In children, acute abdominal complaints are common presentation in the emergency department. The etiologies, presentations, diagnosis and management vary widely and establishing (rapidly) a precise diagnosis is often challenging. Imaging techniques are increasingly important to sort out between all possible diagnoses in order to differentiate cases necessitating acute management from those where the management can be organized more “quietly”. A close collaboration with our paediatric colleagues is mandatory in order to define the panel of differential diagnosis to be considered and the degree of emergency before applying imaging. Familial history, history of the disease, clinical and biological data are all of upmost importance.

The imaging work-up will surely be oriented by this information. Among them one of the most important data is the age of the patient that will help to categorize it. This is the way we have chosen to organize the book.

The armamentarium of imaging techniques is wide. In the setting of emergency suits, US and CT are clearly the imaging techniques mostly performed and highly accurate for the work-up of paediatric abdominal emergencies.

Except for polytrauma where body-CT is the imaging exploration of choice, any work-up of an abdominal “drama” has to start by a highly detailed and complete US examination. US has many advantages: it is highly accurate, harmful, easily and rapidly performed (at bedside if necessary) and is repeatable. Newer equipment, higher resolution transducers are well adapted for children. The technique provides information on any organ of the abdomen when abnormal. The drawbacks of the technique are that it is more operator-dependent than CT, its performances are low among obese patients and too widely aerated abdomen. The technique has proven essential in the wide spectrum of anomalies that can involve the abdomen. In selected indications, Color Doppler, hydrosonography, elastography and the use of contrast enhanced US increase its efficiency.

Unenhanced and contrast enhanced CT (CE-CT) have gained popularity in the emergency departments especially among those dealing with both children and adults. It is well known that the numbers of CT examinations have increased markedly these last years to an unexpected summit. Fortunately, several organizations have arouse a deep reflection reactions about this “overuse” and this has led to a somewhat more limited and more focused use of the technique. CT has many advantages such as rapidity, a better reproducibility than US and accuracy in demonstrating abnormalities in any part of the abdomen. The drawbacks are the irradiation burden, the need for contrast injection and sometimes a need for sedation. So, whenever indicated, the technique (mAS, KvP, position of the patient and all surrounding potential artifacts, etc.) should be optimized to the type of disease and to the morphology of the patient.