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 findings are typical of placental abruption?

  1. AItching of the palms and soles
  2. BLeaking clear fluid without contractions
  3. CPainless bright red bleeding with a soft, relaxed, non-tender uterus
  4. DAbdominal pain, a firm or rigid uterus and dark red bleeding
2.Maternity & obstetric nursingHard

A labouring woman has a temperature of 38.5 °C (101.3 °F), and the fetal baseline has risen from 140 to 170 bpm over the last hour. What is the most likely explanation?

  1. AReassuring fetal response to contractions
  2. BFetal tachycardia due to a maternal opioid
  3. CFetal head compression
  4. DFetal tachycardia due to maternal fever or infection
3.Dosage calculationsMedium
024681010 mL

A child weighing 22 kg is prescribed 2 mg/kg of a drug. The stock solution contains 20 mg/mL. Draw up the dose: what volume V do you give?

22 kg2 mg/kg20 mg/mL
V = mL
4.Dosage calculationsHard
50%stockwater = ? mL

You must prepare 100 mL of a 0.5% (w/v) solution from a 50% (w/v) stock solution. How much water W must be added to the stock?

C₁ = 50%C₂ = 0.5%V₂ = 100 mL
W = mL
5.IV infusion ratesMedium
250 mL60 gtt/mL12 h? gtt/min

Infuse 250 mL over 12 hours with a giving set of 60 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

250 mL12 h60 gtt/mL
R = gtt/min
6.IV infusion ratesHard
390 mLleft? mL/h2 h left

1000 mL was ordered over 6 hours. After 4 hours you find that 390 mL is still in the bag, and the order must still finish on time. By what percentage Δ must the original pump rate be increased?

1000 mL / 6 hafter 4 h: 390 mL
Δ = %

3Solutions

1.Maternity & obstetric nursing

Answer: D · Abdominal pain, a firm or rigid uterus and dark red bleeding

Why this is the answer

Abruption causes pain, uterine tenderness and rigidity, and dark bleeding. The bleeding can be hidden behind the placenta, so blood loss may be much larger than what is visible.

Answer

D · Abdominal pain, a firm or rigid uterus and dark red bleeding
2.Maternity & obstetric nursing

Answer: D · Fetal tachycardia due to maternal fever or infection

Why this is the answer

Maternal fever, often from intra-amniotic infection, is a common cause of fetal tachycardia. The provider is informed, and treatment of fever and infection is expected. Opioids reduce variability rather than raise the rate.

Answer

D · Fetal tachycardia due to maternal fever or infection
3.Dosage calculations

Answer: V = 2.2 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 = 2·22 = 44 mg

Volume

V = 44/20 = 2.2 mL

On the syringe

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

Answer

V = 2.2 mL
4.Dosage calculations

Answer: W = 99 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 = 0.5·100/50 = 1 mL

Water to add

W = 100 − 1 = 99 mL

Answer

W = 99 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

12·60 = 720 min

Drip rate

R = 250·60/720 = 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: Δ = 17 %

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

1000/6 = 166.7 mL/h

New rate

R = 390/2 = 195 mL/h

Percentage change

Δ = (195 − 166.7)/166.7·100% = 17%

Answer

Δ = 17%

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

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