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 baby is at greatest risk of early-onset group B streptococcal infection?

  1. AA baby of a GBS-positive mother with no antibiotics
  2. BA baby whose mother was GBS-negative at 36 weeks
  3. CA baby born at 40 weeks to a mother with no risk factors
  4. DA baby born by planned caesarean with intact membranes
2.Maternity & obstetric nursingHard

Which statement by a woman in early labour shows a need for further teaching about pain relief?

  1. A"Changing position often and walking can help me cope."
  2. B"If I have an epidural, I will not need my blood pressure checked."
  3. C"Breathing slowly and focusing can help between contractions."
  4. D"A warm bath or shower may ease the pain."
3.Dosage calculationsMedium
024681010 mL

A child weighing 20 kg is prescribed 2 mg/kg of a drug. The stock solution contains 10 mg/mL. Draw up the dose: what volume V do you give?

20 kg2 mg/kg10 mg/mL
V = mL
4.Dosage calculationsHard
84 kg170 cmBSA = √(h·w/3600)60 mg/m²D = ? mg

A patient is 170 cm tall and weighs 84 kg. The prescription is 60 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.

170 cm84 kg60 mg/m²
D = mg
5.IV infusion ratesMedium
1500 mL20 gtt/mL12 h? gtt/min

Infuse 1500 mL over 12 hours with a giving set of 20 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

1500 mL12 h20 gtt/mL
R = gtt/min
6.IV infusion ratesHard
500 mg500 mL15 gtt/mL60 mg/h? gtt/min

500 mg of a drug is diluted in 500 mL and given by gravity through a set of 15 gtt/mL. The order is 60 mg per hour. Find the drip rate R in drops per minute.

500 mg/500 mL60 mg/h15 gtt/mL
R = gtt/min

3Solutions

1.Maternity & obstetric nursing

Answer: A · A baby of a GBS-positive mother with no antibiotics

Why this is the answer

GBS colonisation, no intrapartum antibiotics, prolonged rupture of membranes, maternal fever and prematurity increase the risk. Intrapartum IV antibiotics greatly lower early-onset GBS disease.

Answer

A · A baby of a GBS-positive mother with no antibiotics
2.Maternity & obstetric nursing

Answer: B · "If I have an epidural, I will not need my blood pressure checked."

Why this is the answer

Epidurals often cause hypotension, so blood pressure is checked frequently after they are started. Movement, breathing techniques and warm water are effective non-drug measures.

Answer

B · "If I have an epidural, I will not need my blood pressure checked."
3.Dosage calculations

Answer: V = 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 = 2·20 = 40 mg

Volume

V = 40/10 = 4 mL

On the syringe

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

Answer

V = 4 mL
4.Dosage calculations

Answer: D = 119.5 mg

Body-surface-area dosing: many cytotoxic and some paediatric doses are prescribed per square metre of body surface area: dose (mg) = dose per m² × BSA (m²). The Mosteller formula estimates BSA = √(height (cm) × weight (kg)/3600).

Body surface area

BSA = √(170·84/3600) = √3.967 = 1.992 m²

Dose

D = 60·1.992 = 119.5 mg

Answer

D = 119.5 mg
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

12·60 = 720 min

Drip rate

R = 1500·20/720 = 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 = 15 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

500/500 = 1 mg/mL

Volume per hour

60/1 = 60 mL/h

Drip rate

R = 60·15/60 = 15 gtt/min

Answer

R = 15 gtt/min

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