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 with hypothyroidism becomes pregnant. What usually happens to her levothyroxine needs?

  1. AShe switches to iodine tablets instead
  2. BThey usually rise, so levels are checked early
  3. CThey decrease to zero, so she stops the drug
  4. DThey stay the same, so no monitoring is needed
2.Maternity & obstetric nursingHard

A woman has cytomegalovirus (CMV) infection in pregnancy. Which outcome in the baby is a major concern?

  1. AOpen neural tube defects such as spina bifida
  2. BHearing loss and developmental delay
  3. CPhenylketonuria
  4. DClubfoot only
3.Dosage calculationsMedium
45 kg20 mg/kgD = ? mg

A patient weighs 45 kg and is prescribed 20 mg/kg as a single dose. Find the dose D in mg.

45 kg20 mg/kg
D = mg
4.Dosage calculationsHard
125 mg/5 mLV = ? mL

A child weighing 18 kg is prescribed 10 mg/kg per dose of an oral suspension that contains 125 mg in 5 mL. What volume V do you give?

18 kg10 mg/kg125 mg/5 mL
V = mL
5.IV infusion ratesMedium
250 mL60 gtt/mL5 h? gtt/min

Infuse 250 mL over 5 hours with a giving set of 60 gtt/mL. Find the drip rate R in drops per minute.

250 mL5 h60 gtt/mL
R = gtt/min
6.IV infusion ratesHard
450 mL15 gtt/mL28 gtt/mint = ? h

A drip runs at 28 gtt/min through a set of 15 gtt/mL. There are 450 mL left in the bag. How many hours t until it is empty? Round to one decimal place.

28 gtt/min15 gtt/mL450 mL
t = h

3Solutions

1.Maternity & obstetric nursing

Answer: B · They usually rise, so levels are checked early

Why this is the answer

Levothyroxine needs usually rise in pregnancy. Thyroid function is checked as soon as pregnancy is confirmed and regularly afterwards, because untreated hypothyroidism can affect fetal brain development.

Answer

B · They usually rise, so levels are checked early
2.Maternity & obstetric nursing

Answer: B · Hearing loss and developmental delay

Why this is the answer

Congenital CMV is a leading cause of non-genetic sensorineural hearing loss and can cause microcephaly and developmental delay. Hand hygiene after contact with young children's saliva and urine reduces the risk.

Answer

B · Hearing loss and developmental delay
3.Dosage calculations

Answer: D = 900 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.

Dose

20·45 = 900 mg

Answer

D = 900 mg
4.Dosage calculations

Answer: V = 7.2 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

10·18 = 180 mg

Volume

V = (180/125)·5 = 7.2 mL

Answer

V = 7.2 mL
5.IV infusion rates

Answer: R = 50 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

5·60 = 300 min

Drip rate

R = 250·60/300 = 50 gtt/min

Answer

R = 50 gtt/min
6.IV infusion rates

Answer: t = 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

28·60/15 = 112 mL/h

Time left

t = 450/112 = 4.018 ≈ 4 h

Answer

t = 4 h

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