Acute abdomen

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CHAPTER 13 Acute abdomen

Basic principles 205
Medical causes of acute abdominal pain 211
Peritonitis 211
Intra-abdominal abscesses 213

Basic principles

Acute abdomen is the most common cause of emergency admission to a surgical unit. The term ‘acute abdomen’ is difficult to define but it indicates any non-traumatic disorder of acute onset in which the symptoms are predominantly abdominal and for which in some cases, urgent surgery may be indicated. In practice, it represents a spectrum of problems ranging from sudden onset of severe abdominal pain with a life-threatening underlying cause to minor abdominal symptoms of lengthy duration. The most important feature of the acute abdomen is to sort out the severe causes in need of urgent surgery (e.g. ruptured aortic aneurysm, perforated diverticulitis) from severe abdominal pain that does not require surgery (biliary colic, ureteric colic, pancreatitis); and also from those conditions that do not need urgent investigation and treatment (e.g. mild gastroenteritis, constipation). Prompt diagnosis is essential. A careful history and examination will indicate the cause of most acute abdomens.

History

Age

Certain conditions are more likely to occur in certain age groups, e.g. mesenteric adenitis in children, diverticulitis in the older patient.

Pain

This can be remembered from the mnemonic ‘SOCRATES’:

• Site: where did it start, has it moved?
• Onset: sudden, gradual
• Character: e.g. dull, vague, cramping, sharp, burning
• Radiation: e.g. loin to groin in ureteric colic
• Associated factors: e.g. vomiting, diarrhoea, fever, effect of movement, effect of micturition, etc.
• Timing: is the pain constant or intermittent; how long does the pain last?
• Exacerbations and relieving factors: what makes the pain better/worse?
• Severity.

Vomiting

• Did vomiting precede the pain?
• Frequency.
• Character, e.g. bile, faeculent, blood, coffee grounds.

Defaecation

• Constipation: absolute constipation with colicky abdominal pain, distension, and vomiting suggests intestinal obstruction.
• Diarrhoea: frequency, consistency of stools, blood, mucus, pus.

Fever

Any rigors.

Past history

• Previous surgery, e.g. adhesions may cause intestinal obstruction
• Recent trauma, e.g. delayed rupture of spleen
• Menstrual history, e.g. ectopic pregnancy.

Examination

General

Is the patient lying comfortably? Is the patient lying still but in pain, e.g. peritonitis? Is the patient writhing in agony, e.g. ureteric or biliary colic? Is the patient flushed suggesting pyrexia?

Pulse, temperature, respiration

Cervical lymphadenopathy

(e.g. mesenteric adenitis).

Chest

(e.g. referred pain from lobar pneumonia).

Abdomen

Inspection

Moves on respiration. Scars, distended, visible peristalsis (usually chronic obstruction in patient with very thin abdominal wall). Pain on coughing. Hernial orifices. Any obvious masses, e.g. pulsatile mass to suggest aortic aneurysm.

Palpation

Patient relaxed, lying flat, with arms by side. Be gentle and start as far from the painful site as possible. Check for guarding and rigidity. Rebound tenderness is unpleasant and should not be performed in the traditional manner of palpating the abdomen deeply and then suddenly withdrawing the examining hand. The presence of rebound tenderness can be inferred from more subtle signs such as percussing the abdomen, asking the patient to cough and asking whether bumps in the road during the ambulance journey were painful (hospitals always have speed bumps and can provide much information about an acute abdomen!). Check for masses, e.g. appendix mass, pulsatile expansile mass of aortic aneurysm. Check the hernial orifices.

Percussion

For example, tympanitic note with distension due to intestinal obstruction; dullness over bladder due to acute retention.

Auscultation

Take your time (30–60 s), e.g. silent abdomen of peritonitis, high-pitched tinkling bowel sounds of intestinal obstruction.

