Case

A 32-year-old woman presents with a 6-day history of progressive abdominal distension and nausea. She had recently been an inpatient with an episode of acute pancreatitis. The aetiology of the pancreatitis was familial pancreatitis, with her grandmother, father and one brother having episodes of recurrent pancreatitis. She looked well, was afebrile and was not jaundiced or pale. Abdominal examination revealed a moderately distended abdomen that was tense but not tender. The bowel sounds were normal. There was evidence of shifting dullness and a fluid thrill. A provisional diagnosis of ascites was made.

Laboratory blood tests were all normal in particular the amylase, lipase, liver function tests and albumin. A CT scan confirmed marked ascites. The pancreas was slightly enlarged but well perfused with a slightly prominent pancreatic duct. There were no loculated fluid collections or evidence of pseudocyst formation. A diagnostic aspiration of the fluid revealed it was straw-coloured. Analysis confirmed it was an exudate with no cells and an amylase of over 100 000 I/U (serum ascites–albumin gradient < 11 g/L). This confirmed the clinical suspicion of pancreatic ascites.

The following day an ERCP was performed. The pancreatic duct was dilated at 4 mm with no obvious stricture. There was a leak of contrast from the region of the distal body into the peritoneal cavity. An endoscopic pancreatic stent was inserted with good drainage noted. Over the next 3 days the abdominal distension resolved and she was discharged home. Three weeks later a follow-up CT scan confirmed complete resolution of the ascites and a relatively normal pancreas with the stent in situ. She remained well and the stent was removed after 6 months. Unfortunately, she had further episodes of recurrent acute pancreatitis over the next 4 years and is likely to develop chronic pancreatitis.

Preliminary Examination of the Abdomen

The traditionally taught five causes of generalised abdominal distension (the ‘five Fs’) are: flatus, fluid, faeces, fetus and fat. To this list should be added a sixth: massive organomegaly or ‘filthy big tumour’.

For the patient presenting with generalised abdominal distension, a preliminary abdominal examination is worthwhile before a detailed history is taken to determine which of the ‘six Fs’ is the most likely cause. The reason for this departure from the usual sequence of history followed by examination is that history taking can be greatly simplified if the clinician has some prior idea of the underlying problem.

History and Further Examination

A classification of the causes of abdominal distension is presented in Table 20.1 and relevant symptoms are listed in Table 20.2. The duration of abdominal distension and its association with abdominal pain are key questions. Thus, abdominal pain should not usually be expected to be a feature, except with abdominal distension due to gas in bowel obstruction; with the other causes, there may be milder discomfort due to stretching of the parietal peritoneum or the capsule of an organ. Localised pain can occur with organ swelling. Similarly, the speed of development for most causes is slow, except with abdominal distension from gas, in which case it can be fast. Tense swelling of the abdomen due to fluid or a large tumour can cause increased intraabdominal pressure leading to heartburn, nausea, vomiting or dyspnoea (from elevation of the diaphragm). The specific clinical features for each cause are described below.

Table 20.1 Classification of causes of abdominal distension: the ‘six Fs’

Cause	Example	Distension
1. Flatus (gaseous distension)
Bowel obstructed
Open		Generalised
Closed	Sigmoid volvulus	Localised
	Caecal volvulus	Localised
Bowel not obstructed
	Paralytic ileus	Generalised
	Pseudo-obstruction	Generalised
	Irritable bowel syndrome	Generalised
	Acute gastric dilatation	Localised
	Gas bloat	Generalised
2. Fluid (ascites)	See Table 20.3 for detail	Generalised
3. Faeces		Localised
4. Fat		Generalised
5. Fetus		Localised
6. Filthy big tumour (organomegaly)
Liver	See Chapter 19	Localised
Spleen	See Chapter 19	Localised
Ovary	Ovarian cyst	Localised
Uterus	Fibroids	Localised
Kidney	Polycystic kidney	Localised
Hydronephrosis	–	Localised
Bladder	Obstructed bladder	Localised
Mesentery	Tumour	Localised
Retroperitoneum	Tumour	Localised or generalised

Table 20.2 Possible symptoms with abdominal distension

Symptom	Relevance/significance
Abdominal pain: • abdominal tightness/vague generalised ache; • colicky (periumbilical or lower abdominal).

Nausea/vomiting Bowel obstruction Anorexia Non-specific, malignancy, cirrhosis Loss of weight Non-specific, malignancy, cirrhosis Bowel habit (recent and usual) Bowel obstruction, constipation Respiratory symptoms Secondary to elevation of the diaphragm Previous history of malignant disease As a possible cause of ascites Alcohol or drug abuse As a cause of liver disease and ascites Jaundice