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

In early pregnancy, how does the serum hCG level normally change?

  1. AIt stays at the same level throughout the first trimester
  2. BIt rises slowly until it peaks just before birth
  3. CIt roughly doubles every 2 to 3 days in the first weeks
  4. DIt falls steadily from the day of implantation
2.Maternity & obstetric nursingHard

A woman with known mitral stenosis is pregnant. When is she at greatest risk of heart failure?

  1. AOnly in the first trimester, when nausea is worst
  2. BOnly during the first stage of labour
  3. CWhen blood volume peaks in late pregnancy and in the hours after birth
  4. DRisk is the same at every point in pregnancy
3.Dosage calculationsMedium
2 g+ 7.4 mLV = ? mL

A vial contains 2 g of powder. The label says: add 7.4 mL of water for injection to give a total volume of 8 mL. The prescription is 100 mg. What volume V of the reconstituted solution do you give?

2 g+ 7.4 mL → 8 mL100 mg
V = mL
4.Dosage calculationsHard
40 mg/1 mLV = ? mL

A child weighing 12 kg is prescribed 5 mg/kg per dose of an oral suspension that contains 40 mg in 1 mL. What volume V do you give?

12 kg5 mg/kg40 mg/1 mL
V = mL
5.IV infusion ratesMedium
250 mL15 gtt/mL3 h? gtt/min

Infuse 250 mL over 3 hours with a giving set of 15 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

250 mL3 h15 gtt/mL
R = gtt/min
6.IV infusion ratesHard
100 mg50 mL15 mL/h? mg/h

A bag contains 100 mg of a drug in 50 mL and runs at 15 mL/h. How many milligrams per hour D does the patient receive?

100 mg/50 mL15 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: C · It roughly doubles every 2 to 3 days in the first weeks

Why this is the answer

In a normal early intrauterine pregnancy hCG roughly doubles every 48 to 72 hours, then peaks at around 8 to 10 weeks. A slow rise can suggest an ectopic pregnancy or a failing pregnancy.

Answer

C · It roughly doubles every 2 to 3 days in the first weeks
2.Maternity & obstetric nursing

Answer: C · When blood volume peaks in late pregnancy and in the hours after birth

Why this is the answer

Cardiac decompensation is most likely when blood volume peaks in the late second and third trimester and right after birth, when blood from the contracted uterus returns to the circulation. These women need close monitoring postpartum.

Answer

C · When blood volume peaks in late pregnancy and in the hours after birth
3.Dosage calculations

Answer: V = 0.4 mL

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 after mixing

2000 mg/8 mL = 250 mg/mL

Volume

V = 100/250 = 0.4 mL

Answer

V = 0.4 mL
4.Dosage calculations

Answer: V = 1.5 mL

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.

Dose from weight

5·12 = 60 mg

Volume

V = (60/40)·1 = 1.5 mL

Answer

V = 1.5 mL
5.IV infusion rates

Answer: R = 21 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

3·60 = 180 min

Drip rate

R = 250·15/180 = 20.83 ≈ 21 gtt/min

Answer

R = 21 gtt/min

At the bedside you round to the nearest whole drop: 21 gtt/min.

6.IV infusion rates

Answer: D = 30 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 = 2·15 = 30 mg/h

Answer

D = 30 mg/h

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