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 at 22 weeks describes sharp pain on one side of the lower abdomen when she stands up quickly. Her vital signs and fetal heart rate are normal. What is the most likely cause?

  1. ARound ligament pain
  2. BPlacental abruption
  3. CPreterm labour
  4. DAppendicitis
2.Maternity & obstetric nursingHard

At 4 hours, a newborn's temperature is 37.9 °C (100.2 °F). He is wrapped in three blankets under a heater. What should the nurse do first?

  1. ARemove extra layers and recheck
  2. BStart antibiotics without further assessment
  3. CPlace him in a cold bath
  4. DGive an antipyretic medicine immediately
3.Dosage calculationsMedium
37 kgBSA = 1.16 m²250 mg/m²D = ? mg

A patient weighing 37 kg has a body surface area of 1.16 m². The prescription is 250 mg/m². Find the dose D in mg.

37 kgBSA = 1.16 m²250 mg/m²
D = mg
4.Dosage calculationsHard
10%stockwater = ? mL

You must prepare 200 mL of a 1% (w/v) solution from a 10% (w/v) stock solution. How much water W must be added to the stock?

C₁ = 10%C₂ = 1%V₂ = 200 mL
W = mL
5.IV infusion ratesMedium
410 mLleft? mL/h7 h left

500 mL was ordered over 10 hours. After 3 hours you find that 410 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?

500 mL / 10 hafter 3 h: 410 mL
R = mL/h
6.IV infusion ratesHard
1 g500 mL? mL/h0.5 mg/min

A bag contains 1 g of a drug in 500 mL. The order is 0.5 mg per minute. At what rate R do you set the pump, in mL/h?

1 g/500 mL0.5 mg/min
R = mL/h

3Solutions

1.Maternity & obstetric nursing

Answer: A · Round ligament pain

Why this is the answer

Round ligament pain is sharp, brief pain in the groin or lower abdomen with sudden movement as the uterus grows. Moving slowly and flexing the hips towards the abdomen help. Persistent or severe pain needs review.

Answer

A · Round ligament pain
2.Maternity & obstetric nursing

Answer: A · Remove extra layers and recheck

Why this is the answer

Overheating from heavy wrapping or a heater can raise a newborn's temperature. The nurse removes extra layers, rechecks the temperature soon and assesses for signs of infection if it stays high.

Answer

A · Remove extra layers and recheck
3.Dosage calculations

Answer: D = 290 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).

Dose

D = 250·1.16 = 290 mg

Answer

D = 290 mg
4.Dosage calculations

Answer: W = 180 mL

Solution strengths: a percentage strength is grams per 100 mL, so 1% = 1 g/100 mL = 10 mg/mL. A ratio strength 1:1000 means 1 g in 1000 mL = 1 mg/mL; 1:10 000 is 0.1 mg/mL. For a dilution the amount of drug stays the same: C₁·V₁ = C₂·V₂.

Volume of stock

V₁ = 1·200/10 = 20 mL

Water to add

W = 200 − 20 = 180 mL

Answer

W = 180 mL
5.IV infusion rates

Answer: R = 58.57 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

500/10 = 50 mL/h

New rate

R = 410/7 = 58.57 mL/h

Answer

R = 58.57 mL/h

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

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/500 mL = 2 mg/mL

Dose per hour

0.5·60 = 30 mg/h

Pump rate

R = 30/2 = 15 mL/h

Answer

R = 15 mL/h

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