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

Progesterone relaxes smooth muscle in pregnancy. Which common complaint does this help explain?

  1. AIncreased appetite
  2. BGum bleeding
  3. CNasal stuffiness
  4. DConstipation
2.Maternity & obstetric nursingHard

A newborn whose mother had a fever and prolonged rupture of membranes is well at birth. Why does the nurse monitor this baby closely?

  1. AThe baby is likely to be post-term
  2. BThe baby has a higher risk of hip dysplasia
  3. CThe baby will certainly develop jaundice
  4. DThe baby has a higher risk of early sepsis
3.Dosage calculationsMedium
2 g+ 7.4 mLV = ? mL

A vial contains 2 g of powder. The label says: add 7.4 mL of water for injection to give a total volume of 8 mL. The prescription is 200 mg. What volume V of the reconstituted solution do you give?

2 g+ 7.4 mL → 8 mL200 mg
V = mL
4.Dosage calculationsHard
20%stockV₁ = ? mL

You must prepare 500 mL of a 2% (w/v) solution from a 20% (w/v) stock solution. What volume of stock V₁ do you need?

C₁ = 20%C₂ = 2%V₂ = 500 mL
V₁ = mL
5.IV infusion ratesMedium
1500 mL15 gtt/mL6 h? gtt/min

Infuse 1500 mL over 6 hours with a giving set of 15 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

1500 mL6 h15 gtt/mL
R = gtt/min
6.IV infusion ratesHard
580 mLleft? mL/h5 h left

1000 mL was ordered over 10 hours. After 5 hours you find that 580 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: 580 mL
Δ = %

3Solutions

1.Maternity & obstetric nursing

Answer: D · Constipation

Why this is the answer

Progesterone slows gut motility, which causes constipation and contributes to heartburn because the lower oesophageal sphincter relaxes. Gum bleeding and nasal stuffiness are mainly due to oestrogen and increased blood flow.

Answer

D · Constipation
2.Maternity & obstetric nursing

Answer: D · The baby has a higher risk of early sepsis

Why this is the answer

Maternal fever, prolonged rupture of membranes and intra-amniotic infection are risk factors for early-onset sepsis. Many protocols require observation of vital signs and feeding, and sometimes blood tests or antibiotics.

Answer

D · The baby has a higher risk of early sepsis
3.Dosage calculations

Answer: V = 0.8 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

2000 mg/8 mL = 250 mg/mL

Volume

V = 200/250 = 0.8 mL

Answer

V = 0.8 mL
4.Dosage calculations

Answer: V₁ = 50 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 = 2·500/20 = 50 mL

Answer

V₁ = 50 mL
5.IV infusion rates

Answer: R = 63 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

6·60 = 360 min

Drip rate

R = 1500·15/360 = 62.5 ≈ 63 gtt/min

Answer

R = 63 gtt/min

At the bedside you round to the nearest whole drop: 63 gtt/min.

6.IV infusion rates

Answer: Δ = 16 %

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 = 580/5 = 116 mL/h

Percentage change

Δ = (116 − 100)/100·100% = 16%

Answer

Δ = 16%

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

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