The combination of cholestasis, congenital heart disease (mainly affecting the pulmonary vasculature) and anterior-segment abnormalities (primarily posterior embryotoxon) suggests a diagnosis of Alagille syndrome. Clinical features:The facial features are characteristic and include a prominent forehead, deep-set eyes and a pointed chin. The most common skeletal manifestation is butterfly vertebrae, a clefting abnormality of the vertebrae most often seen in the thoracic spine and described in up to 87% of cases. Radio-ulnar synostosis and short phalanges have also been described in Alagille but less frequently. Note: Pectus excavatum is a feature of Noonan syndrome, one of the differential diagnoses of pulmonary valve disease.

Mongolian spots are, hyper-pigmented, non-blanching patches present on the back and gluteal region at birth. They are commonly found in African and Asian ethnic groups, and can also present in infants of Mediterranean and middle eastern descent. Though the spots usually disappear by puberty, some may persist into adulthood.

Oesophageal atresia refers to a congenitally interrupted oesophagus. One or more fistulae may be present between the malformed oesophagus and the trachea. The lack of oesophageal patency prevents swallowing. In addition to preventing normal feeding, this problem may cause infants to aspirate and literally drown in their own saliva, which quickly overflows the upper pouch of the obstructed oesophagus. If a tracheoesophageal fistula (TEF) is present, fluid (either saliva from above or gastric secretions from below) may flow directly into the tracheobronchial tree.The complete absence of gas in the GI tract denotes the absence of a distal tracheoesophageal fistula (TEF)| however, distal fistulae simply occluded by mucous plugs have been rarely reported.If no distal TEF is present, a gastrostomy may be created. In such cases, the stomach is small, and laparotomy is required. In all cases of oesophageal atresia in which a gastrostomy is created, care should be taken to place it near the lesser curvature to avoid damaging the greater curvature, which can be used in the formation of an oesophageal substitute. When a baby is ventilated with high pressures, the gastrostomy may offer a route of decreased resistance, causing the ventilation gases to flow through the distal fistula and out the gastrostomy site. This condition may complicate the use of ventilation.

The origins of the neural tube and the nape of the neck where nuchal translucency measurements are taken are from embryonic ectoderm.The structural development of the head and neck occurs between the third and eighth weeks of gestation. The 5 pairs of branchial arches, corresponding to the primitive vertebrae gill bars, that form on either side of the pharyngeal foregut on day 22 are the embryologic basis of all the differentiated structures of the head and neck. Each arch consists of 3 layers: an outer covering of ectoderm, an inner covering of endoderm, and a middle core of mesenchyme. These arches are separated further into external, ectoderm-lined pharyngeal clefts and internal, endoderm-lined pharyngeal pouchesA population of ectodermal cells adjacent to the neural fold and not included in the overlying surface (somatic) ectoderm gives rise to the formation of the neural crest. These neuroectodermal crest cells are believed to migrate widely throughout the developing embryo in a relatively cell-free enriched extracellular matrix and differentiate into a wide array of cell and tissue types, influenced by the local environment. Most connective and skeletal tissues of the cranium and face ultimately come from the derivatives of neural crest cells.

Embryologically the testes are retroperitoneal structures in the posterior abdominal wall, attached to the anterolateral abdominal wall by the gubernaculum. The gubernaculum ‘pulls’ the testes through the deep inguinal ring, inguinal canal and superficial inguinal ring and over the pelvic brim. The gubernaculum is preceded by the processus vaginalis that is derived from the peritoneum anterior to the testes. The processus vaginalis pushes the muscle and fascial layers. These eventually make up the canal and the spermatic cord, into the scrotum. The gubernaculum persists as the scrotal ligament while part of the processus vaginalis remains as a bursa-like sac i.e. the tunica vaginalis testes. The testes therefore could be caught in any one of these places along its path of descending. The testes are never in the perineum.

The most probable cause for the patient’s presenting symptoms is encephalitis secondary to measles infection.Encephalitis:Encephalitis occurs in 1 per 1000 measles cases. It usually presents within 1–14 days of the rash, usually day 5. It may present with fever, headache, vomiting, stiff neck, meningeal irritation, drowsiness, seizures, reduced consciousness| 15% will have neurological sequelae| 10% mortality.Other options:- Acute disseminated encephalomyelitis occurs in 1 per 1000 measles cases. It is thought to be a postinfectious immune response. Clinical manifestations include fever, headache, neck stiffness, seizures and mental status changes. It could fit this presentation although it tends to present in the recovery phase of measles infection, typically two weeks after the exanthem. In contrast, encephalitis tends to occur within a few days of the rash.- The history is not that of a typical febrile seizure as it lasted >15 minutes. He has also not recovered consciousness at 4 hours. The diazepam should have been eliminated within 4 hours and so should no longer be contributing to his reduced level of consciousness. Also, the history states the recent diagnosis of measles, and so complications of measles should be considered.- Intracranial bleed secondary to thrombocytopenia: Measles is not known to cause thrombocytopenia.- Subacute sclerosing panencephalitis (also known as Dawson’s encephalitis): This is an extremely rare complication of measles. It is a progressive degenerative disease of the central nervous system that occurs 7–10 years after a measles infection. The treatment for SSPE is mainly intraventricular interferon therapy through an Ommaya reservoir. The prognosis is poor, and it is usually fatal.

