Usually, a total serum bilirubin level test is the only one required in an infant with moderate jaundice who presents on the second or third day of life without a history and physical findings suggestive of a pathologic process. Measurement of bilirubin fractions (conjugated vs unconjugated) in serum is not usually required in infants who present as described above. However, in infants who have hepatosplenomegaly, petechiae, thrombocytopenia, or other findings suggestive of hepatobiliary disease, metabolic disorder, or congenital infection, early measurement of bilirubin fractions is suggested. The same may apply to infants who remain jaundiced beyond the first 7-10 days of life, and to infants whose total serum bilirubin levels repeatedly rebound following treatment.

Key observations in the results:

1. Oxygen Saturation Step-Up:
   • There is a significant step-up in oxygen saturation from the right ventricle (72%) to the pulmonary artery (86%). This suggests the presence of left-to-right shunting of blood.
2. Pressure Differences:
   • The pressure in the pulmonary artery is elevated (53/13 mmHg), indicating pulmonary hypertension.

Differential Diagnosis:

1. Patent Ductus Arteriosus (PDA):
   • PDA can cause increased pulmonary blood flow, leading to a step-up in oxygen saturation in the pulmonary artery. The pulmonary artery pressures can also be elevated due to increased blood flow.
2. Primary Pulmonary Hypertension:
   • Typically presents with elevated pulmonary pressures but does not usually show a step-up in oxygen saturation.
3. Pulmonary Stenosis:
   • Would result in elevated right ventricular pressure but would not explain the step-up in oxygen saturation.
4. Septum Primum Atrial Septal Defect (ASD):
   • Would result in a step-up in oxygen saturation from the right atrium to the right ventricle, not between the right ventricle and pulmonary artery.
5. Tetralogy of Fallot:
   • Characterized by right ventricular outflow tract obstruction, VSD, right ventricular hypertrophy, and an overriding aorta. Oxygen saturation levels would typically be lower in the systemic circulation.

Urine culture confirms a diagnosis of a UTI. A kidney ultrasound will be the next best investigation because it will help us to visualise the bladder, kidneys, and ureters to rule out any congenital obstruction in the urinary tract that might be the actual cause of infection in this 2-month old girl.

Hirschsprung’s disease is characterized by congenital absence of the autonomic plexus (Meissner’s and Auerbach’s plexus) in the intestinal wall. Usually limited to the distal colon, it can occasionally involve the entire colon or even the small bowel. There is abnormal or absent peristalsis in the affected segment, resulting in continuous spasm of smooth muscle and partial/complete obstruction. This causes accumulation of intestinal contents and dilatation of proximal segment. Skip lesions are highly uncommon. This disease is seen early in life with 15% patients presenting in first month, 60% by 1 year of age and 85% by the age of 4 years. Symptoms include severe and complete constipation, abdominal distension and vomiting. Patients with involvement of ultra-short segments might have mild constipation with intervening diarrhoea. In older children, symptoms include failure to thrive, anorexia, and lack of an urge to defecate. On examination, an empty rectum is revealed with stool palpable high up in the colon. If not diagnosed in time, it can lead to Hirschsprung’s enterocolitis (toxic megacolon), which can be fulminant and lead to death. Diagnosis involves a barium enema or a rectal suction biopsy. Barium enema shows a transition in diameter between the dilated, normal colon proximal to the narrowed, affected distal segment. It is to be noted that barium enema should be done without prior preparation, which can dilate the abnormal segment, leading to a false-negative result. A 24-hour post-evacuation film can be obtained in the neonatal period – if the colon is still filled with barium, there is a high likelihood of Hirschsprung’s disease. Full-thickness rectal biopsy is diagnostic by showing the absence of ganglion cells. Acetylcholinesterase staining can be done to highlight the enlarged nerve trunks. Abnormal innervation can also be demonstrated by rectal manometry.

