ACUTE ABDOMEN IN THE ELDERLY – A DIAGNOSTIC DILEMMA

Assoc Professor Nasser Amjad MS, FRCS@                            

 

INTRODUCTION:

The evaluation of abdominal pain in elderly patients poses a difficult challenge for surgeons. It also is destined to become an increasingly common problem as the population ages. Almost 50% of elderly patients presenting with acute abdominal pain need hospitalization and of these, at least a third eventually require surgery for their underlying condition. Approximately 40% of elderly patients presenting with abdominal pain initially are misdiagnosed, contributing to the overall mortality rate of approximately 10%.

 

Even in the presence of serious intra-abdominal, elderly patients are more likely than younger patients to present with vague symptoms and have non-specific findings on examination. This is compounded by the fact that elderly patients have a diminished sensorium, allowing pathology to advance to a very dangerous state prior to developing symptoms.

 

A careful history and physical examination as well as a high index of suspicion are crucial to prevent missed diagnoses. We present this patient to highlight these important points when confronted with an elderly patient presenting with abdominal pain.

 

THE PATIENT

Mr. A, s Malay man aged 81 presented with a 2 day history of sudden onset generalized abdominal pain, which according to him was  a continuous aching pain, gradually increasing in severity. It was aggravated on taking food but had no associated nausea or vomiting. He has had no bowel motions for 2 days prior to admission but was passing flatus. On further questioning he did complain of similar type of pain on and off for the last one year which was precipitated on taking food. The attacks were becoming more frequent lately. He also has a history of bronchial asthma of several years duration and did mention about an admission to hospital for a ‘heart disease’ 6 months ago. An ultrasound scan of abdomen which was done during that admission showed gallstones and “swelling of vessels”. He was on several medications for his asthma but was not on steroids

 

On examination he was ill looking, dehydrated and pale. Examination of the cardiovascular system revealed a pulse rate of 96/minute but irregularly regular. BP was 110/90. No cardiomegaly was noted. Examination of the abdomen revealed generalized distension with diffuse tenderness and guarding more marked in the hypogastrium. No obvious masses were palpable. Bowel sounds were sluggish. Hernial orifices were normal. Rectal examination revealed an empty rectum.

 

Our initial diagnosis was Peritonitis due to perforated viscus (perforated peptic ulcer disease or perforated appendix). Differential diagnoses were acute pancreatitis and large bowel obstruction

 

Investigations were carried out and revealed the following. Full blood count: Hg  11g/dl, PCV  34.4, and platelets 124 x 10³ /uL. Differential count: Total 20.6, Differential     N 92.8, L 3.3. Random blood sugar 5.7m.mol/l. BUSE: Blood urea11.8, Na 145, K ⁺  4.5, and Cl 111. SGOT: 25 u/l, SGPT 19 u/l, ALP 132 u/l, Creatine kinase 440 u/l, LDH 653            u/l. Abdominal x-ray showed marginally dilated large bowel loops (Non-specific). Chest x-ray showed no subphrenic gas shadow but cardiomegaly was noted. The echocardiogram indicated ischaemic dilated cardiomyopathy with AF and poor LV function. Ultrasound examination of abdomen showed abdominal aortic aneurysm with a mural thrombus seen. There were no signs of a leak

 

The possibility of bowel ischemia as an alternative diagnosis was suspected due firstly to the presence of atrial fibrillation and secondly the presence of an abdominal aortic aneurysm. A decision was made to proceed with a laparotomy which was done about 36 hours after admission. Laparatomy revealed a gangrenous colon extending from the splenic flexure to the distal sigmoid and the inferior mesenteric artery was completely occluded. The infracted segment was resected and both ends exteriorized. Post operatively the patient was in intensive care but succumbed to multi-organ failure on the 5th post operative day.                          

 

DISCUSSION OF MESENTERIC ISCHAEMIA

Although mesenteric ischemia accounts for no more than 2% of hospitalizations for gastrointestinal conditions, it must be included in the initial differential diagnosis of abdominal pain. Timely diagnosis minimizes the risk of a disastrous bowel infarct. The nonspecific symptoms and the potential for catastrophic outcomes require the physician to be deliberately mindful of this diagnostic possibility and to perform the appropriate investigations in a timely fashion

 

Anatomy: The blood supply to the colon is via the superior mesenteric artery (SMA) and the inferior mesenteric artery (IMA) as shown in the figure.

