The different types of abdominal wall hernias and their features are listed in Box 19.1. Abdominal wall hernias are generally easy to characterise as a cough impulse is usually present, the hernia may present in a characteristic position and it may be possible to reduce the hernia. To separate other masses found within the abdominal wall from masses within the abdominal cavity, ask the patient to contract the anterior abdominal muscles by lifting his or her head from the examining couch with hands behind head, or to straight leg raise both legs simultaneously while keeping the head on the bed. This may help to define the mass as follows:

• A mass within the abdominal cavity (the peritoneal cavity) will be made less distinct, less easy to palpate and may disappear altogether until the abdominal wall muscles are relaxed again.

Box 19.1 Causes of abdominal wall masses

Lumps that could occur anywhere on the body

These arise in the skin and subcutaneous fat and include:

• lipoma;

• sebaceous cyst; and

• neurofibroma.

Lumps specific to the anterior abdominal wall

Arising from a process elsewhere (metastatic)

• Tumour: metastatic nodule in umbilicus secondary to intraperitoneal malignancy (known eponymously as a Sister Mary Joseph nodule)

Arising in the abdominal wall fascia and muscle

• Rectus sheath haematoma (usually painful)

• Desmoid tumour (associated with Gardiner’s syndrome; Ch 22)

Herniae

• Incisional: previous abdominal surgery. Mass in line of scar. Sac and apparent mass may be much larger than hernia neck.

• Umbilical: hernia through umbilicus. Congenital umbilical herniae commonly resolve in infancy.

• Paraumbilical: the neck of the hernia is just lateral to the umbilical scar. Usually present later in life.

• Epigastric: knuckle of extraperitoneal fat extrudes through a small linea alba defect, between xiphoid process and umbilicus. Usually small (under 2 cm), commonly irreducible, no cough impulse.

• Spigelian: rare. Found along linea semilunaris at lateral edge of rectus sheath. Usually a third of the way between the umbilicus and the pubis.

Divarication of the rectus muscles

• Supraumbilical elliptical bulging of attenuated linea alba between the recti when the patient strains. Not a true hernia and no cough impulse.

Figure 19.2 Unexpected palpable metastatic melanoma. Patient presented for assessment of dementia.

• A mass within the abdominal wall muscle layers becomes less easy to define when the abdominal wall muscles are contracted, but is less likely to disappear altogether than the type above.

• A mass that is within the abdominal wall but that is superficial to the abdominal wall muscles will be made more obvious when the abdominal wall muscles are contracted, as it is then palpated against the tightened abdominal wall muscles.

Retroperitoneal Masses

The retroperitoneal region is subdivided into five regions:

• a central column containing the great vessels and surrounding lymph nodes and the pancreas and duodenum overlying them;

• two lateral upper regions containing the kidneys and adrenals, plus the ascending colon on the right and the descending colon on the left; and

• two lateral lower regions that lie below the posterior brim of the pelvis and contain the right ureter and caecum on the right, and the left ureter and the lower descending colon on the left.

Palpation features of retroperitoneal masses

Retroperitoneal masses are fixed by their retroperitoneal attachments and do not move on palpation or with respiration. Retroperitoneal masses in the upper lateral regions may be ballotable on bimanual palpation. This sign is elicited by dipping the fingers of one hand into the renal angle while palpating the corresponding point on the anterior abdominal wall with the other hand. The mass is then held forward by pressure from the posterior hand and may be felt by the other hand palpating through the anterior abdominal wall.

The classic ballotable mass is an enlarged kidney. A mobile but normal right kidney is sometimes ballotable in thin patients. Other laterally placed masses, such as cancers of the ascending and descending colon, are rarely ballotable. Adrenal masses are not ballotable because they are situated above the posterior-inferior chest wall margin. An enlarged spleen is not ballotable. As the spleen enlarges, the lower pole of the spleen expands downwards and forwards into the abdomen while the upper pole remains covered by the posterior rib cage.