According to the Gell and Coombs classification of hypersensitivity reactions, the scenario provided is a type 4 (delayed) reaction.These reactions are mediated by T lymphocytes and cause contact dermatitis. Nickel, commonly found in cheap jewellery, is a common cause of contact dermatitis.Note:There are two main types of contact dermatitis:- Irritant contact dermatitis: It is a common, non-allergic reaction due to weak acids or alkalis (e.g. detergents). These are often seen on the hands. They present typically with erythema, and rarely, crusting and vesicles.- Allergic contact dermatitis: These are type IV hypersensitivity reactions and are often seen on the head following hair dyes.They typically present as acute weeping eczema which predominately affects the margins of the hairline rather than the hairy scalp itself. Treatment is usually with a potent topical steroid.Other options:- Allergic rhinitis is an example of a type 1 (immediate) reaction. It is an IgE mediated. It is a hypersensitivity to a previously innocuous substance.- Type 2 reactions are mediated by IgG and IgM, which binds to a cell, causing cell death. Goodpasture syndrome is an example of a type 2 hypersensitivity reaction.- Immune complexes mediate type 3 reactions. Rheumatoid arthritis is an example of a type 3 hypersensitivity reaction.

Most infants have a good heart rate after birth and establish breathing by about 90 s. If the infant is not breathing adequately aerate the lungs by giving 5 inflation breaths, preferably using air. Until now the infant’s lungs will have been filled with fluid.

Based on the clinical scenario, the patient has features suggestive of acute otitis externa, which can be managed with topic antibiotics.Otitis externa:It can be classified as acute (< 3 weeks) or chronic (> 3 months). Frequent exposure to water, e.g. swimming, is a risk factor for the condition. Itching, pain, hearing loss and discharge are common complaints. Examination demonstrates oedema of the external auditory canal with discharge. Pain may be elicited on the movement of the tragus or pinna. First-line treatment is with topical drops/sprays for one week. Acidic preparations such as 2% acetic acid, antibiotic or combined antibiotic and corticosteroid preparations may be used (1% hydrocortisone and 0.3% gentamicin). Acetic acid can be used as the first-line treatment for mild cases without discharge or hearing impairment. On selecting an appropriate topical preparation remember that topical aminoglycosides are contraindicated if the tympanic membrane is perforated and that chloramphenicol ear drops cause contact dermatitis in approximately 10% of people. Clinoquinol, a combination of antibacterial and antifungal, may be preferred over aminoglycoside containing preparations due to the theoretical lower risk of ototoxicity and dermatitis. However, there is no clear evidence to support the use of one topical preparation over another.Other options:- Admit for IV antibiotics: First line management is with analgesia and topical antibiotic or combined antibiotic and corticosteroid preparations. Thus, IV antibiotics is not an appropriate action.- Oral antibiotics: Oral antibiotics like flucloxacillin or erythromycin are considered only for severe infections such as the spread of cellulitis beyond the ear canal. – Reassurance is not sufficient to treat these patients. They require topic antibiotic therapy.- Referral to ENT: Should be considered only in case of treatment failure. ENT referral can also be considered if there is cellulitis extending past the margin of the external ear canal, extreme pain or extensive swelling and discharge likely to require suction or the insertion of an ear wick. Urgent ENT referral is reserved for suspected cases of malignant otitis externa (with the extension of the condition into the adjacent bone and spreading osteomyelitis).

Hydrops fetalis is a serious condition characterized by excessive fluid accumulation resulting in oedema in one or more of the fetal compartments. The most likely cause is fetal anaemia, and the condition may lead to ascites and pleural effusion. The anaemia that results in hydrops may be caused by Rh incompatibility, Parvovirus B19 infection, toxoplasmosis, hepatitis B, maternal syphilis (strong association), Cytomegalovirus, Turner syndrome, and Noonan syndrome.

