Paediatrics DNB MD Theory Practical exam course
Contact us

Paediatrics DNB MD Theory Practical Exam course

starstarstarstarstar 5.0 (3 ratings)

Language: English

Instructors: Mentorexam

₹15995 43.76% OFF

₹8995

 

Why this course?

Description

Dec 2019, June 2019 and Dec 2018 DNB Paediatrics Question Papers Solved 

Notes and Modules for DNB MD Paediatrics exams

Notes from lectures

Notes for theory

bonus Notes for practicals included free

Hand written Toppers notes for major topics

High yield notes that you need to clear Paediatrics exams

Online content accessible by browser and android app. no hard copies.

Ongoing course and not a crash course

updates

 

Scroll down to see all topics covered ...

DISCLAIMER
December 2019 DNB solved paper 1
PAPER 1-PART A-QUESTION 1 (a,b) (8 pages)
PAPER 1-PART A-QUESTION 2 (a,b) (6 pages)
PAPER 1-PART A-QUESTION 3 (a,b,c) (5 pages)
PAPER 1-PART A-QUESTION 4 (a,b) (8 pages)
PAPER 1-PART A-QUESTION 5 (a,b) (6 pages)
PAPER 1-PART B-QUESTION 6 (a,b) (8 pages)
PAPER 1-PART B-QUESTION 7 (a,b) (4 pages)
PAPER 1-PART B-QUESTION 8 (a,b) (5 pages)
PAPER 1-PART B-QUESTION 10 (a,b) (5 pages)
PAPER 1-PART B-QUESTION 9 (a,b) (5 pages)
PAPER 2-PART B-QUESTION 10 (a,b) (5 pages)
December 2019 DNB Paediatrics solved paper 2
PAPER 2-PART A-QUESTION 1 (a,b) (6 pages)
PAPER 2-PART A-QUESTION 2 (a,b) (4 pages)
PAPER 2-PART A-QUESTION 3 (a,b) (6 pages)
PAPER 2-PART A-QUESTION 4 (a,b) (6 pages)
PAPER 2-PART A-QUESTION 5 (a,b) (6 pages)
PAPER 2-PART B-QUESTION 6 (a,b) (5 pages)
PAPER 2-PART B-QUESTION 7 (a,b) (6 pages)
PAPER 2-PART B-QUESTION 9 (a,b) (6 pages)
PAPER 2-PART B-QUESTION 8 (a,b) (11 pages)
10. DNB-DECEMBER-2019 , PAPER 2-PART B-QUESTION 10 (a,b) (5 pages)
December 2019 DNB Paediatrics solved paper 3
PAPER 3-PART A-QUESTION 1 (a,b) (4 pages)
PAPER 3-PART A-QUESTION 2 (a,b,c) (7 pages)
PAPER 3-PART A-QUESTION 3 (a,b) (6 pages)
PAPER 3-PART A-QUESTION 4 (a,b) (7 pages)
PAPER 3-PART A-QUESTION 5 (a,b) (7 pages)
PAPER 3-PART B-QUESTION 6 (a,b) (8 pages)
PAPER 3-PART B-QUESTION 7 (a,b) (7 pages)
PAPER 3-PART B-QUESTION 8 (a,b) (5 pages)
PAPER 3-PART B-QUESTION 9 (a,b) (5 pages)
PAPER 3-PART B-QUESTION 10 (a,b) (5 pages)
December 2019 DNB Paediatrics solved paper 4
PAPER 4-PART A-QUESTION 1 (a,b) (6 pages)
PAPER 4-PART A-QUESTION 2 (a,b) (4 pages)
PAPER 4-PART A-QUESTION 3 (a,b) (8 pages)
PAPER 4-PART A-QUESTION 4 (a,b) (6 pages)
PAPER 4-PART A-QUESTION 5 (a,b) (4 pages)
PAPER 4-PART B-QUESTION 6 (a,b) (7 pages)
PAPER 4-PART B-QUESTION 7 (a,b) (5 pages)
PAPER 4-PART B-QUESTION 8 (a,b) (4 pages)
PAPER 4-PART B-QUESTION 9 (a,b) (4 pages)
PAPER 4-PART B-QUESTION 10 (a,b) (6 pages)
June 2019 Solved Paper 1
Copy of What is Kangaroo mother care and enumerate its advantages, enumerate its advantages (1 pages)
Copy of Steps in planning a randomized control trial_ (1 pages)
Copy of Signs of liver cell failure and thier pathophysiology (3 pages)
Copy of Safe injection practices_ (1 pages)
Copy of Role of IV immunoglobulin in pediatric practice_ (2 pages)
Copy of Recent National Malaria Management Guidelines_ (2 pages)
Copy of RBSK and its components_ (1 pages)
Copy of Principles of newer diagnsotic tests in tuberculosis (3 pages)
Copy of Pathophysiology of hypovolemic shock (1 pages)
