Case 14 A young woman with diarrhoea and vomiting

Martha was 30 when she saw Dr Vickers, an out-of-hours general practitioner, with a four-hour history of upper abdominal pain followed by vomiting. Dr Vickers recorded there had been indigestion earlier and the pain had moved down. On examination there was some abdominal tenderness (site not recorded). Dr Vickers prescribed some ranitidine. No follow-up advice was recorded.

Martha sought further Out of Hours advice 48 hours later from Dr Clelland, giving a history of severe abdominal pain and fever. The antacid had helped but the pain had returned. Dr Clelland thought the symptoms consistent with gastritis.

Two days later Martha had a laparotomy for a perforated appendix with peritonitis (which had been present for some time).

Why was the diagnosis of appendicitis missed?

Expert comment

Acute abdominal pain is a very common reason for consultations in primary care. The possible causes are legion. In the majority of cases general practitioners are trying to differentiate between those patients who may have a ‘surgical’ acute abdomen and the vast majority who are suffering from self limiting causes of abdominal pain. The incidence of acute abdominal pain presenting to general practitioners or A&E departments is quoted as 11 to 13 per 1000 patients per year (de Wit, 2004). Of these many will be self-limiting conditions that can be managed in the community and observed. A full-time general practitioner will therefore expect to see one or two patients a month with acute abdominal pain.

Appendicitis is a common cause of a surgical acute abdomen and is a frequent cause of litigation against GPs when it is missed and goes on to cause perforation and/ or peritonitis.

For reasons that are not quite clear the incidence of acute appendicitis has been falling for some decades. The quoted incidence of acute appendicitis in the Western world is between 0.7 and 1.6 per 1000 per year (de Wit, 2004). This suggests that a general practitioner may see 1 to 2 cases on his/her list per year. However, in practice a fulltime general practitioner probably now only sees a case of acute appendicitis once every couple of years or so.

The presentation of acute appendicitis is often rather atypical. The variation in the types of clinical presentation of acute appendicitis is often attributed to the anatomical site of the inflamed appendix (since Sir Zachary Cope’s classical work on The early diagnosis of the acute abdomen in 1921 (Cope, 1921). A clinical presentation of acute appendicitis with diarrhoea is a recognized cause of diagnostic error and delay (Murch, 2000).

However at the first consultation in this case the following features were present:

• acute onset of abdominal pain; some vomiting;
  
• pain starting high and moving down;
  
• pain on abdominal palpation;
  
• low-grade fever.

On the face of it these symptoms and signs seem to tally quite well with the ‘classical’ presentation of appendicitis; a history over a few days of generalized central or lower abdominal pain, migrating to the right iliac fossa (as the peritoneal surfaces over the inflamed appendix also become inflamed), with vomiting, constipation and a slightly raised temperature (Wagner et al., 1996).

A review article in the Journal of the America Medical Association considers the sensitivity and specificity of history features and examination findings for appendicitis (Wagner et al., 1996). The article shows that the presence or absence of right lower quadrant pain/tenderness is highly discriminatory, and other features such as the migration of the pain from the centre of the abdomen to the right lower quadrant, pain before vomiting, rigidity and guarding are also very helpful.

In this case the appendicitis was missed. Dr Vickers saw Martha early in the course of her illness. It would have been helpful if he/she had taken a slightly more detailed history and recorded the site of the abdominal tenderness. His/her actions might have been reasonable if careful safety netting advice has been given and recorded.

The consultation demonstrates the cognitive errors of ‘premature anchoring’ – a reluctance to depart from a mundane diagnosis such as gastroenteritis, which the doctor may have seen fairly frequently and ‘premature diagnostic closure’ – in other words a reluctance to obtain or consider further information that may cast doubt on the first diagnostic hypothesis.

At the second consultation Dr Clelland may have been unduly influenced by the prescription of ranitidine by the first GP, leading to a diagnosis of gastritis despite the complaints of severe pain and lower abdominal pain. If he/she had examined Martha’s abdomen it is likely that she would have had guarding or rebound in the right iliac fossa. If no examination was done Dr Clelland was in breach of duty.

This consultation demonstrates ‘confirmation bias’, leading a doctor to prefer to elicit or favour clinical data that supports the chosen hypothesis (e.g. the report that the ranitidine tablets had helped) rather than the date inconsistent with it (e.g. that the pain was now lower abdominal).

If no definite diagnosis can be made, it is prudent to follow the patient up soon, in order to judge whether the symptoms are changing. It can be very helpful to such follow-up if some basic blood tests are obtained. It is also necessary to give and document careful safety netting advice.

In the same general category as the case above is the misdiagnosis of acute gastroenteritis. This illness would typically involve the onset of nausea and vomiting lasting for some hours (up to 24) followed by diarrhoea, which might persist for some days. Abdominal pain is usually colicky, not localized, and usually precedes an episode of diarrhoea. This ‘classical’ picture can lead to a confident diagnosis of gastroenteritis.

When gastroenteritis is diagnosed in the face of persisting vomiting; continuous or localized pain; and in the absence of diarrhoea; the GP is vulnerable to the allegation of having made an untenable diagnosis and therefore having closed his or her mind to the alternatives.

Legal comment

Both Dr Vickers and Dr Clelland seem each to have negligently failed to consider a possible diagnosis of appendicitis. If the correct diagnosis had been made, it is probable that perforation and peritonitis could have been avoided.

Martha therefore appears to have a good claim for compensation for the pain and suffering caused by the perforation and peritonitis. This may only be a few thousand pounds (depending on the circumstances). However, if the peritonitis has caused lasting consequences, then they too would be the subject of compensation. For example, if her fertility is compromised, as a young woman she may have a right to compensation of several tens of thousands of pounds.

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