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

After a circumcision, which finding should be reported?

  1. AA yellowish film over the glans on day 2
  2. BFussiness at the first nappy change
  3. CMild swelling of the glans
  4. DActive bleeding that soaks a nappy
2.Maternity & obstetric nursingHard

After treatment for a molar pregnancy, what is the most important teaching point?

  1. ANo further follow-up is needed once the uterus is empty
  2. BAvoid all physical activity for 6 months
  3. CTry to conceive again as soon as possible to reduce recurrence
  4. DAttend serial hCG checks and use reliable contraception during follow-up
3.Dosage calculationsMedium
1 g+ 4.2 mLV = ? mL

A vial contains 1 g of powder. The label says: add 4.2 mL of water for injection to give a total volume of 5 mL. The prescription is 240 mg. What volume V of the reconstituted solution do you give?

1 g+ 4.2 mL → 5 mL240 mg
V = mL
4.Dosage calculationsHard
53 kg157 cmBSA = √(h·w/3600)135 mg/m²D = ? mg

A patient is 157 cm tall and weighs 53 kg. The prescription is 135 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.

157 cm53 kg135 mg/m²
D = mg
5.IV infusion ratesMedium
390 mLleft? mL/h4 h left

500 mL was ordered over 6 hours. After 2 hours you find that 390 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 / 6 hafter 2 h: 390 mL
R = mL/h
6.IV infusion ratesHard
600 mL60 gtt/mL32 gtt/mint = ? h

A drip runs at 32 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.

32 gtt/min60 gtt/mL600 mL
t = h

3Solutions

1.Maternity & obstetric nursing

Answer: D · Active bleeding that soaks a nappy

Why this is the answer

A yellow film is normal granulation tissue, and mild swelling and fussiness are common. Persistent bleeding, signs of infection or failure to pass urine should be reported.

Answer

D · Active bleeding that soaks a nappy
2.Maternity & obstetric nursing

Answer: D · Attend serial hCG checks and use reliable contraception during follow-up

Why this is the answer

hCG is followed until it is undetectable because persistent trophoblastic disease or choriocarcinoma can develop. A new pregnancy would raise hCG and hide this, so reliable contraception is advised during follow-up.

Answer

D · Attend serial hCG checks and use reliable contraception during follow-up
3.Dosage calculations

Answer: V = 1.2 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.

Concentration after mixing

1000 mg/5 mL = 200 mg/mL

Volume

V = 240/200 = 1.2 mL

Answer

V = 1.2 mL
4.Dosage calculations

Answer: D = 205.2 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 = √(157·53/3600) = √2.311 = 1.52 m²

Dose

D = 135·1.52 = 205.2 mg

Answer

D = 205.2 mg
5.IV infusion rates

Answer: R = 97.5 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

500/6 = 83.33 mL/h

New rate

R = 390/4 = 97.5 mL/h

Answer

R = 97.5 mL/h

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

6.IV infusion rates

Answer: t = 18.8 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

32·60/60 = 32 mL/h

Time left

t = 600/32 = 18.75 ≈ 18.8 h

Answer

t = 18.8 h

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