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 breastfeeding mother asks how she will know her baby is getting enough milk. Which sign is reassuring by day 5 or 6?

  1. AAt least 6 wet nappies a day and yellow stools
  2. BHer breasts never feel full
  3. CThe baby feeds for exactly 5 minutes each side
  4. DThe baby sleeps for 8 hours without feeding
2.Maternity & obstetric nursingHard

A labouring woman has had an epidural for 3 hours. The fundus is displaced and a bulge is seen above the pubic bone. What should the nurse do?

  1. ACheck for bladder distension and empty the bladder
  2. BPrepare her for an emergency caesarean
  3. CStart an oxytocin infusion
  4. DIncrease the rate of the epidural
3.Dosage calculationsMedium
0.5%10 mLm = ? mg

How many milligrams of drug m are in 10 mL of a 0.5% (w/v) solution?

0.5% w/v10 mL
m = mg
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 950 micrograms. The ampoule contains 1 mg/mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

950 mcg1 mg/mL
V = mL
5.IV infusion ratesMedium
1500 mL15 gtt/mL4 h? gtt/min

Infuse 1500 mL over 4 hours with a giving set of 15 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

1500 mL4 h15 gtt/mL
R = gtt/min
6.IV infusion ratesHard
1 g250 mL? mL/h2 mg/min

A bag contains 1 g of a drug in 250 mL. The order is 2 mg per minute. At what rate R do you set the pump, in mL/h?

1 g/250 mL2 mg/min
R = mL/h

3Solutions

1.Maternity & obstetric nursing

Answer: A · At least 6 wet nappies a day and yellow stools

Why this is the answer

Signs of adequate intake include 6 or more wet nappies and several yellow stools a day by day 5 or 6, steady weight gain and a content baby after feeds. Most babies regain birth weight by about 2 weeks.

Answer

A · At least 6 wet nappies a day and yellow stools
2.Maternity & obstetric nursing

Answer: A · Check for bladder distension and empty the bladder

Why this is the answer

Epidurals block bladder sensation, so the bladder can overfill. A full bladder can slow descent of the fetus and cause injury. The nurse should encourage voiding or catheterise per protocol.

Answer

A · Check for bladder distension and empty the bladder
3.Dosage calculations

Answer: m = 50 mg

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

0.5% = 0.5 g/100 mL = 5 mg/mL

Mass of drug

m = 5·10 = 50 mg

Answer

m = 50 mg
4.Dosage calculations

Answer: V = 0.95 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

1 mg/mL = 1000 mcg/mL

Volume

V = 950/1000 = 0.95 mL

Answer

V = 0.95 mL
5.IV infusion rates

Answer: R = 94 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

4·60 = 240 min

Drip rate

R = 1500·15/240 = 93.75 ≈ 94 gtt/min

Answer

R = 94 gtt/min

At the bedside you round to the nearest whole drop: 94 gtt/min.

6.IV infusion rates

Answer: R = 30 mL/h

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 mg/250 mL = 4 mg/mL

Dose per hour

2·60 = 120 mg/h

Pump rate

R = 120/4 = 30 mL/h

Answer

R = 30 mL/h

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