Masses in the central column are covered behind by the spine and the erector spinae muscles whereas masses in the lower lateral regions are protected by the pelvis.

Intraabdominal Masses

Site

On the basis of position (Fig 19.1), we can start to define the likely organ of origin of an intraabdominal mass as shown in Table 19.1. However, we cannot be certain of the organ of origin of a palpable mass on the basis of its position alone. Organs do not necessarily enlarge concentrically from a fixed point. The pattern of enlargement may be determined by surrounding structures, by retroperitoneal attachments and by the pathological process responsible for the organ enlargement. The liver, for example, is limited by the diaphragm along the superior surface and by the diaphragm and ribs along the lateral surface and so tends to enlarge downwards and inwards. The uterus and bladder are limited by the pelvic walls laterally and below and so tend to enlarge upwards in the midline. The kidneys, aorta and pancreas are retroperitoneal and limited behind by the posterior abdominal wall and so tend to expand from their original site in all directions except posterior. An enlarged segment of small bowel is usually not found in the upper reaches of the abdomen because the transverse mesocolon, the transverse colon and the greater omentum are attached to retroperitoneal tissues along a horizontal line at the level of the inferior border of the pancreas. These three organs tend to form a barrier restricting upward migration of small bowel masses.

Table 19.1 Organ of origin of intraabdominal masses by region

Right hypochondrium	Epigastrium	Left hypochondrium
Right lobe of liver	Stomach	Spleen
Gall bladder	Left lobe of liver	Pancreas^∗
	Pancreas^∗	Stomach
	Lymph nodes^∗
	Aorta^∗
Right lumbar region	Periumbilical	Left lumbar
Ascending colon^∗	Omentum	Descending colon^∗
Right kidney^∗	Transverse colon	Left kidney^∗
	Aorta^∗
	Retroperitoneal nodes^∗
Right iliac fossa	Hypogastrium	Left iliac fossa
Appendix	Bladder	Sigmoid colon
Caecum^∗	Uterus	Iliac aneurysm^∗
Iliac aneurysm^∗	Right and left ovary^∗	Left ovary^∗
Right ovary		Iliac nodes^∗
Iliac nodes^∗

∗ Strictly retroperitoneal in position

A single pathological process may have focal or diffuse effects in a given organ and may have different effects on the different organs involved. A cancer of the sigmoid colon may become fixed to the posterior abdominal wall by local invasion. Omental metastatic deposits from the same sigmoid colon cancer will not move with respiration but may be relatively mobile on palpation. Hepatic metastatic deposits from the same cancer may move with respiration as the liver moves, but will not move on palpation.

An enlarged organ may come to fill several adjacent abdominal regions if the degree of enlargement is great. Thus, in the third trimester of pregnancy, an enlarged pregnant uterus can be expected to fill the hypogastrium, the periumbilical region and part of the epigastrium.

The likely organ of origin may be defined by the position of the mass as in Table 19.1.

Discriminating clues that may be found on examination and that the patient may report on closer questioning may help establish the causative process. See Table 19.2 and Box 19.2.

Table 19.2 Clinical clues that may be present with an apparently asymptomatic abdominal mass

Box 19.2 Features of an abdominal mass that should be defined on clinical examination

• Is it superficial or deep to the anterior abdominal wall?

• Is there a cough impulse?

• Is it single or multiple?

• What is the position of the mass?

• What are the shape and dimensions?

• Can all of the margins be palpated? Are the margins sharp, blunt or indistinct?

• Is the surface texture smooth or irregular?

• Is the consistency hard, firm or soft?

• Does it appear to descend from behind the costal margins (can’t get above it) or arise from the pelvis (can’t get below it)?

• Does the mass move with respiration or does it move on palpation?

• Is it indentable?

• Is there tenderness?

• Is there pulsation? (transmitted or expansile)

• Is the inferior margin palpable per rectum or per vagina?