Copy of HIV and feeding 2016 (3 pages)
Copy of Discharge criteria for LBW babies from SNCU_ (2 pages)
Copy of Cyanotic spells (1 pages)
Copy of Csf formation and circulation_ (4 pages)
Copy of Components of hemostatic process and Illustrate the clotting cascade_ (1 pages)
Copy of Approach to a child with suspected inborn error of metabolism (2 pages)
Copy of AEFI vaccine (1 pages)
Copy of WHO guidelines for AFP surveillance_ (1 pages)
Copy of Causes of metabolic acidosis (Marks 5) (June 2019) (1 pages)
Copy of Alveolar-arterial oxygen gradient and its role in diagnosis of lung disease (1 pages)
June 2019 Solved Paper 2
Copy of Wilms tumor (1) (2 pages)
Copy of Vit d defeciency rickets (2 pages)
Copy of Typhoid Vaccines (1 pages)
Copy of Refeeding syndrome_Nutritional recovery syndrome _1 (2 pages)
Copy of Recent National Malaria Management Guidelines_ (2 pages)
Copy of Outline the investigative approach of Global developmental delay_ (1 pages)
Copy of Neonatal screening (2 pages)
Copy of Minimal enteral nutrition for low birth weight neonate (2 pages)
Copy of Management for a 5 year old child presenting with first episode of hematuria_ (3 pages)
Copy of IYCF (Infant young and child feeding) strategy_ (1 pages)
Copy of Iron chelation therapy (2 pages)
Copy of Enumerate indications and techniques of surfactant therapy (1 pages)
Copy of Diagnostic criteria for autism_ (1 pages)
Copy of Diagnosis and treatment of Henoch Schoenlein purpura (HSP) (1 pages)
Copy of Define epilepsy and seizure classification (2 pages)
Copy of Component of cold chain for immunization in a hospital setting and its monitoring_ (2 pages)
Copy of Aplastic anemia-1 (2 pages)
Autoimmune encephalitis_ (2 pages)
June 2019 Solved Paper 3
Copy of Substance abuse in adolescents_ (3 pages)
Copy of Screening and diagnosis of hearing loss_ (2 pages)
Copy of Role of antisecretory drugs in diarrhea_ (1 pages)
Copy of Principles of treatment of diabetes mellitus at home_ (2 pages)
Copy of Ophthalmic finding in inborn errors of metabolism_ (1 pages)
Copy of OP poisoing (4 pages)
Copy of Megaloblastic anemia (1 pages)
Copy of Management of supraventricular tachycardia_ (2 pages)
Copy of Management of aa child with Hyponatremia_ (2 pages)
Copy of Genetic counselling in Duchenne Muscular dystrophy _ (1 pages)
Copy of Fluid therapy in dengue hemorrhagic fever_ (2 pages)
Copy of Differential diagnosis for cholestatic jaundice in neonate (1 pages)
Copy of Differential diagnosis and treatment modalities in dilated cardiomyopathy_ (2 pages)
Copy of Diagnosis and treatment of cystic fibrosis in children (1 pages)
Copy of Clinical exome sequencing (June 2019) (Marks 5) (2 pages)
Copy of celiac disease Serological diagnosis (1 pages)
Copy of Bronchiolitis (2 pages)
Copy of ART IN PEDIATRIC HIV (3 pages)
Copy of Approach to a child with short stature_ (3 pages)
Copy of ADHD (3 pages)
June 2019 Solved Paper 4
Copy of Simulation_Newer medical teaching training technology_ (2 pages)
Copy of Selective hypothermia for management of hypoxic Ischemic Encephalopathy in newborn_ (1 pages)
Copy of Role of prebiotics and probiotics in pediatric practice_ (2 pages)
Copy of Role of iNO therapy in PPHN (1 pages)
