Acute abdominal pain, Acute appendicitis and Other causes of abdominal pain

General principles

No symptom presents a greater challenge to the casualty doctor or the family doctor than acute abdominal pain in children. Probably all children sooner or later experience some abdominal pain. The possible causes arc innumerable, and in this section I shall discuss some of the more important ones and some of the difficulties in diagnosis.
One must know when the child had his last bowel action, and whether he is passing flatus. Enquiry should be made about an upper respiratory tract infection in the last few days, and, in all cases, about medicines taken by the child—for they may be the cause of the pain.
The examination must be a full one. The whole body is inspected, e.g. for a rash, such as that of anaphylactoid pur­pura which often predominantly affects the buttocks. The abdomen is inspected before palpation for distension and peri­stalsis. As already emphasized, when palpating the abdomen one watches the child's face for evidence of tenderness on palpation. One auscultates for peristaltic sounds. In all cases the genitalia are examined for a strangulated hernia or torsion of a testis, and in all cases a rectal examination is required.
The most useful special investigations are usually the white  cell count, ESR, urine examination and culture, and where relevant, examination for sickle cell anaemia.
Abdominal pain is regarded particularly seriously if there is also vomiting, if it has lasted for over three hours, if the child looks ill or if the temperature is raised. It is more likely to be significant if the pain is localized than if it is diffuse. A fairly severe pain may precede the development of diarrhoea: and pain may result from a bad cough or from vomiting. The pres­ence of diarrhoea by no means excludes the diagnosis of acute appendicitis or peritonitis or intussusception. The finding of an excess of white cells in a ccntrifuged specimen of urine must not be thought to prove the presence of pyelonephritis; it may occur in pelvic peritonitis and appendicitis. The ESR is often normal in anaphylactoid purpura.
No child with acute abdominal pain should be sent home by a casually doctor without a senior doctor seeing the child. He may have to be re-examined after an interval- If it is thought that he is fit to go home, the family doctor is told on the telephone, the parents are told to bring the child back immediately if there is any reason for anxiety or deterioration, and in any case the child must be seen next day.

Recurrent abdominal pain

This common condition affects mainly school-age children. Many have attacks of central abdominal pain with vomiting, pallor and often fever. It may be related to migraine. The pain may be very severe. In 94% of cases no organic cause is found: but in the remaining 6% the cause may lie in hy­dronephrosis, recurrent volvulus, urinary tract infection, peptic ulcer or other cause. It is not due to a 'grumbling ap­pendix' or 'chronic appendicitis'. The danger in making the diagnosis when a child has had several attacks is the possibility that the present attack is due to a different cause, such as acute appendicitis. It follows that however many attacks the child may have had, a full history and examination are essential. If the attack has passed at the time of examination the parents should be told to bring the child back as soon as another attack has begun.

Acute appendicitis 
It would be much easier for the doctor if all children with acute appendicitis had the symptoms of abdominal pain, vomi­ting, constipation and fever, the pain commencing in the um­bilical area and settling down in the right iliac fossa. Unfortunately the diagnosis is often more difficult. In several studies it was found that about 10% have dysuria (and there may be an excess of white cells and some albumin in the urine) and about 10% have diarrhoea. Appendicitis can occur at any age, and infants with acute appendicitis usually present with diar­rhoea, urinary symptoms and an abdominal mass, often with acetone in the urine, and the white cell count may be normal, though this is unusual. In 40% of 100 cases of perforated appendix, there had been no localization of pain. When the appendix is rctrocaecal, the pain may be in the upper part of the abdomen on the right, or not localized. Occasionally the pain may be in the left iliac fossa. In some cases there is no pain at all. The temperature is not usually high, but may be over 39c in an occasional case. 
It may be difficult or impossible to distinguish acute appen­dicitis from acute

mesenteric lymphadenitis.

Intsussuception 
If all children with intussusception were aged three to nine months, had had severe rhythmical attacks of abdominal pain, vomiting and pallor, with blood in the stool and a palpable sausage­shaped mass, the diagnosis would be easier. Unfortu­natelythere are many variations from this picture: there may be a normal bowel action on the first day, or even diarrhoea; there is often no blood in the stool; in 10% or more there is no pain, but attacks of severe pallor with or without vomiting; and in 10% there is a history of a preceding upper respiratory tract infection; in 10% there may be a high white cell count; and in about 15% the temperature is raised. 
When a child is said to have had one or more attacks of 'looking awful' and perhaps going limp, it is often difficult to decide whether the cause is something like intussusception or if he has had a fit

Torsion of the testis 
This occurs at any age including infancy: the pain may be abdominal or scrota! and often in the groin. An acute painful swelling in the scrotum should be diagnosed as torsion of  the testisuntil   proved otherwise, and referred urgently to the surgeon for exploration

Pain from the urinary tract 
The causes include pyelonephritis, hydronephrosis, renal cal­culus and acute nephritis. The latter can cause abdominal pain.

Other causes of acute abdominal pain 
These include pneumonia and pleurisy (pain being referred to ihe abdomen), infective hepatitis, Meckel's diverticulitis, acute rheumatic fever, sickle cell anaemia, anaphylactoid purpura, and diabetes or associated hypoglycacmia. A pancreatic pseu­docyst may develop around a monih after an upper abdominal injury, causing pain and vomiting.

Investigations 
These must depend on the history and examination, but the most useful ones will usually be microscopy of urine and cul­ture, and a blood count. If there is a possibility of obstruction, erect and supine views of the abdomen may show fluid levels. Do not treat as a urinary tract infection until it has been proved to be one.