• Is the mass resonant or dull on percussion

• Is there a bruit on auscultation?

Movement with respiration

The diaphragm moves inferiorly with inspiration and back up to its neutral position with expiration. Immediately below the diaphragm are the liver and the spleen. An enlarged liver or spleen will move inferiorly with each inspiratory effort. As well as moving inferiorly, the liver edge and the inferior pole of the spleen move medially relative to the costal margin.

Other organs in the upper abdomen do not move with respiration. Retroperitoneal organs (the pancreas, aorta, kidneys and lymph nodes) are relatively fixed to the posterior abdominal wall, so that they are not displaced inferiorly with each movement of the liver and spleen, which slide over them. Intraabdominal pressure rises during inspiration, compressing hollow organs such as the stomach, transverse colon and small bowel, and limiting the movement of these organs.

An enlarged gall bladder moves inferiorly with respiration as it is firmly attached to the liver. Similarly an inflammatory mass or a neoplastic mass just inferior to the liver but attached to the inferior surface of the liver, though not to retroperitoneal structures, will also move inferiorly with respiration. Hepatic masses or perihepatic masses may not move with respiration if attached to the body wall in front, laterally or behind.

Relation to costal margin and brim of pelvis

Palpation of the upper reaches of the abdominal cavity is prevented by the costal margins. Thus, the full extent of hepatomegaly and splenomegaly is not appreciated by abdominal palpation. Unlike a mass in the transverse colon or omentum, a superior edge of an enlarged liver or spleen by palpation cannot be defined. Palpation of the pelvic cavity is restricted by the pubis in front and by the rest of the pelvic ring laterally and behind. Accordingly, the examiner cannot rely on anterior abdominal examination to define an inferior margin of enlarged organs that lie in the pelvis (bladder and uterus). However, rectal or vaginal examination may allow palpation of the inferior margin of pelvic masses.

Mobility

Most abdominal masses are relatively immobile. Neoplastic masses involving the omentum, transverse colon, sigmoid colon and small bowel are the most likely to display some mobility. All of these organs are anteriorly placed and loosely attached to the posterior abdominal wall by a mesentery. Inflammatory masses of the bowel (which are usually painful) tend to be less mobile because inflammatory adhesions tend to fuse these masses to adjacent structures. So a carcinoma of the small bowel may well result in a mobile mass whereas a mass due to Crohn’s disease of the small bowel will be tender and will usually be adherent and immobile.

Shape, edge and consistency

The most common asymptomatic intraabdominal mass is caused by faecal loading of a segment of colon (Fig 19.3), usually caecum or sigmoid colon. A loaded colon tends to be tubular or sausage-shaped with a lobular surface contour. The orientation of a caecum loaded with faeces is vertical, while that of sigmoid colon is oblique, parallel to the inguinal ligament. Pressure on the surface of the mass by pressing a finger or thumb into it through the anterior abdominal wall may result in indentation of the surface of the mass. This is an uncommon but characteristic diagnostic feature of constipation with faecal loading.

Figure 19.3 Faecal loading in the transverse colon.

Malignant tumours tend to be vaguely nodular to palpation; benign tumours usually have a smooth contour. Malignant tumours tend to be hard in consistency, whereas benign tumours may be soft.

Single or multiple

If more than one mass is found, the differential diagnosis is narrowed. The most common cause of multiple abdominal masses is constipation. The next most common cause is multiple peritoneal secondaries.

Tender or non-tender

An asymptomatic abdominal mass is unlikely to be tender. Tenderness implies inflammation, which may be due to infection, infarction or haemorrhage into the mass (Table 19.3).

