Case description

27-year-old woman with abdominal pain in the right lower abdomen and urge to move

by Jaap van Riet (general practitioner) and Melisa Borg and Maureen van der Schinkel (PhD student)

The CRP-Point of care testing (POCT) makes it tempting to detect or rule out inflammatory conditions with a finger prick. For example, in the case of a young woman with suspicion of appendicitis, a CRP determination was chosen; False security or correct assessment of the severity of illness?

The CRP-POCT is officially validated only for pneumonia and diverticulitis and not in the diagnosis of appendicitis. The NHG standard abdominal pain in children also does not recommend the use of a CRP measurement. The pitfall of a CRP determination when appendicitis is suspected is illustrated by the following case at our GP post.

On Sunday morning, a 27-year-old woman with a clean history came forward, who had suffered from abdominal pain during the night from Saturday to Sunday. In total, there are three contacts between this patient and the HAP that Sunday.

1. Telephone contact: Pain in the lower right abdomen with radiation to the back and urge to move. Mrs. is not sick, does not have a fever, is not nauseous. The voiding and defecation are undisturbed. Paracetamol has not given any improvement.

Policy: Acetaminophen and Ibuprofen. Contact again and review on HAP if this does not help.

• Two hours later on HAP: The lady is not sick, but she is painful. Pain in the lower right abdomen/back. The lady is now nauseous, no fever and there is transport pain. Physical examination shows pressure pain right lower abdomen/flank punctum maximum Mc Burney, no release pain. No fever. Urine: Trace of ery’s, further gb. In addition, a CRP is determined: 14 mg/l.
  Policy: Expectative, reassessment in case of increase in the complaints and otherwise tomorrow via your own GP with possibly. repeat CRP.

• Early evening: Symptoms are unchanged, pain relief does not help. The request for help is stronger pain relief. Physical examination shows a supple abdomen, pressure pain in the lower right abdomen, release pain, contralateral release pain, also psoas irritation. No fever (37.2). In addition, a CRP is determined: 80 mg/l. Because the lady is not sick, with otherwise stable parameters, the GP decides not to present her at the ER since there is no indication for emergency surgery.

Policy: Advice tomorrow presentation of the ER via your own GP. In case of alarm symptoms, she is asked to contact the HAP again, or presentation A&E. The next day, when admitted, it turns out that there is a perforated appendicitis with peritonitis.

For GP 3, the diagnosis of appendicitis was clear. However, no contact was made with the surgeon on duty. From previous experiences, the opinion of the GP on duty was that the surgeon does not want to see sick patients who do not have a fever in the evening.

A recent literature review following a PICO on the value of a CRP test in children with suspected appendicitis shows that:

The sensitivity of a low CRP depending on the cut-off value (5-10 mg/L) ranges from 64.6% to 95.4% (the latter percentage belongs to a selected population who have all undergone an appendectomy with a high a priori probability). The specificity of CRP in the populations was very low (24.5% to 58.2%). No study was found based on a primary care population; The clinical picture has usually progressed further in the referred patients, so that the duration of the disease is generally longer than in patients in primary care. When multiple CRP measurements were taken over time, an increase in CRP with an increase in symptom duration could be demonstrated, and therefore sensitivity increased. A higher diagnostic value compared to, for example, leukocytes was also observed. In all populations, a significantly higher CRP value was found with complicated appenditides compared to uncomplicated appenditides.

All in all, the CRP was insufficiently reliable in ruling out the diagnosis of appendicitis. As far as we can see, there is no known study that could show that the CRP could predict a complicated course.

Takeaways:

• CRP-POCT for appendicitis not validated for primary care, so do not determine!
• Second-line research also shows that the sensitivity (and specificity) of a low CRP for diagnosis of appendicitis is too low for both the exclusion and the demonstration of the disorder.
• In case of a patient who is not ill with the suspicion of appendicitis, contact the surgeon on duty and discuss when the patient can be presented at the ER; e.g. presentation the next morning sober in the ER, earlier when getting sicker. Provide a referral letter in advance.

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