Maternity Nursing: cram pack

Formula sheets, the key method steps for every topic and 6 practice problems, with full solutions at the back.

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1Formulas and methods

Maternity & obstetric nursing

Method

  1. Place the woman in time: weeks of pregnancy, stage of labour or day after birth, and decide what is normal at that point.
  2. Look for the patient in danger: the mother, the fetus or the newborn, or more than one of them.
  3. Link the finding to its cause: VEAL CHOP for decelerations, the four Ts for bleeding, BUBBLE-HE after birth.
  4. Choose the action that improves blood flow and oxygen first (side-lying, stopping oxytocin, fundal massage), then escalate.

Dosage calculations

Dose from strength
volume = dose / strength
Weight-based dose
dose = mg/kg × body weight
Tablets
number = dose / tablet strength
Units
1 g = 1000 mg, 1 mg = 1000 mcg

Method

  1. Convert the ordered dose and the stock strength to the same unit.
  2. Use desired over have times quantity: (D/H) × Q.
  3. For weight-based doses, multiply by the weight in kg first, then divide the daily dose by the number of doses.
  4. Estimate first and check that the answer is reasonable.

IV infusion rates

Pump rate
mL/h = volume (mL)/time (h)
Drip rate
drops/min = volume (mL) × drop factor / time (min)
Infusion time
time (h) = volume (mL)/rate (mL/h)

Method

  1. Pump rate in mL/h: volume divided by time in hours.
  2. Drip rate in drops/min: volume × drop factor divided by time in minutes.
  3. For time remaining: volume left divided by the rate.
  4. Round as the question or the equipment requires.

2Practice problems

1.Maternity & obstetric nursingMedium

When the newborn's head is turned to one side, the arm on that side extends and the other arm flexes. Which reflex is this?

  1. AMoro reflex
  2. BTonic neck reflex
  3. CPalmar grasp reflex
  4. DRooting reflex
2.Maternity & obstetric nursingHard

A newborn has excessive frothy saliva and chokes and turns blue with the first feed. What is the priority?

  1. APlace the baby on its back to sleep
  2. BGive the baby water instead of milk
  3. CStop feeding and report it urgently
  4. DContinue feeding more slowly
3.Dosage calculationsMedium
63 kgBSA = 1.5 m²135 mg/m²D = ? mg

A patient weighing 63 kg has a body surface area of 1.5 m². The prescription is 135 mg/m². Find the dose D in mg.

63 kgBSA = 1.5 m²135 mg/m²
D = mg
4.Dosage calculationsHard
20%stockwater = ? mL

You must prepare 250 mL of a 1% (w/v) solution from a 20% (w/v) stock solution. How much water W must be added to the stock?

C₁ = 20%C₂ = 1%V₂ = 250 mL
W = mL
5.IV infusion ratesMedium
500 mL60 gtt/mL12 h? gtt/min

Infuse 500 mL over 12 hours with a giving set of 60 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

500 mL12 h60 gtt/mL
R = gtt/min
6.IV infusion ratesHard
4 g500 mL? mL/h1.5 mg/min

A bag contains 4 g of a drug in 500 mL. The order is 1.5 mg per minute. At what rate R do you set the pump, in mL/h?

4 g/500 mL1.5 mg/min
R = mL/h

3Solutions

1.Maternity & obstetric nursing

Answer: B · Tonic neck reflex

Why this is the answer

The asymmetric tonic neck reflex gives a "fencing" posture. It fades over the first months; persistence beyond the expected age can suggest neurological problems.

Answer

B · Tonic neck reflex
2.Maternity & obstetric nursing

Answer: C · Stop feeding and report it urgently

Why this is the answer

Drooling and choking with feeds suggest oesophageal atresia with or without tracheo-oesophageal fistula. Feeding is stopped, the pouch is suctioned and the baby is kept upright while surgical review is arranged.

Answer

C · Stop feeding and report it urgently
3.Dosage calculations

Answer: D = 202.5 mg

Body-surface-area dosing: many cytotoxic and some paediatric doses are prescribed per square metre of body surface area: dose (mg) = dose per m² × BSA (m²). The Mosteller formula estimates BSA = √(height (cm) × weight (kg)/3600).

Dose

D = 135·1.5 = 202.5 mg

Answer

D = 202.5 mg
4.Dosage calculations

Answer: W = 237.5 mL

Solution strengths: a percentage strength is grams per 100 mL, so 1% = 1 g/100 mL = 10 mg/mL. A ratio strength 1:1000 means 1 g in 1000 mL = 1 mg/mL; 1:10 000 is 0.1 mg/mL. For a dilution the amount of drug stays the same: C₁·V₁ = C₂·V₂.

Volume of stock

V₁ = 1·250/20 = 12.5 mL

Water to add

W = 250 − 12.5 = 237.5 mL

Answer

W = 237.5 mL
5.IV infusion rates

Answer: R = 42 gtt/min

Infusion rates: a pump is set in mL/h = volume/time in hours. A gravity drip is counted in drops per minute: gtt/min = volume (mL) × drop factor (gtt/mL)/time (min). The drop factor is printed on the tubing package: macrodrip sets deliver 10, 15 or 20 gtt/mL (blood sets often 10 gtt/mL in the US, 15 in the UK) and microdrip sets 60 gtt/mL. Always use the drop factor the question or package gives.

Time in minutes

12·60 = 720 min

Drip rate

R = 500·60/720 = 41.67 ≈ 42 gtt/min

Answer

R = 42 gtt/min

At the bedside you round to the nearest whole drop: 42 gtt/min.

6.IV infusion rates

Answer: R = 11.25 mL/h

Dose-based infusions: concentration = amount of drug in the bag/bag volume. Pump rate (mL/h) = dose per hour/concentration, and dose per hour = mL/h × concentration. Convert per-minute doses to per-hour (× 60) and keep the mass units the same (1 g = 1000 mg, 1 mg = 1000 mcg).

Concentration

4000 mg/500 mL = 8 mg/mL

Dose per hour

1.5·60 = 90 mg/h

Pump rate

R = 90/8 = 11.25 mL/h

Answer

R = 11.25 mL/h

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