Table 19.3 Tender abdominal masses ^∗

Position of mass	Features on examination	Diagnosis
Right hypochondrium	Localised, moves with respiration, can’t get above it	Acute cholecystitis, empyema of the gall bladder Haemorrhage or infarction in a liver tumour (or cyst)
Right hypochondrium	Enlarged liver	Cholangitis Portal pyaemia Hepatic metastases Acute severe right heart failure
Epigastric	Immobile	Pancreatic pseudocyst Pancreatic phlegmon Dissection in abdominal aortic aneurysm
Left hypochondrium	Enlarged spleen	Splenic infarct
Right loin	Enlarged kidney	Pyonephrosis Renal cell carcinoma
Periumbilical	Pulsatile	Dissection in abdominal aortic aneurysm
Right iliac fossa	Immobile	Appendix phlegmon/abscess Crohn’s disease
Hypogastrium	Enlarged bladder Enlarged uterus Enlarged ovary	Acute urinary retention Haemorrhage or infarction in a fibroid Haemorrhage or infarction in an ovarian tumour/cyst Acute pyosalpinx
Left iliac fossa	Immobile, sometimes palpable bimanually	Acute diverticular phlegmon Diverticular abscess

∗ Usually symptomatic

Pulsatile or non-pulsatile

Aneurysms can develop in any large artery in the abdomen, but the aorta is the most commonly affected artery and palpable abdominal aneurysms are almost always in the abdominal aorta. The mass caused by an aneurysm of the abdominal aorta is found in the midline just above the umbilicus and displays expansile pulsation, expanding laterally in both directions with each pulsation. Expansile pulsation is detected by bimanual pulsation over the mass to distinguish it from transmitted pulsation. Transmitted pulsation arises from a mass situated between the aorta and the anterior abdominal wall. This will transmit the aortic pulsation anteriorly, but not laterally. If there is any doubt and the patient is well enough, ask the patient to crouch on hands and knees while the mass is palpated again. If an overlying mass is mobile with respect to the posterior abdominal wall, then the mass may fall away from the aorta and will no longer transmit the pulsation. If the patient is not able to cooperate with this and diagnostic doubt remains an urgent abdominal ultrasound scan or CT scan may be indicated. If the haemodynamic status of the patient is unstable urgent operation may be indicated without resort to scanning.

Percussion note

Solid abdominal tumours are dull to percussion and this technique may help in approximating tumour dimensions. The upper level of liver is not palpable as it is behind the ribs. The level of the superior hepatic margin may be determined by percussion over the lower thorax on the right in the midclavicular line. This, along with palpation of the inferior margin should allow determination of the liver span (its normal span is under 12.5 cm). If this is not done a ptosed liver may be mistaken for hepatomegaly.

Bruit or silent

Auscultation over a mass may reveal a bruit. Bruits are most commonly limited to systole and are caused by turbulent (non-laminar) flow in a narrowed artery. A continuous or machinery bruit may be heard over an extremely vascular tumour. It signifies the presence of significant arteriovenous shunting within the tumour. A bruit over the liver may also occur in acute alcoholic hepatitis or with an arteriovenous malformation.

Bimanually palpable on rectal or vaginal examination

Masses within the lower half of the abdomen, particularly those in the hypogastrium (inferior to the umbilicus), may arise from the pelvic organs, in particular the bladder, uterus or ovaries. Origin from within the pelvis may be suspected if the lower margin of a mass cannot be palpated because of the bony pubis. The mass should be further characterised by bimanual palpation from above and below. This is achieved by palpating the superior edge of the mass with one hand on the abdomen, while attempting to palpate the inferior edge with either the index finger of the other hand in the rectum or the index and middle fingers in the vagina. For a bimanual rectal examination, the patient is positioned in the left lateral decubitus position with the hips and knees flexed. For bimanual vaginal examination, the patient is positioned supine with hips and knees flexed and hips externally rotated.

If a mass arising from within the pelvis can be palpated bimanually its size, surface characteristics and relationship to the uterus may be ascertained using this technique. The lower edge of the bladder cannot be appreciated per rectum or per vagina. An ovarian mass should be distinguishable from the uterus bimanually; the circular indentation of the cervix is used to help identify the uterus.