Aplastic anaemia causes a deficiency of all blood cell types: red blood cells, white blood cells, and platelets. It is more frequent in people in their teens and twenties, but is also common among the elderly. It can be caused by heredity, immune disease, or exposure to chemicals, drugs, or radiation. However, in about one-half of cases, the cause is unknown.The definitive diagnosis is by bone marrow biopsy| normal bone marrow has 30–70% blood stem cells, but in aplastic anaemia, these cells are mostly gone and replaced by fat.First-line treatment for aplastic anaemia consists of immunosuppressive drugs, typically either anti-lymphocyte globulin or anti-thymocyte globulin, combined with corticosteroids, chemotherapy and ciclosporin. Hematopoietic stem cell transplantation is also used, especially for patients under 30 years of age with a related matched marrow donor.

NICE does not recommend the use of antibiotics or tonsillectomy in this case. Paracetamol/Ibuprofen are indicated as they provide antipyretic action and analgesia. Indications for tonsillectomy are 5 or more episodes of acute sore throat/year, symptoms present for at least 2 years, symptoms are severe enough to disrupt a child’s social life. Indications for antibiotics are features of marked systemic upset secondary to the acute sore throat, unilateral peritonsillitis, history of rheumatic fever, an increased risk from acute infection, acute tonsillitis with 3 or more of the following: history of fever, tonsillar exudates, no cough and tender anterior cervical lymphadenopathy.

Non-Hodgkin Lymphoma: The history is of enlarged reticuloendothelial system with abnormalities in all 3 cell lines of the bone marrow (pallor, fever and petechiae). The most likely diagnosis is therefore acute (lymphoblastic) leukaemia. Lymphadenopathy may be prominent: mediastinal nodes are characteristic of T-cell leukaemia. In lymphoma the marrow involvement tends to be much less.

The clinical scenario presented is highly suggestive of vitamin C deficiency (Scurvy).Vitamin C is found in citrus fruits, tomatoes, potatoes, Brussel sprouts, cauliflower, broccoli, cabbage and spinach. Deficiency leads to impaired collagen synthesis and disordered connective tissue. Scurvy is associated with severe malnutrition as well as drug and alcohol abuse, and those living in poverty with limited access to fruits and vegetables.Symptoms and signs include:- Follicular hyperkeratosis and perifollicular haemorrhage- Ecchymosis- Gingivitis with bleeding and receding gums- Sjogren’s syndrome- Arthralgia- Oedema- Impaired wound healing- Generalised symptoms such as weakness, malaise, anorexia and depression

The most appropriate next step would be to request for an EEG (electroencephalogram).The two primary differential diagnoses for the clinical scenario presented would be night terrors (hypnopompic hallucinations) due to underlying narcolepsy or frontal lobe epilepsy.Though occult airway obstruction and obstructive sleep apnoea can cause sleep disturbances, the clinical scenario presented is more suggestive of neurological disorders.The hyper-motor activity, along with arm posturing (often dystonic in appearance) and multiple occurrences per night would favour epilepsy. The daytime somnolence could be secondary to the nocturnal seizures.

Scabies is a dermatological condition caused by infestation of the Sarcoptes Scaibie. The tiny mite, often unseen by the naked human eye, is able to burrow into the stratum corneum where it lays its eggs, causing irritation and a rash related to the immune response against the mite and its eggs, saliva and faeces. On examination, the pathognomic small burrows are often seen on the skin along with small red papules and scratch marks| granulomatous nodules may also be seen especially in darker skin types. Other clinical subtypes such as bullous, and Norwegian (crusted) also exist. Common areas of infection include the hands, wrists, and the interdigital spaces. Infestation can also occur on the genital area, the buttocks, feet, ankles, flexor surfaces. First line treatment is with permethrin 5% dermal cream. It is important that all members of the household are also treated at the same time, and that contaminated bedding, clothes and furniture is adequately disinfected. Scabies is usually associated with overcrowded conditions.

Based on the clinical scenario provided, the most probable diagnosis is Peutz-Jeghers syndrome.Peutz-Jeghers syndrome is an autosomal dominant condition characterised by numerous hamartomatous polyps in the gastrointestinal tract. It is also associated with pigmented freckles on the lips, face, palms and soles.Genetic basis: It follows an autosomal dominant inheritance, and the gene responsible encodes serine-threonine kinase LKB1 or STK11.Classical features of PJS include:- Hamartomatous polyps in the GI tract (mainly small bowel)- Pigmented lesions on lips, oral mucosa, face, palms and soles- Intestinal obstruction, e.g. intussusception- Gastrointestinal bleedingThe treatment is mainly conservative unless complications develop.Note:Hereditary haemorrhagic telangiectasia can also be associated with mucocutaneous lesions and iron-deficiency anaemia, but intestinal polyps are not a feature.

