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 indomethacin generally not used as a tocolytic after about 32 weeks?

  1. AIt can close the fetal ductus arteriosus too early
  2. BIt stimulates stronger contractions late in pregnancy
  3. CIt causes severe maternal hypertension
  4. DIt triggers maternal hypoglycaemia
2.Maternity & obstetric nursingHard

An ultrasound at 30 weeks shows polyhydramnios and no visible fetal stomach bubble. Which fetal condition should be considered?

  1. AOesophageal atresia
  2. BRenal agenesis
  3. CPost-term pregnancy
  4. DFetal growth from maternal diabetes only
3.Dosage calculationsMedium
024681010 mL

A child weighing 20 kg is prescribed 3 mg/kg of a drug. The stock solution contains 50 mg/mL. Draw up the dose: what volume V do you give?

20 kg3 mg/kg50 mg/mL
V = mL
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 4750 units of a drug that comes as 5000 units/mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

4750 units5000 units/mL
V = mL
5.IV infusion ratesMedium
1000 mL15 gtt/mL3 h? gtt/min

Infuse 1000 mL over 3 hours with a giving set of 15 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

1000 mL3 h15 gtt/mL
R = gtt/min
6.IV infusion ratesHard
100 mg250 mL30 mL/h? mcg/min

An infusion of 100 mg in 250 mL runs at 30 mL/h. How many micrograms per minute D does the patient receive?

100 mg/250 mL30 mL/h
D = mcg/min

3Solutions

1.Maternity & obstetric nursing

Answer: A · It can close the fetal ductus arteriosus too early

Why this is the answer

Indomethacin inhibits prostaglandin synthesis. In the fetus this can cause premature closure of the ductus arteriosus and reduced fetal urine output with oligohydramnios, risks that increase with gestational age.

Answer

A · It can close the fetal ductus arteriosus too early
2.Maternity & obstetric nursing

Answer: A · Oesophageal atresia

Why this is the answer

If the fetus cannot swallow, as in oesophageal atresia, amniotic fluid builds up and the stomach is not seen. Renal agenesis causes the opposite, severe oligohydramnios.

Answer

A · Oesophageal atresia
3.Dosage calculations

Answer: V = 1.2 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 = 3·20 = 60 mg

Volume

V = 60/50 = 1.2 mL

On the syringe

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

Answer

V = 1.2 mL
4.Dosage calculations

Answer: V = 0.95 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.

Volume

V = 4750/5000 = 0.95 mL

On the syringe

On this 1 mL syringe every small line is 0.01 mL.

Answer

V = 0.95 mL
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

3·60 = 180 min

Drip rate

R = 1000·15/180 = 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: D = 200 mcg/min

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

100000 mcg/250 mL = 400 mcg/mL

Dose per hour

30·400 = 12000 mcg/h

Dose per minute

D = 12000/60 = 200 mcg/min

Answer

D = 200 mcg/min

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