Several other important observations may be made during a rectal examination. First, the rectum may be loaded with faeces. This is consistent with the presence of one or more abdominal masses caused by constipation. Secondly, there may be evidence of peritoneal spread of a malignant tumour of the stomach, colon or ovary. The sign to seek is the presence of a hard, irregular and relatively fixed tumour mass anterior to the rectum at the tip of the examining finger on rectal examination (Blumer’s shelf), though this is rare. Finally, there may be blood on the glove from a previously unsuspected colon cancer or the hard irregular mass of a rectal tumour (Ch 22).

Having defined the features of the mass, the clinician should review the clinical history with a focus on symptoms possibly associated with the provisional diagnoses. On specific questioning, symptoms that were previously overlooked by the patient might be recalled (see Box 19.3).

Box 19.3 Examples of vague symptoms that may be revealed only after the mass is uncovered

Non-specific symptoms

• Mild abdominal discomfort

• Lethargy, easy fatigueability

• Weight loss, anorexia

• Nausea, vomiting

• Bloating

Symptoms indicating an extraabdominal consequence of the disease process

• Worsening angina due to cardiac decompensation caused by occult blood loss and iron deficiency anaemia

• Dyspnoea from a pleural effusion due to pulmonary spread of an abdominal malignancy

• Superficial thrombophlebitis due to paraneoplastic phenomena

Symptoms suggesting the disease process or organ

• Upper gut—heartburn, dyspepsia, dysphagia, early satiety

• Lower gut—altered bowel habit, blood, mucus or pus in stools, colicky abdominal pain

• Pancreas/biliary tree—pruritus, jaundice, steatorrhoea

Other signs on general physical examination

The physical examination is completed mindful of the working diagnosis, based on the finding of an abdominal mass. Specific examples of relevant positive findings are listed in Table 19.4.

Table 19.4 Examples of extraabdominal signs that may be associated with an asymptomatic abdominal mass

Sign	Associated abdominal mass
Pallor	Gastrointestinal malignancy with occult bleeding
Wasting	Advanced malignancy
Signs of chronic liver disease (palmar erythema, spider naevi, gynaecomastia, testicular atrophy, ascites, caput medusae)	Splenomegaly associated with portal hypertension Hepatic mass due to hepatocellular carcinoma in cirrhosis
Hard, fixed irregular breast lump Hard supraclavicular lymph node Signs of pleural effusion	Hepatomegaly due to metastatic breast cancer Epigastric mass due to stomach cancer Mass of malignant origin or benign ovarian tumour (Meigs’ syndrome)

Office Tests

The finding of occult blood in the faeces provides supportive evidence that an abdominal mass might be due to a gastrointestinal malignancy and guides further examination and testing to the gastrointestinal tract. But, as faecal occult blood testing is neither sensitive nor specific (Ch 10), definitive examinations will be required, for instance by colonoscopy and biopsy. Similarly, the finding of blood or protein in the urine, while also non-specific, may focus attention on the urinary tract.

Imaging

Plain radiology

Plain abdominal x-rays are of limited value in the assessment of abdominal masses. Consequently, this step is often omitted in favour of more powerful imaging tools, particularly cross-sectional imaging such as ultrasound and CT scanning.

Plain abdominal x-ray is useful in the detection of pathological calcification including:

• calcification in the wall of an arterial aneurysm;

• plate-like or curvilinear calcification in the wall of a liver hydatid cyst (Fig 19.4);

• calcification due to chronic pancreatitis;

• calcification in an ovarian mass suggestive of ovarian teratoma.

Figure 19.4 Abdominal x-ray. Incidentally found curved, plate-like calcification (circled) consistent with a hydatid cyst.

A plain chest x-ray examination should also be performed and may reveal:

• rounded shadows due to pulmonary metastases; or

• pleural effusion due to pulmonary metastases.