Rectal examination

This is just as important as the abdominal examination. It should be carried out in the left lateral position. Insert the well-lubricated gloved finger posteriorly into the sacral hollow. Move the finger around in the arc of a circle until it impinges on the peritoneum of the rectovesical or rectouterine pouch. If the patient winces with pain when the finger impinges on the peritoneum, this is a sign of peritonitis in the most dependent part of the pelvis. The pain disappears when the finger comes off the peritoneum as it completes the circle and returns to the sacral hollow. The correct annotation of a positive rectal examination should be ‘tender anteriorly’. ‘Tender high up in the right’ is inappropriate. There seems to be a misconception among medical students that you are feeling the area of the appendix. You are feeling for tenderness due to inflammation of the pelvic peritoneum caused by infected exudates draining to the most dependent part of the pelvis, i.e. the rectovesical or rectouterine pouch.

Vaginal examination

Discharge, tenderness associated with pelvic inflammatory disease, examine the uterus and adnexa, e.g. pregnancy, fibroids, ectopic pregnancy.

Investigations

• FBC: low Hb may indicate chronic bleeding; a raised white cell count with a neutrophil leukocytosis may indicate an inflammatory or infective process
• U&Es: fluid loss may result in renal impairment, vomiting may cause electrolyte abnormalities
• LFTs: may indicate gallstone pathology or hepatitis
• Amylase: a high amylase confirms the diagnosis of pancreatitis; a mildly raised amylase is also seen in ectopic pregnancy, perforated viscus, intestinal obstruction and intestinal ischaemia
• β-hCG: pregnancy/ectopic pregnancy – must be performed in all females of child-bearing age with iliac fossa pain
• CRP: inflammatory marker generally raised within 8 h of an inflammatory process – can be useful in difficult cases, e.g. suspected appendicitis of 12 h duration with a normal WCC and CRP is unlikely to be acute appendicitis
• ABG: generally only indicated in severely ill patients; it can give useful information on tissue perfusion by pH and lactate levels; PaO2 and PaCO2 can give important information for the anaesthetist prior to surgery
• CXR: exclude referred lesion, gas under diaphragm (→ Fig. 13.1)
• AXR: distended bowel with air/fluid levels, gallstones (10% are radio-opaque); calcified aorta, e.g. aneurysm; air in biliary tree (cholecystoduodenal fistula with gallstone ileus)
• USS: e.g. ovarian cyst, ectopic pregnancy, gallstones
• CT: useful in difficult cases – able to demonstrate free fluid, air, dilated bowel, pancreatitis
• KUB
• IVU for stones
• Angiography: e.g. acute GI haemorrhage of obscure cause, superior mesenteric embolus or thrombosis (duplex scanning may also be appropriate).
image

Figure 13.1 Gas (arrow) is seen under the right hemidiaphragm following perforation of a duodenal ulcer.

Causes

Some causes of the acute abdomen are shown in Table 13.1. These conditions are covered in the relevant chapters. (For information on the site of abdominal pain in relation to suspected pathology → Table 13.2.)

TABLE 13.1 Causes of acute abdomen

Gastrointestinal  
Gut Acute appendicitis
Intestinal obstruction
Perforated peptic ulcer
Diverticulitis
Inflammatory bowel disease
Acute exacerbation of peptic ulcer
Gastroenteritis
Mesenteric adenitis
Meckel’s diverticulitis
Liver and biliary tract Cholecystitis
Cholangitis
Hepatitis
Biliary colic
Pancreas Acute pancreatitis
Spleen Splenic infarct and spontaneous rupture
Urinary tract Cystitis
Acute pyelonephritis
Ureteric colic
Acute retention
Gynaecological Ruptured ectopic pregnancy
Torsion of ovarian cyst
Ruptured ovarian cyst
Salpingitis
Severe dysmenorrhoea
Mittelschmerz
Endometriosis
Vascular Ruptured aortic aneurysm
Mesenteric embolus
Mesenteric venous thrombosis
Ischaemic colitis
Acute aortic dissection
Peritoneum Primary peritonitis
Secondary peritonitis
Abdominal wall Rectus sheath haematoma
Retroperitoneal Haemorrhage, e.g. anticoagulants

