Lactology Foundation

ABDOMINAL PAIN, ACUTE, LOCALIZED

A common and extremely important clinical problem is the patient who presents with acute abdominal pain.
This may be referred all over the abdominal wall (see ABDOMINAL PAIN (GENERAL), but here we shall consider those patients who present pain localized to a particular part of the abdominal cavity.

The causes are legion, and it is a useful exercise to summarize the organs that may be implicated together with the pathological processes pertaining to them so that the clinician can consider the possibilities in a logical manner:
1. Gastroduodenal
• Perforated gastric or duodenal ulcer
• Perforated gastric carcinoma
• Acute gastritis (often alcoholic)
• Irritant poisons
2. Intestinal
• Small-bowel obstruction (adhesions, etc.)
• Regional ileitis (Crohn's disease)
• Intussusception
• Sigmoid volvulus
• Acute colonic diverticulitis
• Large-bowel obstruction due to neoplasm
• Strangulated external hernia (inguinal, femoral,
umbilical)
• Acute mesenteric occlusion due to arterial
embolism or thrombosis or to venous
thrombosis
3. Appendix
• Acute appendicitis
4. Pancreas
• Acute pancreatitis
• Recurrent pancreatitis
• Pancreatic trauma
5. Gallbladder and bile ducts
• Calculus in the gallbladder or common bile ducts
• Acute cholecystitis
• Acute cholangitis
6. Liver
• Trauma
• Acute hepatitis
• Malignant disease (primary or secondary)
• Congestive cardiac failure
7. Spleen
• Trauma
• Spontaneous rupture (in malaria or infectious
mononucleosis)
• Infarction
8. Urinary tract
• Renal, ureteric or vesical calculus
• Renal trauma
• Pyelonephritis
• Pyonephrosis
9. Female genitalia
• Salpingitis
• Pyosalpinx
• Ectopic pregnancy
• Torsion of subserous fibroid
• Red degeneration of fibroids
• Twisted ovarian cyst
• Ruptured ovarian cyst
10. Aorta
• Ruptured aneurysm
• Dissecting aneurysm
In addition to causes from intra-abdominal, retroperitoneal and pelvic organs, it is important to remember that acute localized pain may be referred to the abdomen from other structures:
11. Central nervous system
• Herpes zoster affecting the lower thoracic
segments. Posterior nerve root pain (e.g. from
prolapsed intervertebral disc or collapsed
vertebra from trauma or secondary deposits)
12. The heart and pericardium
• Myocardial infarction
• Acute pericarditis
13. Pleura
• Acute diaphragmatic pleurisy

Occasionally, patients are seen who are often well known in the Accident and Emergency Department, presenting with simulated acute abdominal pain due to hysteria or malingering.
Patients with acute abdominal pain present one of the most testing trials to the clinician. In the first place, diagnosis is all-important, since a decision has to be made whether or not the patient requires urgent laparotomy – for example for a perforated peptic ulcer, acute appendicitis or acute intestinal obstruction.
The history and examination are often difficult to elicit, particularly in a very ill patient who is in great pain and hardly wishes either to answer a lot of questions or to submit to a prolonged examination. Finally, there are very few laboratory or radiological aids to diagnosis.
Acute appendicitis, for example, has no specific tests.
A raised white blood count suggests intraperitoneal infection, but something like one-quarter of the cases of acute appendicitis have a white blood cell count below 10,000 per mm3. Plain X-rays of the abdomen may indicate free gas when there is a perforated hollow viscus, but this is not invariably so.
Intestinal obstruction may be revealed by distended loops of bowel on a plain X-ray of the abdomen, but in some 10 percent of small-bowel obstructions the X-rays are entirely normal, since the distended loops of bowel are filled with fluid only so that the typical gas distended loops of bowel are not present.
Ultrasonography of the abdomen may be used to demonstrate distended loops of bowel, fluid collections, gallbladder pathology, the presence of gallstones, a pathological appendix and intussusception. However, accurate diagnosis is heavily observer-dependent and requires the help of an expert ultrasonographer. Computed tomography (CT) is also of great assistance, when available.
One of the few laboratory investigations that the surgeon relies upon heavily is a raised serum amylase activity. When this is above 1000 units per 100 ml serum, it is almost pathognomic of acute pancreatitis, although every now and then a fulminating attack of pancreatitis is seen in which the amylase is not elevated. Unfortunately, more than 200 different assay methods for amylase estimation have been described. Consequently, different hospitals may well have different reference ranges for serum amylase normality. It is therefore essential to know the normal reference range of serum amylase in your own hospital rather than trying to remember values that apply elsewhere. While a very high serum amylase value is typically found in acute pancreatitis and pancreatic trauma, a moderate increase may occur in nonpancreatic acute abdominal disease (e.g. perforated peptic ulcer, intestinal obstruction or infarction). Amylase is cleared from the circulation by the kidneys; anything which interferes with normal renal clearance may therefore also result in a moderate rise in the serum amylase.
Every effort must therefore be made to establish the diagnosis on a careful history and examination.
One of the important aspects in the assessment of the acute abdomen is the establishment of a trend.
Increasing pain, tenderness, guarding or rigidity indicates that there is some progressive intra-abdominal condition. This is also suggested by a rising pulse rate on hourly or half-hourly observations, and it is also suggested by progressive elevation of the temperature. In a doubtful case, repeated clinical examination – together with sequential recordings of the temperature and pulse – will enable the clinician to decide whether the intra-abdominal condition is either subsiding or progressing.