Ultrasound and CT

These modalities should allow definition of the abdominal organ involved and often, the pathologic process responsible for a palpable mass. Each scanning technique has particular advantages. Ultrasound scanning discriminates well between cystic and solid lesions. CT scanning is better in obese people as adjacent structures can be separated visually by intervening lucent fat planes. Ultrasound images are often suboptimal in obese patients. Further, if the space between the anterior abdominal wall and the palpable mass contains gas-filled loops of bowel, these will cast posterior shadows and distortions on the ultrasound scan images but not the CT scan images, making CT scanning the preferred technique for imaging of unexpected abdominal masses (Ch 26).

In practice, if the overall information yielded is inadequate to complete a management plan after the first examination, whether ultrasound or CT, then the other scan is usually performed as well.

Confirmation of an abdominal mass or an enlarged abdominal organ on imaging

The next investigations depend on the results from ultrasound or CT scans.

Liver

First, ask yourself: is the enlargement uniform or irregular? The possible causes of a diffuse, uniform enlargement are listed in Box 19.4. If CT has detected small, low density but non-specific lesions or if liver enlargement is irregular or patchy, ultrasound scanning is useful to determine whether the lumps are solid or cystic. Evaluation of lumps in the liver is discussed in detail in Chapter 26. Cystic hepatic lesions are most commonly due to simple cysts. These may be quite large, may be multiple and are frequently discovered incidentally (Fig 19.5A and 19.5B). Though rare, hepatic neoplastic cysts (cystadenomas) should be excluded. Hydatid cysts are not infrequent in Echinococcus spp. endemic areas but are generally easy to diagnose on ultrasound or CT scans, which usually reveal daughter cysts within the main cyst.

Box 19.4 Causes of hepatomegaly

Diffusely enlarged but irregular

• Metastatic disease

• Cirrhosis

• Hydatid disease

• Polycystic liver disease

Localised swellings

• Riedel’s lobe (a normal variant—the lobe may be palpable in the right lumbar region)

• Metastasis

• Large simple hepatic cyst

• Hydatid cyst

• Hepatoma

• Liver abscess (e.g. amoebic abscess)

From Talley NJ, O’Connor S. Clinical examination. 6th edn. Sydney: Elsevier Australia; 2010.

Figure 19.5 CT scans. Massive hepatic cyst detected on abdominal exam. Elderly patient admitted with a stroke.

If the hepatic lesion is single and solid, it is likely to be a solitary secondary deposit but may be a primary hepatoma, particularly if there is a history of chronic liver disease. The other single solid lesions discussed in Chapter 26 tend to be less massive and are less likely to cause hepatomegaly.

If hepatomegaly is due to multiple solid lesions, metastatic liver disease is the likely explanation. The next step will then be to establish the primary tumour site. The common sources are colon, pancreas, stomach, breast and lung. Histological confirmation of the diagnosis should usually be sought, provided this does not risk compromising the treatment and chances of cure by seeding along the biopsy track or by rupture of the tumour. A biopsy of the primary tumour is preferred as the histology from the liver may well be consistent with malignancy but still be non-discriminatory about the primary site. Furthermore, biopsy of a primary tumour, whether by gastroscopy, colonoscopy, bronchoscopy or needle biopsy, is generally safer than liver biopsy. If the primary tumour cannot be found, then ultrasound or CT-guided biopsy of the hepatic mass may be indicated to secure a diagnosis of metastatic disease but, even then, the primary site may remain enigmatic.

Gall bladder

Gall bladder enlargement due to obstruction of the common bile duct (e.g. carcinoma of the head of the pancreas or ampulla of Vater) will usually be associated with jaundice (Ch 23). A gallbladder mucocele usually forms a smooth, globular swelling in the right upper quadrant and may be relatively painless and non-tender. Enlargement due to carcinoma of the gall bladder is unusual.

