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

Why is tight glucose control before conception important in women with pre-existing diabetes?

  1. AEarly hyperglycaemia raises the risk of birth defects
  2. BIt prevents the need for any monitoring during pregnancy
  3. CIt guarantees that the baby will be born at term
  4. DIt prevents the mother from developing pre-eclampsia
2.Maternity & obstetric nursingHard

A woman is treated with methotrexate for an unruptured ectopic pregnancy. Which statement shows a need for further teaching?

  1. A"I will go to the emergency department if I get sudden severe abdominal pain."
  2. B"I will come back for blood tests until my hCG level is back to zero."
  3. C"I will avoid alcohol while I am being treated."
  4. D"I will take a folic acid supplement to stay healthy while on this drug."
3.Dosage calculationsMedium
45 kg25 mg/kg/day2× per dayD = ? mg

A patient weighs 45 kg. The prescribed dose is 25 mg/kg per day, given in 2 equal doses. How many milligrams D are given per dose?

45 kg25 mg/kg/day2× per day
D = mg
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 0.15 mg. The ampoule contains 1000 micrograms per mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

0.15 mg1000 mcg/mL
V = mL
5.IV infusion ratesMedium
590 mLleft? mL/h2 h left

1500 mL was ordered over 6 hours. After 4 hours you find that 590 mL is still in the bag, and the order must still finish on time. To what rate R in mL/h must the pump be reset?

1500 mL / 6 hafter 4 h: 590 mL
R = mL/h
6.IV infusion ratesHard
600 mL60 gtt/mL28 gtt/mint = ? h

A drip runs at 28 gtt/min through a set of 60 gtt/mL. There are 600 mL left in the bag. How many hours t until it is empty? Round to one decimal place.

28 gtt/min60 gtt/mL600 mL
t = h

3Solutions

1.Maternity & obstetric nursing

Answer: A · Early hyperglycaemia raises the risk of birth defects

Why this is the answer

Hyperglycaemia during organogenesis increases the risk of heart, neural tube and other anomalies and of miscarriage. Good preconception control and high-dose folic acid lower this risk.

Answer

A · Early hyperglycaemia raises the risk of birth defects
2.Maternity & obstetric nursing

Answer: D · "I will take a folic acid supplement to stay healthy while on this drug."

Why this is the answer

Methotrexate is a folic acid antagonist, so folate supplements reduce its effect and should be avoided during treatment. Serial hCG checks, avoiding alcohol and seeking help for signs of rupture are correct.

Answer

D · "I will take a folic acid supplement to stay healthy while on this drug."
3.Dosage calculations

Answer: D = 562.5 mg

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.

Total per day

25·45 = 1125 mg

Per dose

D = 1125/2 = 562.5 mg

Answer

D = 562.5 mg
4.Dosage calculations

Answer: V = 0.15 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

0.15 mg = 150 mcg

Volume

V = 150/1000 = 0.15 mL

Answer

V = 0.15 mL
5.IV infusion rates

Answer: R = 295 mL/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.

Original rate

1500/6 = 250 mL/h

New rate

R = 590/2 = 295 mL/h

Answer

R = 295 mL/h

Many hospitals allow such an adjustment up to 25% without a new order; check local policy.

6.IV infusion rates

Answer: t = 21.4 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.

Rate in mL/h

28·60/60 = 28 mL/h

Time left

t = 600/28 = 21.43 ≈ 21.4 h

Answer

t = 21.4 h

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