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

The membranes have just ruptured. What should the nurse assess first?

  1. AThe degree of cervical effacement
  2. BThe woman's temperature
  3. CThe colour of the fluid only
  4. DThe fetal heart rate
2.Maternity & obstetric nursingHard

A woman at 8 weeks takes valproate for epilepsy. She asks whether she should stop it. Which response is best?

  1. ADo not stop it suddenly; arrange urgent specialist review
  2. BStop the drug today because it causes birth defects
  3. CHalve the dose herself to reduce the risk to the baby
  4. DContinue as usual because epilepsy drugs are all safe in pregnancy
3.Dosage calculationsMedium
024681010 mL

A child weighing 6 kg is prescribed 20 mg/kg of a drug. The stock solution contains 50 mg/mL. Draw up the dose: what volume V do you give?

6 kg20 mg/kg50 mg/mL
V = mL
4.Dosage calculationsHard
100 mg/1 mLV = ? mL

A patient weighs 72.6 lb. The prescription is 5 mg/kg as a single dose, and the stock contains 100 mg in 1 mL. Using 1 kg = 2.2 lb, what volume V do you give? Round to one decimal place.

72.6 lb5 mg/kg100 mg/1 mL1 kg = 2.2 lb
V = mL
5.IV infusion ratesMedium
V = ?15 gtt/mL25 gtt/min8 h

A drip runs at 25 gtt/min through a set of 15 gtt/mL. How many millilitres V does the patient receive in 8 hours?

25 gtt/min15 gtt/mL8 h
V = mL
6.IV infusion ratesHard
400 mL60 gtt/mL20 gtt/mint = ? h

A drip runs at 20 gtt/min through a set of 60 gtt/mL. There are 400 mL left in the bag. How many hours t until it is empty?

20 gtt/min60 gtt/mL400 mL
t = h

3Solutions

1.Maternity & obstetric nursing

Answer: D · The fetal heart rate

Why this is the answer

After rupture of the membranes, check the fetal heart rate first to detect cord prolapse or compression. Then record the colour, odour, amount and time of the fluid.

Answer

D · The fetal heart rate
2.Maternity & obstetric nursing

Answer: A · Do not stop it suddenly; arrange urgent specialist review

Why this is the answer

Valproate is strongly teratogenic, but stopping antiepileptics suddenly can cause seizures that harm mother and fetus. She needs urgent specialist review to change treatment safely, ideally before conception.

Answer

A · Do not stop it suddenly; arrange urgent specialist review
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 = 20·6 = 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: V = 1.7 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

72.6/2.2 = 33 kg

Dose

5·33 = 165 mg

Volume

V = (165/100)·1 = 1.65 ≈ 1.7 mL

Answer

V = 1.7 mL
5.IV infusion rates

Answer: V = 800 mL

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.

Rate in mL/h

25·60/15 = 100 mL/h

Volume

V = 100·8 = 800 mL

Answer

V = 800 mL
6.IV infusion rates

Answer: t = 20 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.

Rate in mL/h

20·60/60 = 20 mL/h

Time left

t = 400/20 = 20 h

Answer

t = 20 h

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