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

What is a "reactive" non-stress test?

  1. ANo accelerations of the fetal heart rate within 40 minutes
  2. BAt least 2 fetal heart rate accelerations within 20 minutes
  3. CLate decelerations with every contraction
  4. DA baseline heart rate above 160 bpm
2.Maternity & obstetric nursingHard

A woman at 30 weeks reports a sudden gush of clear fluid from the vagina without contractions. What is the priority nursing action?

  1. AAdvise a warm bath to see whether the leaking stops
  2. BAssess the fetal heart rate and check the fluid, and avoid a digital examination
  3. CReassure her that it is urine and send her home
  4. DPerform a digital vaginal examination to check dilation
3.Dosage calculationsMedium
024681010 mL

A child weighing 32 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?

32 kg2.5 mg/kg20 mg/mL
V = mL
4.Dosage calculationsHard
93 kg184 cmBSA = √(h·w/3600)100 mg/m²D = ? mg

A patient is 184 cm tall and weighs 93 kg. The prescription is 100 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.

184 cm93 kg100 mg/m²
D = mg
5.IV infusion ratesMedium
V = ?20 gtt/mL25 gtt/min4 h

A drip runs at 25 gtt/min through a set of 20 gtt/mL. How many millilitres V does the patient receive in 4 hours?

25 gtt/min20 gtt/mL4 h
V = mL
6.IV infusion ratesHard
300 mL15 gtt/mL50 gtt/mint = ? h

A drip runs at 50 gtt/min through a set of 15 gtt/mL. There are 300 mL left in the bag. How many hours t until it is empty?

50 gtt/min15 gtt/mL300 mL
t = h

3Solutions

1.Maternity & obstetric nursing

Answer: B · At least 2 fetal heart rate accelerations within 20 minutes

Why this is the answer

A reactive non-stress test shows at least two qualifying accelerations in 20 minutes and indicates fetal well-being. A non-reactive test needs further testing, such as a biophysical profile.

Answer

B · At least 2 fetal heart rate accelerations within 20 minutes
2.Maternity & obstetric nursing

Answer: B · Assess the fetal heart rate and check the fluid, and avoid a digital examination

Why this is the answer

Preterm prelabour rupture of membranes is suspected. The nurse assesses the fetal heart rate and the fluid's colour, amount and odour, and avoids digital examinations, which raise the risk of infection.

Answer

B · Assess the fetal heart rate and check the fluid, and avoid a digital examination
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 = 2.5·32 = 80 mg

Volume

V = 80/20 = 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 = 218 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 = √(184·93/3600) = √4.753 = 2.18 m²

Dose

D = 100·2.18 = 218 mg

Answer

D = 218 mg
5.IV infusion rates

Answer: V = 300 mL

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

Volume

V = 75·4 = 300 mL

Answer

V = 300 mL
6.IV infusion rates

Answer: t = 1.5 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

50·60/15 = 200 mL/h

Time left

t = 300/200 = 1.5 h

Answer

t = 1.5 h

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