 

 

 

 

Acute mesenteric ischemia (AMI) accounts for less than 1% of cases of abdominal pain in elderly patients but is an important cause. It is associated with 50% mortality but this can rise to 90 % if infarction is present. The risk factors for mesenteric ischaemia are age and

Co-morbidities like atherosclerotic disease, arrhythmia, acute myocardial infarction, renal failure, patients on haemodialysis,  hypercoagulability states, patients on vasoactive medications (digoxin, pressors, cocaine, diuretics), and recent hypoperfusive state (e.g. major surgery, cardiac arrest)

 

It is the clinical syndrome resulting from a decrease in blood flow to the small intestine, usually involving the circulation of the superior mesenteric artery (SMA) but can affect the inferior mesenteric artery (IMA) as well resulting in ischaemia to the left colon as in our patient. Emboli are responsible for almost half of all cases of AMI. Emboli result from disruption of a thrombus in the left atrium in the setting of atrial fibrillation as in this patient but can also follow myocardial infarction. Another possible source in this patient could have been from the aortic aneurysm

 

Classification:Mesenteric ischaemia is classified as follows:

 

 

 

Manifestations of mesenteric artery occlusion may range from transient episodes of visceral pain to irreversible infarction. Past history of similar episodes of pain of milder nature in our patient could have been due to chronic ischaemia which is characterized by intermittent insufficiency provoked by increase demand for perfusion during digestion. These recurrent episodes of postprandial abdominal pain sometimes termed ‘intestinal angina.’

 

If unattended it can lead to sustained insufficiency, a condition that invariable lead to actual ischaemic injury. This will ultimately manifest as infarction which could be either partial or full thickness.

 

Clinical presentation: Patients classically present with severe abdominal pain despite having little tenderness on examination. Abdominal pain is disproportionate to the findings on physical examination.  Many patients initially complain of vague symptoms such as lower abdominal pain, abdominal distension, diarrhoea, nausea with vomiting, or anorexia.

 

The patient can also present with chronic ischaemia of bowel. Intestinal angina is a recognized presentation with a history of an aching pain which is poorly localized, being referred to the anterior abdomen. Useful clue is that it seems to be precipitated by meals.

Patients may also present with chronic weight loss due to decreased intake and not decreased absorption. The decrease intake is due more to the fear of precipitating abdominal pain than other factors.

 

 

Insufficient perfusion

ò

Tissue hypoxia

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Mucosal sloughing + ulceration

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Loss of bowel wall integrity

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Bacterial translocation  _    Bacteraemia  

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Luminal content permeation through bowel wall

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                                                                Perforation    _    peritonitis / abscess formation

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Death

 

 

This algorithm shows the pathophysiology of mesenteric ischaemia

 

 

Another mode of presentation is with disturbances in bowel function which may be non- specific like a bloated feeling of the abdomen, generalized abdominal discomfort and a tendency towards diarrhoea or constipation

 

Most are elderly and have other evidence of obliterative artheromatous disease. Some patients are found to have multiple shallow antral gastric and duodenal ulcers which are resistant to the usual therapy which should make you suspect that ischaemia could be a cause. Thrombosis of the origin of the celiac or mesenteric arteries is the end result of severe occlusive arterial disease

Clinical evaluation:

As mentioned above symptoms are non specific and in established infarction, diagnosis becomes more obvious but survival is unusual as it is too late. In some situation other pathologies detected, may delay the diagnosis of mesenteric ischaemia (e.g. peptic ulcer disease, gallstones). Therefore careful history depends on characteristics of the pain and weight loss.

 

 

 

Diagnosis: The clinician should have a high index of suspicion and must look for clues to suggest a vascular event. Lack of reliable, accurate, early clinical diagnostic findings is a factor responsible for late diagnosis. With regard to abdominal pain or discomfort, may not necessarily be sudden in onset, not necessarily be constant or colicky, Bloody stool or diarrhoea may be present but absence of these symptoms like in our patient does not exclude mesenteric ischaemia. Nausea and/or vomiting may or may not be an associated feature.

 

Lack of reliable, accurate, early physical examination findings is another contributing factor for late diagnosis.

 

As shown in the table below, elderly patients over 50y with acute abdominal pain are more likely to have a significant structural explanation

 

 

Features consistent with, but not diagnostic of mesenteric ischaemia are:

 

Blood may be hemoconcentrated (Hct ³ 50)

White cell count may be elevated

Serum amylase may be elevated

Metabolic acidosis may be present at an early stage

 

Imaging: Plain X-ray abdomen /KUB may help in establishing an alternative process. Non-specific gas distribution in an abdominal x-ray is a common finding like what was noted in our patient. “Pathognomonic” findings if seen are usually late and may point to a poor prognosis. They are Pneumatosis intestinalis (Fig.1), Portal venous gas (Fig.2) and Intestinal “thumbprinting” (Fig.3) which are shown below.

 

Colonoscopy, abdominal ultrasonography, and barium radiography are not useful in the diagnostic workup of acute mesenteric ischaemia. Barium enema is contraindicated if the condition is suspected

 

Abdominal computed tomography (CT) scans are valuable in distinguishing not only the possible causes of AMI but also very useful for evaluation of alternative diagnoses in cases where mesenteric ischemia is not the sole consideration.