The most serious side effects of IV Lorazepam include hallucinations, agitation, confusion, amnesia and muscle weakness.

Haemophilia is a X-linked recessive disorder. In X-linked recessive inheritance only males are affected. An exception to this seen in examinations are patients with Turner’s syndrome, who are affected due to only having one X chromosome. X-linked recessive disorders are transmitted by heterozygote females (carriers) and male-to-male transmission is not seen. Affected males can only have unaffected sons and carrier daughters.

Prevalence:

This is the proportion of individuals in a population who have a specific condition, disease, or attribute at a given point in time or over a specific period.

Incidence:

This is the number of new cases of a specific condition, disease, or attribute that develop in a population during a specified period of time.

Specificity:

This refers to the ability of a test to correctly identify those without the condition (true negative rate).

Sensitivity:

This refers to the ability of a test to correctly identify those with the condition (true positive rate).

Probability:

This is a measure of the likelihood that an event will occur. In the context of diseases, it can refer to the likelihood of developing a condition.

Primary rubella infection during pregnancy, particularly during the first trimester, can affect several organs and cause birth defects that are responsible for congenital rubella syndrome (CRS). The most common defects of CRS are hearing impairment (unilateral or bilateral sensorineural), eye defects (e.g., cataracts, congenital glaucoma, or pigmentary retinopathy), and cardiac defects (e.g., patent ductus arteriosus or peripheral pulmonic stenosis). Congenital hearing loss is the most common sequela, occurring in approximately 60% of cases, especially when infection occurs in the 4th month of pregnancy.

The signs and symptoms of vitamin D-dependent rickets begin within months after birth, and most are the same for all types of the condition. The weak bones often cause bone pain and delayed growth and have a tendency to fracture. When affected children begin to walk, they may develop abnormally curved (bowed) legs because the bones are too weak to bear weight. Impaired bone development also results in widening of the metaphysis, especially in the knees, wrists, and ribs. Some people with vitamin D-dependent rickets have dental abnormalities such as thin tooth enamel and frequent cavities. Poor muscle tone (hypotonia) and muscle weakness are also common in this condition, and some affected individuals develop seizures.

The femoral nerve is the main nerve supply for the thigh muscles including the pectineus, iliacus, sartorius, which flex the hip| and the quadriceps femoris made up of the rectus femoris, vests laterals, vastus medialis and vastus intermedius, which extend the knee. The nerve is derived from the L2, L3 and L4 nerve roots, and supplies cutaneous branches to the anteromedial thigh and the medial side of the leg via the saphenous nerve.

Germinal matrix/intraventricular haemorrhage (GM/IVH) is a complication of premature delivery that can result in life-long medical and developmental consequences.Loss of autoregulation of cerebral blood flow is a pathophysiologic feature of germinal matrix/intraventricular haemorrhage (GM/IVH). Prematurity itself results in derangements in cerebral autoregulation. In some patients, a history of additional events that result in loss of autoregulation can be obtained. Furthermore, events that can result in beat-to-beat variability of cerebral blood flow may be identified in some patients.There may be no symptoms. The most common symptoms seen in premature infants include:- Breathing pauses (apnoea)- Changes in blood pressure and heart rate- Decreased muscle tone- Decreased reflexes- Excessive sleep- Lethargy- Weak suck- Seizures and other abnormal movements

The most common congenital cyanotic heart disease and the most common cause of blue baby syndrome, Tetralogy of Fallot shows four cardiac malformations occurring together. These are ventricular septal defect (VSD), pulmonary stenosis (right ventricular outflow obstruction), overriding aorta (degree of which is variable), and right ventricular hypertrophy. The primary determinant of severity of disease is the degree of pulmonary stenosis. Tetralogy of Fallot is seen in 3-6 per 10,000 births and is responsible for 5-7% congenital heart defects, with slightly higher incidence in males. It has also been associated with chromosome 22 deletions and DiGeorge syndrome. It gives rise to right-to-left shunt leading to poor oxygenation of blood. Primary symptom is low oxygen saturation in the blood with or without cyanosis at birth of within first year of life. Affected children ay develop acute severe cyanosis or ‘tet spells’ (sudden, marked increase in cyanosis, with syncope, and may result in hypoxic brain injury and death). Other symptoms include heart murmur, failure to gain weight, poor development, clubbing, dyspnoea on exertion and polycythaemia. Chest X-ray reveals characteristic coeur-en-sabot (boot-shaped) appearance of the heart. Treatment consists of immediate care for cyanotic spells and Blalock–Taussig shunt (BT shunt) followed by corrective surgery.

