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

A woman's epidural has just been inserted. Which nursing action is a priority in the next hours?

  1. ARestrict all oral and IV fluids
  2. BEncourage her to walk around the room on her own
  3. CKeep her lying flat on her back
  4. DCheck her blood pressure and bladder often
2.Maternity & obstetric nursingHard

Shortly after an epidural is started, a labouring woman's blood pressure falls to 86/50 mmHg and the fetal heart rate drops. What should the nurse do first?

  1. AIncrease the epidural infusion rate
  2. BRaise the head of the bed to a high sitting position to improve her breathing
  3. CTurn her onto her side to move the uterus off the large vessels
  4. DAsk her to walk around the room
3.Dosage calculationsMedium
024681010 mL

A child weighing 29 kg is prescribed 4 mg/kg of a drug. The stock solution contains 20 mg/mL. Draw up the dose: what volume V do you give?

29 kg4 mg/kg20 mg/mL
V = mL
4.Dosage calculationsHard
51 kg159 cmBSA = √(h·w/3600)250 mg/m²D = ? mg

A patient is 159 cm tall and weighs 51 kg. The prescription is 250 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.

159 cm51 kg250 mg/m²
D = mg
5.IV infusion ratesMedium
V = ?15 gtt/mL35 gtt/min3 h

A drip runs at 35 gtt/min through a set of 15 gtt/mL. How many millilitres V does the patient receive in 3 hours?

35 gtt/min15 gtt/mL3 h
V = mL
6.IV infusion ratesHard
100 mg250 mL8 mL/h? mg/h

A bag contains 100 mg of a drug in 250 mL and runs at 8 mL/h. How many milligrams per hour D does the patient receive?

100 mg/250 mL8 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: D · Check her blood pressure and bladder often

Why this is the answer

Epidurals cause sympathetic block, so hypotension is common. They also reduce the urge to void, so the bladder is checked and catheterised if needed. Lateral positions avoid aortocaval compression.

Answer

D · Check her blood pressure and bladder often
2.Maternity & obstetric nursing

Answer: C · Turn her onto her side to move the uterus off the large vessels

Why this is the answer

A lateral position relieves aortocaval compression and improves venous return and placental flow. Then increase IV fluids as ordered, notify the anaesthetist or provider and give a vasopressor if prescribed.

Answer

C · Turn her onto her side to move the uterus off the large vessels
3.Dosage calculations

Answer: V = 5.8 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 = 4·29 = 116 mg

Volume

V = 116/20 = 5.8 mL

On the syringe

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

Answer

V = 5.8 mL
4.Dosage calculations

Answer: D = 375.2 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 = √(159·51/3600) = √2.252 = 1.501 m²

Dose

D = 250·1.501 = 375.2 mg

Answer

D = 375.2 mg
5.IV infusion rates

Answer: V = 420 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

35·60/15 = 140 mL/h

Volume

V = 140·3 = 420 mL

Answer

V = 420 mL
6.IV infusion rates

Answer: D = 3.2 mg/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.

Concentration

100/250 = 0.4 mg/mL

Dose rate

D = 0.4·8 = 3.2 mg/h

Answer

D = 3.2 mg/h

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