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 newborn baby girl has a small amount of blood-tinged vaginal discharge on day 3. What should the nurse tell the parents?

  1. AIt shows a urinary tract infection
  2. BIt is a sign of sexual abuse
  3. CIt is caused by maternal hormones
  4. DIt means the baby has a bleeding disorder
2.Maternity & obstetric nursingHard

A woman at 30 weeks has regular painful contractions every 5 minutes with cervical change. Which treatment is expected to protect the baby's lungs if birth occurs?

  1. AMethylergonovine
  2. BAntenatal corticosteroids
  3. COxytocin
  4. DAnti-D immunoglobulin
3.Dosage calculationsMedium
024681010 mL

A child weighing 40 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?

40 kg3 mg/kg50 mg/mL
V = mL
4.Dosage calculationsHard
20k units500 mL? mL/h500 units/h

An infusion contains 20000 units of a drug in 500 mL. The prescription is 500 units per hour. At what rate R do you set the pump, in mL/h?

20000 units/500 mL500 units/h
R = mL/h
5.IV infusion ratesMedium
150 mLleft? mL/h2 h left

500 mL was ordered over 8 hours. After 6 hours you find that 150 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?

500 mL / 8 hafter 6 h: 150 mL
R = mL/h
6.IV infusion ratesHard
400 mg250 mL15 mL/h? mg/h

A bag contains 400 mg of a drug in 250 mL and runs at 15 mL/h. How many milligrams per hour D does the patient receive?

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

3Solutions

1.Maternity & obstetric nursing

Answer: C · It is caused by maternal hormones

Why this is the answer

Pseudomenstruation is caused by withdrawal of maternal hormones after birth and resolves within days. Swollen breasts in either sex have the same cause.

Answer

C · It is caused by maternal hormones
2.Maternity & obstetric nursing

Answer: B · Antenatal corticosteroids

Why this is the answer

Antenatal corticosteroids reduce respiratory distress in preterm babies. Tocolysis may be used to gain time, and magnesium sulfate may be given for fetal neuroprotection when birth before about 32 weeks is likely.

Answer

B · Antenatal corticosteroids
3.Dosage calculations

Answer: V = 2.4 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 = 3·40 = 120 mg

Volume

V = 120/50 = 2.4 mL

On the syringe

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

Answer

V = 2.4 mL
4.Dosage calculations

Answer: R = 12.5 mL/h

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.

Concentration

20000/500 = 40 units/mL

Pump rate

R = 500/40 = 12.5 mL/h

Answer

R = 12.5 mL/h
5.IV infusion rates

Answer: R = 75 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

500/8 = 62.5 mL/h

New rate

R = 150/2 = 75 mL/h

Answer

R = 75 mL/h

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

6.IV infusion rates

Answer: D = 24 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

400/250 = 1.6 mg/mL

Dose rate

D = 1.6·15 = 24 mg/h

Answer

D = 24 mg/h

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