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

Why is it important to do newborn bloodspot screening at the recommended time rather than in the first hours?

  1. AEarlier testing always gives false negatives for all conditions
  2. BThe heel cannot be pricked until the cord falls off
  3. CThe baby's blood cannot be sampled before day 3
  4. DSome results, such as PKU, need milk feeds first
2.Maternity & obstetric nursingHard

A woman has been breastfeeding for 3 weeks. Her baby has gained little weight, feeds briefly and falls asleep at the breast. What is the most appropriate first action?

  1. AReassure her that slow weight gain is normal
  2. BTell her to feed only every 6 hours to build hunger
  3. CAdvise her to stop breastfeeding and use formula only
  4. DObserve a full feed to assess latch and milk transfer
3.Dosage calculationsMedium
024681010 mL

A child weighing 6 kg is prescribed 10 mg/kg of a drug. The stock solution contains 10 mg/mL. Draw up the dose: what volume V do you give?

6 kg10 mg/kg10 mg/mL
V = mL
4.Dosage calculationsHard
23 kg124 cmBSA = √(h·w/3600)100 mg/m²D = ? mg

A patient is 124 cm tall and weighs 23 kg. The prescription is 100 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.

124 cm23 kg100 mg/m²
D = mg
5.IV infusion ratesMedium
500 mL20 gtt/mL5 h? gtt/min

Infuse 500 mL over 5 hours with a giving set of 20 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

500 mL5 h20 gtt/mL
R = gtt/min
6.IV infusion ratesHard
310 mLleft? mL/h5 h left

500 mL was ordered over 10 hours. After 5 hours you find that 310 mL is still in the bag, and the order must still finish on time. By what percentage Δ must the original pump rate be increased?

500 mL / 10 hafter 5 h: 310 mL
Δ = %

3Solutions

1.Maternity & obstetric nursing

Answer: D · Some results, such as PKU, need milk feeds first

Why this is the answer

Phenylalanine builds up only after the baby has had milk feeds, so very early samples can miss PKU. Programmes specify timing, and early samples may need repeating.

Answer

D · Some results, such as PKU, need milk feeds first
2.Maternity & obstetric nursing

Answer: D · Observe a full feed to assess latch and milk transfer

Why this is the answer

Poor weight gain needs assessment of a full feed, including latch, swallowing and duration, and of the baby's health. Support may include more frequent feeds, breast compression and expressed milk, with medical review.

Answer

D · Observe a full feed to assess latch and milk transfer
3.Dosage calculations

Answer: V = 6 mL

Drawing up a dose: volume = (prescribed dose/stock strength) × stock volume. Convert to the same units first, then check that the volume fits the syringe and lands on one of its graduations.

Dose from body weight

D = 10·6 = 60 mg

Volume

V = 60/10 = 6 mL

On the syringe

On this 10 mL syringe every small line is 0.2 mL.

Answer

V = 6 mL
4.Dosage calculations

Answer: D = 89.01 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).

Body surface area

BSA = √(124·23/3600) = √0.7922 = 0.8901 m²

Dose

D = 100·0.8901 = 89.01 mg

Answer

D = 89.01 mg
5.IV infusion rates

Answer: R = 33 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

5·60 = 300 min

Drip rate

R = 500·20/300 = 33.33 ≈ 33 gtt/min

Answer

R = 33 gtt/min

At the bedside you round to the nearest whole drop: 33 gtt/min.

6.IV infusion rates

Answer: Δ = 24 %

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.

Original rate

500/10 = 50 mL/h

New rate

R = 310/5 = 62 mL/h

Percentage change

Δ = (62 − 50)/50·100% = 24%

Answer

Δ = 24%

Many hospitals allow such an adjustment up to 25% without a new order; check local policy.

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