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

What do accelerations of the fetal heart rate usually indicate?

  1. ACompression of the umbilical cord
  2. BFetal sleep
  3. CPlacental insufficiency
  4. DThe fetus is well oxygenated
2.Maternity & obstetric nursingHard

A woman at 33 weeks with bright red vaginal bleeding is admitted, and placenta praevia is suspected. Which order should the nurse question?

  1. AArrange an ultrasound to locate the placenta
  2. BPerform a digital cervical examination to assess dilation
  3. CStart continuous fetal heart monitoring
  4. DInsert a large-bore IV cannula and send a group and screen
3.Dosage calculationsMedium
024681010 mL

A child weighing 16 kg is prescribed 2.5 mg/kg of a drug. The stock solution contains 10 mg/mL. Draw up the dose: what volume V do you give?

16 kg2.5 mg/kg10 mg/mL
V = mL
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 900 units of a drug that comes as 1000 units/mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

900 units1000 units/mL
V = mL
5.IV infusion ratesMedium
870 mLleft? mL/h7 h left

1000 mL was ordered over 10 hours. After 3 hours you find that 870 mL is still in the bag, and the order must still finish on time. To what rate R in mL/h must the pump be reset?

1000 mL / 10 hafter 3 h: 870 mL
R = mL/h
6.IV infusion ratesHard
200 mg250 mL15 mL/h? mg/h

A bag contains 200 mg of a drug in 250 mL and runs at 15 mL/h. How many milligrams per hour D does the patient receive?

200 mg/250 mL15 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: D · The fetus is well oxygenated

Why this is the answer

Accelerations are abrupt rises above the baseline (at term at least 15 bpm for at least 15 seconds). They are a reassuring sign of a well-oxygenated fetus with an intact nervous system.

Answer

D · The fetus is well oxygenated
2.Maternity & obstetric nursing

Answer: B · Perform a digital cervical examination to assess dilation

Why this is the answer

A digital vaginal examination is avoided until placenta praevia has been ruled out by ultrasound, because it can trigger severe haemorrhage. The other orders are appropriate.

Answer

B · Perform a digital cervical examination to assess dilation
3.Dosage calculations

Answer: V = 4 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 = 2.5·16 = 40 mg

Volume

V = 40/10 = 4 mL

On the syringe

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

Answer

V = 4 mL
4.Dosage calculations

Answer: V = 0.9 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 = 900/1000 = 0.9 mL

On the syringe

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

Answer

V = 0.9 mL
5.IV infusion rates

Answer: R = 124.3 mL/h

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

1000/10 = 100 mL/h

New rate

R = 870/7 = 124.3 mL/h

Answer

R = 124.3 mL/h

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

6.IV infusion rates

Answer: D = 12 mg/h

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.

Concentration

200/250 = 0.8 mg/mL

Dose rate

D = 0.8·15 = 12 mg/h

Answer

D = 12 mg/h

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