Maternity Nursing: cram pack

Formula sheets, the key method steps for every topic and 6 practice problems, with full solutions at the back.

New problemsBack to the course

In the print window, choose “Save as PDF” to keep a copy on your device.

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 placental hormone causes insulin resistance in the second half of pregnancy?

  1. AHuman chorionic gonadotrophin (hCG)
  2. BRelaxin
  3. CHuman placental lactogen (hPL)
  4. DOxytocin
2.Maternity & obstetric nursingHard

Just after the membranes rupture, there is painless vaginal bleeding and the fetal heart rate drops sharply. The mother's vital signs are normal. Which condition is most likely?

  1. APlacental abruption
  2. BBloody show
  3. CUterine rupture
  4. DRuptured vasa praevia
3.Dosage calculationsMedium
024681010 mL

A child weighing 38 kg is prescribed 2.5 mg/kg of a drug. The stock solution contains 25 mg/mL. Draw up the dose: what volume V do you give?

38 kg2.5 mg/kg25 mg/mL
V = mL
4.Dosage calculationsHard
49 kg137 cmBSA = √(h·w/3600)175 mg/m²D = ? mg

A patient is 137 cm tall and weighs 49 kg. The prescription is 175 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.

137 cm49 kg175 mg/m²
D = mg
5.IV infusion ratesMedium
590 mLleft? mL/h4 h left

1000 mL was ordered over 8 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?

1000 mL / 8 hafter 4 h: 590 mL
R = mL/h
6.IV infusion ratesHard
550 mLleft? mL/h5 h left

1000 mL was ordered over 10 hours. After 5 hours you find that 550 mL is still in the bag, and the order must still finish on time. By what percentage Δ must the original pump rate be increased?

1000 mL / 10 hafter 5 h: 550 mL
Δ = %

3Solutions

1.Maternity & obstetric nursing

Answer: C · Human placental lactogen (hPL)

Why this is the answer

Human placental lactogen, together with other placental hormones, reduces maternal insulin sensitivity so more glucose is available to the fetus. This is why gestational diabetes usually appears in the second half of pregnancy.

Answer

C · Human placental lactogen (hPL)
2.Maternity & obstetric nursing

Answer: D · Ruptured vasa praevia

Why this is the answer

Rupture of the membranes can tear unprotected fetal vessels in vasa praevia. Fetal blood loss causes rapid bradycardia while the mother stays stable. An emergency caesarean is needed.

Answer

D · Ruptured vasa praevia
3.Dosage calculations

Answer: V = 3.8 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 = 2.5·38 = 95 mg

Volume

V = 95/25 = 3.8 mL

On the syringe

On this 10 mL syringe every small line is 0.2 mL.

Answer

V = 3.8 mL
4.Dosage calculations

Answer: D = 239 mg

Body-surface-area dosing: many cytotoxic and some paediatric doses are prescribed per square metre of body surface area: dose (mg) = dose per m² × BSA (m²). The Mosteller formula estimates BSA = √(height (cm) × weight (kg)/3600).

Body surface area

BSA = √(137·49/3600) = √1.865 = 1.366 m²

Dose

D = 175·1.366 = 239 mg

Answer

D = 239 mg
5.IV infusion rates

Answer: R = 147.5 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

1000/8 = 125 mL/h

New rate

R = 590/4 = 147.5 mL/h

Answer

R = 147.5 mL/h

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

6.IV infusion rates

Answer: Δ = 10 %

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

1000/10 = 100 mL/h

New rate

R = 550/5 = 110 mL/h

Percentage change

Δ = (110 − 100)/100·100% = 10%

Answer

Δ = 10%

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

ExamProblems · examproblems.com/courses/maternity-nursing