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

Why is mild anaemia common in the second trimester even in healthy women?

  1. AIron is lost in the urine because kidney filtration rises
  2. BThe bone marrow stops producing red cells during pregnancy
  3. CPlasma volume rises more than red cell mass
  4. DThe fetus breaks down maternal red blood cells
2.Maternity & obstetric nursingHard

A newborn is apnoeic after being warmed, dried and stimulated. What is the next step?

  1. AStart chest compressions immediately
  2. BWait and assess the 5-minute APGAR score before doing anything
  3. CHold the baby upside down and slap the back
  4. DStart positive-pressure ventilation with a bag and mask
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
25%stockwater = ? mL

You must prepare 250 mL of a 2% (w/v) solution from a 25% (w/v) stock solution. How much water W must be added to the stock?

C₁ = 25%C₂ = 2%V₂ = 250 mL
W = mL
5.IV infusion ratesMedium
1500 mL20 gtt/mL10 h? gtt/min

Infuse 1500 mL over 10 hours with a giving set of 20 gtt/mL. Find the drip rate R in drops per minute.

1500 mL10 h20 gtt/mL
R = gtt/min
6.IV infusion ratesHard
250 mg50 mL8 mL/h? mg/h

A bag contains 250 mg of a drug in 50 mL and runs at 8 mL/h. How many milligrams per hour D does the patient receive?

250 mg/50 mL8 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: C · Plasma volume rises more than red cell mass

Why this is the answer

Plasma volume increases more than red cell mass, so haemoglobin concentration falls (physiological or dilutional anaemia). Iron deficiency can add to this and should still be checked.

Answer

C · Plasma volume rises more than red cell mass
2.Maternity & obstetric nursing

Answer: D · Start positive-pressure ventilation with a bag and mask

Why this is the answer

If the newborn is apnoeic or gasping, or the heart rate is below 100/min after the initial steps, positive-pressure ventilation starts within the first minute. Effective ventilation is the most important step in newborn resuscitation.

Answer

D · Start positive-pressure ventilation with a bag and mask
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: W = 230 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 = 2·250/25 = 20 mL

Water to add

W = 250 − 20 = 230 mL

Answer

W = 230 mL
5.IV infusion rates

Answer: R = 50 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

10·60 = 600 min

Drip rate

R = 1500·20/600 = 50 gtt/min

Answer

R = 50 gtt/min
6.IV infusion rates

Answer: D = 40 mg/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.

Concentration

250/50 = 5 mg/mL

Dose rate

D = 5·8 = 40 mg/h

Answer

D = 40 mg/h

ExamProblems · examproblems.com/courses/maternity-nursing