A low serum free T4 level with a low, or normal serum TSH level would indicate secondary hypothyroidism. A normal TSH response to TRH is a rise at 20 minutes post-dose and then a fall by 60 minutes, while a normal prolactin response would be a rise at 20 minutes and then a fall by 60 minutes. A continued rise of TSH at 60 minutes implies hypothalamic damage. Secondary hypothyroidism is indicated by a low baseline TSH level, while primary hypothyroidism is demonstrated by a raised TSH.

If a child is not saying single words with meaning by 18 months it suggests that he or she is not following normal developmental milestones and further investigation is needed. Children are usually expected to be dry by day at the age of 3 years and dry by night at the age of 4 years, however 10% of 5 year old children and 5% of 10 year old children still wet the bed.

The submandibular glands provide the bulk of salivary secretions contributing close to 70%. The sublingual glands provide 5% and the remainder from the parotid.

Increasing the volume of the TV and the child’s loss of hearing may suggest that he has otitis media with effusion but the fever and the ear pain and fever strongly points to otitis externa as the diagnosis.

The most appropriate action in this baby would be to perform HIV PCR and commence cART and PCP prophylaxis if HIV positive.Treatment guidelines for HIV-positive infants state that all should receive combination antiretroviral therapy (cART) and Pneumocystis jiroveci pneumonia (PJP) prophylaxis, irrespective of CD4 count or viral load.

The most probable lesion in the patient is a dermoid cyst.Rationale:Dermoid cysts are embryological remnants and may be lined by hair and squamous epithelium (like teratomas). They are often located in the midline and may be linked to deeper structures resulting in a dumbbell shape to the lesion. Complete excision is required as they have a propensity to local recurrence if not excised.Note:Desmoid tumours are a different entity entirely. These lesions most commonly develop in ligaments and tendons. They are also referred to as aggressive fibromatosis and consist of dense fibroblastic lesions (resembling scar tissue). They should be managed in a similar manner to soft tissue sarcomas.

The IM dose of adrenaline for anaphylaxis in:< 6 months: 150 micrograms (0.15ml 1 in 1,000)6 months - 6 years: 150 micrograms (0.15ml 1 in 1,000)6 - 12 years: 300 micrograms (0.3ml 1 in 1,000)Adult and child > 12 years: 500 micrograms (0.5ml 1 in 1,000)Anaphylaxis:Anaphylaxis is an acute, rapidly progressing, potentially life-threatening IgE mediated Type I hypersensitivity reaction.It involves the release of mediators from mast cells, basophils and inflammatory cells. It is characterised by oedematous swelling of the airway mucosa giving rise to dyspnoea and respiratory distress. The most common cause of anaphylaxis in children is a food allergy.Risk factors for death in patients with anaphylaxis include asthma, age 11+, peanut allergy, and delay in adrenaline administration.Management of anaphylaxis includes:- ABCD- Remove the allergen- IM adrenaline or Nebulised adrenaline- IV Hydrocortisone – pro re nata IV fluid support. – Followed by observation.

Low oxygen delivery in hypotension, hypoxia, oedema, intracranial hypertension or changes in cerebral blood flow should all be prevented to avoid secondary brain injury. There is no evidence to suggest that hypothermia prevents secondary brain injuries.

DiGeorge syndrome usually presents at a young age with abnormal faces. Chest x-ray is characterised by an absent thymic shadow and recurrent infections due to an abnormal T-cell mediated immune response. Sometimes it presents by convulsions of the new-born due to hypocalcaemia as a result of a malfunctioning parathyroid gland and low levels of PTH.

The Chi squared test is used to find the relationship between two variables, determining whether they are not independent of each other. This test of statistical significance allows you to determine the degree of confidence with which you can accept or reject the null hypothesis. The student t test compares the significant differences in data means, while rank correlation, linear regression and the correlation coefficient all help to measure the linear relationship between variables.

Power calculations are a important step in study design and preparation, but do not directly help with the interpretation of the results. They are used to determine how many subjects are needed in order to avoid errors in accepting or rejecting the null hypothesis. These calculations are not usually complex and for the best results, the power of the test should be set to above 80%.

Advanced paternal age is associated with poor quality sperm leading to a reduction in overall fertility along with an increase in the occurrence of various medical disorders in the fetus. Advanced paternal age has been implicated as a risk factor for diseases like retinoblastoma, Marfan’s syndrome, neurofibromatosis, achondroplasia, autism spectrum disorders, schizophrenia, and acute lymphoblastic leukaemia. Down’s syndrome is mostly considered a consequence of advanced maternal age, but advanced paternal age has also been implicated as a risk factor. Turner syndrome is not found to be caused by advanced paternal age.