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 a baby of a mother with poorly controlled diabetes often large?

  1. AThe mother's insulin crosses the placenta
  2. BFetal hyperinsulinaemia acts as a growth hormone
  3. CThe baby inherits a gene for large size
  4. DDiabetes always prolongs the pregnancy
2.Maternity & obstetric nursingHard

A woman has had a large postpartum haemorrhage and is receiving several units of blood. Which other complication should the nurse watch for?

  1. AHypoglycaemia from the transfused blood
  2. BCoagulopathy from loss of clotting factors
  3. CPostpartum depression within the hour
  4. DHypertension caused by the volume of blood lost
3.Dosage calculationsMedium
024681010 mL

A child weighing 8 kg is prescribed 2.5 mg/kg of a drug. The stock solution contains 20 mg/mL. Draw up the dose: what volume V do you give?

8 kg2.5 mg/kg20 mg/mL
V = mL
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 1120 micrograms. The ampoule contains 4 mg/mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

1120 mcg4 mg/mL
V = mL
5.IV infusion ratesMedium
1500 mL10 gtt/mL6 h? gtt/min

Infuse 1500 mL over 6 hours with a giving set of 10 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

1500 mL6 h10 gtt/mL
R = gtt/min
6.IV infusion ratesHard
1000 mg250 mL20 gtt/mL300 mg/h? gtt/min

1000 mg of a drug is diluted in 250 mL and given by gravity through a set of 20 gtt/mL. The order is 300 mg per hour. Find the drip rate R in drops per minute.

1000 mg/250 mL300 mg/h20 gtt/mL
R = gtt/min

3Solutions

1.Maternity & obstetric nursing

Answer: B · Fetal hyperinsulinaemia acts as a growth hormone

Why this is the answer

Maternal glucose crosses the placenta, so the fetal pancreas makes extra insulin, which promotes growth and fat storage. After birth this extra insulin continues and can cause neonatal hypoglycaemia.

Answer

B · Fetal hyperinsulinaemia acts as a growth hormone
2.Maternity & obstetric nursing

Answer: B · Coagulopathy from loss of clotting factors

Why this is the answer

Massive haemorrhage and transfusion of red cells can deplete clotting factors and platelets, leading to further bleeding. Massive transfusion protocols include plasma, platelets and sometimes fibrinogen.

Answer

B · Coagulopathy from loss of clotting factors
3.Dosage calculations

Answer: V = 1 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 = 2.5·8 = 20 mg

Volume

V = 20/20 = 1 mL

On the syringe

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

Answer

V = 1 mL
4.Dosage calculations

Answer: V = 0.28 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.

Same units

4 mg/mL = 4000 mcg/mL

Volume

V = 1120/4000 = 0.28 mL

Answer

V = 0.28 mL
5.IV infusion rates

Answer: R = 42 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 = 1500·10/360 = 41.67 ≈ 42 gtt/min

Answer

R = 42 gtt/min

At the bedside you round to the nearest whole drop: 42 gtt/min.

6.IV infusion rates

Answer: R = 25 gtt/min

Dose-based infusions: concentration = amount of drug in the bag/bag volume. Pump rate (mL/h) = dose per hour/concentration, and dose per hour = mL/h × concentration. Convert per-minute doses to per-hour (× 60) and keep the mass units the same (1 g = 1000 mg, 1 mg = 1000 mcg).

Concentration

1000/250 = 4 mg/mL

Volume per hour

300/4 = 75 mL/h

Drip rate

R = 75·20/60 = 25 gtt/min

Answer

R = 25 gtt/min

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