GENERAL FEATURES
General inspection of the patient is all-important and must never be omitted. The flushed face and coated tongue of acute appendicitis, the agonized expression of the patient with a perforated ulcer, the writhing colic of a patient with ureteric stone, biliary colic or small-bowel obstruction are all most helpful. The skin is inspected for the pallor suggestive of haemorrhage, and for the jaundice that may be associated with biliary colic with a stone impacted at the lower end of the common bile duct. In such a case, there will also be bile pigment that can be detected in the urine.

ABDOMINAL EXAMINATION
The patient must be placed in a good light, and the entire abdomen exposed from the nipples to the knees. The abdomen is inspected. Failure of movement with respiration may suggest an underlying peritoneal irritation. Abdominal distension is present in intestinal obstruction, and visible peristalsis may be seen from rhythmic contractions of the small bowel in these circumstances. Retraction of the abdomen may occur in acute peritonitis so that the abdomen assumes a scaphoid appearance, for example following perforation of a peptic ulcer.
Guarding – a voluntary contraction of the abdominal wall on palpation – denotes an underlying inflammatory disease, and this is accompanied by localized tenderness. Rigidity is indicated by an involuntary tightness of the abdominal wall and may be generalized or localized. Localized rigidity over one particular organ suggests local peritoneal involvement, for example in acute appendicitis or acute cholecystitis.
Percussion of the abdomen is useful. Dullness in the flanks suggests the presence of intraperitoneal fluid (e.g. blood in a patient with a ruptured spleen).
A resonant distended abdomen is found in obstruction, and loss of liver dullness suggests free gas within the peritoneal cavity in a patient with a ruptured hollow viscus.
In intestinal obstruction, the bowel sounds are increased and have a particular 'tinkling' quality.
In some cases, borborygmi may be audible without using the stethoscope. A complete absence of bowel sounds suggests peritonitis.
Examination of the abdomen is not complete until the hernial orifices have been carefully inspected and palpated. It is easy enough to miss a small strangulated inguinal, femoral or umbilical hernia that, surprisingly enough, may have been completely overlooked by the patient.
A rectal examination is then performed. In intestinal obstruction, the rectum has a characteristic 'ballooned' empty feeling, although the exact mechanism of this is unknown. In pelvic peritonitis, there will be tenderness anteriorly in the pouch of Douglas. A tender mass suggests an inflamed or twisted pelvic organ, and this can be confirmed by bimanual vaginal examination.
THE URINE AND SPECIAL INVESTIGATIONS
The presence of blood, protein, pus or bile pigment in the urine may help to distinguish a renal or biliary colic from other causes of intra-abdominal pain. As well as routine testing of a urine specimen, a drop placed under the microscope and viewed with a 1/6th lens (staining is not required) constitutes a useful test. It is
the work of a few minutes to see if pus cells or red cells are obvious. In obscure cases of abdominal pain, the urine should be examined for porphyrins to exclude porphyria, particularly when the attack appears to have been precipitated by barbiturates.
The clinical assessment of the patient with acute localized abdominal pain, based on a careful history and examination together with examination of the urine, may be supplemented by laboratory and radiological investigations. A full blood count, plain X-ray of the abdomen, and estimation of the serum amylase in suspected pancreatitis may all be helpful, although, as mentioned above, the findings must be interpreted with caution. In suspected ruptured ectopic pregnancy, the urinary beta human chorionic gonadotrophin (beta hCG) is positive. Ultrasound of the pelvis may be helpful if a twisted ovarian cyst or some other pelvic pathology is suspected. Ultrasonography is also valuable in demonstrating gallstones in acute cholecystitis. An emergency intravenous urogram is indicated when a ureteric stone or some other renal pathology is suspected.
An electrocardiogram and appropriate cardiac enzyme estimations are performed if it is suspected that the upper abdominal pain is referred from a myocardial infarction, and a chest X-ray may demonstrate a basal pneumonia. Computed tomography is particularly useful in demonstrating the swollen and oedematous pancreas of acute pancreatitis. It must be stressed, however, that the clinical features take precedence over all other diagnostic aids.
Nothing can be simpler, or more difficult, than diagnosing a patient with the so-called 'acute abdomen'. Particular difficulties will be encountered in infants (where history may be difficult and examining a screaming child most demanding), and in the elderly, where again it is often difficult to obtain an accurate history and where physical signs are often atypical.