritoneal cavity, commonly seen in patients with cirrhosis. Key signs and symptoms include abdominal distension, discomfort, and dyspnea. The primary investigation is an ascitic tap to analyse the fluid's content, and the Serum Ascites Albumin Gradient (SAAG) helps determine the cause. Management strategies target the underlying cause, dietary restrictions, and diuretic therapy. Refractory cases may require regular therapeutic paracentesis.

# Definition

Ascites is defined as the abnormal accumulation of fluid within the peritoneal cavity. This condition is typically associated with liver disease, particularly cirrhosis, but can also occur due to other medical conditions affecting the heart, kidneys, or peritoneum.

# Epidemiology

Ascites is a common complication of cirrhosis and represents a key landmark in the natural history of chronic liver disease. The prevalence and incidence of ascites depend significantly on the severity and duration of liver disease.

# Aetiology

The mechanism of ascites formation is complex and not fully understood. It is thought to involve portal hypertension causing increased hydrostatic pressure, leading to the transudation of fluid into the peritoneal cavity.

Causes include liver disorders (cirrhosis, acute liver failure, liver metastases), cardiac causes (right heart failure) and others such as Budd-Chiari, Portal vein thrombosis etc. (see below).

Other types of ascites can form due to reduced oncotic pressure (nephrotic syndrome, Kwashiorkor), or due to malignancy (peritoneal carcinomatosis, or peritoneal metastasis), or infection (increased permeability – TB), and other causes of 3rd spacing (acute pancreatitis).

# Signs and Symptoms


- Abdominal distension
- Abdominal discomfort or pain
- Dyspnea
- Reduced mobility
- Anorexia and early satiety due to pressure on the stomach
- Tense abdomen
- Shifting dullness
- Stigmata of the underlying cause (see below)

# Differential Diagnosis

The differential diagnosis for ascites includes conditions like:

- Cirrhosis: jaundice, spider angioma, palmar erythema, hepatic encephalopathy
- Heart failure: dyspnea, orthopnoea, lower extremity oedema
- Budd Chiari syndrome: abdominal pain, liver enlargement, jaundice
- Constrictive pericarditis: dyspnea, peripheral oedema, raised jugular venous pressure
- Hepatic failure: jaundice, coagulopathy, mental status changes
- Peritoneal cancer: abdominal pain, weight loss, changes in bowel habits
- Tuberculosis: fever, night sweats, weight loss, cough
- Pancreatitis: severe abdominal pain, nausea, vomiting
- Nephrotic syndrome: proteinuria, hypoalbuminaemia, edema

# Investigations

- The primary investigation for ascites is an ascitic tap, which can provide valuable information about the content of the ascitic fluid. This is usually done under USS guidance to avoid e.g. perforating bowel.
- The SAAG can help to determine the cause of ascites. It is calculated by subtracting the albumin concentration of the ascitic fluid from the serum albumin concentration.
- Bloods (to help determine the underlying cause) - FBC, U+E, LFTs, CRP
- Imaging - CT abdomen, CXR (looking for signs of right-sided heart failure)

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# Serum ascites albumin gradient (SAAG)calculation

The **serum ascites albumin gradient** (SAAG) can help to determine the cause of ascites.

Calculation: serum albumin concentration – ascites albumin concentration

## Causes of a high SAAG (>11g/L)

- Cirrhosis
- Heart failure
- Budd Chiari syndrome
- Constrictive pericarditis
- Hepatic failure

A high SAAG (>11g/L) suggests that the cause of the ascites is due to raised portal pressure. Raised hydrostatic pressure forces water into the peritoneal cavity whilst albumin remains within the vessels, thus resulting in a higher difference in the albumin concentration between the serum and ascitic fluid.

## Causes of a low SAAG (<11g/L)

- Cancer of the peritoneum, metastatic disease
- Tuberculosis, peritonitis and other infections
- Pancreatitis
- Hypoalbuminaemia - nephrotic syndrome, Kwashiokor

# Management

The management of ascites primarily involves:

- Addressing the underlying cause
- High SAAG - implementing a salt-restricted diet and fluid restriction
- Administering **spironolactone** is first line. Providing adjunctive diuretic therapy such as furosemide if spironolactone is insufficient.
- Conducting regular therapeutic paracentesis for patients with ascites refractory to medical management, whereby the fluid is drained from the abdomen over a few hours. These patients require replacement with human albumin solution (HAS) in order to avoid the ascites re-accumulating.
- If the ascitic tap shows neutrophils >250mm<sup>3</sup>, this is diagnostic of **spontaneous bacterial peritonitis**, a serious complication of ascites. This is treated with intravenous piperacillin-tazobactam.
	- Prophylactic antibiotics – 1st line = ciprofloxacin (indication if cirrhotic with ascites and ascites protein <15g/L, until ascites has resolved OR previous SBP OR hepato-renal syndrome OR child pugh C)
- For refractory ascites in portal hypertension, a TIPS (transjugular intrahepatic portosystemic) shunt procedure can be considered.

# References

[British Society of Gastroenterology - Management of Ascites in Cirrhosis](https://www.bsg.org.uk/clinical-resource/guidelines-on-the-management-of-ascites-in-cirrhosis/)

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An example appearance of ascites.
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Gastroenterology
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A neutrophil count exceeding 250/mm³ in ascitic fluid indicates spontaneous bacterial peritonitis in patients with liver disease.
A 50-year-old female with known non-alcoholic fatty liver disease (NAFLD) and associated ascites presents to the emergency department unwell. She is pyrexial and has generalised abdominal pain. Paracentesis is performed.

Which of the following results from the ascitic fluid would confirm a diagnosis of spontaneous bacterial peritonitis (SBP)?
a