Massive splenomegaly

• Haematological disease (e.g. chronic myeloid leukaemia, myelofibrosis)

Moderate splenomegaly

The above cause plus:

• portal hypertension (hepatic and prehepatic causes);

• haematological disease (e.g. lymphoma, leukaemia, thalassaemia);

• storage disease (e.g. Gaucher’s disease).

Small splenomegaly

The above causes plus:

• infective (hepatitis, leptospirosis, malaria, bacterial endocarditis)

• haematological disease (e.g. haemolytic anaemias, essential thrombocythaemia, polycythaemia rubra vera)

• connective tissue diseases or vasculitis (e.g. rheumatoid arthritis, systemic lupus erythematosus, polyarteritis nodosa)

• solitary cyst, polycystic syndrome, hydatid cyst

• infiltration (amyloid, sarcoid)

Hepatosplenomegaly

• Chronic liver disease with portal hypertension

• Haematological disease (e.g. myeloproliferative disease, lymphoma)

• Infection (e.g. acute viral hepatitis, infectious mononucleosis)

• Infiltration (e.g. amyloid, sarcoid)

• Connective tissue disease (e.g. systemic lupus erythematosus)

From Talley NJ, O’Connor S. Clinical examination. 6th edn. Sydney: Elsevier Australia; 2010.

The spleen may be reported as enlarged on CT scanning but if the spleen is not palpable and there is no apparent cause, the radiological finding of slight splenic enlargement is often misleading.

Colon

Asymptomatic masses arising in the colon are most likely to be due to constipation or to tumours, usually malignant. Smaller benign tumours of the colon may cause intussusception, when the key presenting feature is usually colicky abdominal pain.

Faecal masses (Fig 19.3) are quite firm but should be indentable and should disappear with purgation. Neoplastic masses arising in the colon are usually firm to hard. They may or may not be mobile, but do not indent. As is also the case for masses in the stomach, colonic masses are poorly imaged by ultrasound. By the time colonic neoplastic masses are palpable, the origin in colon can usually be determined by CT scan. However, conclusive diagnosis requires a tissue biopsy for histopathology. Biopsy usually requires a colonoscopy. Staging of malignant tumours is described in Chapter 22.

Small bowel

A palpable small bowel mass will be apparent on CT. The causes of asymptomatic small bowel masses are shown in Table 19.5. Unlike the stomach and the colon, endoscopy of the small bowel is difficult. If further radiological imaging of a small bowel mass is required after CT, it is usually achieved by small bowel series, often carried out as a small bowel enema or CT enterography. If radiological imaging has not been adequate and there is no suggestion of an obstructing lesion in the small bowel, capsule endoscopy may be indicated. Small bowel enteroscopy is available in highly specialised centres.

Table 19.5 Causes of small bowel masses

Cause	Pathology	Comment
Cyst	Mesenteric cyst	Congenital Fluid collection in the mesentery derived from remnants of reduplicated bowel

Tumour Benign Malignant

Lipoma

Hamartoma (e.g. Peutz-Jeghers syndrome)

Adenocarcinoma

Carcinoid tumour Lymphoma

Intussusception May have a polyp or tumour at its leading edge Inflammation Crohn’s disease

Inflammatory mass therefore usually fixed and often tender

Check for anal/perianal signs and for extraabdominal signs

Preoperative biopsy of a small bowel tumour may not be possible. However, a PET scan may reveal a glucose avid tumour in the small bowel, suggesting malignancy, either adenocarcinoma or lymphoma. If the neoplastic process is confined to the small bowel, histological confirmation may not be achieved until small bowel resection has been carried out. If there is disease outside the small bowel, for instance in lymph nodes or in the liver, biopsy of these may yield definitive histopathology.

Omentum

Normal omentum is never palpable. Omentum becomes palpable only when it is infiltrated by tumour, usually by transperitoneal spread (transcoelomic metastases). The common sites of origin of transcoelomic metastases are colon, ovary, stomach and pancreas. Melanoma is the most common extraabdominal primary malignancy causing metastases to the omentum and small bowel. Omental secondaries are usually associated with some degree of ascites. Tapping the ascites, with ultrasound guidance if the amount is subclinical, provides a specimen for cytology (Ch 20). If ascitic fluid is not available for cytology, transcutaneous needle biopsy of omental masses is usually possible under imaging guidance.

