Which of the following definitions correctly describes uterine tachysystole?
- A Contractions lasting longer than 90 seconds on two consecutive occasions
- B More than 5 contractions in 10 minutes, averaged over a 30-minute window ✓
- C A contraction frequency of 6 or more in 10 minutes accompanied by fetal heart rate abnormalities
- D Resting tone above 25 mmHg between contractions on intrauterine pressure monitoring
Correct answer: B. More than 5 contractions in 10 minutes, averaged over a 30-minute window
Explanation
Tachysystole is defined purely by contraction frequency: more than 5 contractions in 10 minutes averaged over a 30-minute window, regardless of whether the fetal heart rate is normal or abnormal. Option C is wrong because fetal heart changes are not required for the diagnosis; tachysystole with a normal CTG still needs attention but is defined by frequency alone. Resting tone and duration are separate parameters and do not feature in this definition.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.