Neurofibromatosis Type 1 (also known as von Recklinghausen disease) does not present with cataracts.The eye findings in NF1 are Lisch’s nodules, which are pigmentary lesions seen on the iris and constitute one of the major diagnostic features in this condition. Note:Interestingly, in another syndrome closely related to it, Neurofibromatosis type 2 (NF-2), cataracts can occur. Early detection in family members may be made by finding lens opacities (both congenital polar cataracts and posterior lenticular opacities). Other options:- Incontinentia pigmenti is an X-linked dominant disorder with pigmentary skin changes, mental retardation and eye involvement in 40% of cases. – Myotonic dystrophy is a triplet-repeat disorder with neurological symptoms and cataracts. – Lowe syndrome (oculo-cerebro-renal syndrome) is an X-linked recessive condition. Males with this X-linked recessive condition have cataracts, hypotonia, mental retardation, generalised aminoaciduria and renal tubular acidosis with hypophosphatemia. – Wilson disease is an inborn error of copper metabolism. The clinical features include hepatic involvement, progressive neurological features, eye involvement, including Kayser–Fleischer rings and cataracts.

The patient is suffering from an anaphylactic reaction to the cashew nut he consumed.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:- Resuscitation – ABCD- Remove the allergen- IM adrenaline is given at ten microgram/kg or Nebulised adrenaline 5ml 1:1,000- IV Hydrocortisone is given at 4mg/kg- pro re nata IV fluid support. – Followed by observation.

Measles and chickenpox are spread by droplets. Thus, patients should be isolated. Rheumatic fever and post-streptococcal glomerulonephritis are immune mediated diseases that don’t require isolation. Herpetic gingivostomatitis spreads by direct transmission of infected secretions to the stratified squamous epithelium. HSP is not an infectious disease.

Case control studies are used to determine the relationship between exposure to a risk factor and the resultant outcomes. It finds patients in the general population who have a certain condition and retrospectively searches for past exposure to possible risk factors for the disease. Controls are people who do not have the disease found in the general population. This type of study is useful for rare diseases, and is less time consuming to conduct. While cohort studies can be used to study rare diseases they measure the relative risk of developing the disease over time based on exposure. Ecological or cross-sectional studies attempt take a snapshot of a whole population, and thus are inappropriate for rare diseases as larger sample numbers are needed. A randomised control trial is better suited to determine the effect of an intervention.

Gait variations in children are usually physiologically normal and only become a cause of concern when they persist or are associated with pain or other medical symptoms. Genu varus, also known as knock knees causes an outward rotation of the leg, leading the toes pointing outwards. The condition usually resolves by the age of 18 months. In comparison, in- toeing occurs with genu varus. Metatarsus adductus is also associated with an inward pointing of the toes.

An odds ratio (OR) is a measure of association between an exposure and an outcome. The OR represents the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure. Odds ratios are most commonly used in case-control studies, however they can also be used in cross-sectional and cohort study designs as well (with some modifications and/or assumptions). Wherea = Number of exposed casesb = Number of exposed non-casesc = Number of unexposed casesd = Number of unexposed non-casesOR=(a/c) / (b/d) = ad/bc

Favus is a fungal infection of the scalp, resulting in the formation of a yellowish crusted plaque over the scalp and leads to scar formation with alopecia. Tinea capitus is a fungal infection of the scalp resulting in scaling and non scarring hair loss. Folliculitis presents with multiple perifollicular papules which can be caused by both bacteria and fungi. Cradle cap usually affects infants where the whole scalp is involved. It can lead to hair loss and responds to topical antifungals and keratolytics.

