An intrauterine pressure catheter in a woman being augmented shows four contractions in 10 minutes. Each contraction rises from a resting tone of 15 mmHg to a peak of 55 mmHg. What is the Montevideo unit value, and does it represent adequate uterine activity?
- A 120 MVU, inadequate
- B 160 MVU, inadequate ✓
- C 200 MVU, adequate
- D 280 MVU, adequate
Correct answer: B. 160 MVU, inadequate
Explanation
Montevideo units equal the peak intensity minus baseline resting tone multiplied by the number of contractions in 10 minutes: (55 minus 15) equals 40 mmHg intensity, times 4 contractions equals 160 MVU. Adequate uterine activity in active labour is generally taken as 200 MVU or more, so 160 MVU indicates inadequate contractility warranting continued or escalated oxytocin augmentation rather than a diagnosis of cephalopelvic disproportion.
Reference: Williams Obstetrics, 26th ed.
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