Which of the following defines tachysystole in the context of oxytocin-induced labor?
- A Any contraction lasting longer than 90 seconds
- B More than 5 contractions in 10 minutes, averaged over a 30-minute window ✓
- C More than 4 contractions in 10 minutes regardless of fetal heart rate
- D Contractions exceeding 60 mmHg peak pressure above baseline
Correct answer: B. More than 5 contractions in 10 minutes, averaged over a 30-minute window
Explanation
Tachysystole is defined as more than five contractions in 10 minutes, averaged over a 30-minute window, irrespective of whether the fetal heart rate tracing is normal. It can occur spontaneously or with stimulation. The key distractor C fails because four to five contractions per 10 minutes remain within normal limits; the diagnosis does not require an abnormal CTG, though it mandates closer surveillance.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.