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

A woman who has had a caesarean asks when she can drive again. Which answer is most accurate?

  1. AWhen she can brake hard without pain
  2. BOnly after her stitches are removed by a doctor
  3. CThe same day she is discharged
  4. DNever before 6 months
2.Maternity & obstetric nursingHard

An Rh-negative mother's baby is found to be Rh-negative. What is the correct action regarding postnatal anti-D?

  1. APostnatal anti-D is not needed
  2. BGive anti-D to the baby instead
  3. CGive anti-D only if the mother had a miscarriage before
  4. DGive a double dose of anti-D
3.Dosage calculationsMedium
25 kg5 mg/kgD = ? mg

A patient weighs 25 kg and is prescribed 5 mg/kg as a single dose. Find the dose D in mg.

25 kg5 mg/kg
D = mg
4.Dosage calculationsHard
200 mg/5 mLV = ? mL

A child weighing 8 kg is prescribed 12.5 mg/kg per dose of an oral suspension that contains 200 mg in 5 mL. What volume V do you give?

8 kg12.5 mg/kg200 mg/5 mL
V = mL
5.IV infusion ratesMedium
250 mL10 gtt/mL5 h? gtt/min

Infuse 250 mL over 5 hours with a giving set of 10 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

250 mL5 h10 gtt/mL
R = gtt/min
6.IV infusion ratesHard
2 g250 mL? mL/h1.5 mg/min

A bag contains 2 g of a drug in 250 mL. The order is 1.5 mg per minute. At what rate R do you set the pump, in mL/h?

2 g/250 mL1.5 mg/min
R = mL/h

3Solutions

1.Maternity & obstetric nursing

Answer: A · When she can brake hard without pain

Why this is the answer

There is no fixed time. She can drive when she can brake suddenly, look over her shoulder and wear a seat belt comfortably. Many women need about 4 to 6 weeks, and insurance rules may apply.

Answer

A · When she can brake hard without pain
2.Maternity & obstetric nursing

Answer: A · Postnatal anti-D is not needed

Why this is the answer

Postnatal anti-D prevents sensitisation to Rh-positive fetal cells. An Rh-negative baby carries no D antigen, so the mother cannot be sensitised by this birth.

Answer

A · Postnatal anti-D is not needed
3.Dosage calculations

Answer: D = 125 mg

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.

Dose

5·25 = 125 mg

Answer

D = 125 mg
4.Dosage calculations

Answer: V = 2.5 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.

Dose from weight

12.5·8 = 100 mg

Volume

V = (100/200)·5 = 2.5 mL

Answer

V = 2.5 mL
5.IV infusion rates

Answer: R = 8 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 = 250·10/300 = 8.333 ≈ 8 gtt/min

Answer

R = 8 gtt/min

At the bedside you round to the nearest whole drop: 8 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

2000 mg/250 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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