CONTRACTION STRESS TEST (OXYTOCIN CHALLENGE TEST) POLICY Obstetricians order a Contraction Stress Test (CST) for an atypical Nonstress Test (NST) and/or for concerns about fetal well-being and fetal ability to tolerate labour. A CST should NOT be performed when a vaginal delivery is contraindicated. Registered Nurses (RN) certified in fetal health assessment perform and interpret electronic fetal monitoring tracings and report the results to the obstetrician. The CST may be performed using maternal nipple stimulation or an oxytocin infusion (Oxytocin Challenge Test, or OCT). Applicability: CST’s occur in the Delivery Suite area in the Acute Perinatal Program. PROCEDURE 1.1 Gather Materials For CST using nipple stimulation only: For OCT, also gather: . Fetal monitor and attachments . Infusion pump . Intravenous (IV) administration sets, intravenous catheter #18 . Intravenous solutions . Oxytocin, 30 International Units (IU) . Syringe with needle, 3 millilitres (mL) 1.2 Procedure Preparation Monitor baseline vital signs and perform ongoing assessments, hourly or more frequently, as required. Initiate NST for a minimum 20 minutes. Note: If contractions spontaneously occur, the response may be interpreted as a test result. 1.3 Contraction Stress Test (CST) Using nipple stimulation: Instruct the woman to rub one nipple through her clothing with the palmar surface of her fingers rapidly, but gently, for two minutes. Stop for five minutes and assess uterine activity. If the desired contraction pattern is not achieved, instruct the woman to proceed with a second cycle of two minutes of stimulation. If contractions remain insufficient, bilateral nipple stimulation may be considered. Should nipple stimulation fail to induce contractions that meet the test criteria, oxytocin infusion should be considered. Note: Nipple stimulation is associated with no greater risk of uterine hyperstimulation and has a shorter average testing time than oxytocin infusion. Using IV oxytocin: Establish a primary IV line (usually with normal saline). Prepare a secondary IV with oxytocin 30 IU diluted in 500 mL IV solution. Connect the IV with the oxytocin solution into the port closest to the insertion site. Attach the IV oxytocin line to the infusion pump. Start the oxytocin infusion at 0.5 milliunit (mU)/ minute to 1 mU/ minute. WW.04.05 Fetal Maternal Newborn and Family Health Policy & Procedure Manual Effective Date: 16-MAR-2009 Page 1 of 3 Refer to online version – Print copy may not be current – Discard after use CONTRACTION STRESS TEST (OXYTOCIN CHALLENGE TEST) Increase the oxytocin infusion rate by 1 mU/minute every 30 minutes up to 16 mU/min or until three contractions lasting one minute each within a 10 minute period occur or until the CST/OCT is considered as positive (see below). If unable to achieve the required pattern of contractions at 16 mU/ minute of oxytocin, obtain further orders. The test is complete when this uterine contraction pattern (3 contractions lasting one minute each within a 10 minutes period) is achieved. It is not necessary to increase this frequency. 1.4 CST/ OCT Interpretation and Monitoring Check the fetal heart rate (FHR) tracing and uterine activity recording is interpretable and is continuous on both channels. Interpretation of the Contraction Stress Test or Oxytocin Challenge Test Negative Positive Equivocal Normal Late decelerations . Suspicious: At least one late deceleration, but pattern not baseline FHR follow more than repetitive. tracing 50% of the . Hyperstimulation: Uterine contractions lasting at least 90 without late induced seconds or occurring more frequently than every 2 decelerations. contractions. minutes accompanied by late decelerations. Unsatisfactory: desired number and length of contractions not achieved or poor quality tracing. 1.5 Post Procedure Actions Registered Nurse - Discontinue the oxytocin infusion and notify the physician if: Bleeding and/or continuous abdominal pain occurs. The fetal heart tracing is abnormal. Notify physician when test complete. When physician orders the CST/ OCT discontinued, continue primary IV infusion, and FHR and uterine monitoring until contractions subside. Physician - Interpret the CST/ OCT as positive, negative or equivocal and determine the next steps in care. Negative Positive Equivocal Plan for further fetal surveillance as Plan to proceed with Plan to repeat OCT within 24 indicated by maternal/ fetal condition delivery by: hours, if appropriate Or . Induction of labour Or Order induction of labour Or use other methods of fetal . Cesarean delivery* assessment *Note: A fetus demonstrating an atypical/ abnormal NST and a positive CST/OCT is less likely to tolerate labour and will require careful intrapartum observation. DOCUMENTATION Fetal Monitor Label and Fetal Heart Tracing Fluid Balance Record – 12 Hour Labour Partogram Medication Added Label Physician’s Orders WW.04.05 Fetal Maternal Newborn and Family Health Policy & Procedure Manual Effective Date: 16-MAR-2009 Page 2 of 3 Refer to online version – Print copy may not be current – Discard after use CONTRACTION STRESS TEST (OXYTOCIN CHALLENGE TEST) REFERENCES Guidelines for Identification of the High Risk Fetus and Newborn, and for Notification of the Neonatal Intensive Care Unit Resuscitation Team. Huddleston, JF. (2002). Continued utility of the contraction stress test? Clin Obstet Gynecol;45(4):1005-14. Infusion Therapy Pump Use Labour Induction: Administration of Oxytocin Liston, R., Sawchuk, D., Young, D., (2007, September). Fetal Health Surveillance: Antepartum and Intrapartum Consensus Guideline No.197. SOGC. JOGC Vol 29(9) Supplement 4. http://www.sogc.org/guidelines/documents/gui197CPG0709r_000.pdf Pocket Card - Oxytocin Induction/Augmentation Procedure WW.04.05 Fetal Maternal Newborn and Family Health Policy & Procedure Manual Effective Date: 16-MAR-2009 Page 3 of 3 Refer to online version – Print copy may not be current – Discard after use .