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 finding is expected in a healthy breastfed newborn on day 3?

  1. AA weight loss of about 15% of birth weight
  2. BNo wet nappies in the last 24 hours
  3. CA weight loss of about 6% of birth weight
  4. DA weight gain of 300 g since birth
2.Maternity & obstetric nursingHard

A woman with a previous caesarean is having a trial of labour. Which induction agent should the nurse question?

  1. AMisoprostol
  2. BA balloon catheter
  3. COxytocin used per protocol
  4. DAmniotomy
3.Dosage calculationsMedium
024681010 mL

A child weighing 11 kg is prescribed 15 mg/kg of a drug. The stock solution contains 25 mg/mL. Draw up the dose: what volume V do you give?

11 kg15 mg/kg25 mg/mL
V = mL
4.Dosage calculationsHard
10%stockwater = ? mL

You must prepare 100 mL of a 2.5% (w/v) solution from a 10% (w/v) stock solution. How much water W must be added to the stock?

C₁ = 10%C₂ = 2.5%V₂ = 100 mL
W = mL
5.IV infusion ratesMedium
500 mL15 gtt/mL6 h? gtt/min

Infuse 500 mL over 6 hours with a giving set of 15 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

500 mL6 h15 gtt/mL
R = gtt/min
6.IV infusion ratesHard
600 mL20 gtt/mL25 gtt/mint = ? h

A drip runs at 25 gtt/min through a set of 20 gtt/mL. There are 600 mL left in the bag. How many hours t until it is empty?

25 gtt/min20 gtt/mL600 mL
t = h

3Solutions

1.Maternity & obstetric nursing

Answer: C · A weight loss of about 6% of birth weight

Why this is the answer

A loss of up to about 7–10% of birth weight is common in the first days, with birth weight usually regained by about 10–14 days. A larger loss or too few wet nappies needs a feeding assessment.

Answer

C · A weight loss of about 6% of birth weight
2.Maternity & obstetric nursing

Answer: A · Misoprostol

Why this is the answer

Misoprostol is avoided in women with a uterine scar because of a high risk of uterine rupture. Mechanical methods, amniotomy and carefully monitored oxytocin may be used.

Answer

A · Misoprostol
3.Dosage calculations

Answer: V = 6.6 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 = 15·11 = 165 mg

Volume

V = 165/25 = 6.6 mL

On the syringe

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

Answer

V = 6.6 mL
4.Dosage calculations

Answer: W = 75 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.

Volume of stock

V₁ = 2.5·100/10 = 25 mL

Water to add

W = 100 − 25 = 75 mL

Answer

W = 75 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

6·60 = 360 min

Drip rate

R = 500·15/360 = 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: t = 8 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

25·60/20 = 75 mL/h

Time left

t = 600/75 = 8 h

Answer

t = 8 h

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