TABLE 13.2 Site of abdominal pain in relation to suspected pathology

Whole abdomen Generalized peritonitis and mesenteric infarction
Right upper quadrant Acute cholecystitis
Cholangitis
Hepatitis
Peptic ulceration
Left upper quadrant Peptic ulceration
Pancreatitis
Splenic infarct
Right lower quadrant Appendicitis
Ovarian cyst
Ectopic pregnancy
Pelvic inflammatory disease
Meckel’s diverticulum
Mesenteric adenitis
Ureteric colic
Rectus sheath haematoma
Right-sided lobar pneumonia
Left lower quadrant Sigmoid diverticular disease
Ovarian cyst
Ectopic pregnancy
Pelvic inflammatory disease
Ureteric colic
Rectus sheath haematoma
Left-sided lobar pneumonia
Radiating pain Peptic ulcer
Back Pancreatitis
Aortic aneurysm
Acute aortic dissection
Groin Ureteric colic
Testicular torsion

Diagnosis

Diagnosing patients with an acute abdomen is the ‘bread and butter’ of the on-call general surgeon. The legion of causes is almost impossible to remember. Furthermore, you will spend your entire life in the A&E department if you slavishly attempt to rule out all the causes of an acute abdomen. An easy method to classify patients with an acute abdomen is given below:

• Acute abdomen + shock, e.g. ruptured abdominal aortic aneurysm, pancreatitis
• Generalized peritonitis, e.g. perforated viscus
• Localized peritonitis, e.g. acute appendicitis
• Bowel obstruction
• Medical causes, e.g. lobar pneumonia.

These patients can then be divided into a number of management strategies. For example, not all patients with localized peritonitis need an operation. Indeed not all patients with pain and shock need an operation. An unnecessary laparotomy in pancreatitis can exacerbate the condition considerably.

Management

Strategies include:

• Immediate operation – these patients will die unless taken to theatre immediately, e.g. ruptured abdominal aortic aneurysm.
• Preoperative preparation and operation urgently within 6 h – elderly patients may present with an acute abdomen and require urgent operation; however, preoperative dehydration and electrolyte abnormalities need to be corrected before going to theatre.
• Urgent operation (within 24 h) – certain conditions, particularly in young patients, may be dealt with on a routine emergency list, e.g. acute appendicitis, small bowel obstruction with no adverse symptoms (e.g. no fever, no leukocytosis, no peritonism).
• Conservative treatment – numerous causes of an acute abdomen only require conservative treatment, i.e. nil by mouth, antibiotics (e.g. acute cholecystitis).
• Observation – many patients may have equivocal clinical signs but be in the early stages of a condition. Time is a great diagnostic tool and frequent re-examination may reveal evolving signs.
• Discharge.

Patients must be continually reassessed and evaluated as patients can move from one group to another; for example a young man admitted with RIF pain and booked for urgent operation within 24 h may perforate and thus display generalized peritonitis – in this instance the patient would require immediate operation.

Treatment

• Relieve pain
• Intravenous fluids and nasogastric suction
• Broad-spectrum antibiotics if peritonitis or sepsis
• Surgery if indicated.

Indications for surgery in the acute abdomen

There are no hard and fast rules but patients with the following symptoms will almost certainly require surgery:

• Localized peritoneal irritation with guarding or rigidity
• Spreading tenderness
• Tense or progressive distension
• Generalized peritonitis
• Shock with bleeding or sepsis
• Free gas on radiograph
• Mesenteric occlusion on angiography
• Blood, bile, pus or bowel contents on paracentesis.

Medical causes of acute abdominal pain

Occasionally, certain medical conditions may cause acute abdominal pain.

Referred pain

May be caused by degenerative disease of thoracic spine, herpes zoster, lobar pneumonia, pleurisy, MI.

Haematological

This may be due to sickle cell crisis.

