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

Which woman on the antenatal unit should the nurse see first?

  1. AAt 38 weeks: irregular Braxton Hicks contractions
  2. BAt 30 weeks: mild ankle swelling in the evening
  3. CAt 28 weeks: due for routine anti-D
  4. DAt 34 weeks: severe headache, BP 164/110 mmHg
2.Maternity & obstetric nursingHard

A pregnant woman involved in a car crash asks how to wear a seat belt. Which instruction is correct?

  1. ALap belt under the bump, shoulder belt between the breasts
  2. BDo not wear a seat belt in pregnancy
  3. CWear only the shoulder part of the belt
  4. DPut the lap belt across the top of the bump, above the uterus
3.Dosage calculationsMedium
2%w/vV = ? mL

A dose of 100 mg is needed from a 2% (w/v) solution. What volume V contains this dose?

100 mg2% w/v
V = mL
4.Dosage calculationsHard
250 mg/5 mLV = ? mL

A patient weighs 35.2 lb. The prescription is 5 mg/kg as a single dose, and the stock contains 250 mg in 5 mL. Using 1 kg = 2.2 lb, what volume V do you give?

35.2 lb5 mg/kg250 mg/5 mL1 kg = 2.2 lb
V = mL
5.IV infusion ratesMedium
1000 mL10 gtt/mL8 h? gtt/min

Infuse 1000 mL over 8 hours with a giving set of 10 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

1000 mL8 h10 gtt/mL
R = gtt/min
6.IV infusion ratesHard
50 mg500 mL3 mL/h? mcg/min

An infusion of 50 mg in 500 mL runs at 3 mL/h. How many micrograms per minute D does the patient receive?

50 mg/500 mL3 mL/h
D = mcg/min

3Solutions

1.Maternity & obstetric nursing

Answer: D · At 34 weeks: severe headache, BP 164/110 mmHg

Why this is the answer

Severe-range blood pressure with a headache suggests pre-eclampsia with severe features and a risk of eclampsia or stroke. The other women are stable.

Answer

D · At 34 weeks: severe headache, BP 164/110 mmHg
2.Maternity & obstetric nursing

Answer: A · Lap belt under the bump, shoulder belt between the breasts

Why this is the answer

The lap belt should sit low under the abdomen across the hips and thighs, with the shoulder belt across the chest and to the side of the bump. Wearing a seat belt greatly reduces maternal and fetal injury.

Answer

A · Lap belt under the bump, shoulder belt between the breasts
3.Dosage calculations

Answer: V = 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.

Concentration

2% = 20 mg/mL

Volume

V = 100/20 = 5 mL

Answer

V = 5 mL
4.Dosage calculations

Answer: V = 1.6 mL

Dose calculation: the amount to give equals what is prescribed divided by what you have, times the quantity it comes in: amount = (desired dose/stock strength) × stock volume. Always keep the units the same (convert g to mg, mg to mcg first) and check that the answer is sensible.

Weight in kg

35.2/2.2 = 16 kg

Dose

5·16 = 80 mg

Volume

V = (80/250)·5 = 1.6 mL

Answer

V = 1.6 mL
5.IV infusion rates

Answer: R = 21 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

8·60 = 480 min

Drip rate

R = 1000·10/480 = 20.83 ≈ 21 gtt/min

Answer

R = 21 gtt/min

At the bedside you round to the nearest whole drop: 21 gtt/min.

6.IV infusion rates

Answer: D = 5 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

50000 mcg/500 mL = 100 mcg/mL

Dose per hour

3·100 = 300 mcg/h

Dose per minute

D = 300/60 = 5 mcg/min

Answer

D = 5 mcg/min

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