The median nerve is a peripheral nerve originating in the cervical roots C5–T1 of the brachial plexus. It supplies motor innervation to the anterior forearm flexors, the thenar muscles, and the two lateral lumbricals as well as sensory innervation to the lateral palm and anterior, lateral three and a half fingers. Motor and sensory deficits depend on whether the lesion is proximal (above the elbow) or distal (below the elbow). While proximal lesions present with the “hand of benediction,” distal lesions present with either the “pinch sign” (anterior interosseous nerve syndrome) or, in the case of carpal tunnel syndrome, with mildly impaired thumb and index finger motion. Both proximal lesions and carpal tunnel syndrome result in reduced sensation in the area of the thumb, index and middle finger. Anterior interosseus nerve syndrome does not cause any sensory deficits. Chronic injuries to the nerve result in atrophy of median nerve innervated muscles while acute injuries do not have this feature. Treatment is mostly conservative and focuses on rest and immobilization.

ASD is an acyanotic congenital heart disease, characterized by the failure of the interatrial septum to form completely, which results in the mixing of left and right-sided blood. There are various types of ASD, some of them are ostium primum septal defect and patent foramen ovale. Clinical findings associated with ASD are a systolic ejection murmur, fixed splitting of second heart sound, prolonged PR interval, both left and right axis deviation (primum and secundum ASD, respectively). The most common finding is an incomplete right bundle branch block.

The heart is the first organ to form and become functional, emphasizing the importance of transport of material to and from the developing infant. It originates about day 18 or 19 from the mesoderm and begins beating and pumping blood about day 21 or 22. It forms from the cardiogenic region near the head and is visible as a prominent heart bulge on the surface of the embryo. Originally, it consists of a pair of strands called cardiogenic cords that quickly form a hollow lumen and are referred to as endocardial tubes. These then fuse into a single heart tube and differentiate into the truncus arteriosus, bulbus cordis, primitive ventricle, primitive atrium, and sinus venosus, starting about day 22. The primitive heart begins to form an S shape within the pericardium between days 23 and 28. The internal septa begin to form about day 28, separating the heart into the atria and ventricles, although the foramen ovale persists until shortly after birth. Between weeks five and eight, the atrioventricular valves form. The semilunar valves form between weeks five and nine.

Coverings of the spermatic cord:Spermatic cord is covered by three concentric layers of fasciae, derived from the layers the of anterior abdominal wall. Developmentally, each covering is acquired as the processus vaginalis descends into the scrotum through the layers of the abdominal wall. The layers are:External spermatic fascia: It is derived from the external oblique muscle. It attaches to the margins of superficial inguinal ring.Cremasteric fascia: It is derived from the internal oblique muscle. It covers the cremaster muscle.Internal spermatic fascia: It is derived from the fascia transversalis (fascia covering the transversus abdominis muscle). It is attached to the margins of the deep inguinal ring.

The sympathetic chain lies posterior to the parietal pleura. During a thorascopic sympathectomy, this structure will have to be divided. The intercostal vessels lie posteriorly. They may be damaged with troublesome bleeding but otherwise are best left alone as the deliberate division will not improve surgical access.The sympathetic nervous system:The cell bodies of the preganglionic efferent neurones lie in the lateral horn of the grey matter of the spinal cord in the thoracolumbar regions.The preganglionic efferents leave the spinal cord at levels T1-L2. These pass to the sympathetic chain.Lateral branches of the sympathetic chain connect it to every spinal nerve. These postganglionic nerves will pass to structures that receive sympathetic innervation at the periphery.Sympathetic chains:These lie on the vertebral column and run from the base of the skull to the coccyx.Clinical correlation:Interruption of the head and neck supply of the sympathetic nerves will result in an ipsilateral Horner’s syndrome.For the treatment of hyperhidrosis, the sympathetic denervation can be achieved by removing the second and third thoracic ganglia with their rami. Removal of T1 will cause a Horner’s syndrome and is therefore not performed.In patients with vascular disease of the lower limbs, lumbar sympathectomy may be performed, either radiologically or (more rarely now) surgically. The ganglia of L2 and below are disrupted. Care should be taken to preserve the L1 ganglion. If it is removed in male patients, ejaculation may be compromised.

Infantile spasm belongs to the spectrum of seizure disorders. Infantile spasm manifests itself with loss of consciousness and jerky movements. The peak age of onset is between 4 and 6 months. Approximately 90% of infantile spasms begin before 12 months of age. It is rare for infantile spasms to begin during the first 2 weeks of life or after 18 months.