Infective and inflammatory

These medical conditions are possible: tabes dorsalis, Henoch–Schönlein purpura.

Endocrine and metabolic

These conditions include uraemia, hypercalcaemia, diabetic ketoacidosis, Addison’s disease, acute intermittent porphyria.

Peritonitis

Peritonitis is an inflammatory or suppurative response of the peritoneal lining to direct irritation. It may be localized or generalized, bacterial or chemical. Localized peritonitis is due to transmural inflammation of a viscus, e.g. appendicitis, cholecystitis, diverticulitis. It may remain localized through being contained by omental wrapping or adhesion of adjacent structures. In many cases, however, it becomes generalized, spreading to involve the whole peritoneum. Sudden perforation of a viscus usually results in generalized peritonitis. With the latter the patient is seriously ill. Hypovolaemia results from massive exudation into the peritoneal cavity, and septicaemia may result if the cause is infective, e.g. faecal peritonitis from perforated diverticulitis. Chemical peritonitis results from gastric or pancreatic juice, bile, urine or blood in the peritoneal cavity. Bile causes little reaction if sterile but causes severe peritonitis if infected or mixed with pancreatic juice. Blood and urine cause little reaction if sterile but a severe reaction occurs if they are infective. (For a classification of peritonitis, → Table 13.3.)

TABLE 13.3 Causes of peritonitis

Acute  
Bacterial Primary (rare):

• streptococci, pneumococci
• haematogenous spread
• occurs in young girls, ascites, nephrotic syndrome and postsplenectomy

Secondary (common):

• related to perforation, infection, inflammation or ischaemia of GI or GU tract

Chemical Gastric juice (e.g. perforated gastric ulcer) Pancreatic juice (e.g. acute pancreatitis) Bile (e.g. perforation of the gall bladder) Blood (e.g. ruptured spleen) Urine (e.g. intraperitoneal rupture of the bladder) Chronic Tuberculosis Starch (immunological reaction)

Symptoms and signs

These depend on the degree of peritonitis and the precipitating cause. They also relate to the abdominal signs from the original pathology and manifestations of systemic infection. Usually there is sudden onset of abdominal pain made worse by coughing and movement. Initially it may be localized (it may remain so in some cases) but often gradually spreads to involve the whole abdomen. Nausea, vomiting, fever, abdominal tenderness (localized or generalized), guarding, rigidity, distension, absent bowel sounds when ileus supervenes. Manifestations of systemic infection include tachycardia, sweating, rigors, tachypnoea, oliguria, disorientation, shock and Gram-negative septicaemia. In advanced cases, and with delay in presentation, renal, respiratory, and cardiac failure may result.

Investigations

• Hb
• PCV
• WCC
• U&Es: dehydration, ARF
• LFTs
• Amylase
• CXR: gas under diaphragm, small pleural effusion
• AXR: distended bowel (ileus), local ileus (‘sentinel’ loop – appendicitis, pancreatitis)
• USS: free fluid, localized collections
• CT – pancreatitis.

Complications

Systemic

Hypovolaemic shock, septic shock, ARDS, DIC, multiorgan failure, immunological failure.

Local

Intraperitoneal sepsis: residual abscesses, e.g. subphrenic or pelvic, wound infection, anastomotic breakdown, fistula formation, adhesions.

Prognosis

Overall mortality in generalized peritonitis is around 40%. Factors affecting mortality include age (elderly patients with faecal peritonitis have a high mortality), causation, duration of symptoms, degree of bacterial contamination, concomitant disease processes and organ failure.

Treatment

Principles of treatment involve the following:

Resuscitation

This requires pain relief with narcotic analgesics, i.v. fluids, NG aspiration, correction of electrolyte imbalance, catheterization. UO should be monitored and CVP (especially in elderly). Oxygen and antibiotics.