Copy of Role of CB-NAAT (Cartridge based nucleic acid amplification test )in diagnosis of pediatric tuberculosis_ (2 pages)
Copy of Recent Neonatal Resuscitation (NRP) Guideline (3 pages)
Copy of Nutritional requirements of preterm neonate_ (2 pages)
Copy of Management of two year old child coming to emergency room with severe respiratory distress (2 pages)
Copy of Management of an eight -month old baby with diarrhea without dehydration_ (1 pages)
Copy of Liver transplantation_ Indication and procedure_ (1 pages)
Copy of Kawasaki disease (3 pages)
Copy of Indications of platelet transfusion in pediatric practice_ (1 pages)
Copy of Immunomodulator therapy in nephrotic syndrome_ (2 pages)
Copy of Human milk banking_ Criterion for donors, collection and storage (2 pages)
Copy of Fetal therapy (2 pages)
Copy of Enumerate management in cerebral palsy_ (2 pages)
Copy of Dry blood PCR for HIV testing_ (2 pages)
Copy of Combined vaccines_ (1 pages)
Copy of Bone marrow aspiration (2 pages)
Copy of Advances in treatment of hemophilia_ (2 pages)
Copy of ​Indications of Nasal high flow oxygen in neonates_ (1 pages)
December 2018 Solved Question Papers 1-4
Celiac disease Serological diagnosis (1 pages)
Bronchiolitis (2 pages)
Anti cytokine drugs (2 pages)
Zinc (2 pages)
Tyrosinemia (1 pages)
Snake bite envenomation (1 pages)
SLE diagnostic criteria (1 pages)
recurrent wheeze in children (2 pages)
Portal hypertension Clinical features and diagnosis (2 pages)
Pediatric cochlear implants (2 pages)
Pathogenesis of eisenmengerization (2 pages)
OP poisoing (4 pages)
Kawasaki disease (3 pages)
Juvenile dermatomyositis (2 pages)
Infective endocarditis prophylaxis (2 pages)
Hyperkalemia (3 pages)
H1N1 (3 pages)
Clinical features and diagnosis of HSP (2 pages)
Brutons agammaglobunemia X linked agammaglobunemia (2 pages)
Adolescent vaccination (2 pages)
Acute Myocarditis management (2 pages)
Renal osteodystrophy (2 pages)
Vesicoureteric reflux (3 pages)
Trichotillomania (1 pages)
Syndromes associated with obesity (1 pages)
Neuroblastoma clinical features and diagnosis (2 pages)
Medical management of PDA (1 pages)
Management of Chronic ITP (2 pages)
Fulminant liver failure (2 pages)
Epistaxis causes and treatment (2 pages)
Diptheria complications (1 pages)
Differentials for microcytic hypochromic anemia (1 pages)
Diamond-blckfan anemia (2 pages)
ADHD (3 pages)
Neuronal migration disorder (2 pages)
Neonatal mortality rate India (1 pages)
Bronchogenic cyst (1 pages)
Notes
BPD (15 pages)
CF (51 pages)
cough (22 pages)
OTITIS MEDIA (8 pages)
PLEURAL FLUID (29 pages)
Practical exam
ABG analysis (37 pages)
basic drugs (142 pages)
ecg basics (92 pages)
Vaccine part 1 (70 pages)
vaccine part2 (58 pages)
Newborn case (10 pages)
CVS History cyanotic heart disease (2 pages)
CNS History (31 pages)
Respiratory (29 pages)
Gastroenterology (22 pages)
Neonatology HY notes
Neonatology HY_1 (21 pages)
Neonatology HY_2 (22 pages)
Neonatology HY_3 (22 pages)
Neonatology HY_4 (19 pages)
Acute Lymphoblastic Leukemia HY notes (31 pages)
Approach to hemolytic anaemia (61 pages)
Blood Groups (27 pages)
Childhood asthma (69 pages)
Child with chronic diarrhea (39 pages)
Chemotherapy (108 pages)
A- Celiac disease (34 pages)
B- Celiac Disease (37 pages)
