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 statement about the lactational amenorrhoea method (LAM) is correct?

  1. AIt becomes more reliable after the periods return
  2. BIt works for as long as the mother breastfeeds at all
  3. CIt needs full breastfeeding, no periods and a baby under 6 months
  4. DIt is reliable even when the baby is formula-fed at night
2.Maternity & obstetric nursingHard

A woman at 20 weeks presents with painless cervical dilation and bulging membranes, without contractions. She lost a previous pregnancy in the same way. What is the likely diagnosis?

  1. APlacenta praevia
  2. BCervical insufficiency
  3. CPreterm labour caused by infection
  4. DPlacental abruption
3.Dosage calculationsMedium
024681010 mL

A child weighing 29 kg is prescribed 5 mg/kg of a drug. The stock solution contains 25 mg/mL. Draw up the dose: what volume V do you give?

29 kg5 mg/kg25 mg/mL
V = mL
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 1.66 mg. The ampoule contains 2000 micrograms per mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

1.66 mg2000 mcg/mL
V = mL
5.IV infusion ratesMedium
60 gtt/mL100 mL/h? gtt/min

An infusion is ordered at 100 mL/h, but no pump is available. It runs by gravity through a giving set of 60 gtt/mL. Find the drip rate R in drops per minute.

100 mL/h60 gtt/mL
R = gtt/min
6.IV infusion ratesHard
1 g250 mL? mL/h1 mg/min

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

1 g/250 mL1 mg/min
R = mL/h

3Solutions

1.Maternity & obstetric nursing

Answer: C · It needs full breastfeeding, no periods and a baby under 6 months

Why this is the answer

LAM is effective only if the mother is fully or nearly fully breastfeeding day and night, her periods have not returned and the baby is under 6 months. Ovulation can occur before the first period.

Answer

C · It needs full breastfeeding, no periods and a baby under 6 months
2.Maternity & obstetric nursing

Answer: B · Cervical insufficiency

Why this is the answer

Painless second-trimester cervical dilation without contractions suggests cervical insufficiency. A cervical cerclage may be offered in a later pregnancy.

Answer

B · Cervical insufficiency
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 = 5·29 = 145 mg

Volume

V = 145/25 = 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: V = 0.83 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

1.66 mg = 1660 mcg

Volume

V = 1660/2000 = 0.83 mL

Answer

V = 0.83 mL
5.IV infusion rates

Answer: R = 100 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.

Millilitres per minute

100/60 = 1.667 mL/min

Drip rate

R = 1.667·60 = 100 gtt/min

Answer

R = 100 gtt/min

With a microdrip set (60 gtt/mL), gtt/min equals mL/h.

6.IV infusion rates

Answer: R = 15 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

1·60 = 60 mg/h

Pump rate

R = 60/4 = 15 mL/h

Answer

R = 15 mL/h

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