Lisa Thompson, RN, MSN
KAMMCO, Nurse Reviewer

Oxytocin is one of the most frequently used medications in obstetric practice. The goal of oxytocin use is to promote contractions that result in a similar labor pattern to that seen with spontaneous labor. Excessive uterine activity, or tachysystole, while using oxytocin has been associated with abnormal fetal heart rate patterns.

Uterine tachysystole is defined as more than five contractions in ten minutes, averaged over a 30-minute window (American College of Obstetricians and Gynecologists, 2010). Tachysystole should be qualified as to the presence or absence of associated fetal heart rate decelerations (American College of Obstetricians and Gynecologists, 2009). Other characteristics of uterine activity are also important, such as duration, intensity, and relaxation time (American College of Obstetricians and Gynecologists, 2009). Intervening for tachysystole by decreasing or discontinuing oxytocin is advised by the American College of Obstetricians and Gynecologists (ACOG). Many cases of excessive uterine activity are oxytocin dose related and can be resolved by decreasing the infusion rate of oxytocin.

Example of Tachysystole

UTERINE ACTIVITY AND FETAL OXYGENATION
The healthy, term fetus is developed to tolerate disruption posed by normal labor without a change in fetal oxygen saturation. When contractions become too frequent, and the relaxation time between contractions becomes shortened or incomplete, fetal hypoxemia may result. The fetus who enters labor in a less than optimal state (i.e., intrauterine growth restriction, prematurity, etc.) may have increased difficulty tolerating excessive uterine activity. In laboring women receiving oxytocin, management of tachysystole generally involves efforts to reduce uterine activity to minimize risk of evolving fetal hypoxemia or acidemia (American College of Obstetricians and Gynecologists, 2010). If uterine tachysystole with Category III FHR tracings occur, prompt evaluation is required and intravenous infusion of oxytocin should be decreased or discontinued to correct the pattern (American College of Obstetricians and Gynecologists, 2009). Knowledge of the effects of excessive uterine activity on fetal oxygenation should prompt an intervening action at the time it is noted, rather than waiting to intervene until there is evidence of interrupted fetal oxygenation.

OXYTOCIN AND LITIGATION
Oxytocin use and clinical management of uterine activity during labor are areas of great importance in the defense of perinatal malpractice claims. Oxytocin has been associated with claims of negligence in cases of adverse outcomes. Obstetric doctors and nurses are often accused of breaching the standard of care regarding the use of oxytocin. Allegations may state “administering extremely high doses of oxytocin” or “causing excessive uterine activity”.

Errors involving intravenous oxytocin administration for induction or augmentation of labor are most often dose related and include failure to avoid or treat tachysystole or failure to assess or treat a fetal heart rate pattern indicative of disruption in oxygenation. Preventing tachysystole with careful low-dose oxytocin titration and promptly treating it when it occurs will decrease the risk of injury to the fetus and therefore decrease the risk of litigation.

CLINICAL PRACTICE RECOMMENDATIONS

1. Every hospital’s labor and delivery department should have guidelines in place for the administration of oxytocin for augmentation and induction of labor, as well as managing complications, such as tachysystole, associated with the use of oxytocin. All clinicians should be familiar with their hospital policies and procedures. Ensure new staff are educated on the policies and current staff review them periodically.
2. Titration of oxytocin and management of uterine activity necessitate that clinicians be knowledgeable of definitions for uterine activity as well as the physiology of uterine activity and fetal oxygenation.
3. Knowledge of the National Institute of Child Health and Human Development terminology for interpreting electronic fetal monitor tracings and patterns that indicate fetal hypoxemia is essential for all clinicians involved in caring for the patient undergoing induction or augmentation of labor.
4. Accurately document tachysystole, especially when accompanied by fetal heart rate changes, and note any interventions to resolve in the patient record. Document communications among clinicians.
5. Maintain the line of communication with obstetric care providers regarding labor progress and any indication of disruption in fetal oxygenation. All who provide care to patients in labor should be knowledgeable regarding management of uterine activity, careful titration of oxytocin, and normal uterine activity versus tachysystole.

REFERENCES
American College of Obstetricians and Gynecologists. (2009). Induction of Labor. Practice Bulletin No. 107. Reaffirmed 2016. Obstetrics & Gynecology, 114, 386-97.
American College of Obstetricians and Gynecologists. (2010). Management of Intrapartum Fetal Heart Rate Tracings. Practice Bulletin No. 116. 116, 1232-40.