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 at 39 weeks with a healthy pregnancy asks about walking in early labour. What is the best advice?

  1. AUpright positions always make labour slower
  2. BShe must stay in bed on her back for the whole labour
  3. CWalking will cause the cord to prolapse
  4. DWalking and upright positions can help progress
2.Maternity & obstetric nursingHard

A woman with pre-eclampsia has repeated blood pressures of 168/112 mmHg 15 minutes apart. What is the appropriate action?

  1. ANotify the provider promptly so antihypertensive treatment can be started without delay
  2. BGive a large drink of water
  3. CLet her rest quietly on her left side and recheck the blood pressure in 4 hours before reporting
  4. DEncourage her to lie flat and rest
3.Dosage calculationsMedium
10%w/vV = ? mL

A dose of 400 mg is needed from a 10% (w/v) solution. What volume V contains this dose?

400 mg10% w/v
V = mL
4.Dosage calculationsHard
25k units250 mL? mL/h1500 units/h

An infusion contains 25000 units of a drug in 250 mL. The prescription is 1500 units per hour. At what rate R do you set the pump, in mL/h?

25000 units/250 mL1500 units/h
R = mL/h
5.IV infusion ratesMedium
1000 mL15 gtt/mL8 h? gtt/min

Infuse 1000 mL over 8 hours with a giving set of 15 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

1000 mL8 h15 gtt/mL
R = gtt/min
6.IV infusion ratesHard
100 mg50 mL5 mL/h? mg/h

A bag contains 100 mg of a drug in 50 mL and runs at 5 mL/h. How many milligrams per hour D does the patient receive?

100 mg/50 mL5 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: D · Walking and upright positions can help progress

Why this is the answer

Upright positions and mobility in the first stage can shorten labour and reduce the need for epidurals. She can choose positions that feel comfortable.

Answer

D · Walking and upright positions can help progress
2.Maternity & obstetric nursing

Answer: A · Notify the provider promptly so antihypertensive treatment can be started without delay

Why this is the answer

Severe-range hypertension (160 systolic or 110 diastolic or more) in pregnancy raises the risk of stroke and must be treated urgently, ideally within an hour, with drugs such as labetalol, hydralazine or nifedipine as prescribed.

Answer

A · Notify the provider promptly so antihypertensive treatment can be started without delay
3.Dosage calculations

Answer: V = 4 mL

Solution strengths: a percentage strength is grams per 100 mL, so 1% = 1 g/100 mL = 10 mg/mL. A ratio strength 1:1000 means 1 g in 1000 mL = 1 mg/mL; 1:10 000 is 0.1 mg/mL. For a dilution the amount of drug stays the same: C₁·V₁ = C₂·V₂.

Concentration

10% = 100 mg/mL

Volume

V = 400/100 = 4 mL

Answer

V = 4 mL
4.Dosage calculations

Answer: R = 15 mL/h

Dose calculation: the amount to give equals what is prescribed divided by what you have, times the quantity it comes in: amount = (desired dose/stock strength) × stock volume. Always keep the units the same (convert g to mg, mg to mcg first) and check that the answer is sensible.

Concentration

25000/250 = 100 units/mL

Pump rate

R = 1500/100 = 15 mL/h

Answer

R = 15 mL/h
5.IV infusion rates

Answer: R = 31 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

8·60 = 480 min

Drip rate

R = 1000·15/480 = 31.25 ≈ 31 gtt/min

Answer

R = 31 gtt/min

At the bedside you round to the nearest whole drop: 31 gtt/min.

6.IV infusion rates

Answer: D = 10 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

100/50 = 2 mg/mL

Dose rate

D = 2·5 = 10 mg/h

Answer

D = 10 mg/h

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