22.1 High-Yield Numbers, Mnemonics & Cross-Topic Review

The Capstone Review: How This Chapter Fits

Every organ-system chapter in this guide taught you a body of knowledge. The Arab Board Pediatrics Part 1 Written Exam rewards a slightly different skill on test day: instant recall of the numeric cutoffs, scoring systems, and mnemonics that appear as the single distinguishing detail in a five-option best-of-five vignette. This section pulls those anchors out of every organ system and lines them up side by side so you can drill them as a block in the final days before your exam, rather than hunting through 21 separate chapters.

Use this section as a self-test: cover the right-hand column of each table below and see whether you can reproduce it from memory. Whatever you cannot reproduce is your revision list.

Neonatology: The First Minutes and Days

The Apgar score is assessed at 1 and 5 minutes after birth (repeated every 5 minutes until 20 minutes if the 5-minute score is below 7). Five components, each scored 0-2, maximum 10:

During Neonatal Resuscitation Program (NRP) chest compressions, the compression-to-ventilation ratio is 3:1 — three compressions and one breath every 2 seconds, targeting 90 compressions and 30 breaths per minute (120 total events/min). This ratio is unique to newborn resuscitation. Once you move into pediatric basic life support, the ratios change again and are among the most commonly crossed numbers on the exam:

Do not mix NRP (3:1), single-rescuer pediatric (30:2), and two-rescuer pre-pubertal pediatric (15:2) ratios in the same vignette.

Gestational age at the bedside is estimated with the Ballard score (neuromuscular plus physical maturity criteria). A well newborn's blood glucose below roughly 40-45 mg/dL in the first 24 hours should trigger a hypoglycemia work-up and feeding or dextrose intervention — this numeric threshold is one of the most frequently re-tested labs across the neonatology chapters of this guide.

Fluids and Growth: The Numbers Every Question Assumes You Know

The Holliday-Segar '4-2-1' rule for maintenance intravenous fluids is arguably the single most exam-tested formula in general pediatrics:

(Equivalently, per 24 hours: 100 mL/kg for the first 10 kg, 50 mL/kg for the next 10 kg, 20 mL/kg thereafter.) A 25 kg child therefore needs 40 + 20 + 5 = 65 mL/hr maintenance.

Dehydration severity is graded clinically as mild (under 5% body-weight loss), moderate (5-10%), and severe (over 10%) in infants and young children (in older children and adolescents the bands shift slightly lower, roughly 3%/6%/9%). Deficit replacement equals percent dehydration times weight in kg times 10 mL/kg, added on top of ongoing maintenance.

Developmental milestones cluster around recognizable ages — a milestone still absent at roughly 1.5 to 2 times the expected age is a red flag worth working up:

Immunization: Timing Anchors

Most Arab League national schedules are built on the WHO Expanded Programme on Immunization (EPI) skeleton: a birth dose (BCG, an oral polio zero dose, and hepatitis B), a primary series at 6, 10, and 14 weeks (a pentavalent or DTP-containing vaccine, polio, Hib, pneumococcal conjugate, and rotavirus), and a first measles-containing dose around 9 months, followed by boosters and a second measles-containing dose in the second year of life. Exact ages and vaccine choices vary by national ministry of health, so treat this as a spacing anchor rather than a substitute for the dedicated immunization chapters — the exam is more likely to test the logic of a schedule (minimum intervals, catch-up principles, live-versus-inactivated timing around immunoglobulin) than one specific national calendar.

Cardiology: Jones Criteria and the Innocent Murmur

The revised Jones criteria diagnose acute rheumatic fever after evidence of a preceding group A streptococcal infection, requiring 2 major criteria, or 1 major plus 2 minor criteria:

• Major: carditis, polyarthritis (or migratory monoarthritis in high-risk populations), Sydenham chorea, erythema marginatum, subcutaneous nodules.
• Minor: fever, polyarthralgia (or monoarthralgia in high-risk populations), elevated ESR/CRP, prolonged PR interval.

Because acute rheumatic fever remains relatively common across parts of the Arab League, the exam favors the high-risk-population thresholds (monoarthritis counts as major; a lower fever cutoff and monoarthralgia count as minor) — do not default only to the low-risk criteria you may recall from other reference texts.

An innocent (Still's) murmur is classically a soft, vibratory, musical systolic murmur, loudest at the lower left sternal border, that softens when the child stands and is louder supine, with no thrill, no diastolic component, and no associated symptoms — the 'no red flags' pattern is itself testable.

Respiratory: The Croup Score

The Westley croup score (0-17, based on level of consciousness, cyanosis, stridor, air entry, and retractions) grades severity: under 4 is mild, 4-6 is moderate, and above 6 is severe. Mild croup is managed with a single dose of oral dexamethasone; moderate-to-severe croup adds nebulized epinephrine to dexamethasone plus 2-4 hours of observation for rebound stridor.

Musculoskeletal and Infectious Disease: Kocher Criteria

The Kocher criteria distinguish septic arthritis of the hip from transient synovitis using four independent predictors: non-weight-bearing, ESR over 40 mm/hr, fever over 38.5C, and WBC over 12,000/mm3. The probability of septic arthritis rises steeply with the number of criteria present: roughly under 3% with one criterion, about 40% with two, about 93% with three, and about 99% with all four present — memorize this as a rising curve, not four isolated numbers.

Endocrinology: Diabetic Ketoacidosis (DKA) Diagnostic Triad

DKA is diagnosed only when all three elements are present together — glucose elevation alone is not enough:

Up to roughly one-third of children with new-onset type 1 diabetes present in DKA, so unexplained vomiting, dehydration, or altered mental status in a child should trigger a bedside glucose check. On management vignettes, remember that cerebral edema — signaled by headache, declining consciousness, or Cushing triad during treatment — is the leading cause of DKA-related death in children, not the metabolic numbers themselves.

Adolescent Medicine: Tanner Staging

Tanner (sexual maturity rating) stages run from 1 (prepubertal) to 5 (adult) for breast development, genital development, and pubic hair, scored independently. In girls, thelarche (breast budding) is typically the first sign of puberty (average around 10-11 years), with menarche following roughly 2-2.5 years later, usually at Tanner breast stage 3-4. In boys, testicular enlargement (volume over 4 mL, or long axis over 2.5 cm) is the first sign of puberty, and it typically appears somewhat later than the first sign in girls.

Cross-System Mnemonics Worth Memorizing

• 5 T's of cyanotic congenital heart disease: Tetralogy of Fallot, Transposition of the great arteries, Truncus arteriosus, Tricuspid atresia, Total anomalous pulmonary venous return.
• VACTERL association: Vertebral, Anal, Cardiac, Tracheoesophageal fistula, Renal, Limb anomalies.
• CHARGE syndrome: Coloboma, Heart defect, Atresia choanae, Retarded growth/development, Genital anomaly, Ear anomaly.
• CRASH and burn (Kawasaki disease): Conjunctivitis, Rash, Adenopathy (cervical, usually unilateral), Strawberry tongue/mucosal changes, Hand-foot changes, plus fever ('the burn') for 5 days or more.

On the Exam

Expect the numbers in this section to surface as the deciding detail in an otherwise straightforward vignette — for example, a stem describing a limping, febrile child expects you to weigh the Kocher criteria pattern rather than simply name a diagnosis outright. Treat every table above as a flashcard, not just a reading passage.