Treatment of causative lesion

In generalized peritonitis this almost invariably requires surgery. Acute pancreatitis is the exception. Principles of operative treatment involve removal of all infected material from the peritoneal cavity, correction of the underlying cause, and attempts to prevent complications. Swab for C&S. Thorough examination of the peritoneal cavity, debridement of serosal surfaces, removal of affected organ, e.g. appendicectomy, colectomy. Formation of stomas rather than anastomosis, which may leak in the presence of infection and unprepared bowel. Peritoneal lavage. Peritoneal drains. Occasionally, the abdomen should be left open and the exposed bowel covered with moist swabs (laparostomy).

Postoperative care

Attention should be paid to fluid and electrolyte balance. UO should be monitored. Antibiotic therapy, nutritional support and surveillance for sepsis. Ventilation may be necessary. CVVH or dialysis may be required for ARF.

Intra-abdominal abscesses

An abscess is a localized collection of pus. Intra-abdominal abscesses can be divided into intraperitoneal and extraperitoneal. Following peritonitis pus may collect in either the subphrenic spaces, the pelvis or in locules between loops of bowel.

Intraperitoneal abscesses

These tend to arise in dependent areas of the abdomen where fluid may collect. They include:

• Subphrenic – occur following anastomotic leaks in gastric or hepatobiliary surgery, after splenic surgery, perforated peptic ulcer, acute cholecystitis and acute appendicitis
• Paracolic – occur with perforations secondary to inflammatory bowel disease, diverticulitis, malignancy or anastomotic leaks
• Right iliac fossa – occur with appendicitis, perforated peptic ulcer, inflammatory bowel disease
• Pelvic – as the most dependent part of the abdomen, pelvic abscesses are the most common type of intra-abdominal abscesses and can be caused by all the above plus gynaecological causes.

Extraperitoneal abscesses

These are much less common than intraperitoneal abscesses; they most frequently follow infections of organs in the retroperitoneum or where peritoneal organs have perforated into the retroperitoneum. Extraperitoneal abscesses are most commonly associated with:

• Pancreatitis
• Posterior perforation of duodenal ulcer
• Posterior colonic perforations
• Pyelonephritis
• Spinal infections, e.g. osteomyelitis.

Extraperitoneal abscesses can also present as a psoas abscess; these can occur primarily due to haematogenous spread, tuberculosis of the thoraco-lumbar spine or secondary to local infections, e.g. Crohn’s disease.

Symptoms and signs

General signs include malaise, swinging pyrexia, tachycardia, localized pain and tenderness, prolonged ileus. Signs specific to the position of the abscess include:

• Subphrenic – chest pain, shortness of breath (secondary to basal atelectasis), shoulder tip pain (referred from diaphragmatic irritation), hiccups
• Pelvic – diarrhoea, urinary frequency, passage of mucus PR, boggy fluctuant mass on PR or PV examination
• Psoas – pain on extension of the hip (patients tend to hold their hip in flexion); palpable psoas abscess below the inguinal ligament.

Investigations

• Hb
• WCC
• ESR
• LFTs: occasionally raised
• Blood culture may be positive
• CXR: pleural effusion, raised hemidiaphragm, atelectasis
• AXR: ileus, air/fluid levels in abscess cavities (rare)
• USS
• CT
• Indium-labelled white cell scan.

Treatment

For well-localized, non-loculated abscesses, percutaneous drainage under US or CT control. If there are multiple abscesses or they are multiloculated, open drainage at laparotomy will be required.

Procedures

Laparotomy

The following description relates to laparotomy for peritonitis of unknown origin (rather than trauma).