Chronic kidney disease (40 pages)
Ewing sarcoma presentation (51 pages)
DENGUE (53 pages)
Ebola (25 pages)
Diagnosis and Management of Inborn Error of Metabolism (41 pages)
CRF in Children (47 pages)
Gluten-free-trip (61 pages)
Growth (24 pages)
H I E (34 pages)
Haemopoiesis (29 pages)
Hemodialysis (28 pages)
Chronic Liver Disease (42 pages)
Acute pancreatitis (54 pages)
MAINTENANCE IV Fluids (34 pages)
Hypertensive-Emergencies (54 pages)
IRON DEFICIENCY AS A RISK FACTOR FOR SIMPLE FEBRILE SEIZURE (13 pages)
Juvenile Myasthenia Gravis (44 pages)
LYMPHOMA (44 pages)
MANAGEMENT OF UPPER GI BLEEDING IN CHILDREN (44 pages)
MDR-TB (27 pages)
NEC (27 pages)
Neonatal-HIV (40 pages)
Newborn Screening in Indian Perspectives (43 pages)
Hepatoblastoma (27 pages)
PERSISTENTRECURRENT PNEUMONIA (31 pages)
PEM (40 pages)
Obesity (60 pages)
NNA- Newborn Neurobehavioural assessment (28 pages)
NIPPV- Non Invasive Positive Pressure Ventilation (37 pages)
Newer ANTI EPILEPTICS (31 pages)
Newborn_resuscitation_programme_NRP (26 pages)
CONGENITAL HEART DISEASES (78 pages)
MAS- Meconium Aspiration Syndrome (38 pages)
Congenital Hypothyroidism (11 pages)
Rh_Blood_Group_System (32 pages)
ZIKA VIRUS DISEASE (ZIKA) (50 pages)
VEP-Visual Evoked Potentials (55 pages)
SHOCK IN CHILDREN (23 pages)
RNTCP Guidelines and Management of Tuberculosis in children (44 pages)
Renal Replacement Therapy (RRT) (36 pages)
Recent Advances in Neonatal Septicemia (75 pages)
Hematopoietic Stem Cell Transplantation (67 pages)
Important Topics
ADOLESCENT (95 pages)
CF (51 pages)
OTITIS MEDIA (8 pages)
ELECTROLYTES (43 pages)
inotrpe (51 pages)
NB VENT (71 pages)
PLEURAL FLUID (30 pages)
SICK CHILD (43 pages)
Approach to intracranial mass (94 pages)
Trisomies (77 pages)
Pediatric Emergencies
ABG (53 pages)
ecg (63 pages)
anaphylaxis and serum sickness (25 pages)
Bleeding Neonate (65 pages)
CHF (53 pages)
CRASH CART (65 pages)
EXCESSIVE CRY (57 pages)
Onco emergencies (60 pages)
PARDS (35 pages)
SNAKE BITE (71 pages)
PEDIATRIC DERMATOLOGICAL EMERGENCIES (44 pages)
op (46 pages)
Pediatric Endocrinology
AMBIGUOUS_GENITALIA (77 pages)
CAH (48 pages)
PITUITARY (73 pages)
PUBERTY DELAY (76 pages)
RICKETS (66 pages)
SHORT STATURE (64 pages)
hypothyroidism (82 pages)
Pediatric Nephrology
AKI (19 pages)
CKD (73 pages)
UTI (62 pages)
Pediatric Cardiology
ACHD (96 pages)
AFF (55 pages)
ARF (82 pages)
BE (67 pages)
CYANOSIS (62 pages)
MYOCARDITIS (65 pages)
Pediatric Infections
ANASARCA (53 pages)
ART IN CHILDREN (94 pages)
END GAME STRATEGY FOR POLIO ERADICATION (51 pages)
FEVER (48 pages)
HAI (51 pages)
Pneumonia (61 pages)
PNEUMONIA (72 pages)
PUO (71 pages)
SEPSIS (61 pages)
TBM (66 pages)
DENGUE (91 pages)
HIV 1 (73 pages)
HIV-2 (50 pages)
MALARIA (92 pages)
PID (72 pages)
swine flu (46 pages)
TORCH (65 pages)
Pediatric Hemato Onc
ALL (63 pages)
APLASTIC (51 pages)
Pediatric Miscellaneos
CSA (77 pages)
IEM (45 pages)
Pediatric Pulmonology
BPD (16 pages)
Bronchial asthma (91 pages)
BRONCHIOLITIS (30 pages)
cough (23 pages)
Respiratory monitoring in PICU (65 pages)
Pediatric Rheumatology
ARTHHRALGIA (46 pages)
ARTHRITIS (97 pages)
Biologicals (29 pages)
HSP (44 pages)
KD treatment update (46 pages)
peripheral gangrene (37 pages)
