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

Why is an indwelling catheter placed before a caesarean birth?

  1. ATo measure the baby's fluid balance
  2. BTo prevent postpartum haemorrhage
  3. CTo keep the bladder empty during surgery
  4. DTo collect a urine sample for culture
2.Maternity & obstetric nursingHard

An Rh-negative mother's baby is found to be Rh-negative. What is the correct action regarding postnatal anti-D?

  1. AGive anti-D to the baby instead
  2. BPostnatal anti-D is not needed
  3. CGive a double dose of anti-D
  4. DGive anti-D only if the mother had a miscarriage before
3.Dosage calculationsMedium
024681010 mL

A child weighing 40 kg is prescribed 2 mg/kg of a drug. The stock solution contains 25 mg/mL. Draw up the dose: what volume V do you give?

40 kg2 mg/kg25 mg/mL
V = mL
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 1200 units of a drug that comes as 10000 units/mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

1200 units10000 units/mL
V = mL
5.IV infusion ratesMedium
1000 mL10 gtt/mL2 h? gtt/min

Infuse 1000 mL over 2 hours with a giving set of 10 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

1000 mL2 h10 gtt/mL
R = gtt/min
6.IV infusion ratesHard
950 mLleft? mL/h3 h left

1500 mL was ordered over 6 hours. After 3 hours you find that 950 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?

1500 mL / 6 hafter 3 h: 950 mL
Δ = %

3Solutions

1.Maternity & obstetric nursing

Answer: C · To keep the bladder empty during surgery

Why this is the answer

An empty bladder reduces the risk of bladder injury during surgery and allows urine output to be monitored. It is usually removed once the woman can walk.

Answer

C · To keep the bladder empty during surgery
2.Maternity & obstetric nursing

Answer: B · Postnatal anti-D is not needed

Why this is the answer

Postnatal anti-D prevents sensitisation to Rh-positive fetal cells. An Rh-negative baby carries no D antigen, so the mother cannot be sensitised by this birth.

Answer

B · Postnatal anti-D is not needed
3.Dosage calculations

Answer: V = 3.2 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 = 2·40 = 80 mg

Volume

V = 80/25 = 3.2 mL

On the syringe

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

Answer

V = 3.2 mL
4.Dosage calculations

Answer: V = 0.12 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 = 1200/10000 = 0.12 mL

On the syringe

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

Answer

V = 0.12 mL
5.IV infusion rates

Answer: R = 83 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

2·60 = 120 min

Drip rate

R = 1000·10/120 = 83.33 ≈ 83 gtt/min

Answer

R = 83 gtt/min

At the bedside you round to the nearest whole drop: 83 gtt/min.

6.IV infusion rates

Answer: Δ = 26.67 %

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

1500/6 = 250 mL/h

New rate

R = 950/3 = 316.7 mL/h

Percentage change

Δ = (316.7 − 250)/250·100% = 26.67%

Answer

Δ = 26.67%

This is more than a 25% increase: most hospitals require you to contact the prescriber instead of catching up, and to assess the patient for fluid overload.

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