Metastatic disease in the omentum always denotes advanced disease, whatever the organ of origin. Once cytology or histopathology is available, medical oncology advice should be sought though further treatment, while possibly providing worthwhile palliation, is unlikely to be curative. A gynaecological opinion should also be sought if an ovarian source seems likely.

Aorta

An abdominal aortic aneurysm may present as an asymptomatic mass detected on clinical examination or as an unexpected finding on abdominal imaging. After an abdominal aortic aneurysm has been detected, it is important to measure its width (side to side), as the risk of sudden rupture of the aneurysm is related to aneurysm width. While a reasonable estimate of the width of an aneurysm can be made on clinical examination, ultrasound or CT scanning is more accurate. If the proximal extent of the aneurysm cannot be defined it may involve the renal arteries, making subsequent repair more difficult. This may be difficult to ascertain on physical examination and the width and proximal extent should always be checked on an abdominal ultrasound or CT scan. The management decision should be made by a vascular surgeon, but operative graft replacement or endoluminal grafting is usually indicated if the aneurysm is greater than 5.5 cm in diameter. If the aneurysm is 3–4 cm, monitor with ultrasound every 2–3 years; if 4–5.4 cm, monitor every 6 months. An expansion of over 0.5 cm in 6 months is another indication for surgery.

Bladder

An enlarged bladder is nearly always an obstructed bladder and initially should be drained by urinary catheterisation. The abdomen should then be re-examined.

Ovaries

Ovarian enlargement may be suggested by a mass arising from the pelvis with the lower margin palpable on bimanual examination as outlined above. Ultrasound scanning is useful for sorting solid masses from cysts or cystic neoplasms, but full assessment of suspected ovarian neoplasms usually requires abdominal and pelvic CT scanning. Specialist gynaecological opinion should be sought when an enlarged ovary is discovered incidentally or is suspected.

Other Investigations

Blood tests

An abdominal mass, whether truly asymptomatic or not, usually denotes a significant clinical problem. A faeces-loaded colon is an exception, though severe constipation can still be a significant clinical management issue. Simple haematological and biochemical screening is usually done early in the process of investigating an abdominal mass and usually includes a full blood count, liver function tests and serum levels of urea, creatinine and electrolytes. While these often provide useful information about systemic consequences of the mass and the process that has caused it, they are not diagnostic tests. More specific blood tests may be indicated once the organ of origin and the likely pathological process are better defined from the history and examination and the ultrasound or CT scans. With the diagnostic possibilities narrowed, a more appropriate selection of specific diagnostic tests can be made (see Table 19.6).

Table 19.6 Further evaluation of abdominal masses by blood tests

Clinical diagnosis	Further blood test and rationale
Possible gastrointestinal malignancy	Tumour markers (Ch 17) including: • lower gut—carcinoembryonic antigen (CEA); • upper gut—CA 19-9.

Possible hepatoma

Tumour marker: alpha-fetoprotein (Ch 17)

Risk factors for hepatoma/indicators of chronic viral liver disease: hepatitis B and C serology

Significant liver replacement Coagulation studies should be checked prior to any intervention (e.g. liver biopsy) that might be complicated by excessive bleeding Possible hydatid disease of the liver Hydatid serology—to confirm the diagnosis and to ensure that biopsy is not attempted as leakage from the cyst might cause intraperitoneal spread of the disease (Ch 26) Pancreatic mass

Tumour marker: CA-19-9

Endocrine screen depending on symptoms (insulin, gastrin, vasoactive intestinal peptide, glucagon)

Endocrine tumour prognosis better than prognosis for adenocarcinoma of the pancreas and management is different (Ch 26)