Which of the following definitions corresponds to uterine tachysystole?
- A More than 3 contractions in 10 minutes each lasting longer than 90 seconds
- B Contractions exceeding 200 Montevideo units with fetal heart rate abnormalities
- C More than 5 contractions in 10 minutes, averaged over a 30-minute window ✓
- D Resting tone above 25 mmHg between contractions on an intrauterine catheter
Correct answer: C. More than 5 contractions in 10 minutes, averaged over a 30-minute window
Explanation
ACOG defines tachysystole as more than five contractions in 10 minutes, averaged over a 30-minute window, and it is described separately from fetal heart rate findings, meaning it can be diagnosed even with a normal CTG. Option B confuses adequacy thresholds with frequency, option A invents a duration-based criterion, and elevated resting tone defines hypertonus, a distinct concept assessed only with internal monitoring.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.