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 16 weeks has an amniocentesis. Which instruction after the procedure is correct?

  1. ANo follow-up is needed for any symptoms
  2. BBed rest is required for 2 weeks
  3. CReport fever, leaking fluid or bleeding
  4. DDrink no fluids for 24 hours
2.Maternity & obstetric nursingHard

A woman has a painful, red breast with a fluctuant swelling that has not improved after antibiotics. What should be suspected?

  1. AA blocked duct needing only massage
  2. BNormal engorgement
  3. CA breast abscess needing drainage
  4. DAn allergic reaction to the antibiotic
3.Dosage calculationsMedium
94 kgBSA = 1.84 m²175 mg/m²D = ? mg

A patient weighing 94 kg has a body surface area of 1.84 m². The prescription is 175 mg/m². Find the dose D in mg.

94 kgBSA = 1.84 m²175 mg/m²
D = mg
4.Dosage calculationsHard
40 mg/1 mLV = ? mL

A patient weighs 147.4 lb. The prescription is 2 mg/kg as a single dose, and the stock contains 40 mg in 1 mL. Using 1 kg = 2.2 lb, what volume V do you give? Round to one decimal place.

147.4 lb2 mg/kg40 mg/1 mL1 kg = 2.2 lb
V = mL
5.IV infusion ratesMedium
1240 mLleft? mL/h4 h left

1500 mL was ordered over 6 hours. After 2 hours you find that 1240 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 2 h: 1240 mL
R = mL/h
6.IV infusion ratesHard
400 mL15 gtt/mL42 gtt/mint = ? h

A drip runs at 42 gtt/min through a set of 15 gtt/mL. There are 400 mL left in the bag. How many hours t until it is empty? Round to one decimal place.

42 gtt/min15 gtt/mL400 mL
t = h

3Solutions

1.Maternity & obstetric nursing

Answer: C · Report fever, leaking fluid or bleeding

Why this is the answer

After amniocentesis, she should report fever, leaking fluid, bleeding, severe cramps or reduced movements. Rh-negative women receive anti-D. Normal activity can usually resume soon.

Answer

C · Report fever, leaking fluid or bleeding
2.Maternity & obstetric nursing

Answer: C · A breast abscess needing drainage

Why this is the answer

A fluctuant, persistent painful mass despite antibiotics suggests a breast abscess. It needs ultrasound and drainage. Breastfeeding from the other breast can usually continue.

Answer

C · A breast abscess needing drainage
3.Dosage calculations

Answer: D = 322 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 = 175·1.84 = 322 mg

Answer

D = 322 mg
4.Dosage calculations

Answer: V = 3.4 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.

Weight in kg

147.4/2.2 = 67 kg

Dose

2·67 = 134 mg

Volume

V = (134/40)·1 = 3.35 ≈ 3.4 mL

Answer

V = 3.4 mL
5.IV infusion rates

Answer: R = 310 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 = 1240/4 = 310 mL/h

Answer

R = 310 mL/h

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

6.IV infusion rates

Answer: t = 2.4 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

42·60/15 = 168 mL/h

Time left

t = 400/168 = 2.381 ≈ 2.4 h

Answer

t = 2.4 h

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