The presentation of the patient and the characteristic ring-like (Bull’s eye) rash are highly suggestive of a diagnosis of Lyme disease caused by Borrelia burgdorferi. The spirochete is transmitted by Ixodid ticks. The initial presentation of this infection includes an erythema migrans rash that starts from the site of tick bite and gradually expands. Other features supporting the diagnosis are the history of camping, fever, joint pain, and the neurological symptoms presenting as facial nerve palsy.

The most probable diagnosis in this patient would be Friedreich’s ataxia.Friedreich’s ataxia is also called spinocerebellar degeneration. It is an autosomal recessive condition. The onset of ataxia is around ten years of age. Intelligence is preserved. Cerebellar impairment, distal muscle weakness, pes cavus, hammer-toes and progressive kyphoscoliosis are present. Deep tendon reflexes are absent, particularly the ankle jerk. Loss of vibration and position sense occurs because of degeneration of the posterior columns. Hypertrophic cardiomyopathy can occur with progression to congestive cardiac failure.Other options:- Ataxia Telangiectasia: ataxia develops earlier, around two years of age, with loss of ambulation by adolescence. Nystagmus is present. Telangiectasia becomes evident by mid-childhood and is found on bulbar conjunctiva, over the bridge of the nose and on the ears. These children have an increased risk of developing lymphoreticular malignancies.- Abetalipoproteinemia: begins in childhood with steatorrhea and failure to thrive. Neurological symptoms appear in late childhood. These include ataxia, retinitis pigmentosa, peripheral neuritis, abnormalities in position and vibration sense, muscle weakness and mental retardation. Vitamin E is undetectable in serum in these patients.- Acute cerebellar ataxia: occurs in children of 1-3 years of age and is a diagnosis of exclusion. It often follows acute viral infections like varicella, coxsackievirus or echovirus by 2-3 weeks. It is an autoimmune response to a viral agent affecting the cerebellum. Prognosis is excellent with complete recovery present. Very small numbers have long term sequelae like ataxia, incoordination, speech disorder and behavioural problems.- Acute labyrinthitis: It is difficult to differentiate acute labyrinthitis from acute cerebellar ataxia in a toddler. It is associated with middle ear infections, vertigo and vomiting.

Nonspecific triggers of inflammation in patients with atopic dermatitis may include physical or chemical irritants. The following simple measures should be followed in daily life to reduce the frequency and severity of irritant-induced atopic dermatitis flares :Skin care products that contain alcohol and astringents should be avoided.New clothes should be laundered before use to remove formaldehyde and other chemicals.Liquid detergents are preferred over powder detergents for laundering clothes, as liquids are easier to rinse out. A second rinse cycle may also improve removal of residual detergent.Patients should shower immediately after swimming in chlorinated pools and should subsequently apply moisturizer.Fragrance-free skin products that are hypoallergenic or made for sensitive skin may be less irritating than other kinds of skin products.Prenatal and postnatal probiotic supplementation may be helpful in preventing the development of atopic dermatitis in young children. In a 2008 meta-analysis, the most commonly studied probiotic was Lactobacillus rhamnoses GG. Larger, randomized controlled studies are needed to confirm these initial findings.Breastfeeding during the first 4 months of life may reduce the incidence and severity of childhood atopic disease but only modestly and only in those at high risk.

The history is suggestive of a post-traumatic seizure which frequently occurs after moderate or severe traumatic brain injury. Although upgoing plantars can be identified in a post-ictal status, an intracranial bleed has to be excluded. A single seizure cannot be considered epilepsy

Androgen excess is one of the most common causes of advanced bone age. It usually occurs in precocious puberty or congenital adrenal hyperplasia.

Tetralogy of Fallot (TOF), a congenital heart defect, includes the following: right ventricular hypertrophy, ventricular septal defect, abnormal position of the aorta and pulmonary valve stenosis. The O2 saturation in patients with TOF is typically lower than normal and the condition usually becomes symptomatic early in life. A feature of the disease with high diagnostic significance is squatting or crouching of the infant as a compensatory mechanism to increase the peripheral vascular resistance.