VASCULITIS (55 pages)
Approach to a child with rheumatological disorder (65 pages)
Pediatric Neurology
adhd (70 pages)
Brain tumours (88 pages)
FC (87 pages)
stroke (74 pages)
ataxia (23 pages)
CP (121 pages)
HEADACHE (35 pages)
MD (56 pages)
HEREDITARY ATAXIA (59 pages)
HYDROCEPHALUS (63 pages)
PD (46 pages)
seizure mimics (64 pages)
TICS & TOURETTE (64 pages)
Neonatology
IVH (73 pages)
neonatal jaundice (73 pages)
NEONATAL SEIZURE (55 pages)
neonatal shock presentation (55 pages)
neonatal resuscitation (97 pages)
Pediatric Gastroenterology
AD (77 pages)
AH (59 pages)
CHRONIC DIARRHEA (12 pages)
hepatitis (47 pages)
HUS (48 pages)
Liver Abscess (20 pages)
pancreatitis (100 pages)
Hand written Topper Notes
Acute liver failure (18 pages)
Acute GI bleeding (14 pages)
Acute flaccid paralysis (12 pages)
Acuite diarrhea (18 pages)
Acquired eye diseases (6 pages)
Breast feeding (12 pages)
Autism (16 pages)
Ascitis (6 pages)
Adoption (8 pages)
Acute pancreatitis (16 pages)
Coarctation of aorta (12 pages)
chronic liver disease (6 pages)
Child Abuse and sleep disorders (42 pages)
Chikungunya (10 pages)
Celiac disease (10 pages)
Fulminant hepatic failure (12 pages)
Fever unknown focus (8 pages)
Exocrine pancreas (8 pages)
Enzyme deficiencies (6 pages)
congenital cataracts (4 pages)
Neonatal Cholestasis (6 pages)
Manifestations of liver disease (14 pages)
Hypertrophic pyloric stenosis (6 pages)
Hearing loss (10 pages)
FUO (12 pages)
Polio (2) (6 pages)
PANDAS CANS PANS (12 pages)
Otitis media (16 pages)
Orthopaedic (10 pages)
Obesity (18 pages)
Severe acute malnutrition (22 pages)
Recurrent abdominal Pain (16 pages)
Probiotics in gastrointestinal disorders (6 pages)
PPH (10 pages)
Polio (10 pages)
swine flu (8 pages)
Vegetative disorders (14 pages)
Endocrinology nutrients homeostasis
Hypercalcemia (4 pages)
Hyperparathyroidism (10 pages)
Hypophosphatemia (4 pages)
Micronutrients (16 pages)
acid base balance (5 pages)
Calcium vit d rickets (15 pages)
Fluid electrolytes (4 pages)
Hormones peptides calcium homeostasis bone mketabolism (4 pages)
Hyperkalemia (3 pages)
Hypernatremia (5 pages)
Hypervitaminosis D (2 pages)
Hypocalcemia hypoparathyroidism (7 pages)
Hypokalemia (6 pages)
Metabolic acidosis (5 pages)
Metabolic alkalosis (5 pages)
hemostasis (8 pages)
Regulation Plasma osmolality (3 pages)
Adrenal (16 pages)
Diabetic keto acidosis (6 pages)
Pituitary (2 pages)
disorder sexual development (4 pages)
Non ketotic hyperosmolar coma (2 pages)
Gastrointestinal System
cysticercosis (4 pages)
Infantile spasms (3 pages)
Systemic
Salicylic poisoning (3 pages)
Lead poisoning (4 pages)
Henoch schonlein purpura (1 pages)
Juvenile idiopathic arthritis (16 pages)
Developmental dysplasia hip (8 pages)
Skeletal dysplasias (4 pages)
Steven Johnson Syndrome (6 pages)
Takayasu arteritis (6 pages)
Toxic shock syndrome (6 pages)
vasculitis syndrome (7 pages)
Infectious
Pertusis (10 pages)
Neurology
Neural tube defects (5 pages)
Newer antiepileptic drugs (2 pages)
Blood supply of brain (1 pages)
Infantile tremor syndrome (2 pages)
Microcephaly (3 pages)
Myasthenia Gravis (3 pages)
Pediatric stroke (5 pages)
Status epilepticus (4 pages)
conditions that mimic seizures (2 pages)
Acute disseminated encephalomyelitis (4 pages)
