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

After birth of the baby, the placenta has not been delivered after a long time despite active management. What is this called?

  1. APlacental abruption
  2. BUterine inversion
  3. CRetained placenta
  4. DPlacenta praevia
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. AObserve a full feed to assess latch and milk transfer
  2. BTell her to feed only every 6 hours to build hunger
  3. CAdvise her to stop breastfeeding and use formula only
  4. DReassure her that slow weight gain is normal
3.Dosage calculationsMedium
024681010 mL

A child weighing 24 kg is prescribed 4 mg/kg of a drug. The stock solution contains 20 mg/mL. Draw up the dose: what volume V do you give?

24 kg4 mg/kg20 mg/mL
V = mL
4.Dosage calculationsHard
48 kg144 cmBSA = √(h·w/3600)135 mg/m²D = ? mg

A patient is 144 cm tall and weighs 48 kg. The prescription is 135 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.

144 cm48 kg135 mg/m²
D = mg
5.IV infusion ratesMedium
500 mL20 gtt/mL2 h? gtt/min

Infuse 500 mL over 2 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 mL2 h20 gtt/mL
R = gtt/min
6.IV infusion ratesHard
4 g500 mL? mL/h2 mg/min

A bag contains 4 g of a drug in 500 mL. The order is 2 mg per minute. At what rate R do you set the pump, in mL/h?

4 g/500 mL2 mg/min
R = mL/h

3Solutions

1.Maternity & obstetric nursing

Answer: C · Retained placenta

Why this is the answer

A retained placenta is one that has not been delivered within the expected time, usually about 30 minutes with active management. It increases the risk of haemorrhage and may need manual removal.

Answer

C · Retained placenta
2.Maternity & obstetric nursing

Answer: A · 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

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

Answer: V = 4.8 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 = 4·24 = 96 mg

Volume

V = 96/20 = 4.8 mL

On the syringe

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

Answer

V = 4.8 mL
4.Dosage calculations

Answer: D = 187.1 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 = √(144·48/3600) = √1.92 = 1.386 m²

Dose

D = 135·1.386 = 187.1 mg

Answer

D = 187.1 mg
5.IV infusion rates

Answer: R = 83 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

2·60 = 120 min

Drip rate

R = 500·20/120 = 83.33 ≈ 83 gtt/min

Answer

R = 83 gtt/min

At the bedside you round to the nearest whole drop: 83 gtt/min.

6.IV infusion rates

Answer: R = 15 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

2·60 = 120 mg/h

Pump rate

R = 120/8 = 15 mL/h

Answer

R = 15 mL/h

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