The most common cause for acute bloody diarrhoea in a 10-year-old child is Campylobacter.Note:Campylobacter is the most common bacterial cause of gastroenteritis in the UK. It typically presents with bloody diarrhoea, fever, abdominal pain and vomiting. The primary source of Campylobacter is uncooked poultry. Treatment is generally supportive unless the child is immunosuppressed or the symptoms are persistent.Other options:- E. coli 0157:H7: It causes acute haemorrhagic diarrhoea, usually afebrile. It can lead to haemolytic uremic syndrome (haemolytic anaemia, acute renal failure and thrombocytopenia), which is the commonest cause of acute renal failure in children.- Rotavirus: It rarely causes bloody diarrhoea.- Salmonella and Yersinia: While they can cause bloody diarrhoea, they are much less common compared to Campylobacter.

The most appropriate imaging modalities to be used in this child would be CT Head, C-spine and Abdomen/Pelvis and chest X-ray (CXR).The C-spine cannot be cleared, this alongside a multi-trauma presentation means a CT C-spine is indicated rather than X-rays alone. The imaging modality for blunt trauma to the chest is CXR; if this shows significant thoracic trauma, a CT chest should be considered. Other options:- CT Head and Abdomen/Pelvis with CXR and X-ray C-spine: This child is at risk of C-Spine injury following the mechanism of trauma. He had a reduced GCS, has undergone a multi-region trauma and is now intubated. NICE head injury guidelines, therefore, recommend using CT.- CT Head, C-spine and Abdomen/Pelvis X-rays: Imaging of the chest is required following blunt trauma and for endotracheal tube position.- MRI Head: If there were concerns of abnormal neurology, then spinal MRI could be considered.- Whole-body CT: It is not recommended in children in view of the high radiation doses.

Liddle’s syndrome,  is an autosomal dominant disorder, that is characterized by early, and frequently severe, high blood pressure associated with low plasma renin activity, metabolic alkalosis, low blood potassium, and normal to low levels of aldosterone. Liddle syndrome involves abnormal kidney function, with excess reabsorption of sodium and loss of potassium from the renal tubule. Bartter Syndrome also presents with hypokalaemia, however blood pressure of these patients is usually low or normal.

Developmental dysplasia of the hip (DDH) is a spectrum of anatomical abnormalities of the hip joint in which the femoral head has an abnormal relationship with the acetabulum.Plain radiographs are of limited value for diagnosis in the new-born child because the femoral head and acetabulum are largely cartilaginous. Ultrasound scanning is the investigation of choice to evaluate DDH in infants younger than six months of age and is useful to diagnose more subtle forms of the disorder when a clinical exam is equivocal. It is also the only imaging modality that enables a three-dimensional real-time image of a neonate’s hip.

The most worrying condition is testicular torsion and to exclude it exploratory surgery is required.

Crossover trials are characterized by the switching of study participants throughout the treatment groups, keeping a random order of switching. This randomization is important to determine any carry-over effect of different treatment modalities. The benefit of this study is the evaluation of the efficacy of various short-term treatment options for the relief of chronic conditions. The washout period is small in this type of study. Crossover studies are more efficient than the parallel studies, but they should be used according to the treatment options and outcomes.

Dandy-Walker syndrome is characterised by symptoms of brain maldevelopment that are seen in this patient. A large cranium indicates hydrocephalus, and the hypotonia indicates poor limb development.

Intussusception is the most suggested case here based on the child’s symptoms. The urgent course of treatment is to bring the child to a paediatric surgical unit. If air reduction attempts fail, surgery will have to be done. Risk factors for intussusception include viral infection and intestinal lymphadenopathy.

The hypothalamus and pituitary gland control how much testosterone the testes produce and secrete. The hypothalamus sends a signal to the pituitary gland to release gonadotrophic substances (follicle stimulating hormone and luteinizing hormone). Luteinizing hormone (LH) stimulates testosterone production.

Fetal alcohol syndrome (FAS) is a common yet under-recognized condition resulting from maternal consumption of alcohol during pregnancy. The diagnosis of fetal alcohol syndrome (FAS) is based on findings in the following 3 areas: (1) characteristic facial anomalies (see image below), (2) growth retardation (intrauterine growth restriction and failure to have catch-up growth), and (3) CNS involvement (cognitive impairment, learning disabilities, or behavioural abnormalities).Key characteristic craniofacial abnormalities include the following:- Smooth philtrum- Thin, smooth vermilion border of the upper lipShort palpebral fissures (< 10th percentile for age)Other craniofacial abnormalities are as follows:- Midface hypoplasia- Microphthalmia- Strabismus- PtosisCNS and neurobehavioral abnormalities include the following:- Microcephaly- Intellectual impairment (mild-to-moderate mental retardation)- Cognitive impairment- Developmental delay- Irritability in infancy- Hyperactivity in childhood or attention deficit hyperactivity disorder (ADHD)- Seizures- Delayed or deficient myelination- Agenesis or hypoplasia of the corpus callosumSkeletal abnormalities include the following:- Radioulnar synostosis- Flexion contractures- Camptodactyly- Aberrant palmar creases, especially hockey-stick palmar crease- Clinodactyly- Klippel-Feil anomaly- Hemivertebrae- Scoliosis- Dislocated jointsOther major congenital anomalies include the following:- Cleft palate- Heart defects- Renal anomalies- DiGeorge sequenceFunctional problems include the following:- Refractive problems (e.g., myopia, astigmatism)- Hearing lossGrowth deficiency includes the following:- Infant small for gestational age (< 10th percentile for weight or length)- Postnatal growth deficiency