Bells palsy (6 pages)
Brain Abscess (6 pages)
Demyelinating disorders of CNS (1 pages)
Spinal muscular atrophy (7 pages)
Urology Nephrology
Acute Kidney Injury (11 pages)
Dialysis (7 pages)
UTI (12 pages)
UTI a (18 pages)
Vesicoureteric reflux (14 pages)
Hemolytic uremic syndrome (8 pages)
Acute post streptococcal glomerulonephritis (6 pages)
Autosomal recessive polycystic kidney disease (6 pages)
Proteinuria (10 pages)
Rapidly progressive glomerulonephritis (4 pages)
Hematuria (7 pages)
Hemolytic uremic syndrome (5 pages)
Nephrotic syn (5 pages)
Nephrotic synrome (8 pages)
Hematology immunology
Anaemia (14 pages)
Blood component separation techniques (2 pages)
Blood transfusion therapy (1 pages)
Disseminated intravascular coagulation (6 pages)
G6pd deficiency (5 pages)
Graft versus host disease (7 pages)
Hematopoetic stem cell transplantation (7 pages)
Hemolytic anemia (4 pages)
Hemophiliia (11 pages)
Hereditary spherocytosis (4 pages)
immune hemolytic anemias (6 pages)
Immune thrombocytopenia (8 pages)
Immunization (30 pages)
Intravenous immunoglobulin (7 pages)
Iron deficiency anemia (4 pages)
Mechanism of antibiotic resistance (3 pages)
Pancytopenias (6 pages)
Predisposition thrombosis (6 pages)
Spleen (7 pages)
Thalassemia syndromes (16 pages)
Von willebrand disease (8 pages)
Megaloblastic Anemia (13 pages)
Iron deficiency Anemia (6 pages)
Disseminated intravascular coagulation (2 pages)
pancytopenia (2 pages)
Acquired pancytopenia (7 pages)
Fanconi Anemia (3 pages)
Polycythemia (3 pages)
Von willebrand disease (3 pages)
THrombotic disorders in children (4 pages)
Hemolytic anemia (10 pages)
hemophilia (6 pages)
Basic Topics
Parental evaluation of development PEDS (4 pages)
Tests of intelligence (2 pages)
Developmental screening surveillance (16 pages)
Preschool development (15 pages)
Adolescent health and development (16 pages)
Developmental Milestones (22 pages)
Growth and development (10 pages)
Growth velocity and height velocity (10 pages)
Sexual maturity rating Tanner staging (4 pages)
Developmental delay (6 pages)
Hearing Visual and other assessments (6 pages)
Child Abuse and sleep disorders (42 pages)
Adolescent Acne (6 pages)
Fetal assessment prenatal diagnosis (10 pages)
Cardiothoracic
Antihypertensives in children (3 pages)
BP algorithm (11 pages)
Hypertensive encephalopathy (9 pages)
Systemic hypertension (6 pages)
Ventricular tachyarrythmias (9 pages)
AIDS (13 pages)
Ophthalmology
Retinopathy of prematurity (7 pages)
Respiratory system
Breath holding spells (2 pages)
Carbon monoxide poisoning (3 pages)
More solved questions updates
Steroid resistant and dependent nephrotic syndrome (2 pages)
Plasmapheresis (3 pages)
Indications for splenectomy in thalassemia (1 pages)
DKA (3 pages)
Congenital hypothyroidism screening, evaluation, treatment (3 pages)
HPV vaccine (2 pages)
ASHA (2 pages)
Diagnosis of biliary atresia (1 pages)
Dengue fever Diagnostic tests (1 pages)
Cyanotic spells (2 pages)
UPGRADE TO NEW COURSE PACKAGE

Reviews

5
star star star star star
people 3 total
5
 
3
4
 
0
3
 
0
2
 
0
1
 
0
Launch your GraphyLaunch your Graphy
100K+ creators trust Graphy to teach online
MentorExam.com 2024 Privacy policy Terms of use Contact us Refund policy