• Incision – ‘incision of indecision’ approximately 10 cm centred on the umbilicus. Depending on the findings, the incision may then be extended up (bile) or down (faeces). The skin is incised with a knife and continued down to the linea alba with diathermy.
• Opening the peritoneum – the linea alba is opened along the length of the incision. Using two clips, the peritoneum is tented up and incised with scissors. The peritoneal opening is extended so that the operator and assistant can insert a finger and lift up the abdominal wall so that the remaining peritoneum may be incised under direct vision.
• Examination of the peritoneal cavity – once inside the abdomen, a thorough and stepwise search of its contents is undertaken as follows:

— Liver from right to left (including gallbladder)
— Spleen
— Oesophagus, stomach from proximal to distal and then to the duodenum
— Kocher’s manoeuvre will be required to visualize the remainder of the duodenum and head of pancreas
— The right kidney is palpated
— The lesser sac will need to be opened to visualize the body and tail of the pancreas
— The left kidney is palpated
— Small bowel is examined from the ligament of Treitz to the ileocaecal valve taking care to examine both sides and the mesentery
— As the small bowel is out of the abdomen the retroperitoneum can be palpated taking particular note of an aortic aneurysm
— The caecum and appendix is then examined and follows onto the rest of the colon
— Female reproductive organs
— Hernial orifices.

• Abdomen closure – the commonest technique is to use loop PDS, one from the top of the incision and the other from the bottom and meeting approximately half way down (do not tie the knot at the umbilicus). The bites of linea alba should be 1 cm deep and 1 cm apart. The skin may be closed with clips or a subcuticular suture (clips are better after a contaminated procedure, as some clips may be removed in the postoperative period in the event of wound infection).

Perforated peptic ulcer

If the diagnosis is known preoperatively, then an upper midline incision may be used. If not an ‘incision of indecision’ may be performed and extended upwards if bile is seen.

The following are steps in the procedure:

• Perform a laparotomy as above. With a perforated viscus, a hiss of air will be heard as the peritoneum is incised.
• Send fluid for culture and sensitivity.
• Examine the duodenum (perforations are usually in D1) and stomach for perforations (if gastric ulcer then it will need to be biopsied to rule out malignancy).
• Using 3/0 Vicryl under run the ulcer with two or three sutures, starting 1 cm from the medial edge and exiting 1 cm from the lateral edge (take care not to catch the back wall). These sutures are then tied to approximate the edges of the ulcer. Do not tie the sutures too hard as the tissues will be friable and the suture will cut through. Do not cut the ends of the sutures at this point.
• Fashion a pedicle of omentum and lay across the perforation. Tie the sutures over the omentum to secure it in place.
• Wash out the abdomen thoroughly with copious amounts of normal saline, particularly above and below the liver and in the pelvis.
• Close the abdomen as for laparotomy.
• A drain is not usually needed.

Appendicectomy

Many appendicectomies are now performed laparoscopically. However, it is still important to understand the principles of open appendicectomy.

• A Lanz skin crease incision is made across McBurney’s point (junction of the middle and outer third of a line joining the anterior superior iliac spine and the umbilicus).
• The incision extends down to the external oblique, which is incised in the line of the incision. The muscles can then be split in the direction of their fibres.
• The peritoneum is picked up between clips (once the second clip is applied, re-apply the first clip so as to drop any bowel that may have been picked up). Open the peritoneum in the line of the wound.
• Any free fluid is sent for culture and sensitivity.
• The appendix can be delivered into the wound by: (1) following the taenia coli down to the caecum where they converge on the appendix; (2) sweeping the finger from medial to lateral under the caecum and feeling for the inflamed appendix and pulling it up into the wound.
• Make a window in the mesoappendix at the point where the appendix meets the caecum. Place two clips across the mesoappendix and divide it. Suture ligate both ends.
• The base of the appendix is crushed with a haemostat. Another haemostat is placed below the crushed segment and the crushed segment is then ligated.
• Place another haemostat above the tie and divide the appendix with a knife.
• Place a seromuscular purse string suture around the base of the appendix and bury the stump by tying it.
• If the appendix is normal, look for another cause of abdominal pain, e.g. Crohn’s disease, Meckel’s diverticulum or ovarian pathology.
• Wash out the abdomen (especially the pelvis) with copious amounts of saline.
• Close the peritoneum with 3/0 Vicryl, the external oblique aponeurosis with 2/0 Vicryl and then close the skin with either clips or subcuticular suture.

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